Abandoned Site An inactive hazardous waste disposal or storage facility which cannot be easily traced to a specific owner, or a location where illegal dumping has taken place.

Abrasion Scraped skin.

Abrasive Blasting Respirator A respirator designed to protect the wearer from inhalation, impact, and abrasion of materials used for, or generated in, abrasive blasting.

Absolute A chemical substance relatively free of impurities, e.g., absolute alcohol.

Absolute Pressure The total pressure within a vessel, pipe, etc., not offset by external atmospheric pressure. See psia, psig.

Absorb To soak up. The incorporation of a liquid into a solid substance, as by capillary, osmotic, solvent, or chemical action. See Adsorb.

Absorption Entry of a chemical into the body, often into the bloodstream.

As used in hazardous waste handling (HAZWOPER), absorption means the hazardous waste physical treatment method which involves adding materials to the waste to decrease its fluid content; suitable absorbents include soil and fly ash.

Acceptable Environmental Conditions The conditions that must exist in a permit space to allow entry and to ensure that employees involved with a permit required confined space entry can safely enter into and work within the space.

Acclimation To accustom or become accustomed to a different climate, environment, or circumstance.

ACGIH American Conference of Governmental Industrial Hygienists. An organization of professionals in governmental agencies or educational institutions engaged in occupational safety and health programs. ACGIH develops and publishes recommended occupational exposure limits for chemical substances and physical agents (see TLV and BEI). (1330 Kemper Meadow Drive, Cincinnati, OH 45240; 513-742-2020)

Acid An inorganic or organic compound that 1) reacts with metals to yield hydrogen; 2) reacts with a base to form a salt; 3) dissociates in water to yield hydrogen ions; 4) has a pH of less than 7.0; and 5) neutralizes bases or alkalis. All acids contain hydrogen and turn litmus paper red. They are corrosive to human tissue and are to be handled with care. See Base; pH.

Acid-Fast Bacilli (AFB) Bacteria that retain certain dyes after being washed in an acid solution. Most acid-fast organisms are mycobacteria. When AFB are seen on a stained smear of sputum or other clinical specimen, a diagnosis of TB should be suspected; however, the diagnosis of TB is not confirmed until a culture is grown and identified as M. tuberculosis.

Acidosis A condition of decreased alkalinity of the blood and tissues. Symptoms may include sickly sweet breath, headache, nausea, vomiting, visual disturbances; usually the result of excessive acid production. Tissues and CNS functions are disturbed.

Acoustic 1. Pertaining to the ears or sense of hearing. 2. Something designed to assist hearing.

Acoustics The quality of sound in an environment. Offices with poor acoustics can be noisy. Safety statistics indicate that when workers are continually exposed to high noise levels, they will ultimately suffer significant hearing loss.

Acquired Drug Resistance A resistance to one or more drugs that develops while a patient is receiving therapy, and which usually results from the patient's non-adherence to therapy or the prescription of an inadequate treatment regimen.

Acquired Immunodeficiency Syndrome (AIDS) A disease in which the body lacks the ability to protect itself from disease. It is caused by the Human Immunodeficiency Virus (HIV) which spreads throughout the body, killing the immune system. People get sick from infections that the body is normally able to combat, and this results in unusual diseases. People do not die from AIDS; they die from secondary infections and malignancies that develop.

Acrid Irritating and bitter (usually referring to smell).

ACS, American Chemical Society Professional society that establishes standards of purity for a number of reagents, e.g., the ACS Reagent Grade. They publish Chemical Abstracts and a host of professional journals and magazines dealing with various areas of chemistry, chemical engineering, and allied sciences. (1155 Sixteenth St., N.W., Washington, DC 20036; [202] 872-4567.)

Action Level The exposure level (concentration in air) at which OSHA regulations to protect employees take effect (29 CFR 1910.1001-1047); e.g., workplace air analysis, employee training, medical monitoring, and record keeping. Exposure at or above action level is termed occupational exposure. Exposure below this level can also be harmful. This level is generally half the PEL.

Activated Carbon A highly absorbent form of carbon, used to remove odors and toxic substances from gaseous emissions or liquid effluents.

Active Ingredient The ingredient of a product that actually does what the product is designed to do.

Acute Short term; can refer to an exposure or a health effect that occurs over a short period of time, such as minutes, hours, or several days.

Acute Exposure Exposure of short duration, usually to relatively high concentrations or amounts of material.

Acute Health Effect An adverse effect on a human or animal body, with symptoms developing rapidly. See Chronic Health Effect.

Acute Lethality The death of animals immediately or within 14 days after a single dose of or exposure to a toxic substance.

Acute Toxicity Adverse health effects resulting from brief exposure to a chemical (e.g. seconds, minutes, hours).

Acutely Hazardous Waste A waste that is considered a substantial hazard whether improperly managed or not. EPA includes waste shown to be fatal to humans in low doses, waste shown in mammalian studies to have specific toxicities, and explosives.

Adherence Refers to the behavior of patients when they follow all aspects of the treatment regimen as prescribed by the medical provider and also refers to the behavior of the health care workers and employers when they follow all guidelines pertaining to infection control.

Adjunct Something which is added to another to produce a desired effect.

Administrative Controls A number of measures used to reduce worker exposure, including work practices, labeling and warning devices, training, environmental monitoring, assignment scheduling, housekeeping, maintenance, and management.

Adrenaline A hormone in the body that is released whenever you become frightened or anxious. Adrenaline, which is part of the "fight or flight" response, causes an increase in heart rate and blood pressure and stimulates the clotting factor of the blood. Low level noise in the workplace, though not outwardly threatening, arouses the body with the release of adrenaline.

Adsorb To attract and retain gas or liquid molecules on the surface of another material. See Absorb.

Adsorption 1. The condensation of gases, liquids, or dissolved substances on the surfaces of solids. 2. A hazardous waste physical treatment process where substances in waste streams adhere to and become attached to adsorbents such as activated carbon.

Aerobic Having oxygen (O2) as part of the environment; growing only in the presence of oxygen, such as aerobic organisms; occurring only in the presence of oxygen, such as aerobic decomposition.

Aerobics Exercise that's hard enough to elevate your heart rate, make you perspire, and breathe hard. Regular exercise is necessary to keep muscles toned.

Aerosol 1. A fine suspension in air or other gas of liquid (mist, fog) or solid (dust, fume, smoke) particles small enough (0.01 to 100 microns) to stay suspended. See Smoke; Fog; Mist. 2. The droplet nuclei that are expelled by an infectious person (e.g. by coughing or sneezing); these droplet nuclei can remain in the air and can transmit airborne pathogens to other persons.

Affected Employee An employee whose job requires him/her to operate or use a machine or equipment on which servicing or maintenance is being performed under lockout or tagout, or whose job requires him/her to work in an area in which such servicing or maintenance is being performed.

Agent Any substance, force, radiation, organism, or influence affecting the body. The effects may be beneficial or injurious.

AIA The American Institute of Architects, a professional body that develops standards for building ventilation.

AICS The Australian Inventory of Chemical Substances. This list contains chemical substances which can be used commercially in Australia. It is similar to TSCA Chemical Substances Inventory in the U.S.

AIDS See Acquired Immunodeficiency Syndrome.

Air Bag Protective device designed to serve as a "cushion" between front seat occupants and vehicle interior immediately following a "head-on" or front angle crash.

Air Changes The ratio of the volume of air flowing through a space in a certain period of time (i.e., the airflow rate) to the volume of that space (i.e., the room volume); this ratio is usually expressed as the number of air changes per hour (ACH).

Air Cleaner A device for filtering, cleaning, and removing particulates from intake air to an engine.

Airline Respirator An atmosphere-supplying respirator in which the respirable gas is not designed to be carried by the wearer. Also known as a supplied-air respirator.

Air Mixing The degree to which air supplied to a room mixes with the air already in the room, usually expressed as a mixing factor. This factor varies from 1 (for perfect mixing) to 10 (for poor mixing), and it is used as a multiplier to determine the actual airflow required (i.e., the recommended ACH multiplied by the mixing factor equals the actual ACH required).

Air Monitoring Measurement of a chemical's concentration in air.

Air Pollutant Dust, fumes, mist, smoke and other particulate matter, vapor, gas, odorous substances, or any combination thereof which is emitted into or otherwise enters the ambient air.

Air-purifying Respirator A respirator designed to remove air contaminants (i.e., dust, fumes, mists, gases, vapors, or aerosols) from the ambient air or air surrounding the respirator user.

ALARA Acronym for "as low as reasonably achievable."

Alcoholism A disease characterized by the excessive use of alcohol. Because alcohol reduces awareness, employees who drink to excess on-the-job place themselves and their co-workers in danger.

Alkali A chemical that: 1) is usually corrosive to human tissue and must be handled with care; 2) has a pH of more than 7.0; 3) neutralizes acids to form salts; 4) dissociates in water yielding hydroxide ions; 5) turns litmus paper blue; and 6) may also be called a base or caustic. Common commercial alkalis are sodium carbonate (soda ash), caustic soda and caustic potash, lime, lye, waterglass, regular mortar, Portland cement, and bicarbonate of soda. See Acid; Base; pH.

Allergen A substance that causes an allergic reaction.

Allergic Reaction An abnormal physiological response to a chemical or physical stimuli by a sensitive person.

Allergy A condition in which an initial symptomless exposure to a specific allergen later gives rise to a sensitivity to further exposure. Symptoms may be exhibited in a variety of ways, usually by respiratory distress or skin eruptions.

Alopecia Loss of hair.

ALR Allergenic effects.

Alternator Generator in which alternating current is changed to direct current by means of rectifiers (diodes).

Alveolar Fluid Fluid inside the lungs in small air sacs.

Alveoli The small air sacs in the lungs that lie at the end of the bronchial tree. The site in the lungs where carbon dioxide in the blood is replaced by oxygen from the lungs, and the site where TB infection usually begins.

Ambient Usual or surrounding conditions of temperature, humidity, etc.

Amnesia Memory loss.

Amniotic Fluid Fluid inside the uterus (womb) during pregnancy.

Ampere The measure of electrical current flowing through a wire. Less than one ampere of electricity can kill a human being.

Amphoteric Possessing both basic and acidic properties.

Anaerobic Life or processes that occur in the absence of molecular oxygen; growing in the absence of molecular oxygen, such as anaerobic bacteria; occurring in the absence of molecular oxygen, such as anaerobic decomposition.

Analgesia Reduced sensitivity to pain.

Anchorage Point Secure mounting point to which a fall-safety harness can be attached.

Anemia A reduction in the number of red blood cells, caused by bleeding, destruction of blood cells, or an inability to replace blood cells.

Anergy The inability of a person to react to skin test antigens (even if the person is infected with the organisms tested) because of immunosuppression.

Anesthesia Loss of sensation, including loss of touch, pain, vibration sense, and/or temperature sense.

Anesthetic A chemical that causes a total or partial loss of sensation. Overexposure to anesthetics can cause impaired judgment, dizziness, drowsiness, headache, unconsciousness, and even death. Examples include alcohol, paint remover, and degreasers.

Angina Pectoris Chest pain caused by inadequate blood supply to the heart.

Anhydride A compound derived from another compound (as an acid) by removing the elements that compose water, i.e. hydrogen and oxygen.

Anhydrous Without water. Describes a substance in which no water molecules are present in the form of a hydrate or as water of crystallization.

Anorexia Loss of appetite.

Anosmia Loss of the sense of smell.

Anoxia A lack of oxygen in blood or tissues (literally, "without oxygen"). See Hypoxia.

ANSI American National Standards Institute. A privately funded organization that identifies industrial/public national consensus standards and coordinates their development. Many ANSI standards relate to safe design/performance of equipment and safe practices or procedures. (1430 Broadway, New York, NY 10018; [212] 642-4900.)

Antagonism When the effect of one chemical or material counteracts (works against) the effect of another.

Ante Room A small room leading from a corridor into an isolation room; this room can act as an airlock, preventing the escape of contaminants from the isolation room to the corridor.

Anti-lock Brake System (ABS) Provides rapid and repeated brake pulsations to bring vehicle to a stop without wheel lockup or skidding.

Anti-smog Device A special part or system designed to reduce or eliminate emission of harmful gasses caused by incomplete combustion.

Antibodies Special proteins made by the body's immune system after exposure to an infection or a vaccine. Immunity to the infection usually results.

Antidote A remedy to counteract a poison's toxic effects; it may act to eliminate, absorb, or neutralize the poison.

Antifreeze A liquid, usually ethylene glycol, added to water to lower freezing point.

Antiseptic Chemical agent used to kill bacteria, viruses, and parasites; similar to a disinfectant.

Anuria Absence or defective excretion of urine.

Anxiety Severe nervousness. The feeling that something foreboding is about to happen. In today's uncertain business environment, many workers have become anxious about the future. Developing your sense of humor is an effective weapon against anxiety.

Apnea Temporary stoppage of breathing.

Appearance A material's physical state (solid, gas, or liquid), its color, odor, size, consistency and other visual attributes.

Approved A respirator that has been evaluated and listed as permissible by the National Institute for Occupational Safety and Health (NIOSH), the Mine Safety and Health Administration (MSHA), or the Bureau of Mines (BM).

AQTX, Aquatic Toxicity The adverse effects on fresh or salt water life forms that result from exposure to a toxic substance. See TLm.

Aqueous, aq Describes a water-based solution or suspension. Frequently describes a gaseous compound dissolved in water.

Aquifer Geological formation, group of formations, or part of a ground formation, usually gravel or porous, which is capable of yielding water to wells or springs.

Area A structural unit (e.g., a hospital ward or laboratory) or functional unit (e.g., an internal medicine service), in which health care workers provide services to and share air with a specific patient population, or work with clinical specimens that may contain viable airborne pathogens (such as M. tuberculosis). The risk for exposure in a given area depends on the prevalence of the pathogen in the populations served and the characteristics of the environment.

Argyria Local or generalized gray-blue colored impregnation of body (skin) tissue with silver.

Aromatic Applied to a group of hydrocarbons and their derivatives characterized by the presence of the benzene nucleus (molecular ring structure). Includes chemicals such as toluene and xylene, as well as benzene.

Arrhythmia Irregular heartbeat.

Arthralgias Joint pains.

Article A manufactured item that is specifically shaped or formed with its function dependent on its shape or design. Hazard laws exclude articles unless they give off harmful dust or fumes during use.

Asbestos A fireproof mineral once used in the manufacture of building materials and heating systems. Many office complexes built twenty-five to thirty years ago probably contain asbestos. Asbestos is not considered a health hazard unless it becomes airborne.

Asbestosis Chronic lung disease caused by inhaling airborne asbestos fibers.

Asphyxia Lack of oxygen and interference with the oxygenation of the blood. Can lead to unconsciousness and death.

Asphyxiant A vapor or gas that can cause unconsciousness or death by suffocation (lack of oxygen). Most simple asphyxiants are harmful to the body only when they become so concentrated that they reduce (displace) the available oxygen in the air (normally about 21%) to dangerous levels (18% or lower). Examples of simple asphyxiants are carbon dioxide, nitrogen, hydrogen, and helium. Chemical asphyxiants like carbon monoxide (CO) reduce the blood's ability to carry oxygen, or like cyanide, interfere with the body's utilization of oxygen.

Asphyxiation A condition that causes asphyxia or suffocation. Asphyxiation is one of the principal potential hazards of working in confined spaces.

Aspiration When a liquid or solid from the mouth or throat is sucked into the lungs; in some cases, this may be fatal (when stomach acids or solvents are aspirated).

Aspiration Hazard The danger of drawing material into the lungs, leading to an inflammatory response that can be fatal.

Assigned Protection Factor (APF) The number assigned by NIOSH to indicate the capability of a respirator to afford a certain degree of protection in terms of fit and filter/cartridge penetration.

Asthma A disease characterized by recurrent attacks of dyspnea, wheezing, and perhaps coughing caused by spasmodic contraction of the main airways in the lungs.

Astigmatism A condition in a lens of a protector in which there is a difference in refractive power in one meridian from that in another meridian.

ASTM American Society for Testing and Materials. An organization that devises consensus standards for materials characterization and use. (100 Barr Harbor Dr, West Conshohocken, PA 19428; [610] 832-9500.)

Asymptomatic Not exhibiting symptoms.

Ataxia A loss of muscular coordination.

atm Atmosphere. A unit of pressure equal to the average pressure that air exerts at sea level. 1 atm = 1.013 x 105 N/m2, or 14.7 lb/in.2, or 760 mm Hg or 101 kPa. Generally used in connection with high pressures.

Atmosphere-supplying Respirator A respirator that supplies the wearer with air or oxygen from a source independent of the immediate ambient atmosphere. This includes air-supplied respirators and self-contained breathing apparatus (SCBA).

Atmospheric Tank A storage tank designed to operate at pressures from atmospheric through 0.5 p.s.i.g. (pounds per square inch gauge, 3.45 Kpa).

Atomic Number The number of protons (positively charged particles) found in the nucleus of an atom.

Atomic Weight Approximately the sum of the number of protons and neutrons found in the nucleus of an atom. Also known as the mass number.

Atrophy Reduction in size or function of tissue, organs, or the entire body caused by lack of use.

Attendant Individual stationed outside one or more permit spaces who monitors the authorized entrants and who performs all attendant's duties assigned in the employer's permit space program.

Atypical Bacteria An irregular or unusual type of bacteria.

Authorized Employee A person who locks out or tags out machines or equipment in order to perform servicing or maintenance on those machines or equipment. An affected employee becomes an authorized employee when that employee's duties include performing servicing or maintenance covered under this section. See Lockout/Tagout.

Authorized Entrant An employee authorized by the employer to enter a permit confined space. See Permit Required Confined Space.

Autoclave Device that uses steam under pressure to sterilize medical equipment.

Autoignition Temperature The minimum temperature at which a substance ignites without application of a flame or spark. Do not heat materials to greater than 80% of this temperature. Along with the flash point, autoignition temperature gives an indication of relative flammability.

Automatic Sprinkler System A safety device, located in the ceiling, that is activated by the heat of a fire. When engaged, automatic sprinkler heads will emit a spray of water to extinguish flames.

Autopsy The process of examining a body after death to determine the cause of death, identify or confirm diagnosis, or to study the disease process.

Autoreactive A compound that is reactive under normal conditions without initiation by heat or other compounds or change in conditions.

Axle Shaft or shafts of a vehicle upon which wheels are mounted.

AZT See Zidovudine.

Bacillus Refers to rod-shaped bacterial microorganisms.

BACTEC One of the most frequently used radiometric methods for detecting the early growth of mycobacteria in culture. It provides rapid growth (in 7-14 days) and rapid drug testing (in 5-6 days). When BACTEC® is used with rapid species identification methods, M. tuberculosis can be identified within 10-14 days of specimen collection.

Bacteria Microscopic living organisms. There are thousands of species of bacteria, many of which live on the skin or inside the human body. Bacteria are capable of reproducing themselves outside the human body and can produce their own food supplies. Many are harmless, and some serve a useful function. However, many can cause infection.

BAL British Anti-Lewisite. A name for the drug dimercaprol, a treatment for inhalation or ingestion of specific toxic metal compounds.

Base Substance that (usually) liberates OH anions when dissolved in water. Bases react with acids to form salts and water. Bases have a pH greater than 7 in solution, turn litmus paper blue, and may be corrosive to human tissue. A strong base is called alkaline or caustic. Examples are lye and DRANO™. See Acid; Alkali; pH.

Baume, Be A scale of specific gravities devised by the French chemist Antoine Baumé (c. 1800; pronounced bo-may) that indicates concentration of materials in a solution. Baumé degree increases as specific gravity decreases.

BBP's See Bloodborne pathogens.

BCG Bacille Calmette-Guérin vaccine. A TB vaccine used in many parts of the world.

BCM Blood-clotting mechanism effects.

BEI, Biological Exposure Indexes Numerical values based on procedures to determine the amount of a material the human body absorbs by measuring the material or its metabolic products in tissue, fluid, or exhaled air. See the ACGIH publication Documentation of the Threshold Limit Values and Biological Exposure Indices.

Benign Not harmful; may refer to a noncancerous tumor.

Bilirubin A chemical normally formed in the liver from the breakdown of red blood cells. Its level increases in many forms of liver disease, such as hepatitis, and causes yellowing of the skin and the white surface of the eye (sclera). This condition is called jaundice.

Bioaccumulation The process that occurs when toxic substances are passed up through the food chain, traveling from soil to plants to grazing animals to human beings.

Bioassay The employment of living organisms to determine the biological effect of a substance, factor, or condition.

Biochemical Oxygen Demand, BOD The dissolved oxygen required to decompose organic matter in water used to estimate degree of contamination in water supplies. Commonly reported as the BOD value after 5 days.

Bioconcentration The process by which a chemical is passed through the food chain from soil to plants and animals where it accumulates and is ultimately passed to humans.

Biodegradable An organic material's capacity for decomposition as a result of attack by microorganisms. Sewage-treatment routines are based on this property. Biodegradable materials do not persist in nature.

Biohazardous Substances obtained from living tissues that create a risk of infection.

Biological Hazardous Wastes Any substances of a human or animal origin, other than food wastes, which are disposed of and could harbor or transmit pathogenic organisms. These include pathological specimens such as tissues, blood elements, excreta, secretions, bandages, and related substances.

Biological Magnification The concentration of certain substances up through the food chain. A very important mechanism in concentrating pesticides and heavy metals in organisms such as fish.

Biological Monitoring Analysis of body substances, such as blood or urine, to determine the extent of hazardous material absorption or accumulation.

Biological Treatment A process by which hazardous waste is rendered non-hazardous or is reduced in volume by relying on the action of microorganisms to degrade organic waste.

Blanking or Blinding The absolute closure of a pipe, line, or duct by the fastening of a solid plate (such as a spectacle blind or a skillet blind) that completely covers the base and that is capable of withstanding the maximum pressure of the pipe, line, or duct with no leakage beyond the plate.

BLD Blood effects.

Bleach A solution of sodium hypochlorite; can be used for chemical decontamination (killing) of BBP's; considered a high-level disinfectant.

Bleed To remove air from hydraulic brake system while fluid in system is under pressure.

BLEVE, Boiling Liquid Expanding Vapor Explosion Used when describing fires involving compressed gases in cylinders which rupture due to extreme pressures and proceed to burn rapidly.

Blood Generally refers to human blood, human blood components, and products made from human blood.

Blood Alcohol Content (BAC) The percentage of alcohol circulating in the bloodstream. According to National Safety Council statistics, a driver with a BAC of .10 is 7 times more likely to be involved in a fatal car crash than a sober driver.

Bloodborne Pathogens (BBP's) Viruses, bacteria, or parasites carried in the blood or other body fluids of infected persons and that, under certain conditions, can be spread to others.

Blue-light Transmittance Transmittance of optical radiation weighted by its ability to cause photochemical damage to the retina.

Blurred Vision Inability to see clearly.

BOD, Biochemical Oxygen Demand Amount of oxygen needed by bacteria to stabilize organic matter under aerobic conditions. Used to estimate degree of contamination in water supplies.

Body Burden The total toxic material a person has ingested or inhaled from all sources over time and retained in the body. For example, lead can be ingested from drinking water channeled through lead-soldered pipes, lead glazes on dishes, or flakes from painted surfaces, as well as from many industrial operations.

Boiling Point, BP The temperature at which a liquid's vapor pressure equals the surrounding atmospheric pressure so that the liquid rapidly vaporizes. Flammable materials with low BPs generally present special fire hazards [e.g., butane, BP = -0.5 °C (31 °F); gasoline, BP =38 °C (100 °F)]. For mixtures, a range of temperature is given.

Bonding A safety practice where two objects (tanks, cylinders, etc.) are interconnected with clamps and wire. This equalizes the electrical potential between the objects and helps prevent static sparks that can ignite flammable materials transferred between tanks. See Grounding.

Booster A mechanical or hydraulic device attached to brake or steering system to increase power or ease of operation.

Booster Phenomenon An occurrence in which some persons (especially older adults) who are skin tested many years after infection with M. tuberculosis have a negative reaction to an initial skin test, followed by a positive reaction to a subsequent skin test. The second (positive) reaction is caused by a boosted immune response. Two-step testing is used to distinguish new infections from boosted reactions. See Two-Step Testing; Purified Protein Derivative (PPD) Test Conversion.

BP See Boiling Point.

Bradycardia Slowed heartbeat (less than 60 beats per minute).

Brake Cylinder A cylinder in which a movable piston or pistons converts hydraulic pressure to mechanical force to move brake shoes against the drum or the pads against the rotor.

Brake Drum A round metal "bowl" fitting over the brake shoes. The brake cylinder then forces the shoes against the inner surface of the "bowl" to stop or slow the vehicle.

Brake Fade A condition where repeated severe applications of brakes cause heat expansion of brake drum or loss of frictional ability or both, which results in reduced brake effectiveness.

Brake Fluid A specific liquid for use in hydraulic brake systems.

Brake Rotor Round metal plate against which the brake pads are forced by the brake cylinder to stop or slow vehicle.

Brake Shoe Backing to which brake lining is attached.

Brim An integral part of the shell extending outward over the entire circumference.

British Anti-Lewisite See BAL.

Bronchioles Smaller air passages of the lungs which branch off the bronchi.

Bronchiolitis Obliterans A serious lung condition caused by massive exposure to an irritant and resulting in obliteration of the small breathing tubes (bronchioles) and replacement with scar tissue.

Bronchitis Inflammation of the bronchial tubes (main airways) in the lungs.

Bronchoscopy A procedure for examining the respiratory tract that requires inserting an instrument (a bronchoscope) through the mouth or nose into the trachea. This procedure can be used to obtain diagnostic specimens.

Bronchospasm A condition caused by narrowing of the airways and resulting in wheezing sounds and shortness of breath.

Bronchus (plural: bronchi; sometimes called bronchial tubes). Air passages branching off the windpipe to carry air to the lungs.

Btu British thermal unit. The quantity of heat required to raise the temperature of l lb of water from 17° C (63 °F) to 18° C (64 °F). Compare to Calorie.

Buffer A substance that reduces the change in hydrogen ion concentration (pH) otherwise produced by adding acids or bases to a solution. A pH stabilizer.

Bulk Density The mass (weight) per unit volume of a solid particulate material as it is normally packed, with voids between particulates containing air. Usually expressed as lb/ft3 or g/cm3.

Bulk Packaging A packaging, other than a vessel or a barge, including a transport vehicle or freight container, in which hazardous materials are loaded with no intermediate form of containment and which has:

(1) A maximum capacity greater than 450 L (119 gallons) as a receptacle for a liquid;

(2) A maximum net mass greater than 400 kg (882 pounds) and a maximum capacity greater than 450 L (119 gallons) as a receptacle for a solid; or

(3) A water capacity greater than 454 kg (1,000 pounds) as a receptacle for a gas as defined in 49 CFR 173.115.

Bump Cap Headwear that offers very limited protection against low or fixed objects.

Bureau of Solid Waste Management The branch of a state's Department of Environmental Resource responsible for planning, directing, evaluating, coordinating, and organizing a statewide waste management and enforcement program, including the Hazardous Waste Management Program.

Burn Destruction of skin or other tissues caused by heat, electricity, or chemicals.

Burning Rate The time it takes a specified sized sample of solid material (e.g., 1 in by 1 in) to burn a designated distance. The rate is given in units of distance/time.

C Indicates continuous exposure when used with toxicological data; e.g., "LC50 > 5 mg/m3, 24 h-C" means continuous exposure for 24 hr. OSHA also uses C to designate ceiling exposure limit. See Ceiling Limit; TLV.

C Degrees Celsius (centigrade). Metric temperature scale on which 0 = water's freezing point and 100 = its boiling point. °F = (°C x 9/5) + 32. °C = (°F - 32) x 5/9. See °F.

c, ca Circa, about, approximately.

CAA Clean Air Act. Public Law PL 91-604, 40 CFR 50-80. EPA has jurisdiction. Effective Dec. 31, 1970, and significantly amended several times, most recently in 1990. The regulatory vehicle that sets limitations and monitors airborne pollution hazardous to public health or natural resources. The EPA sets national ambient air-quality standards. Enforcement and issuance of discharge permits are carried out by the states and are called state implementation plans. The CAA is directed toward by-products discharged into the air from stationary sources (i.e., factories) and mobile sources (i.e., automobiles) rather than use and assessment of specific chemicals.

Caffeine A chemical found in coffee and some carbonated drinks that stimulates the nervous system. Caffeine increases the stress levels of some people.

Calcification The process of depositing calcium in a tissue, which renders it inflexible and unable to change.

Calcium One of the necessary elements of a healthy diet which needs to be replenished daily to maintain bone strength.

Calorie Unit of heat. The amount of heat required to raise 1 g of water 1°C. See Btu.

Camshaft Shaft containing lobes or cams which operate engine intake and exhaust valves.

Cancer, Carcinoma A malignant tumor or cancer; a new growth of cells that tends to grow rapidly, infiltrate other tissue, and metastasize (spread). Each cancer is believed to originate from a single "transformed" cell that grows (splits) at a fast, abnormally regulated pace, no matter where it occurs in the body. Cancer is the second most common cause of death in the US. The National Toxicology Program (NTP) reports that one- to two-thirds of cancers are associated with our environment.

Canister Cartridge. The element of a gas and vapor or particulate air-purifying respirator which contains the sorbent, filter, and/or catalyst that removes specific contaminants from the air drawn through it.

Capable of Being Locked Out An energy-isolating device is capable of being locked out if it has a hasp or other means of attachment to which, or through which, a lock can be affixed, or it has a locking mechanism built into it. Other energy-isolating devices are capable of being locked out if lockout can be achieved without the need to dismantle, rebuild, or replace the energy-isolating device or permanently alter its energy-control capability. See Lockout.

Capreomycin An injectable second line antituberculosis drug used primarily for the treatment of drug resistant TB.

CAR Carcinogenic effects.

Carbohydrates An organic compound of food that provides quick energy for the body and insulation from stress. Breads, cereals, fruits, and vegetables are excellent sources of carbohydrates.

Carbon Dioxide, CO2 A dense, colorless gas produced by combustion and decomposition of organic subtances and as a by-product of many chemical processes. CO2 does not burn and is relatively nontoxic and unreactive. High concentrations, especially in confined places, can create hazardous oxygen-deficient environments that can cause asphyxiation. CO2 is 1.5 times as dense as air, making it useful as a fire-extinguishing agent to block oxygen and smother a fire.

Carbon Monoxide, CO A colorless, odorless, flammable, and very toxic gas produced by incomplete combustion of carbon compounds and as a by-product of many chemical processes. A chemical asphyxiant, it reduces the blood's ability to carry oxygen. Hemoglobin absorbs CO 200 times more readily than it does oxygen.

Carcinogen A material that either causes cancer in humans, or, because it causes cancer in animals, is considered capable of causing cancer in humans. A material is considered a carcinogen if 1) the International Agency for Research on Cancer (IARC) has evaluated and found it a carcinogen or potential carcinogen; 2) the National Toxicology Program's (NTP) Annual Report on Carcinogens lists it as a carcinogen or potential carcinogen; or 3) OSHA regulates it as a carcinogen; or 4) one positive study has been published. "Select Carcinogen" is defined in 29 CFR 1910.1450, within OSHA's "Occupational Exposures to Hazardous Chemicals in Laboratories" standard, as a substance: a) OSHA regulates as a carcinogen; b) the NTP lists as "known to be carcinogen;" c) the IARC lists as Group 1, "carcinogenic to humans;" or d) the IARC lists as Group 2A or 2B, "reasonably anticipated to be carcinogen," since it causes statistically significant tumor incidence in animals per criteria listed in section 2, paragraph b.

Carcinoma A type of cancer.

Cardiopulmonary Resuscitation Technique used by trained First Aid providers to maintain or restore circulation of oxygenated blood in a person whose normal heart and respiration have stopped.

Cardiovascular System of the human body involving the heart and blood vessels.

Cargo Tank A bulk packaging that:

(1) Is a tank intended primarily for the carriage of liquids or gases and includes appurtenances, reinforcements, fittings and closures. See Tank.

(2) Is permanently attached to or forms a part of a motor vehicle, or is not permanently attached to a motor vehicle but which, by reason of its size, construction or attachment to a motor vehicle, is loaded or unloaded without being removed from the motor vehicle; and

(3) Is not fabricated under a specification for cylinders, portable tanks, tank cars or multi-unit tank car tanks.

Carpal Tunnel Syndrome An affliction of the wrist in which the sleeve connecting the nerves of the hand to those of the forearm becomes inflamed through constant, repetitive motion. This injury causes pain and loss of sensation in the hand, as well as diminished strength of the hand's grasp.

Carrier A person who has a disease capable of being spread to others, but who has no current symptoms of the disease. Some people with infections caused by HIV or HBV are carriers.

As used in the transportation of hazardous materials, carrier means a person engaged in the transportation of passengers or property by:

(1) Land or water, as a common, contract, or private carrier, or

(2) Civil aircraft.

CAS Number (CAS Registration Number) An assigned number used to identify a chemical. CAS stands for Chemical Abstracts Service, an organization that indexes information published in Chemical Abstracts by the American Chemical Society and that provides index guides by which information about particular substances may be located in the abstracts. Sequentially assigned CAS numbers identify specific chemicals, except when followed by an asterisk (*) which signifies a compound (often naturally occurring) of variable composition. The numbers have no chemical significance. The CAS number is a concise, unique means of material identification. (Chemical Abstracts Service, Div. of American Chemical Society, Box 3012, Columbus, OH 43210; [614] 447-3600.)

Catalyst A substance that modifies (slows, or more often quickens) a chemical reaction without being consumed in the reaction.

Catalytic Converter Emission control device in exhaust stream after exhaust manifold and before muffler that chemically treats exhaust gas to reduce emissions.

Cataract A loss of transparency in the eye's crystalline lens or its capsule.

Catastrophic Release A major uncontrolled emission, fire, or explosion, involving one or more highly hazardous chemicals that presents serious danger to employees in the workplace, and possibly the surrounding community.

Caustic Corrosive or able to damage body tissue. This usually applies to metal hydroxides or other alkali materials (bases). See Alkali.

Cavity A hole in the lung resulting from the destruction of pulmonary tissue by TB or other pulmonary infections or conditions. TB patients who have cavities in their lungs are referred to as having "cavitary disease" and they are often more infectious than TB patients without cavitary disease.

CC Closed cup. Identifies one of the methods used to measure flash points of flammable liquids.

cc, cm3 Cubic centimeter.

CDC See Centers for Disease Control.

Ceiling Limit, C The concentration of a hazardous material not to exceed at any time. "An employee's exposure (to a hazardous material) shall at no time exceed the ceiling value." (OSHA)

Celsius See °C.

Center of Gravity The point at which two opposing forces are equally balanced. The center of gravity of a lifted load is the point where all of the weight rests.

Centers for Disease Control (CDC) A division of the United States Public Health Service, which is part of the Department of Health and Human Services. CDC, located in Atlanta, GA, is responsible for keeping statistics on all types of infections, including HIV, hepatitis, and tuberculosis, and giving advice to the U.S. Government and health care professionals on preventing and treating infections.

Centigrade See °C. Celsius is now this temperature scale's preferred name.

Centimeter, cm 1/100 meter. A cm = approximately 0.4 in.

Centipoise, cP A metric (cgs) unit of the measure of viscosity equal to 1/100 poise. The viscosity of water at 20 °C (68 °F) is almost 1 centipoise.

Central Nervous System (CNS) See CNS, Central Nervous System.

Central Nervous System (CNS) Depression Drowsiness, dizziness, and headache caused by a chemical acting on the brain; higher doses can cause unconsciousness, coma, or death.

Centrifugal To move or propel something away from the center toward the outside.

CEPA, (Canada) Environmental Protection Act Federal legislation, administered by Environment Canada, designed to protect the environment.

CERCLA The Comprehensive Environmental Response, Compensation, and Liability Act. The Superfund Law, Public Law PL 96-510, found at 40 CFR 300. The EPA has jurisdiction. Enacted Dec. 11, 1980, and amended thereafter, CERCLA provides for identification and cleanup of hazardous materials released on land, into the air, waterways, and groundwater. It covers areas affected by newly released materials and older leaking or abandoned dump sites. Report releases of hazardous materials to the National Response Center, (800) 424-8802. CERCLA established the superfund, a trust fund to help pay for cleanup of hazardous materials sites. The EPA has authority to collect cleanup costs from those who release the waste material. Cleanup funds come from fines and penalties, from taxes on chemical/ petrochemical feed stocks, and the U.S. Treasury Dept. A separate fund collects taxes on active disposal sites to finance monitoring after they close. CERCLA is a result of the serious problems that arose from the release of hazardous materials in the Love Canal area near Niagara Falls, NY, in Aug. 1978.

Cerebrospinal Fluid Fluid surrounding the brain and spinal cord.

CFC Chlorofluorocarbon. Associated with damage to the Earth's ozone layer.

CFR See Code of Federal Regulations.

cgs Metric units of measure based upon centimeter, gram, and second.

Chain Mail Gloves Gloves made of interlocking metal design to protect against sharp objects.

Challenge Agent The testing substance introduced into a test chamber when performing a quantitative respirator fit test.

Checklist A term used in Process Safety Management, for complex processes, the "what if" study can be best organized through the use of a checklist. Operator practices and job knowledge are audited in the field, the suitability of equipment and materials of construction is studied, the chemistry of the process and the control systems are reviewed, and the operating and maintenance records are audited.

Chelating Agent 1. A substance (e.g. EDTA) which can remove heavy metal toxins (such as lead, mercury, or arsenic) from the blood by complexing them and allowing their excretion in urine. 2. Used to avoid scale deposition from water; etc.

Chemical Any element, chemical compound, or mixture of elements and/or compounds where chemical(s) are distributed.

Chemical Burn Destruction of skin or other tissue similar to that of a thermal burn, but caused by contact with a chemical.

Chemical Cartridge Respirator A respirator using various chemical substances to purify inhaled air of certain contaminative gases and vapors. Approved for concentrations no more than 10 times the TLV for a half facepiece and 100 times the TLV for a full facepiece, provided the contaminant has warning properties (odor or irritation) near the TLV.

Chemical Change (Reaction) Change of composition in properties due to rearrangement of elements, atoms, or molecules.

Chemical Compound A substance composed of definite proportions by weight of two or more elements, and whose properties differ from those of its elements. See Mixture.

Chemical Family A group of single elements or compounds of a common general type. For example, acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) are of the ketone family; acrolein, furfural, and acetaldehyde are of the aldehyde family.

Chemical Formula The number and kind of atoms comprising a molecule of a material. Water's chemical formula is H2O. Each water molecule consists of 2 atoms of hydrogen and 1 atom of oxygen.

Chemical Hygiene Officer Per 29 CFR 1910.1450; OSHA regulation, "Occupational Exposures to Hazardous Chemicals in Laboratories." The designated, qualified employee who assists in the development and implementation of the CHP. See CHP.

Chemical Name A chemical's scientific name. Complex chemicals may have more than one name, corresponding to different naming systems.

Chemical Pneumonitis Inflammation of the lungs caused by inhaling a chemical that is irritating or otherwise toxic to the lungs.

Chemical Reactivity A chemical's tendency to react with other materials. Undesirable and dangerous effects such as heat, explosions, or production of noxious substances can result.

Chemical Treatment The process by which hazardous waste is rendered non-hazardous or suitable for transport by changing the chemical composition of the waste.

Chemiluminescence Emission of light during a chemical reaction other than burning.

Chemotherapy Treatment of an infection or disease by means of oral or injectable drugs.

CHEMTREC Chemical Transportation Emergency Center. Established in Washington, DC, by the Chemical Manufacturers Association (CMA) to provide emergency information on materials involved in transportation accidents. 24-hour number: (800) 424-9300.

Chest Radiograph In patients showing signs or symptoms of TB, a radiograph of the chest is taken to view the respiratory system. Abnormalities, such as lesions or cavities in the lungs and enlarged lymph nodes, may indicate the presence of TB.

Chills A sensation of cold associated with shivering and often fever.

Chin Protector That portion of a device that offers protection to a wearer's chin, or lower face and neck.

Chin Strap An adjustable strap that fits under the chin to secure the helmet to the head.

Chloracne A severe form of skin acne caused by exposure to certain chlorinated chemical compounds.

Chlorolysis Hazardous waste chemical treatment method by which chlorinated organic compounds are recycled and converted into useful industrial products through the addition and mixing of excess chlorine to the organic waste.

CHP, Chemical Hygiene Plan Per 29 CFR 1910.1450, OSHA standard; "Occupational Exposures to Hazardous Chemicals in Laboratories." Effective 5/1/90. A written plan that includes specific work practices, standard operating procedures, equipment, engineering controls, and policies to ensure that employees are protected from hazardous exposure levels to all potentially hazardous chemicals in use in their work area. This OSHA standard provides for training, employee access to information, medical consultations, examinations, hazard identification procedures, respirator use, and record keeping practices. See ¶ E of the Standard.

Chronic Lasting a long time, such as chronic active or chronic persistent hepatitis.

Chronic Exposure Continuous or intermittent exposure extending over a long time period, usually applies to relatively low material amounts or concentrations.

Chronic Health Effect An adverse effect on a human or animal body with symptoms that develop slowly over a long time period and persist or that recur frequently. See Acute Health Effect.

Chronic Toxicity Adverse health effects resulting from long-term exposure to a chemical (e.g. months, years, decades).

Cirrhosis A disease of the liver in which extensive scar tissue develops. Hepatitis B infection and overuse of alcohol are two of the leading causes of cirrhosis in the United States. Cirrhosis often leads to death unless a liver transplant is performed.

Class See Hazard Class.

Class 1 (explosive). Any substance or article, including a device, that is designed to function by explosion (i.e., an extremely rapid release of gas and heat) or which, by chemical reaction within itself, is able to function in a similar manner even if not designed to function by explosion, unless the substance or article is otherwise classed under the provisions of DOT regulations. Div. 1.1 (mass explosion hazard); Div. 1.2 (projection hazard); Div. 1.3 (fire hazard & minor blast hazard or minor projection hazard); Div. 1.4 (minor explosion hazard); Div. 1.5 (very insensitive explosives); Div. 1.6 (extremely insensitive explosives). See 49 CFR 173.50 for detailed definitions of each division.

Class 2. Div. 2.1 (flammable gas); Div. 2.2 (non-flammable, non-poisonous compressed gas, including compressed gas, liquefied gas, pressurized cryogenic gas and compressed gas in solution); or Div. 2.3 (gas poisonous by inhalation). See 49 CFR 173.115 for detailed definitions of each division.

Class 3 (flammable liquid). A liquid having a flash point of not more than 60.5 °C (141 °F), or any material in a liquid phase with a flash point at or above 37.8 °C (100 °F) that is intentionally heated and offered for transportation or transported at or above its flash point in a bulk packaging, with the exceptions detailed in 49 CFR 173.120.

Class 4. Div. 4.1 (flammable solid); Div. 4.2 (spontaneously combustible material); or Div. 4.3 (dangerous when wet material). See 49 CFR 173.124.

Class 5. Div. 5.1 (oxidizing material) or Div. 5.2 (organic peroxide). See 49 CFR 173.127.

Class 6. Div. 6.1 (poisonous material), or Div. 6.2 (infectious substance). See 49 CFR 173.132.

Class 7 (radioactive material). Any material having a specific activity greater than 0.002 microcuries per gram (µCi/g). See definition of Specific Activity and other technical definitions in 49 CFR 173.403.

Class 8 (corrosive material). A liquid or solid that causes visible destruction or irreversible alterations in human skin tissue at the site of contact, or a liquid that has a severe corrosion rate on steel or aluminum, in accordance with the criteria given in 49 CFR 173.136(a).

Class 9 (miscellaneous hazardous material). A material that has an anesthetic, noxious, or other similar property that could cause extreme annoyance or discomfort to a person so as to prevent the correct performance of assigned duties; and meets the definition in 49 CFR 171.8 for a hazardous substance or a hazardous waste. See Hazardous Substance; Hazardous Waste.

Class A Helmet Helmet designed to reduce the impact of falling objects and to reduce the danger of contact with exposed low voltage conductors (proof-tested at 2,200 volts).

Class B Helmet Helmet designed to reduce the impact of falling objects and to reduce the danger of contact with exposed high voltage conductors (proof-tested at 20,000 volts).

Class C Helmet Helmet designed to reduce the impact of falling objects. This class offers no electrical protection.

Clastogenic An agent that causes damage to genetic material (i.e., breakage or disruption of chromosomes).

Closed Circuit Respirator An SCBA in which the air is rebreathed after exhaled carbon dioxide has been removed and the oxygen content has been restored by a compressed or liquid oxygen source or an oxygen-generating solid.

Closed Cup See CC.

Closed System Equipment designed and used so that there is no release of the chemical into the surrounding environment.

Cluster Two or more PPD skin test conversions occurring within a 3-month period among health care workers in a specific area or occupational group, and epidemiologic evidence suggests occupational (nosocomial) transmissions.

Clutch Friction device used to connect and disconnect a driving force from a driven member.

CNS, Central Nervous System The brain and spinal cord. CNS is used frequently to indicate a material's effects on the CNS, including headache, tremors, drowsiness, convulsions, hypnosis, anaesthesia, nervousness, irritability, narcosis, dizziness, fatigue, lethargy, memory loss, impaired concentration, sleep disturbance, etc.

CNS Depression See Central Nervous System Depression.

COD, Chemical Oxygen Demand The amount of oxygen required under designated test conditions to oxidate waterborne organic and inorganic material. Used in measuring the degree of pollution in domestic and industrial waters.

Code of Federal Regulations (CFR) A collection of the regulations established by law. Contact the agency that issued the regulation for details, interpretations, etc. Copies are sold by the Superintendent of Documents, Government Printing Office, Washington, DC 20402; (202) 783-3238.

Coefficient of Water/Oil Distribution Also called the octanol/water partition coefficient, it is the ratio of the solubility of a chemical in water to its solubility in oil. Used to indicate how easily human or other organisms can absorb or store a material. Sometimes abbreviated Ko/w; may also be expressed as its logarithm, log Ko/w.

Coil Springs Spiral-shaped, coiled steel or steel alloy, used usually in "A-arm" suspensions for rebound control.

Colic Crampy pain of the abdomen.

Coma Extended loss of consciousness due to an injury, illness, or poison.

Combination Packaging A combination of packaging, for transport purposes, consisting of one or more inner packagings secured in a non-bulk outer packaging. It does not include a composite packaging.

Combustible A material that will burn under most conditions and may ignite easily depending on its flash point. The DOT defines combustible liquids as a liquid with a flash point above 141 °F (60.5 °C) and below 200 °F (93 °C). Both NFPA and OSHA generally define a combustible liquid as a liquid with a flash point at or above 100 °F (38 °C) but below 200 °F (93.3 °C). See Flammable

Combustible Liquid Any liquid that does not meet the definition of any other hazard class specified in the DOT regulations, except Class 9, and has a flash point above 60.5 °C (141 °F) and below 93 °C (200 °F).

Common Name A designation for a material other than its chemical name, such as code name or code number or trade, brand, or generic name. May be used as the "product identifier" in Canadian law [Workplace Hazardous Materials Information System (WHMIS) regulations].

Composite Packaging A packaging consisting of an outer packaging and an inner receptacle, so constructed that the inner receptacle and outer packaging form an integral packaging. Once assembled, it remains thereafter an integrated single unit; it is filled, stored, shipped and emptied as such.

Compressed Gas Any material which is a gas at normal temperature and pressure, and contained under pressure as a dissolved gas or liquefied by compression or refrigeration.

As used in the transportation of hazardous materials, compressed gas means a non-flammable, nonpoisonous compressed gas - including compressed gas, liquefied gas, pressurized cryogenic gas and compressed gas in solution - that exerts in the packaging an absolute pressure of 280 kPa (41 psia) at 20 °C (68 °F), and does not meet the definition of a gas poisonous by inhalation or non-liquefied compressed gas.

Concentration Strength of a chemical in the air or in a liquid solution; often described in parts per million (ppm), milligrams per cubic meter (mg/m3), or percent (%).

Confined Space A space that: 1) is large enough and so configured that an employee can bodily enter and perform assigned work; 2) has limited or restricted means for entry or exit (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that have limited or restricted means of entry); 3) a space with little ventilation where an oxygen-deficient environment may develop or where chemicals may reach high concentrations; and 4) is not designed for continuous human occupancy.

Conjunctivitis Inflammation of the conjunctiva, the delicate membrane that lines the eyelid and covers the eyeball.

Constant Velocity Joint Double universal joint required on front wheel drive vehicles to both transfer engine power to the front wheels and compensate for steering movement.

Consumer Commodity A material that is packaged and distributed in a form intended or suitable for sale through retail organizations for consumption by individuals for purposes of personal care or household use. This term also includes drugs and medicines.

Consumer Products Safety Commission See CPSC.

Contact A person who has shared the same air with a person who has infectious TB for a sufficient amount of time to allow possible transmission of M. tuberculosis.

Contact Dermatitis Skin rash caused by contact with something (chemical, soap, cosmetic, jewelry); may be due to irritation or an allergic reaction (sensitization).

Container Any bag, barrel, bottle, box, can, cylinder, drum, reaction vessel, storage tank, or the like that contains a hazardous chemical. For purposes of MSDS or HazCom, pipes or piping systems are not considered to be containers.

Contaminant An undesired or unwanted agent that has rendered a substance impure.

Contaminated Containing or likely to contain viruses, bacteria, or parasites that could cause infection.

Contaminated Laundry Laundry soiled with blood or other potentially infectious materials, or possibly containing sharps.

Contaminated Sharps Any contaminated object that can penetrate the skin, including needles, scalpels, broken glass, broken capillary tubes, and exposed ends of dental wires.

Continuous Flow Respirator An atmosphere-supplying respirator that provides a continuous flow of respirable gas to the respiratory inlet covering (facepiece, hood, etc.).

Contracture Scarring of the skin and/or subcutaneous tissues causing a limitation of the normal movement of a body part.

Conversion, PPD See Purified Protein Derivative (PPD) Test Conversion.

Convulsions Violent body spasms; fits or seizures.

Coolant Liquid circulated through cooling system of a "water-cooled" engine, usually a mixture of 50% ethylene glycol and 50% water.

COR Corrosive effects.

Cornea Transparent structure of the eyeball's external layer.

Corrosion Rate Expressed in inches or millimeters of steel (or other defined material) per year, at a stated temperature.

Corrosive A chemical that causes visible destruction of or irreversible alterations in living tissue by chemical action at the site of contact, or which causes a severe corrosion rate in steel or aluminum. A waste that exhibits a "characteristic of corrosivity (40 CFR 261.22)," as defined by RCRA, and may be regulated by EPA as a hazardous waste.

Corrosivity Characteristic that defines a waste that can extract and make soluble toxic contaminants from other waste. Must have a pH less than 2 or greater than 12.5 or corrode steel (SAE 1020) at a rate greater than 1/4-inch/year.

Cover Lens An expendable pane of clear material to protect a lens from damage.

cP See Centipoise.

CPR (Cardiopulmonary Resuscitation) A life-saving technique used on victims whose hearts have stopped beating. Contact your local American Heart Association, Red Cross, or National Safety Council Chapter for training.

CPSC Consumer Products Safety Commission. A Federal agency responsible for regulating hazardous materials when they are used in consumer goods per the Hazardous Substances Act and Poison Prevention Packaging Act of 1970.

Cradle-to-Grave The tracing of the source, quantity, concentration and type of hazardous waste from generation through final disposal.

Crankshaft Mainshaft of an engine that, through the connecting rods, changes the reciprocating motion of the pistons into rotary motion.

Creativity The ability to devise new solutions to old problems. Exercising your creativity will allow you more control over your work environment and minimize your stress.

Critical Pressure/Critical Temperature A temperature above which a gas cannot be liquefied by pressure. The critical pressure is that pressure required to liquefy a gas at its critical temperature.

Crown Strap That portion of a helmet that offers protection to a wearer's forehead.

Crown Straps The part of the protective headware suspension system that passes over the head.

Cryogenic Relating to extremely low temperature. For example, refrigerated gases are cryogenic materials that can cause frostbite on contact.

Cryogenic Liquid A refrigerated, liquefied gas having a boiling point colder than -90 °C (-130 °F) at 101.3 kPa (14.7 psi) absolute. A material meeting this definition is subject to requirements of the DOT regulations for shippers, transporters, and manufacturers without regard to whether it meets the definition of a non-flammable, non-poisonous compressed gas as defined in 49 CFR 173.115(b).

CTD, Cumulative Trauma Disorder See Over-Use Syndrome.

cu ft, ft3 Cubic foot. Cu ft is more usual.

cu m, m3 Cubic meter. m3 is preferred.

Cube adaptor An electrical device that allows you to plug several extensions into a single socket. Overloading circuits in this manner creates a fire hazard. The use of cube adaptors should be banned in your office.

Culture The process of growing bacteria in the laboratory so that organisms can be identified.

CUM Cumulative.

Cumulative Trauma Disorder (CTD) The most common type of injury among workers today. Workplace repetitive stress injuries (RSI's) have doubled since 1985 and are responsible for 56% of all workplace illnesses.

Cutaneous Pertaining to the skin (dermal).

Cutout Box An enclosure designed for surface mounting and having swinging doors or covers secured directly to - and telescoping with - the walls of the box proper. Pertains to lockout/tagout.

CVS Cardiovascular system (heart and blood vessels).

CWA Clean Water Act. Public Law PL 92-500. Found at 40 CFR 100-140 and 400-470. Effective November 18, 1972, and amended significantly since then. EPA and Army Corps of Engineers have jurisdiction. CWA regulates the discharge of nontoxic and toxic pollutants into surface waters. Its ultimate goal is to eliminate all discharges into surface waters. Its interim goal is to make surface waters usable for fishing, swimming, etc. EPA sets guidelines, and states issue permits (NPDES, Natural Pollutant Discharge Elimination System permit) specifying the types of control equipment and discharges for each facility.

Cyanosis A dark blue to purplish coloration of the skin and the mucous membrane caused by lack of oxygen utilization by the body.

Cycloserine (CS) A second line oral antituberculosis drug, used primarily for treating drug resistant TB.

Cylinder A pressure vessel designed for pressures higher than 40 psia and having a circular cross section. It does not include a portable tank, multi-unit tank car tank, cargo tank, or tank car.

Dangerous When Wet A label required for certain materials being shipped under U.S. DOT, ICAO, and IMO regulations. Any of this labeled material that is in contact with water or moisture may produce flammable gases. In some cases, these gases are spontaneously combustible.

Dangerous When Wet Material A material that, by contact with water, is likely to become spontaneously flammable or to give off flammable or toxic gas at a rate greater than 1 liter per kilogram of the material per hour, when tested in accordance with paragraph 4 of Appendix E to 49 CFR Part 173.

Dangerously Reactive Material A material that can react by itself (e.g., polymerize) or with air or water to produce a hazardous condition. Preventive measures can be taken if you know what conditions may cause the dangerous reaction.

Dec, Decomp Decompose, Decomposition. Breakdown of a material (by heat, chemical reaction, electrolysis, decay, or other processes) into parts, elements, or simpler compounds.

Decibels The measure of sound waves audible to the human ear. Sounds greater than 85 decibels for prolonged periods can cause hearing loss. 120 decibels is considered to be the threshold of pain.

Decomposition Breakdown of a material or substance (by heat, chemical reaction, electrolysis, decay, or other processes) into parts, elements, or simpler compounds.

Decontamination Destruction of viruses, bacteria, or parasites, usually by means of chemicals, dry or steam heat, or ethylene oxide sterilization.

Defensive Driving The National Safety Council defines defensive driving as the ability behind the wheel "to save lives, time and money in spite of the conditions around you and the actions of others."

Deliquescent A term used to characterize water-soluble salts (usually powdered) that tend to absorb moisture from the air and to soften or dissolve as a result. See Hygroscopic; Hydrophilic.

Delirium A mental state characterized by confusion, disturbed or slurred speech, and sometimes hallucinations.

Demand Respirator A mode of operation for atmosphere-supplying respirators in which air flows into the respirator only when inhalation creates a lower pressure within the facepiece than the ambient atmospheric pressure.

Demulcent A material capable of soothing or protecting inflamed, irritated mucous membranes.

Density Ratio of weight (mass) to volume of a material, usually in grams per cubic centimeter or pounds per gallon. See Specific Gravity and Bulk Density.

Dermal Pertaining to the skin (cutaneous).

Dermal Toxicity Adverse effects resulting from a material's absorption through skin. Ordinarily used to denote effects on experimental animals.

Dermatitis Skin rash; inflammation of the skin (see also Contact Dermatitis).

Designated Area An area of (or device within) a lab to be used for work with select carcinogens, reproductive toxins, and other materials which have a high degree of acute toxicity. An administrative control intended to minimize the potential for employee exposure to hazardous chemicals.

Designated Facility A hazardous waste treatment, storage, or disposal facility that has been designated on the manifest by the generator.

Dessicant A substance, such as silica gel, that removes moisture (water vapor) from the air and is used to maintain a dry atmosphere in containers.

Detector Tubes Color-changing tubes through which air can be drawn to detect the presence of chemicals.

Detonation An engine sound that indicates combustion has occurred too soon (before the piston has reached the top of the compression stroke). It becomes audible through a vibration of combustion chamber walls and has a pinging or knocking sound.

Diaphoresis Perspiration, especially profuse.

Diarrhea Loose and frequent stools.

Dielectric A non-conducting substance such as a material used to manufacture Class A and B helmets.

Diesel engine Named after its inventor, Dr. Randolph Diesel, the engine ignites fuel in the cylinder from heat generated by very high compression instead of using a spark. Fuel is more like kerosene rather than gasoline and no spark plug or carburetor is required.

Dieseling Engine tends to keep running after ignition key is turned off. The heat of compression ignites the air fuel mixture instead of the spark plug.

Diffusion Rate The rate at which one gas or vapor disperses into or mixes with another gas or vapor. The rate is a function of the density of the vapor or gas when compared to air (air = 1).

Dilution Ventilation See General Ventilation.

When associated with tuberculosis, dilution ventilation means an engineering control technique to dilute and remove air-borne contaminants by the flow of air into and out of the area. Air that contains droplet nuclei is removed and replaced by contaminant-free air. If the flow is sufficient, droplet nuclei become dispersed, and their concentration in the air is diminished.

Directly Observed Therapy (DOT) An adherence-enhancing strategy in which a health care worker or other designated person watches the patient swallow each dose of medication.

Discs The area between each vertebrae which acts as a cushion for the spine. Injury to discs is medically referred to as secondary back pain.

Disinfectant Chemical agent capable of killing bacteria, viruses, and parasites. The strongest and most effective are high-level disinfectants.

Dispersion Particulate matter suspended in air or other fluid; the dilution and mixing of contaminants in the ambient environment.

Disposable Respirator A respiratory protective device which cannot be resupplied with an unused filter or cartridge and which is to be discarded in its entirety after its useful service life has been reached.

Disposal Incineration, long-term storage, treatment or discharge, deposit, injection, dumping, spilling, leaking, or placing of a hazardous waste into or on land or water.

Disposal Facility A facility or part of a facility where hazardous waste is intentionally placed into or on any land or water, and at which waste will remain after closure.

Disseminated Tuberculosis TB spread throughout the body, and not limited to the lungs.

Distillation A hazardous waste physical treatment process which involves the evaporation of a liquid or slurry (liquid mixture of insoluble matter) and separation of the components of the resulting vapor.

Division A subdivision of a hazard class.

DNA Probe A technique that allows rapid and precise identification of mycobacterium (e.g., M. tuberculosis and M. bovis) that are grown in culture. The identification can often be completed in two hours.

Doffing To remove.

Domestic Transportation Transportation between places within the United States other than through a foreign country.

Domestic Waste Solid waste, garbage and rubbish, which originate in residential areas.

Donning To put on.

Dose The amount of a chemical substance or drug absorbed into the body. Individual dose rate is the dose delivered per unit of time.

Dose Equivalent A quantity used for radiation protection purposes that expresses on a common scale for all radiations, the irradiation incurred by exposed persons. It is defined as the product of the absorbed dose, the quality factor and any other modifying factors.

Dose/Response The relationship whereby increased health effects are experienced as the dose increases.

DOT Identification Numbers Four-digit numbers [preceded by UN (United Nations) or NA (North America)] used to identify particular materials for regulation of their transportation. See DOT publications that describe the regulations (49 CFR 172.102). These numbers are called product identification numbers (PINs) under the Canadian Transportation of Dangerous Goods Regulation. Those numbers used internationally may carry a "UN" prefix (e.g., UN 1170, ethyl alcohol), but those used only North America have an "NA" prefix (e.g., NA 9121, ferric sulphate).

DOT. U.S. Dept. of Transportation Regulates transportation of materials to protect the public as well as fire, law enforcement, and other emergency-response personnel. DOT classifications specify the use of appropriate warnings, such as Oxidizing Agent or Flammable Liquid. (400 7th St., SW, Washington, DC 20590.)

Double Block and Bleed The closure of a line, duct, or pipe by closing or tagging two inline valves and by opening and locking or tagging a drain or vent valve in the line between the two closed valves.

Drive Shaft Shaft connecting transmission output shaft to differential pinion shaft.

Driving Axles Used to hold, align, and drive rear wheels and support weight of vehicle on rear wheel drive cars. Or, half shafts on front wheel drive cars that provide power to front wheels.

Droplet Nuclei Microscopic particles (1 to 5 microns in diameter) produced when a person coughs, sneezes, shouts, or sings. The droplets produced by an infectious TB patient can carry tubercle bacilli and can remain suspended in the air for prolonged periods of time and can be carried on currents in the room.

Drug Abuse Ingesting substances that alter your state of mind. Like alcoholism, drug abuse interferes with an employee's awareness and judgment, creating unsafe working conditions.

Drug Susceptibility Pattern The anti-tuberculosis drugs to which the tubercle bacilli cultured from a patient are susceptible or resistant, based on susceptibility tests.

Drug Susceptibility Tests Laboratory tests that determine if the tubercle bacilli cultured from a patient are susceptible or resistant to various antituberculosis drugs.

Drum A flat-ended or convex-ended cylindrical packaging made of metal, fiberboard, plastic, plywood, or other suitable materials. This definition also includes packagings of other shapes made of metal or plastic (e.g., round taper-necked packagings or pail-shaped packagings) but does not include cylinders, jerricans, wooden barrels or bulk packagings.

Dual Master Cylinder Primary unit consisting of two sections for displacing fluid under pressure in a split hydraulic brake system.

Dust Solid particles suspended in air, often produced by some mechanical process such as crushing, grinding, abrading, or blasting. Dusts may be inhalation, fire, or dust-explosion hazards.

As defined for process safety managment, dust means solid particles suspended in air, generated by handling, crushing, grinding, abrading, blasting, rapid impact, detonation, or decapitation of organic or inorganic materials, such as rock, ore, metal, coal, wood, or grain. Dusts may be inhalation, fire, or dust-explosion hazards.

Dynamic Exertion Any muscular movement of the body.

Dysfunction Impaired or abnormal function.

Dysplasia Abnormal growth or development of organs or cells.

Dyspnea A sense of difficulty in breathing; shortness of breath.

Dysuria Difficult or painful urination.

EC50 (Median) effective concentration. The concentration of a material expressed in ppm or ppb in the environment (usually water), a single dose of which is expected to cause a biological effect on 50% of a group of test animals.

Ecchymosis Bruise.

ECP See Exposure Control Plan.

Eczema A skin rash characterized by redness, itching, sometimes blistering; may become scaly or crusty.

ED50 (Median) effective dose, usually expressed in mg/kg, that produced a specified effect in 50% of the test population.

Edema Swelling due to accumulation of fluid in body tissues.

EEC European Economic Community.

Effective Dose Equivalent The sum over the tissues of the product of the dose equivalent in a tissue and the weighting factor representing its proportion of the total stochastic (cancer and genetic) risk resulting from irradiation of tissue to the total risk when the whole body is irradiated uniformly.

Effluent Solid, liquid, or gas wastes which enter the environment as a by-product of man-oriented processes; the discharge or outflow of water from ground or subsurface storage.

EFI Electronic Fuel Injection.

EINECS The European Inventory of Existing Chemical Substances. A list of chemical substances identified by CAS and EINECS numbers that were marketed in the European Community between 1/1/71 and 9/18/81.

Elastomeric A natural or synthetic elastic substance.

Electrical Short When an appliance is faulty, electrical current will leak away from the normal circuitry. Since electricity is ground seeking, touching this equipment will draw the current into your body.

Electrocution Receiving a lethal dose of electricity that causes the heart to beat convulsively, and possibly stop beating.

Electrolysis A hazardous waste chemical treatment method by which chemical changes are accomplished at the surface of electrodes carrying an electric current and immersed in a chemical solution.

Electrolyte A substance (as an acid, base, salt) that dissociates into ions when in aqueous solution and that provides ionic conductivity. Electrolytes are lost from the body through perspiration as salts, causing impairment of CNS functions if not adequately replaced.

Electronic Ignition A system that electronically controls current flow in primary circuit.

Element A substance composed entirely of one kind of atom; a solid, liquid, or gaseous matter, which can't be further decomposed into simpler substances by chemical means. Elements are designated by chemical symbols.

Elevated Temperature Material A material that, when offered for transportation or transported in a bulk packaging:

(1) Is in a liquid phase and at a temperature at or above 100 °C (212 °F);

(2) Is in a liquid phase with a flash point at or above 37.8 °C (100 °F) that is intentionally heated and offered for transportation or transported at or above its flash point; or

(3) Is in a solid phase and at a temperature at or above 240 °C (464 °F).

ELINICS A list of approximately 400 chemicals identified by EINECS numbers, established with the European Community from 9/18/81 to 6/30/90. The list was published on 5/29/91 and is a supplement to EINECS. Additional supplements will be added as necessary.

Embolism Obstruction of a blood vessel by a transported clot, a mass of bacteria, etc.

Embryo An organism in the early stages of development before birth. In humans, the developing child is considered an embryo from conception to the end of the second month of pregnancy.

Embryotoxin A material harmful to a developing embryo at a concentration that has no adverse effect on the pregnant female.

Emergency Any occurrence (including any failure of hazard control or monitoring equipment) or event, internal or external to the permit space, that could endanger entrants.

Emergency Response Team (ERT) A team of individuals properly trained and medically certified to respond to industrial emergencies and to enter IDLH environments.

Emesis Vomiting.

Emetic An agent, such as syrup of ipecac, which induces vomiting. Never use emetics if victim is not alert or after ingestion of solvents; always seek medical advice before giving an emetic.

Emission Something discharged into the air.

Emissions Substances discharged into the air from a point source or unit process.

As applied to motor vehicles, emissions means exhaust gasses, fuel vapors, and crankcase oil fumes released to atmosphere.

Emphysema An irreversible lung condition in which the alveolar walls lose resiliency, resulting in excessively reduced lung capacity.

EMT Emergency Medical Technician.

Emulsion A suspension, each in the other, of two or more unlike liquids which usually will not dissolve in each other.

Encapsulation A hazardous waste physical treatment process which encases or encloses the waste with either adhesive coating materials or specially-lined containers, such as steel-lined drums or concrete blocks, in order to isolate and keep it from contaminating the environment.

End-of-service-life Indicator A system that warns the user of the approach of the end of adequate respiratory protection.

Endothermic A chemical reaction that absorbs heat.

Endotracheal Intubation Inserting a tube into the passage leading to the lung (trachea) through the nose or mouth for the purpose of ensuring an open airway for breathing.

Energized Connected to an energy source or containing residual or stored energy.

Energy Absorbing Bumper System designed to protect vehicle from major damage during impact at low speeds.

Energy Control Procedure Written instructions adopted by the employer that describe how equipment and procedures are to be shut down for lockout/tagout and later released from lockout/tagout for safe startup.

Energy Control Program A safety program adopted by the employer that includes energy control procedures plus provisions for inspecting the procedures and training employees for lockout/ tagout.

Energy Isolating Device A mechanical device that physically prevents the transmission or release of energy, including - but not limited to - the following: a manually operated electrical circuit breaker; a disconnect switch; a manually operated switch by which the conductors of a circuit can be disconnected from all ungrounded supply conductors, and, in addition, no pole can be operated independently; a line valve; a block; and any similar device used to block or isolate energy. Push buttons, selector switches, and other control circuit-type devices are not energy-isolating devices.

Energy Source Any source of electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other energy.

ENGERIX-B One of the commercially available vaccines for HBV; derived from genetically modified yeast.

Engineering Controls Engineering control systems reduce potential hazards by isolating the worker from the hazard or by removing the hazard from the work environment. Methods include substitution, ventilation, isolation, and enclosure. This is preferred over administrative controls and personal protective equipment.

Engulfment The surrounding and effective capture of a person by a liquid or finely divided (flowable) solid substance that can be aspirated to cause death by filling or plugging the respiratory system or that can exert enough force on the body to cause death by strangulation, constriction, or crushing.

Entry The action by which a person passes through an opening into a permit required confined space. Entry includes ensuing work activities in that space and is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space.

Entry Permit The written or printed document that is provided by the employer to allow and control entry into a permit space and that contains the information specified in the entry permit.

Entry Permit System The employer's written procedures for preparing and issuing permits for entry and returning the permit space to service following termination of entry and designating by name or title the individuals who may authorize entry.

Entry Supervisor The person (such as the employer, foreman, or crew chief) responsible for determining if acceptable entry conditions are present at a permit space where entry is planned, for authorizing entry and overseeing entry operations, and for terminating entry as required by the entry permit.

EP Extreme pressure.

EPA Hazardous Waste The designation that the U.S. Environmental Protection Agency (EPA) has assigned to certain hazardous wastes.

EPA, (U.S.) Environmental Protection Agency A Federal agency with environmental protection regulatory and enforcement authority. Administers the CAA, CWA, RCRA, TSCA, and other Federal environmental laws. (400 M Street, SW, Washington, DC 20460; [202] 382-2090.)

Epidemiology The study of disease in populations rather than in individuals. Determination of the incidence (rate of occurrence) and distribution of a particular disease (by age, sex, occupation, location, etc.) may provide data about causes of the disease.

Epidermal Pertaining to the outer layer of skin.

Epiphora Excessive flow of tears.

Epistaxis Nosebleed.

Ergonomics A science, derived from two Greek words meaning the "laws of work," which seeks to maximize employee effectiveness while minimizing employee harm by designing workplace equipment that provides the utmost comfort and safety for a particular job.

ERT See Emergency Response Team.

Erythema Redness of the skin; usually due to a local increase in blood flow.

Escape-only Respirator A respirator intended only for use during emergency egress from a hazardous atmosphere.

Esters Organic compounds which may be made by interaction between an alcohol and an acid, and by other means. Esters are nonionic compounds, and include solvents and natural fats.

Ethambutol A first line, oral antituberculosis drug sometimes used concomitantly with isoniazid, rifampin, and pyrazinamide.

Ethionamide A second line oral anti-tuberculosis drug used primarily for treating drug resistant TB.

Ethylene Glycol Liquid chemical (antifreeze) mixed 50/50 with water to form low-freezing/high boiling point coolant.

Etologic Agent See Infectious Substance (etologic Agent).

Etiology All of the factors that contribute to the cause of a disease or an abnormal condition.

Euphoria A feeling of well-being or elation.

Evacuate To quickly and calmly leave an area in order to avoid exposure to a potentially harmful situation.

Evaporation Vaporization of a liquid or solid material to form its gaseous state in air. As temperature and surface area exposed to air increase, so does the rate of evaporation; volatile chemicals tend to evaporate faster.

As used in hazardous waste handling (HAZWOPER), evaporation means a hazardous waste physical treatment process by which suspended and dissolved solids are separated from liquid waste by evaporation of the liquid.

Evaporation Rate The rate at which a material vaporizes (volatilizes, evaporates) from the liquid or solid state when compared to a known material's vaporization rate. Evaporation rate can be useful in evaluating a material's health and fire hazards. The known reference material is usually normal butyl acetate (N-BuAc or n-BuAc), with a vaporization rate designated as 1.0. Vaporization rates of other solvents or materials are then classified as 1) Fast evaporating if greater than 3.0, e.g., methyl ethyl ketone (MEK), 3.8; acetone, 5.6; hexane, 8.3; 2) Medium evaporating if 0.8 to 3.0, e.g., 190-proof (95%) ethyl alcohol, 1.4; VM&P naphtha, 1.4; MIBK, 1.6; 3) Slow evaporating if less than 0.8, e.g., xylene, 0.6; isobutyl alcohol, 0.6; normal butyl alcohol, 0.4; water, 0.3; mineral spirits, 0.1.

Exhaust Emissions Products of incomplete combustion that are discharged to the atmosphere through exhaust system of vehicle.

Exhaust Pipe Pipe connecting engine exhaust manifold to muffler to conduct spent combustion gasses away from engine.

EX Number A number, with the prefix "Ex-", assigned by the Associate Administrator for Hazardous Materials Safety to identify a recognized explosive.

Exothermic A chemical reaction that gives off heat.

Explosive A material that produces a sudden, almost instantaneous release of pressure, gas, and heat when subjected to abrupt shock, high temperature, or an ignition source.

Explosive Limits Some operating materials have minimum and maximum concentrations in air which can be detonated by spark, shock, fire, etc. The lowest concentration is known as the lower explosive limit (LEL). The highest concentration is known as the upper explosive limit (UEL). See Flammable Limits.

Explosive-proof Equipment Apparatus enclosed in a case capable of withstanding an explosion of a specified gas or vapor and preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flash, or explosion of the gas or vapor within, and operating at an external temperature so that a surrounding flammable atmosphere will not be ignited.

Exposure Subjection of a person to a toxic substance or harmful physical agent in the course of employment through any route of entry (e.g., inhalation, ingestion, skin contact, or absorption); includes past exposure and potential (e.g., accidental or possible) exposure, but does not include situations where the employer can demonstrate that the toxic substance or harmful physical agent is not used, handled, stored, generated, or present in the workplace in any manner different from typical nonoccupational situations. Exposure to a substance or agent may or may not be an actual health hazard. An industrial hygienist evaluates exposures and determines if permissible exposure levels are exceeded.

When associated with tuberculosis, exposure means the condition of being subjected to something (e.g, infectious agents) that could have a harmful effect. A person exposed to M. Tuberculosis does not necessarily become infected. See Transmission.

Exposure Control Plan (ECP) A written document required for each workplace in which exposure to BBP's is likely to occur. The ECP must describe in detail how the employer will reduce or eliminate exposure to BBP's, how employees will be trained concerning BBP's, how employees will be medically evaluated after an exposure incident, and how Hepatitis B vaccination will be provided to workers.

Exposure Incident Contact with blood or other potentially infectious materials that results from a worker's job duties, and creates some potential for infection. Such exposures may include injection through the skin or contact with the eye, mouth, other mucous membrane, or non-intact skin.

Exposure Limits The concentration in workplace air of a chemical deemed the maximum acceptable. This means that most workers can be exposed at given levels or lower without harmful effects. Exposure limits in common use are 1) TLV-TWA (threshold limit value - time-weighted average); 2) STEL (short-term exposure limit); and 3) C (ceiling value).

Extinguishing Media, Agents The type of fire extinguisher or extinguishing method appropriate for a specific material. Some chemicals react violently in the presence of water, so other methods, such as the use of foam or CO2, should be followed.

F, Fahrenheit The temperature scale in which 212 °F is the boiling point of water at 760 mm Hg and 32 °F is the freezing point.

f/cc Fibers per cubic centimeter of air.

Faceshield A protective device commonly intended to shield the wearer's face, or portions thereafter, in addition to the eyes, from certain hazards. Faceshields are secondary protectors and shall be used only with primary protectors.

Facility The buildings, containers, or equipment which contain a process.

Failure Mode and Effect Analysis (FMEA) A methodical study of component failures. This review checks a diagram of the operation and assesses all components that could fail and conceivably affect the safety of the operation. These components are listed on a data tabulation sheet and individually analyzed.

Fasciculation Muscular twitching.

Fatigue Tiredness, localized or involving the whole body. Localized fatigue affects a specific part of the body and causes muscles to lose their ability to contract, resulting in a loss of control. Whole body fatigue contributes to an overall feeling of weakness and loss of alertness. Fatigue reduces an employee's ability to perform and often causes accidents. Office worker fatigue can sometimes be attributed to lack of mobility during the day.

Fault Tree Analysis A qualitative or quantitative model of all undesirable outcomes, such as a toxic gas release or explosion, that could result from a specific initiating event.

Feasibility Study A detailed examination of the technical, environmental, engineering, economic, legal, and practical suitability of a proposed facility or technology for use at a specific location.

Febrile Running a fever.

Federal Register (U.S ) See FR.

Fiber A basic form of matter, usually crystalline, with a high ratio of length to diameter. Examples: animal (wool); vegetable (cotton); mineral (asbestos, steel); and synthetic (rayon, carbon, high polymers).

Fibrosis The formation of fibrous tissue in excess of amounts normally present in lung-tissue walls, in response to inhaled material. This reduces the oxygen and CO2 exchange efficiency and lung capacity.

FIFRA The Federal Insecticide, Fungicide, and Rodenticide Act. Enacted on 10/21/72, this act provides the regulatory authority for registration and use of pesticides and similar products intended to kill or control insects, rodents, and weeds.

Fight or Flight Response The stimulation of the nervous system to a frightening or threatening situation. When the body is alerted, adrenaline begins to pour into the bloodstream.

Filter A media component used in respirators to remove solid and/or liquid particles from the inspired air.

Filtration A hazardous waste physical treatment process which removes suspended particles from liquid by forcing fluid through a porous substance (paper, cloth, fine clay, sand, or charcoal), entrapping suspended particles on or within the filter medium.

Fines Finely crushed or powdered material or fibers; especially those smaller than the average in a mix of various sizes.

Fire Diamond (NFPA Hazard Rating) The National Fire Protection Agency (NFPA) visual rating system that addresses the health, flammability, reactivity, and related hazards of a material which may exist due to a short term, acute exposure caused by a fire spill, or similar emergency. Per "NFPA 704" publication.

Position A - Health Hazard (Blue). Degree of hazard; level of short-term protection

0 = Ordinary Combustible Hazards in a Fire

1 = Slightly Hazardous

2 = Hazardous

3 = Extreme Danger

4 = Deadly

Position B - Flammability (Red). Susceptibility to burning

0 = Will Not Burn

1 = Will Ignite if Preheated

2 = Will Ignite if Moderately Heated

3 = Will Ignite at Most Ambient Conditions

4 = Burns Readily at Ambient Conditions

Position C - Reactivity, Instability (Yellow). Energy released if burned, decomposed, or mixed

0 = Stable and Not Reactive with Water

1 = Unstable if Heated

2 = Violent Chemical Change

3 = Shock and Heat May Detonate

4 = May Detonate

Position D - Special Hazard (White).

OX = Oxidizer

W = Use No Water, reacts!

Fire Extinguisher A hand-held device used to fight fires. There are three types of fire extinguishers: pressurized water, dry chemical, and carbon dioxide gas. It's important that you know how to properly use an extinguisher. Ask your employer to train you before an emergency occurs.

Fire Point The lowest temperature at which a liquid produces sufficient vapor to flash near its surface and continues to burn -- usually 10 to 30 °C higher than the flash point.

First Aid Immediate measures that can be taken by the victim or others before qualified medical help arrives in order to reduce or eliminate the potential effects of a chemical exposure or other injury.

First Line Drugs The most often used anti-tuberculosis drugs (i.e., INH, rifampin, pyrazinamide, ethambutol, and streptomycin).

Fit Check A test conducted by the wearer to determine if the respirator is properly seated to the face.

Fit Factor An estimate of the ratio of the average concentration of a challenge agent in a test chamber to the average concentration inside the respirator as worn with a high-efficiency filter.

Fit-test The use of a challenge agent to evaluate the fit of an individual's respirator.

Fixed Room-Air HEPA Recirculation Systems Nonmobile devices or systems that remove airborne contaminants by recirculating air through a HEPA filter. These may be built into the room and permanently ducted, or mounted to the wall or ceiling within the room. In either situation, they are fixed in place and are not easily movable.

Flammable Describes any solid, liquid, vapor, or gas that ignites easily and burns rapidly. See Combustible.

Flammable Aerosol An aerosol that yields a flame projection exceeding 18 inches at full valve opening, or a flashback (a flame extending back to the valve) at any degree of valve opening.

Flammable Gas A gas that at normal atmospheric pressure forms a flammable mixture with air at a concentration of 13% by volume or less; or over a concentration range greater than 12% by volume, regardless of lower limit.

Flammable Limits (Flammability Limits, Explosive Limits) Minimum and maximum concentrations of a flammable gas or vapor between which ignition can occur. Concentrations below the lower flammable limit (LFL) are too lean to burn, while concentrations above the upper flammable limit (UFL) are too rich. All concentrations between LFL and UFL are in the flammable range, and special precautions are needed to prevent ignition or explosion.

Flammable Liquid A liquid that gives off vapors readily ignitable at room temperature. The DOT defines a flammable liquid as a liquid with a flash point of not more than 141 °F (60.5 °C). The NFPA and OSHA generally define a flammable liquid as a liquid with a flash point below 100° F (37.8 °C ).

Flammable Solid A solid, other than a blasting agent or explosive, that can cause fire through friction, absorption of moisture, spontaneous chemical change, or retained heat from manufacturing or processing, or which can be ignited readily, and when ignited, burns so vigorously and persistently as to create a serious hazard. A flammable solid ignites and burns with a self-sustained flame at a rate greater than one-tenth of an inch per second along its major axis.

Flash Back Occurs when a distant spark or ignition source ignites a trail of flammable material (e.g., gasoline vapor). The flame then travels along the trail of the material back to its source.

Flash Point, FP Lowest temperature at which a flammable liquid gives off sufficient vapor to form an ignitable mixture with air near its surface or within a vessel. FP is determined by laboratory tests in cups. See Fire Point.

Flooding Too much fuel for operating conditions.

Fluid A substance which flows or conforms to the outline of its container, either as a liquid, gas, or solid.

Fluorochrome Stain A technique for staining a clinical specimen with fluorescent dyes to perform a microscopic examination (smear) for mycobacteria. This technique is preferable to other staining techniques because the mycobacteria can be easily seen and the slides can be quickly read.

FM See Formula Mass.

Foam Fire-fighting material consisting of water and foaming agents into which air is blown, producing a voluminous, stable blanket of bubbles. The foam clings to vertical and horizontal surfaces and flows freely over burning materials. Foam puts out a fire by blanketing it, excluding air, and blocking escape of volatile vapor. Its flowing properties resist mechanical interruption and reseal the burning material.

Fog A visible suspension of fine droplets of liquid in a gas; e.g., water in air.

Fomites Linens, books, dishes, or other objects used or touched by a patient. These objects are not involved in the transmission of M. tuberculosis.

Formula The scientific expression of a chemical composition of a material (e.g., water is H2O, sulfuric acid is H2SO4, sulfur dioxide is SO2).

Formula Mass The sum of atomic weights of the atoms in a molecule. For example, water (H2O) has a formula mass of 18.0, the atomic weights being [hydrogen: 2(1.0) + oxygen: 16] = 18.0.

Formula Weight See Molecular Weight.

FP See Flash Point.

FR The Federal Register. A daily publication that lists and discusses Federal regulations. Available from the Government Printing Office, Washington, DC.

Fracture A broken bone, either open or closed. An open fracture has penetrated the skin, causing a gash. A closed fracture is not associated with an open wound.

For PPE, a lens will be considered to have fractured if it cracks through its entire thickness, including a laminar layer, if any, and across a complete diameter into two or more separate pieces, or if any lens material visible to the naked eye becomes detached from the ocular surface.

Freezing Point The temperature at which a material changes from a liquid to a solid state upon cooling. This information is important because a frozen material may burst its container or the hazards could change.

Front The part of a spectacle frame that is intended to contain the lens or lenses.

Fugitive Emission Gas, liquid, solid, vapor, fume, mist, fog, or dust that escapes from process equipment or a product.

Full Protective Clothing Fully protective gear that prevents skin contact with, inhalation of, or ingestion of gases, vapor, liquids, and solids (dusts, etc.). Includes SCBA (self-contained breathing apparatus).

Full Thickness Burn Third-degree burn causing complete destruction of the skin and subcutaneous tissues including nerves and blood vessels; the skin may appear charred or ulcerated.

Fume Gas-like emanation containing minute solid particles arising from the heating of a solid body such as lead. This physical change is often accompanied by a chemical reaction, such as oxidation. Particles are usually of a size which readily reach the air sacs (alveoli) of the lungs. Odorous gases and vapors are not considered fumes.

Fuse A piece of wire which will carry a limited amount of current only, above which it melts and breaks electrical circuit to avoid damage from excessive current.

g Gram. Metric unit of weight. See kg.

g/kg Grams per kilogram is an expression of dose used in oral and dermal toxicology testing to denote grams of a substance dosed per kilogram of animal body weight. Also see kg (kilogram).

Gangrene Death of tissue leading to its rotting.

Gas A formless fluid which disperses in air; often found in tanks or cylinders and may be created by a chemical reaction. It can be changed to its liquid or solid state only by increased pressure and/or decreased temperature.

Gastric Aspirate A procedure sometimes used to obtain a specimen for culture when a patient cannot cough up adequate sputum. A tube is inserted into the mouth or nose and into the stomach to recover sputum that was coughed into the throat and then swallowed. This procedure is particularly useful for diagnosis in children, who are often unable to cough up sputum.

Gastric Lavage Washing out the stomach with a tube and fluids. Pumping the stomach.

Gastroenteritis Stomach and intestine inflammation.

Gastrointestinal Tract (GI Tract) The stomach and intestine as a functional unit.

Gauntlet The area of the glove between the wrist and the reinforced edge of the opening.

Gavage Feeding by means of a stomach tube.

General Dilution Ventilation A method of ventilation which allows contaminants to mix with the room air and then is diluted to acceptable exposure levels.

General Exhaust A system for exhausting air containing contaminants from a general work area. See Local Exhaust.

General Ventilation Also known as dilution ventilation. The removal of contaminated air and its replacement with clean air from the general workplace area as opposed to local ventilation, which is specific air changing in the immediate area of a contamination source. An example of local ventilation is a laboratory fume hood.

Generator The person who, by nature of ownership, management, or control, is responsible for causing or allowing the creation of hazardous waste.

Generic Name A common, possibly chemical, name applied generally to a substance. For example, bleach is the generic name for the chemical sodium hypochlorite. Chlorox™ is a tradename for bleach. A chemical name may be used as a generic name, but tradenames are not generic names.

Gestation The development of the fetus in the womb from conception to birth (i.e., pregnancy).

GFCI See Ground Fault Circuit Interrupter.

GI, GIT See Gastrointestinal Tract.

Gingivitis Inflammation of the gums.

Glare The reflection of natural and artificial light on an object. Glare causes eyestrain and headaches for VDT users. Reduce glare on your VDT by drawing shades or drapes or constructing a monitor hood using some tape and three file folders.

Glove Cuff Roll The roll or reinforced edge of an insulating glove at the cuff.

Glucose A substance in the blood which provides energy for muscle movement.

Glutaraldehyde A high-level chemical disinfectant capable of killing BBP's.

Goggle A protective device intended to fit the face immediately surrounding the eyes in order to shield the eyes from a variety of hazards.

Granuloma An abnormal lump or mass of inflamed tissue, which is caused by an infection.

GRAS Generally recognized as safe. A phrase applied to food additives approved by the Food and Drug Administration (FDA).

Grip Span The range in which your hand should have to spread in order to hold a tool handle. The grip span of hand tools should measure no more than 2 inches to 3 inches.

Ground A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth.

Ground Fault Circuit Interrupter A device that senses a loss of current to ground, i.e., a short circuit from a power tool in a worker's hands, and "interrupts" or cuts off the power. The worker is spared a shock. Many building codes now require that GFCIs be installed in new construction.

Grounded Connected to earth or to some conducting body that serves in place of the earth.

Grounding A safety practice to conduct any electrical charge to the ground, preventing sparks that could ignite a flammable material. See Bonding.

Groundwater The portion of the subsurface water which is in the zone of saturation where nearly all openings between soil particles are filled with water; area where water is apt to flow most freely.

h, hr(s) Hour(s). "h" is preferred.

Half-Life Biological half-life: The time required for a biological system such as that of a human, to eliminate by natural processes half the amount of a substance that has entered it. Radiological half-life: The time in which half the atoms of a particular radioactive substance disintegrate to another nuclear form. Measured half-lives vary from millionths of a second to billions of years. Effective half-life: The time required for the amount of a radioactive nuclide deposited in a living organism to be diminished 50 percent as a result of the combined action of radioactive decay and biological elimination.

Handshield A hand-held welding helmet. See Welding Helmet.

Harness An arrangement of very strong straps that encircle a person's body to create a secure means of attaching that person to one or more lines, for preventing falls, providing secure positioning, or aiding retrieval in the event of an accident.

The complete assembly by means of which the helmet is maintained in position on the wearer's head.

HAV See Hepatitis A Virus.

Hazard The likelihood of injury under a given set of environmental conditions; for a chemical this depends on toxicity, level of exposure, duration, and individual susceptibility.

Hazard and Operability Study (HAZOP) A formally structured method of systematically investigating each element of a system for all of the ways in which important parameters can deviate from the intended design conditions to create hazards and operability problems. The hazard and operability problems are typically determined by a study of the piping and instrument diagrams (or plant model) by a team of personnel who critically analyze effects of potential problems arising in each pipeline and each vessel of the operation.

Hazard Class The category of hazard assigned to a hazardous material under the criteria of 49 CFR Part 173 and the provisions of the 49 CFR 172.101 Table. A material may meet the defining criteria for more than one hazard class, but it is assigned to only one hazard class. See Class.

Hazard Communication Rule Requires chemical manufacturers and importers to assess the hazards associated with the materials in their workplace (29 CFR 1910.1200). Material safety data sheets, labeling, and training are all results of this law. You are urged to acquire and become familiar with these regulations. Contact your local OSHA office. See OSH Act.

Hazard Warning Defined by OSHA as "any words, pictures, symbols, or combination thereof appearing on a label or other appropriate form of warning which convey the hazard(s) of the chemical(s) in the container(s)".

Hazard Zone One of four levels of hazards (Hazard Zones A through D) assigned to gases, as specified in 49 CFR 173.116(a), and one of two levels of hazards (Hazard Zones A and B) assigned to liquids that are poisonous by inhalation, as specified in 49 CFR 173.133(a). A hazard zone is based on the LC50 value for acute inhalation toxicity of gases and vapors, as specified in 49 CFR 173.133(a).

Hazardous Atmosphere An atmosphere that may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue (i.e. escape unaided from a permit space), injury, or acute illness from one or more of the following causes: 1) flammable gas, vapor, or mist in excess of 10% of its lower flammable limit (LFL); 2) airborne combustible dust at a concentration that meets or exceeds its LFL; 3) atmospheric oxygen concentration below 19.5% or above 23.5%; 4) atmospheric concentration of any substance for which a dose or a permissible exposure limit is published in subpart G, Occupational Health and Environmental Control or subpart Z, toxic and hazardous substances of this part and which could result in employee exposure in excess of its dose or permissible exposure limit; and 5) any atmospheric condition that is immediately dangerous to life and health.

Hazardous Chemical A substance which meets the definitions for "health hazard" under the Hazard Communication standard (29 CFR 1910.1200(c)).

Hazardous Chemical, Material In a broad sense, any substance or mixture of substances having properties capable of producing adverse effects on the health or safety of a human. In 1971 OSHA adopted the following definition in regulations affecting employers in operations subject to the Federal Longshoremen's and Harbor Worker's Compensation Act. "The term Hazardous Material means a material which has one or more of these characteristics: 1) Has a flash point below 140 °F (60 °C), closed cup, or is subject to spontaneous heating; 2) Has a threshold limit value below 400 ppm for gases and vapors, below 15 mg/m3 for fumes, and below 25 mppcf (million particles per cubic foot) for dusts; 3) Has a single dose oral LD50 below 500 mg/kg; 4) Is subject to polymerization with the release of large amounts of energy; 5) Is a strong oxidizing or reducing agent; 6) Causes first-degree burns to skin [from a] short time exposure, or is systemically toxic by skin contact; or 7) In the course of normal operations, may produce dusts, gases, fumes, vapors, mists, or smokes which have one or more of the above characteristics." Included are substances that are carcinogens, toxic, irritants, corrosives, sensitizers, and agents which damage the lungs, skin, eyes, mucous membranes, etc.

Hazardous Decomposition A breaking down or separation of a substance into its constituent parts, elements, or into simpler compounds accompanied by the release of heat, gas, or hazardous materials.

Hazardous Decomposition Products Hazardous products resulting from decomposition of a material. For example, vinyl chloride, a compound widely used to make plastics, releases poisonous hydrogen chloride, carbon monoxide, and phosgene gases when burned.

Hazardous Exposure Level 1) The permissible exposure limit (PEL) for the hazardous chemical in 29 CFR Part 1910 Subpart Z, of the General Industry Standards of the Occupational Safety and Health Administration (OSHA); or 2) If there is no PEL for the hazardous chemical, the Threshold Limit Value (TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) in the latest edition of Threshold Limit Values for Chemical Substances and Physical Agents in the Work Environment; or 3) If there is no PEL or TLV for the hazardous chemical, the NIOSH Recommended Exposure Limit (REL); or 4) If there is no PEL, TLV, or REL for the hazardous chemical, an exposure level based on available scientific information, including material safety data sheets (MSDSs).

Hazardous Material A substance or material, which has been determined by the Secretary of Transportation to be capable of posing an unreasonable risk to health, safety, and property when transported in commerce, and has been so designated. The term includes hazardous substances, hazardous wastes, marine pollutants, elevated temperature materials, materials designated as hazardous under the provisions of 49 CFR §172.101 and §172.102, and materials that meet the defining criteria for hazard classes and divisions in 49 CFR Part 173. See Hazardous Chemical; Hazardous Chemical, Material.

Hazardous Materials In a broad sense, hazardous materials are any substance or mixture of substances having properties capable of producing adverse effects on the health and safety or the environment of a human being.

Hazardous Substance As used in the DOT regulations, a material, including its mixtures and solutions, that:

(1) Is listed in Appendix A to 49 CFR 172.101;

(2) Is in a quantity, in one package, that equals or exceeds the reportable quantity (RQ) listed in Appendix A to §172.101; and

(3) When in a mixture or solution:

(i) For radionuclides, conforms to paragraph 6 of Appendix A to §172.101.

(ii) For other than radionuclides, is in a concentration by weight that equals or exceeds the concentration corresponding to the RQ of the material, as shown in the following table. This definition does not apply to petroleum products that are lubricants or fuels. See 40 CFR 300.6.
RQ in pounds (kilograms)
Concentration by Weight

Percent PPM

5000 (2270) 10100000
1000 (454) 220000
100 (45.4) 0.22000
10 (4.54) 0.02200
1(0.454) 0.002 20

Hazardous Waste Any solid waste which is ignitable, corrosive, reactive, or toxic, and which may pose a substantial or potential hazard to human health and safety, or to the environment, when improperly managed.

HDV See Hepatitis D Virus.

Headband The part of the harness that encircles the head.

Headgear That part of a protective helmet, hood or faceshield that supports the device on the wearer's head.

Health Care Professional (HCP) Physician, nurse, or other health professional knowledgeable in recognition, prevention, and treatment of infections caused by BBP's. HCPs are licensed by the government of the state in which they practice.

Health Hazard A chemical for which there is significant evidence based on at least one study conducted in accordance with established scientific principles, that acute or chronic health effects may occur in exposed employees. The term health hazard includes chemicals which are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, heptatoxins, nephrotoxins, neurotoxins, agents which act on the hematopoietic system, and agents which damage the lungs, skin, eyes, or mucous membranes.

Health Surveillance The continuing scrutiny of specific individuals for the purpose of identifying disorders or health states, especially those which may relate to exposure to hazardous materials.

Heat Cramps Salt removed from the body as the result of excessive perspiration can cause cramps in the limbs or abdominal muscles.

Heat Strokes A loss of fluid and salt from the body through exposure to a hot environment resulting in excessive perspiration that causes the body temperature to rapidly rise. Heat stroke is a life-threatening emergency requiring physician attention.

Heavy Metals High-density metallic elements (e.g. mercury, chromium, cadmium, arsenic, and lead) which are generally toxic to plant and animal life in low concentrations.

Helmet A device that is worn to provide protection for the head, or portions thereof, against impact, flying particles, electric shock, or any combination thereof, and that includes a suitable harness.

Hematoma Bleeding into the tissues.

Hematuria Blood in the urine; gross hematuria results from enough blood to turn the urine orange or red; microscopic hematuria cannot be seen with the naked eye.

Hemolysis Destruction of red blood cells, leading to release of hemoglobin.

Hemolytic Anemia A loss of red blood cells due to destruction.

Hemoptysis Coughing up blood.

Hemorrhage Loss of blood in significant amounts; can be external bleeding, as with a laceration, or internal bleeding.

HEPA High-Efficiency Particulate Air Filter. A specialized filter that is capable of removing 99.97% of particles 0.3 microns or greater in diameter. Filters may be used in ventilation systems to remove particles from air or in personal respirators to filter air before it is inhaled by the person wearing the respirator. The use of HEPA filters in ventilation systems requires expertise in installation and maintenance.

Hepatic Pertaining to the liver.

Hepatitis A disease of the liver caused by infection, exposure to certain chemicals, adverse reactions to medications, or overuse of alcohol. Hepatitis may cause jaundice and result in cirrhosis.

Hepatitis A Virus (HAV) One of the viruses that can cause hepatitis. Infection occurs within 2 to 6 weeks after exposure to food or water contaminated by sewage. HAV infection can temporarily be very disabling, but most people recover completely.

Hepatitis B Immune Globulin (HBIG) A preparation that gives the recipient immediate passive immunity to HBV; usually given after a known or likely exposure to HBV.

Hepatitis B Virus (HBV) One of the viruses that causes hepatitis. It can be spread by exposure to blood or other body fluids. It can be detected by blood testing and prevented by vaccines. HBV is currently responsible for 200 deaths in the United States per year due to infection contracted at work.

Hepatitis C Virus (HCV) One of the viruses that can cause hepatitis. A newly developed blood test can detect HCV infection, but there is no current treatment.

Hepatitis D Virus (HDV) A virus that is a less common cause of hepatitis. It only infects those who are already infected with HBV.

Hepatitis E Virus (HEV) A rare cause of hepatitis in the United States. It is similar in many ways to HAV.

HEPTAVAX The first commercially available vaccine for HBV. It was derived from the plasma of people who had been infected with HBV. It is no longer available.

HEV See Hepatitis E Virus.

High-level Disinfectant Chemical agent capable of killing all known BBP's. Examples are bleach and glutaraldehyde.

Highly Hazardous Chemical A substance possessing toxic, reactive, flammable, or explosive properties as identified by the Process Safety Management standard (Title 29 CFR 1910.119).

Highly Toxic A chemical falling within any of the following categories: 1) A chemical with a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each; 2) A chemical with a median lethal dose (LD50) of 200 milligrams or less per kilogram of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between 2 and 3 kilograms each; 3) A chemical that has a median lethal concentration (LC50) in air of 200 parts per million by volume or less of gas or vapor, or 2 milligrams per liter or less of mist, fume, or dust, when administered, by continuous inhalation for one hour (or less if death occurs within one hour) to albino rats weighing 200 and 300 grams each.

HIV Human Immunodeficiency Virus. Infection with the virus that causes Acquired Immunodeficiency Syndrome (AIDS). HIV infection is the most important risk factor for the progression of latent TB infection to active TB.

HMIS The hazardous materials identification system developed by the National Paint and Coatings Association (NPCA) to provide information on the acute health, reactivity, and flammability hazards encountered in the workplace. This system also includes temperatures under fire conditions (especially for flammability and reactivity). A number is assigned to a material indicating degree of hazard, from 0 for the least up to 4 for the most severe. Letters designate personal protective equipment. (Details from Labelmaster, 5724 N Pulaski Rd, Chicago, IL 60646; [312] 478-0900.) See NPCA.

Hood For PPE, a respiratory device that completely covers the head, neck, and portions of the shoulders.

For engineering controls, and enclosed cabinet or other local ventilating system which draws in and exhausts air from a work area to prevent or minimize release of chemical or biological contaminants into the air. See Local Exhaust Ventilation.

Horsepower Energy required to lift 550 lb. 1 ft. in 1 sec.

Host An organism which affords a place for a parasite to lodge or remain in existence.

Hot Tap A procedure used in repair, maintenance, and service activities that involves welding on a piece of equipment (pipelines, vessels, or tanks) under pressure, in order to install connections or appurtenances. It is commonly used to replace or add sections of pipeline without the interruption of service for air, gas, water, steam, and petrochemical distribution systems.

Hot Work Work involving electric or gas welding, cutting, brazing, or similar flame or spark-producing operations.

Hot Work Permit The employer's written authorization to perform operations which could provide a source of ignition, such as riveting, welding, cutting, burning, or heating.

Hydrolysis The process by which a chemical compound is decomposed by reaction with water.

Hydrophilic Describing materials having large molecules that tend to absorb and retain water, causing them to swell and frequently to gel. See Deliquescent.

Hygroscopic Readily adsorbing available moisture in any form. See Deliquescent.

Hyperaemia Congestion of blood in a body part.

Hypergolic Self-igniting upon contact of its components without a spark or external aid; especially rocket fuel or a propellant that consists of combinations of fuels and oxidizers.

Hypersensitivity Condition of being sensitized or allergic to a specific chemical.

Hypertension Chronic high blood pressure. Although stress doesn't cause hypertension, it can aggravate the condition. If you suffer from hypertension, and you work in a high stress office environment, you are at risk for a stroke or heart attack. See your doctor right away for effective treatment.

Hyperthermia Excessively high body temperature.

Hyperventilation Rapid, deep breathing.

Hypocalcemia Calcium deficiency of the blood.

Hypothermia Excessively low body temperature.

Hypoxia Insufficient oxygen reaching the tissues of the body. See Anoxia.

I Intermittent.

I.V. Intravenous Injection of a substance into a vein.

IARC International Agency for Research on Cancer. One of the three sources that OSHA refers to for data on a material's carcinogenicity. (World Health Organization, Geneva, Switzerland; distributed in the USA from 49 Sheridan Avenue, Albany, NY 12210 [518] 436-9686.)

IATA International Air Transport Association.

ICAO International Civil Aviation Organization.

IDLH See Immediately Dangerous to Life and Health.

Ignitability Identifies a waste that may cause a fire during routine disposal and storage conditions. A characteristic, which identifies a waste as hazardous, when the waste has a flashpoint of less than 60 _C (140 °F).

Ignitable Capable of being set afire.

Ignitable Waste A liquid with a flashpoint less than 60 °C (140 °F), a waste which is an oxidizer, or ignitable compressed gas or non-liquid, or a waste liable to cause fires through friction, absorption of moisture, or spontaneous chemical changes.

Ignition Source Any material that can fuel a fire. In offices, stacks of paper and electrical equipment, such as computers and copy machines, are potential sources of fire.

Ignition System Means for igniting fuel in cylinders. Includes spark plugs, wiring, distributor, ignition coil, and source of electrical current.

Ignition Temperature The lowest temperature at which a combustible material ignites in air and continues to burn independently of the heat source.

Ignition Timing Synchronization of distributor to engine crankshaft so ignition takes place in each cylinder in proper firing order.

IMDG Code, IMO Classification The IMDG (International Maritime Dangerous Goods) Code assigns divisions, classes, and codes to materials in shipment. These are explosives, flammables, oxidizers, poisons, corrosives, and other regulated substances. The code also assigns labeling and the DOT UN/NA and PINs. (International Maritime Organization, #4 Albert Embankment, London, SE 175R, United Kingdom.)

Immediately Dangerous to Life and Health (IDLH) The maximum concentration from which one could escape within 30 minutes without any escape-impairing symptoms or irreversible health effects. Used to determine respirator selection. (Note: Carcinogenic effects were not considered in setting these values.)

Immiscible Liquids which will not mix with each other, but will form 2 separate layers or will result in cloudiness or turbidity.

Immune System The infection-fighting system of the body which includes the spleen, the white blood cells, lymph nodes, and antibodies, as well as other cells and organs specialized for this purpose.

Immunity Protection from infection. Immunity can be either active (occurring after recovery from infection or after vaccination) or passive (occurring after receiving antibodies). Active immunity lasts many years; passive lasts a few months.

Immunization Process by which a person achieves immunity. It can be active or passive.

Immunocompromised Damage to the body's immune system resulting in a reduction in the ability of the body to overcome or resist disease.

Immunosuppressed A condition in which the immune system is not functioning normally (e.g., severe cellular immunosuppression resulting from HIV infection or immunosuppressive therapy). Immunosuppressed persons are at greatly increased risk for developing active TB after they have been infected with M. tuberculosis. No data are available regarding whether these persons are also at increased risk for infection with M. tuberculosis after they have been exposed to the organism.

Impact Resistance The ability of a device to withstand impact as required by the ANSI Z87.1-1989 standard.

Impermeable Not allowing passage of a chemical; for example, chemical-resistant gloves or apron.

Impervious Describes a material that does not allow another substance to penetrate or pass through it. Impermeable.

IM Portable Tank See Intermodal Portable Tank.

Incompatible Materials that could cause dangerous reactions by direct contact with one another; an incompatible waste.

Incompatible Waste A hazardous waste unsuitable for placement within a specific portion of a landfill because it may cause containment material to corrode or decay. Combined with other wastes, may produce heat, pressure, fire, explosion, violent reaction, toxic dusts, mists, fumes, or gases. Also, a hazardous waste which, if mixed, becomes more hazardous than either waste individually.

Independent Suspension A suspension system that allows the wheel on one side of the vehicle to rise or fall independently of the wheel on the other side.

Individual Susceptibility Differences between individuals in their response to a given toxic exposure (see also Susceptibility).

Induced Sputum Sputum obtained from a patient unable to cough up a spontaneous specimen. The patient inhales a mist of saline (salt water), which stimulates a cough from deep within the lungs.

Induration An area of swelling produced by an immune response to an antigen. In tuberculin skin testing or anergy testing, the diameter of the indurated area is measured 48-72 hours after the injection, and the result is recorded in millimeters.

Inert Chemically and biologically inactive; does not react with the body.

Inert Ingredients Anything other than the active ingredient in a product; not having active properties. Inert ingredients may be hazardous. For example, the propellant gas in aerosol spray, such as hair spray, may be flammable.

Inerting The displacement of the atmosphere in a permit space by a noncombustible gas (such as nitrogen) to such an extent that the resulting atmosphere is noncombustible.

Infection Disease caused by a virus, bacteria, or parasite. The condition in which organisms capable of causing disease (e.g., M. tuberculosis) enter the body and elicit a response from the host's immune defenses. TB infection may or may not lead to clinical disease.

Infection Control Plan A plan required by OSHA to prevent the transmission of infection in the workplace.

Infectious Capable of transmitting infection.

Infectious Substance (etiologic agent) A viable microorganism, or its toxin, that causes or may cause disease in humans or animals, and includes those agents listed in 42 CFR 72.3 of the regulations of the Department of Health and Human Services; or any other agent that causes or may cause severe, disabling or fatal disease. The terms "infectious substances" and "etiologic agent" are synonymous. See 49 CFR 173.134.

Infectious Waste Waste that contains pathogens. May consist of tissues, organs, body parts, blood, and body fluids that are removed during surgery (see Biological Hazardous Waste).

Inflammable Capable of being easily set on fire and continue burning, especially violently. Do not confuse with nonflammable. See Combustible and Flammable.

Inflammation A local response to cellular injury due to trauma, infection, or chemical irritation; symptoms include swelling, redness, pain, tenderness, and loss of function.

Ingestion Swallowing a chemical or biological substance; may inadvertently result from eating, drinking, or smoking in the workplace or with contaminated hands.

INH Isoniazid. A first line, oral drug used either as preventative therapy or in combination with several other drugs to treat TB disease.

Inhalation Entry of a chemical substance to the lungs by breathing.

Inhibitor A material added to another to prevent an unwanted reaction; e.g., polymerization.

Injectable A medication that is usually administered by injection into the muscle (intramuscular [IM]) or the bloodstream (Intravenous [IV]).

Injection The subsurface emplacement of a fluid or waste. Entry of a chemical substance, biological agent or medication through the skin.

Injection Well A well into which fluids are injected.

Inner Packaging A packaging for which an outer packaging is required for transport. It does not include the inner receptacle of a composite packaging.

Inorganic Compounds Chemical compounds which do not contain the element carbon.

Inorganic Materials Compounds derived from other than vegetable or animal sources that do not generally contain carbon atoms. Some simple carbon compounds are considered inorganic (e.g., CO2, carbonates, cyanides).

Insol Insoluble.

Insole The inner part of footwear upon which the foot rests and which conforms to the bottom of the last.

Interlock An interlock is a device that prevents the operation of a machine while the cover or door of the machine is open or unlocked, and which will also hold the cover or door closed and locked while the machine is in motion.

Intermittent Therapy Therapy administered either two or three times per week rather than daily. Intermittent therapy should be administered only under the direct supervision of a health care worker or other designated person. See Directly Observed Therapy.

Intermodal Portable Tank or IM Portable Tank A specific class of portable tanks designed primarily for international intermodal use.

International Transportation Transportation:

(1) Between any place in the United States and any place in a foreign country;

(2) Between places in the United States through a foreign country; or

(3) Between places in one or more foreign countries through the United States.

Interstitial Fibrosis Scarring of the lungs.

Intradermal Within the layers of the skin.

Intraperitoneal A route of administration for toxicological studies. A material is injected into the peritoneal (abdominal/pelvic) cavity.

Involuntary Muscles Muscles of the body over which you have no control, such as those of the stomach and heart.

Iodism An abnormal condition resulting from prolonged (chronic) exposure to iodine or its compounds - characterized by emaciation, skin eruptions, headache, excess salivation, runny nose, and sneezing.

IRDS Primary irritation dose.

Iridocyclitis Inflammation of both the eye's iris and its ciliary body.

IRR Irritant effects. Any irritant effect on the skin, eye, or mucous membrane.

Irritant A noncorrosive material that causes a reversible inflammatory effect on living tissue by chemical action at the site of contact as a function of concentration or duration of exposure.

A substance capable of causing a reversible or irreversible inflammatory effect to the skin, eyes, nose, throat, or lungs.

Irritating Material A material with properties similar to tear gas that causes extreme irritation, especially in confined spaces.

Isolation The process by which a permit space is removed from service and completely protected against the release of energy and material into the space by such means as: blanking or blinding; misaligning or removing sections of lines, pipes, or ducts; a double block and bleed system; lock out or tag out of all sources of energy; or blocking or disconnecting all mechanical linkage.

Isomers Chemical compounds with the same molecular weight and atomic composition but differing molecular structure; e.g., n-pentane and 2-methylbutane.

Jaundice Yellowish discoloration of tissue (skin), whites of eyes (sclera), and bodily fluids with bile pigment (bilirubin) caused by liver damage, gall bladder disease, or hemolysis.

Job-Related Stresses Activities that ask the body to operate beyond the capability of one or more of its structures. Job stresses can make work harder to do well, cause fatigue, and may be associated with injuries.

Joint A joint permits movement between bones that meet, but do not touch. Without joints, the degree of flexibility humans enjoy would be impossible. Injuries to joints can be more painful than fractures.

Jump Start Use of jumper cables to transfer electrical energy from a good battery to a discharged battery.

Kanamycin An injectable, second line antituberculosis drug used primarily for treatment of drug resistant TB.

Ketosis The condition marked by excessive production or accumulation of ketone bodies in the body caused by disturbed carbohydrate metabolism.

kg, kilogram 1000 gram.

Kickback Kickback occurs when a power tool suddenly stops. When this happens, much of the force of the tool is transferred back to the operator's wrists and forearms.

Knock Term used to describe engine noise made by loose or worn mechanical parts, preignition, detonation, etc.

Knock Sensors. Designed to eliminate knock associated with detonation or preignition.

L, l. Liter Basic metric unit of volume. One liter of water weighs 1 kg and is equal to 1.057 quarts.

Label Any written, printed, or graphic sign or symbol displayed on or affixed to containers of hazardous chemicals. A label should identify the hazardous material, appropriate hazard warnings, and name and address of the chemical manufacturer, importer, or other responsible party.

Laboratory Per 29 CFR 1910.1450. A facility where the "laboratory use of hazardous chemicals" occurs, where relatively small quantities of hazardous chemicals are used on a non-production basis.

Laboratory Scale (Activity) The work involves containers of substances used for reactions and transfers that are designed for easy and safe handling by one person. Workplaces that produce commercial quantities of materials are excluded from the definition of "Laboratory."

Laboratory Use Of hazardous chemicals is when all of these conditions are met: a) Chemical manipulations are carried out on a "laboratory scale." b) Multiple chemical procedures or chemicals are used. c) The procedures are neither part of nor simulate a production process. d) Protective lab practices and equipment are available and in common use to minimize the potential for employee exposure to hazardous chemicals.

Laboratory-type Hood An enclosed laboratory cabinet with a moveable sash or fixed access port on the front, connected to a ventilating system which may incorporate air scrubbing or filtering facilities. In operation it draws in and then exhausts air from the lab to prevent or minimize the escape of air contaminants. It enables employees to manipulate materials in the hood using only their hands and arms. Walk-in hoods are permitted if airflow and exhaust remove contaminants and the employee is not within the enclosure when contaminants are released.

Laceration A jagged tear or wound of the skin.

Lacrimation Production of tears by the eyes.

Lacrimator A material that upon exposure to it causes tears.

Land Treatment Facility A facility or part of a facility where hazardous waste is applied or incorporated into the soil surface. It is a disposal facility if the waste remains after closure.

Landfill Disposal of trash and waste products at a controlled location that is then sealed and buried under earth. Increasingly seen as a less than satisfactory disposal method because of the long-term environmental impact of waste materials in the ground.

Lanyard The stout rope or synthetic material line used to attach a worker to a secure anchorage point as security against fall injuries.

Laryngitis Inflammation of the vocal cords resulting in hoarseness.

Lassitude Weariness, tiredness.

Latency Period of time between exposure and symptoms of toxicity.

Latency Period The time that elapses between exposure and the first manifestations of disease or illness. Latency periods can range from minutes to decades, depending on hazardous material and disease produced.

Latent Phase An asymptomatic stage after TB, HIV, or other infection. The agent is present and capable of producing disease, though not yet active. Disease could occur months or years later, or not at all.

Latent TB Infection Infection with M. tuberculosis, usually detected by a positive PPD skin test result, in a person who has no symptoms of active TB and who is not infectious.

Lavage A washing of a hollow organ, such as the stomach, using a tube and fluids.

Lay Language Language that is easily understood by the general public without specialized training.

LC50 Lethal concentration 50, median lethal concentration. The concentration of a material in air that on the basis of laboratory tests (respiratory route) is expected to kill 50% of a group of test animals when administered as a single exposure in a specific time period, usually 1 hr. LC50 is expressed as parts of material per million parts of air, by volume (ppm) for gases and vapors, as micrograms of material per liter of air (µg/l), or milligrams of material per cubic meter of air (mg/m3) for dusts and mists, as well as for gases and vapors.

LCLo Lethal concentration low. The lowest concentration of a substance in air reported to have caused death in humans or animals. The reported concentrations may be entered for periods of exposure that are less than 24 hr (acute) or greater than 24 hr (subacute and chronic).

LD50 Lethal dose 50. The single dose of a substance that causes the death of 50% of an animal population from exposure to the substance by any route other than inhalation. LD50 is usually expressed as milligrams or grams of material per kilogram of animal weight (mg/kg or g/kg). The animal species and means of administering the dose (oral, intravenous, etc.) should also be stated.

LDLo Lethal Dose Low. The lowest dose of a substance introduced by any route, other than inhalation, reported to have caused death in humans or animals.

Leachate A liquid containing decomposed waste, bacteria, and other noxious and potentially harmful materials that drain from landfills. In a secure landfill, this leachate is trapped in the facility. In a sanitary landfill, the soil below the site is expected to filter the leachate before it reaches groundwater.

Leaching The movement of a substance down through or out of soil as a result of its mixing and moving with water. Important when assessing a material's ability to contaminate groundwater.

LEL See Lower Explosive Limit, Lower Flammable Limit.

Lens The transparent part of a protective device through which the wearer sees.

Lens, Impact-resistant A lens capable of withstanding the appropriate impact tests of ANSI standard Z87.1.

Lens, Non-removable A lens and holder that are homogeneous and continuous.

Lens, Plano (non Rx, sometimes called afocal) A lens that does not incorporate a corrective prescription. This lens is not necessarily flat.

Lens, Prescription (Rx) A lens manufactured to the wearer's individual corrective prescription.

Lesion An abnormal change caused by injury or disease which results in structure or tissue alterations.

Lethal Concentration, LC A concentration of a substance that is sufficient to kill a test animal.

Lethargy A sense of fatigue, drowsiness, and laziness.

Leukemia A progressive, malignant disease of the blood-forming organs.

Leverage Positioning the body in such a way to act effectively. Lack of good leverage can lead to injuries and accidents in the workplace.

LFL Lower Flammable Limit, See Lower Explosive Limit.

LFM lfm. Linear feet per minute, a unit of air velocity.

Lift-front A type of lens that covers the viewing area of a protector immediately in front of the wearer's eyes and that can be positioned outside of the line of sight during normal use of the protector. Lift-fronts are not normally intended to provide primary protection against impact hazards.

Ligament A band of tough tissue which serves to connect one bone to another.

Light Optical radiation weighted by its ability to cause visual sensations.

Limits of Flammability See Flammable Limits.

Line Breaking The intentional opening of a pipe, line, or duct that is or has been carrying flammable, corrosive, or toxic material, and inert gas, or any fluid at a volume pressure or temperature capable of causing injury.

Lining An all-inclusive term used to describe the various parts used for the inside of the upper part of the footwear.

Lipid Granuloma A mass of chronically inflamed tissue that is usually infective.

Lipid Pneumonia A chronic condition caused by aspiration of oily substances into the lungs.

Liquid A state of matter in which the substance is a formless fluid that flows with gravity.

Load Range Tire designation, with a letter (A,B,C, etc.) used to indicate a given tire's load and inflation limits.

Local Exhaust A system for capturing and exhausting contaminants from the air at the point where the contaminants are produced (welding, grinding, sanding, other processes or operations).

Local Exhaust Ventilation A technique to capture and remove airborne contaminants by enclosing the contaminant source or by means of a hood placed very near the contaminant source.

Local Toxicity Adverse effect of a chemical at the point where the chemical contacts the body.

Local Ventilation The drawing off of contaminated air directly from its source. This type of ventilation is recommended for hazardous airborne materials. Treatment of exhausted air to remove contaminants may be required.

Lockout The placement of a lockout device on an energy-isolating device, in accordance with an established procedure, ensuring that the energy-isolating device and the equipment being controlled cannot be operated until the lockout device is removed.

Lockout Device A device that utilizes a positive means such as a lock, either key or combination type, to hold an energy-isolating device in a safe position and prevent the energizing of a machine or equipment. Included are blank flanges and bolted slip blinds.

Lockout/Tagout OSHA standard 29 CFR 1910.147 "Control of Hazardous Energy (lockout/tagout)." Designed to protect employees, when involved in service and maintenance activities, against the unexpected start-up of machines or equipment or the release of stored energy that could cause injuries.

Lower Explosive Limit, Lower Flammable Limit. (LEL, LFL) Refers to the lowest concentration of gas or vapor (% by volume in air) that burns or explodes if an ignition source is present at ambient temperatures. See Flammable Limits.

Luminous Transmittance The fraction of light (380-780 nm) passing through a medium.

Lymph Nodes Small nodules of tissue under the skin containing white blood cells. Lymph nodes (sometimes called lymph glands) are easily felt in the neck, under the arms, and in the groin. They often swell as a result of infections.

m, Meter The basic metric measure of length equivalent to 39.371 in.

m3 cu m. Cubic meter; m3 is preferred. A metric measure of volume, approximately 35.3 cubic feet or 1.3 cubic yards.

Macula Blotch, spot or discoloration on the skin.

Major Message That portion of a tag's inscription that is more specific than the signal word and that indicates the specific hazardous condition or the instruction to be communicated to the employee. Examples include: "Do Not Open," "Do Not Energize," "Do Not Close," "Do Not Start," "Do Not Operate," or a corresponding pictograph used alone or with a written text.

Malaise A feeling of general discomfort, distress, or uneasiness; an out-of-sorts feeling.

Manifest A form used to identify the quantity, composition, and origin, routing, and destination of hazardous waste during transportation from the point of generation to the point of disposal, treatment, or storage.

Mantoux Test A method of skin testing that is performed by injecting 0.1 mL of PPD-tuberculin containing 5 tuberculin units into the dermis (i.e., the second layer of skin) of the forearm with a needle and syringe. This test is the most reliable and standardized technique for tuberculin testing. See Tuberculin Skin Test; Purified Protein Derivative (PPD)-Tuberculin Test.

Marking The descriptive name, identification number, instructions, cautions, weight, specification, or UN marks or combinations thereof, required by DOT regulations, on outer packagings of hazardous materials.

Marine Pollutant A hazardous material that is listed in 49 CFR 172.101, Appendix B and, when in a solution or mixture of one or more marine pollutants, is packaged in a concentration equal to or exceeding one of the following:

(1) Ten percent by weight of the solution or mixture for materials listed in Appendix B; or

(2) One percent by weight of the solution or mixture for materials that are identified as severe marine pollutants ("PP" in the S.M.P. column) in Appendix B.

Master Cylinder Single or dual primary unit for displacing hydraulic fuel under pressure in brake system.

Material Poisonous by Inhalation

(1) A gas meeting the criteria in 49 CFR 173.115(c) and assigned to Hazard Zone A, B, C, or D in accordance with 49 CFR 173.116(a);

(2) A liquid (other than a mist) meeting the defining criteria in 49 CFR 173.132(a)(1)(iii) and assigned to Hazard Zone A or B in accordance with 49 CFR 173.133(a); or

(3) Any material identified as an inhalation hazard by a special provision in Column 7 of the 49 CFR 172.101 HMT.

Material Safety Data Sheet A fact sheet summarizing information about material identification; hazardous ingredients; health, physical, and fire hazards; first aid; chemical reactivities and incompatibilities; spill, leak, and disposal procedures; and protective measures required for safe handling and storage. OSHA has established guidelines for the descriptive data that should be concisely provided on a data sheet to serve as the basis for written hazard communication programs. The thrust of the law is to have those who make, distribute, and use hazardous materials responsible for effective communication. See the Hazard Communication Rule, 29 CFR, 1910.1200, as amended, Sec. g. The Chemical Manufacturers Association (CMA) has developed a set of guidelines for developing a consistent MSDS format that has been accepted by ANSI. Also see Schedule I, Sec. 12, of the Canadian Hazardous Products Act.

Maximum Safe Storage Temperature (MSST) See SADT (Self-Accelerating Decomposition Temperature).

Maximum Use Concentration (MUC) The maximum concentration of an air contaminant in which a particular respirator can be used, based on the respirator's assigned protection factor. The MUC cannot exceed the use limitations specified on the NIOSH approval label for the cartridge, canister, or filter. The MUC can be determined by multiplying the assigned protection factor for the respirator by the permissible exposure limit (PEL) for the air contaminant for which the respirator will be used.

Mechanical Exhaust A powered device, such as a motor-driven fan, or stream venturi tube, for removing contaminants from a workplace, vessel, or enclosure.

Medical Surveillance To monitor and follow an individual's health closely by utilizing various screening methods.

Melting Point The temperature above which a solid changes to a liquid upon heating.

Mercaptans A group of organic compounds resembling alcohols, but with sulfur replacing the oxygen of the hydroxyl group. For example, ethanethiol [C2H5SH].

Mesolthelioma A fast-acting, fatal form of lung cancer caused by the inhalation of asbestos fibers.

Metabolism The process of change some chemicals go through after absorption by the body.

Metastasis The transmission of a disease from one part of the body to another.

Metatarsal Referring to the bones of the foot located between the toes (phalanges) and the upper foot (tarsus).

Meter (m) The basic metric measure of length; equivalent to 39.371 in.

Methemoglobinemia The presence of methemoglobin in the bloodstream caused by the reaction of materials with the hemoglobin in red blood cells that reduces their oxygen-carrying capacity. Methemoglobin is a soluble, brown, crystalline blood pigment that differs from hemoglobin in that it contains the iron (III) ion instead of iron (II) and is unable to combine reversibly with molecular oxygen.

mg Milligram (1/1000, 10-3, of a gram).

mg/kg Milligram per kilogram. Dosage used in toxicology testing to indicate a dose administered per kg of body weight.

mg/m3 Milligram per cubic meter of air. mg/m3 = ppm x MW/24.45 at 25 °C. A unit for expressing concentration of dusts, gases, or mists in air.

Microgram (g) One-millionth (10-6) of a gram.

Micrometer (m) One-millionth (10-6) of a meter; often referred to as a micron.

Micron () See micrometer.

Miliary Tuberculosis A serious form of TB with multiple organ involvement.

Milliampere One-thousandth of an ampere.

Milligrams per Cubic Meter (mg/m3) A concentration unit for air contaminants; mass of the contaminant divided by the volume of air containing it.

Millimeter (mm) 1/1000 (10-3) of a meter.

min Minute.

Mine Safety and Health Administration See MSHA.

Miosis Pinpoint pupils of the eye.

Miscible When two liquids or two gases are completely soluble in each other in all proportions. While gases mix with one another in all proportions, the miscibility of liquids depends on their chemical natures.

Misfiring Failure of an explosion (no spark) to occur in one or more cylinders while engine is running. This may be a continuous or intermittent failure.

Mist Suspended liquid droplets in the air generated by condensation from the gaseous to the liquid state or by mechanically breaking up a liquid by splashing or atomizing.

MITI Japanese Ministry of International Trade and Industry.

Mixing The degree to which air supplied to a room mixes with the air already in the room; generally expressed in terms of a Mixing Value. A low value (i.e., 1) indicates good mixing; a higher value (i.e., 10) indicates poor mixing.

Mixture A heterogeneous association of materials that cannot be represented by a chemical formula and that does not undergo chemical change due to interaction among the mixed materials. The constituent materials may or may not be uniformly dispersed and can usually be separated by mechanical means (as opposed to a chemical reaction). Uniform liquid mixtures are called solutions. For material safety data sheets, OSHA CPL 23-02.38A state, "If a hazardous chemical is present in the mixture in reportable quantities (i.e., 0.1% for carcinogens and 1.0% for other health hazards), it must be reported unless the mixture has been tested as a whole".

As used in the transportation of hazardous materials, mixture means a material composed of more than one chemical compound or element.

ml Milliliter. One thousandth of a liter. A metric unit of capacity, for all practical purposes equal to 1 cubic centimeter. One cubic inch is about 16 ml.

MLD Mild irritation effects.

mm Millimeters.

mm Hg A measure of pressure in millimeters of a mercury column above a reservoir, or difference of level in a U-tube. See atm.

MMI Mucous membrane effects.

MOD Moderate irritation effects.

Mole mol. The quantity of a chemical substance that has a mass in grams numerically equal to the formula mass. For example, table salt (NaCl) has a formula mass of 58.5 (Na, 23, and Cl, 35.5). Thus, one mole of NaCl is 58.5 g.

Molecular Weight The sum of atomic weights of the atoms in a molecule. For example, water (H2O) has a molecular weight of 18.015, the atomic weights being hydrogen = 2 (1.008) + oxygen = 15.999.

Molecule The smallest particle of a chemical compound, which is an arrangement of various atoms bound together by physical properties, which cannot be further subdivided without ceasing to have that compound's nature and properties.

Monomer A compound of relatively low molecular weight which, under certain conditions, either alone or with another monomer, forms various types and lengths of molecular chains called polymers or copolymers of high molecular weight.

Mortality Rate The death rate.

Mouth-to-mouth Resuscitation A life-saving technique used to revive a person who has stopped breathing. Contact your local American Red Cross for training.

MPH Miles per hour.

mppcf Millions of particles per cubic foot of air, based on impinger samples counted by light-field techniques (OSHA).

MSHA Mine Safety and Health Administration. A Federal agency within the U.S. Dept. of Labor that devises and promulgates mandatory safety and health rules for mines.

MSST (Maximum Safe Storage Temperature) See SADT (Self-Accelerating Decomposition Temperature).

Mucous Membrane The mucous-secreting membrane lining the hollow organs of the body, i.e., nose, mouth, stomach, intestine, bronchial tubes, and urinary tract.

Muffler A chamber attached to exhaust systems which reduces noise created by engine exhaust. Also helps dissipate heat.

Multiple Drug Resistant Tuberculosis (MDRTB) Active TB caused by M. tuberculosis organisms that are resistant to more than one antituberculosis drug; in practice, often refers to organisms that are resistant to both INH and rifampin with or without resistance to other drugs. See Acquired Drug Resistance; Primary Drug Resistance.

Muscle Contraction All body movements are accomplished by muscle contractions. When muscles contract, energy is necessary in the form of glucose and waste products are released in the form of lactic acid.

Mutagen A material that induces genetic changes (mutations) in the DNA of chromosomes. Chromosomes are the "blueprints" of life within individual cells. Mutagens may affect future generations if sperm or egg cells are affected.

MW See Molecular Weight.

Myalgias Muscle aches.

Mycobacteria A specific species of bacteria which have like characteristics.

Mycobacterium Tuberculosis Complex. A group of closely related mycobacterial species that can cause active TB (e.g., M. tuberculosis, M. bovis, and M. africanum). Most TB in the United States is caused by M. tuberculosis.

N (Newton) The metric unit of force, approximately equal to the weight of a 102.5 g mass.

n- Normal. A chemical name prefix signifying a straight-chain structure; i.e., no branches.

NA, ND Not applicable, not available; not determined.

NA Number See DOT Identification Numbers.

Nanometer (nm) One billionth of a meter. 10-9 meters.

Nape Strap A strap that fits behind the head to secure the helmet to the head; it may be an integral part of the headband.

Narcosis Stupor, sleepiness, or unconsciousness often produced by exposure to certain organic chemicals.

Nascent Just formed, as from a chemical reaction.

National Fire Protection Association See NFPA.

National Institute of Occupational Safety and Health (NIOSH) A Federal agency, part of the Centers for Disease Control (CDC), responsible for conducting research and making recommendations for the prevention of work-related illness and injuries. (NIOSH, [800] 356-4674)

National Toxicology Program See NTP.

Nausea A tendency to vomit; a feeling of sickness in the stomach.

NCI National Cancer Institute. A part of the National Institutes of Health that studies cancer.

Necrosis Localized death of tissue.

Needlestick Injury Occurs when a needle or other sharp object pierces the skin. Any blood or other body fluid on a needle can be injected into the body, and this could transmit BBP's (especially Hepatitis B).

Negative Pressure The relative air pressure difference between two areas in a health care facility. A room that is at negative pressure has a lower pressure than adjacent areas, which keeps air from flowing out of the room and into adjacent rooms or areas.

Negative Pressure Respirator A respirator in which the air pressure inside the facepiece is positive during exhalation in relation to the outside air pressure, and is negative during inhalation in relation to the outside air pressure.

NEO Neoplastic effects; production of tumors.

Neoplasm A new or abnormal tissue growth that is uncontrollable and progressive.

Nephrotoxic Toxic to the kidneys.

Nerves Any of the cord-like fibers or bundles of fibers connecting the body organs with the central nervous system.

Neuritis Inflammation of the nerves.

Neurotoxic Toxic to the nervous system.

Neutral Safety Switch Eliminates possibility of starting engine when automatic transmission gear selector lever is in any position other than park or neutral or when clutch is not engaged in manual transmission.

Neutralization The process by which acid or alkaline properties of a solution are altered by the addition of certain reagents to bring the hydrogen and hydroxide concentrations to an equal value; sometimes referred to as pH of 7, the value of pure water.

Neutralize To render less chemically reactive; to change the pH to about 7 (neutral) by adding acid to a basic compound or base to an acidic compound.

NFPA National Fire Protection Association. An international voluntary membership organization formed to promote/improve fire protection and prevention and establish safeguards against loss of life and property by fire. Best known for the National Fire Codes, 16 volumes of standards, recommended practices, and manuals developed (and periodically updated) by NFPA committees. NFPA 704M publication is the code for showing hazards of materials using the familiar diamond-shaped label with appropriate numbers or symbols (NFPA hazard rating). See Fire Diamond. (1 Batterymarch Park, PO Box 9101, Quincy, MA 02269-9101; [800] 344-3555, [617] 770-3000.)

NFPA Hazard Rating See Fire Diamond.

ng Nanogram. One billionth, 10-9, of a gram.

NIOSH See National Institute for Occupational Safety and Health.

NLM National Library of Medicine. A government library in Bethesda, Maryland containing medical documents.

NOC Not otherwise classified.

NOEL No observable effect level.

Noise Reduction Rating An indication of the effectiveness of hearing protection devices (earplugs, earmuffs) in blocking excessive noise from the ears.

Non-Bulk Packaging A packaging that has:

(1) A maximum capacity of 450 L (119 gallons) or less as a receptacle for a liquid;

(2) A maximum net mass of 400 kg (882 pounds) or less and a maximum capacity of 450 L (119 gallons) or less as a receptacle for a solid; or

(3) A water capacity of 454 kg (1,000 pounds) or less as a receptacle for a gas as defined in 49 CFR 173.115.

Non Permit Confined Space A confined space that does not contain or, with respect to atmospheric hazards, have potential to contain, any hazard capable of causing death or serious physical harm.

Non-point Source Source from which pollutants emanate in an unconfined and unchannelled manner, including: water effluent not controlled through NPDES (National Pollutant Discharge Elimination System) permits or traceable to a discrete identifiable origin, but result from natural processes, such as nonchannelled runoff, precipitation, drainage, or seepage; and air contaminant emissions from landfills and surface impoundments.

Nonflammable Incapable of easy ignition. Does not burn, or burns very slowly. Also, a DOT hazard class for any compressed gas other than a flammable one.

Nonflammable Gas Any material, or mixture, in a cylinder or tank, other than poison gas, or flammable gas having in a container an absolute pressure exceeding 40 psi at 70 °F, or having an absolute pressure exceeding 104 psi at 130 °F (Title 49 CFR and CGA).

Nonpolar Solvents The aromatic and petroleum hydrocarbon groups characterized by low dielectric constants.

NOR Not otherwise regulated.

Normal Production Operations The utilization of a machine or equipment to perform its intended production function.

Normally Unoccupied Remote Facility A facility which is operated, maintained, or serviced by employees who visit the facility only periodically to check its operation and to perform necessary operating or maintenance tasks. No employees are permanently stationed at the facility.

NOS Not otherwise specified.

n.o.s. Description. A shipping description from the 49 CFR 172.101 HMT that includes the abbreviation "n.o.s.", and is listed in 49 CFR 172.203(k)(3), regarding additional description requirements.

Nosocomial An occurrence, usually an infection, that is acquired in a hospital or as a result of medical care.

NO x A general formula for oxides of nitrogen (NO, NO2). They react with moisture in the respiratory tract to produce acids that corrode and irritate tissue, causing congestion and pulmonary edema. Symptoms of acute exposure can develop over 6 to 24 hr. Chronic exposure to low levels can cause irritation, cough, headache, and tooth corrosion. Exposure to 5 to 50 ppm of NO2 can cause slowly evolving pulmonary edema. Commonly produced by combustion processes, including motor vehicle engines.

NPCA National Paint and Coatings Association. The trade association of manufacturers that developed the HMIS labeling system. (1500 Rhode Island Avenue, NW, Washington, DC 20005; [202] 462-6272.) See HMIS.

NRC National Response Center. A notification center that must be called if an RQ (reportable quantity) is released, or an oil or chemical spill or other environmental accident occurs. (1-800-424-8802).

NRC (non-reusable container) A packaging (container) whose reuse is restricted in accordance with the provisions in 49 CFR 173.28.

NRR See Noise Reduction Rating.

NTP National Toxicology Program. Federal activity overseen by the Department of Health and Human Services with resources from the National Institutes of Health, the Food and Drug Administration, and the Centers for Disease Control. Its goals are to develop tests useful for public health regulations of toxic chemicals, to develop toxicological profiles of materials, to foster testing of materials, and to communicate the results for use by others. (NTP Information Office, MD E1-02, Box 12233, Research Triangle Park, NC 27709, [919] 541-3419.)

Nuclide A species of atom having a specified number of neutrons and protons in its nucleus.

Nuisance Dust Particulates that do not produce significant organic disease or toxic effect from "reasonable" concentrations and exposures.

Nuisance Particulates Dusts that do not produce significant organic disease or toxic effect from "reasonable" concentrations and exposures. Otherwise known as "Particulates not otherwise classified" (PNOC). The 1992-93 ACGIH TLV is 10 mg/m3. The value is for total dust containing no asbestos and <1% crystalline silica.

Nystagmus Rapid, rhythmic, involuntary horizontal movements of the eyes.

Occupant Safety Device The parts of your automobile designed to reduce injury in the event of a crash. Safety belts, shoulder harnesses, air bags, and head rests are examples of occupant safety devices that have been installed in vehicles to enhance your safety.

Occupational Exposure See Action Level.

Occupational Hazard A source of danger resulting from someone's job.

Occupational Safety and Health Act See OSH Act.

Occupational Safety and Health Administration See OSHA.

Odor A description of the smell of the substance.

Odor Threshold The lowest concentration detectable by odor; note that published values vary greatly, as does an individual's ability to detect chemical odors; air monitoring is a much more reliable way to detect chemical hazards for many substances.

OEL Occupational Exposure Limit. See Exposure Limits.

Oil Oil of any kind or in any form, including, but not limited to, petroleum, vegetable oil, animal oil, fuel oil, sludge, oil refuse, and oil mixed with wastes other than dredged spoil.

Olefins A class of unsaturated hydrocarbons characterized by relatively great chemical activity and obtained from petroleum and natural gas.

Olfactory Relating to the sense of smell.

Olfactory Fatigue Inability to smell something as the concentration increases or after adjusting to the odor; this is a classic property of hydrogen sulfide.

Oliguria Scanty or low volume of urine.

Opaque Impervious to light rays.

Open Transfer Any transfer that at any time involves contact of a moving fluid with atmosphere, air, or oxygen. Open transfer of flammable liquids, especially OSHA Class IA liquids, is dangerous due to the release of flammable vapors into the work area. Since there is a risk of fire or explosion if an ignition source is present, do these transfers only in a hood.

Operator A person who controls the use of an aircraft, vessel, or vehicle.

OPIM See Other Potentially Infectious Materials.

Oral Relating to the mouth.

Oral Toxicity Adverse effects resulting from taking a substance into the body by mouth. Ordinarily used to denote effects in experimental animals.

Organic Compounds Chemicals which contain carbon.

Organic Materials Compounds composed of carbon, hydrogen, and other elements with chain or ring structures. Almost all chemical constituents of living matter are of this type, but many compounds of this type are manufactured and do not occur naturally.

Organic Peroxide A compound containing the bivalent -O-O- structure and which is a structural derivative of hydrogen peroxide (H2O2) where one or both hydrogen atoms are replaced by an organic radical. These compounds tend to be reactive and unstable.

As used in the transportation of hazardous materials, organic peroxide means any organic compound containing oxygen (O) in the bivalent -O-O- structure and that may be considered a derivative of hydrogen peroxide, where one or more of the hydrogen atoms have been replaced by organic radicals; unless any of the exceptions listed in 49 CFR 173.128(a) apply.

Organic Solvents Liquid chemicals (hydrocarbons) that can dissolve oil and grease.

ORM ORM-A: materials with an anesthetic, irritating, noxious, toxic, or other property whose leakage can cause extreme discomfort to transportation personnel. ORM-B: materials (including solids wet with water) that can cause damage to a vehicle if they leak. ORM-D: materials such as consumer commodities which present limited hazards during transportation due to their form, quantity, and packaging. ORM-E: materials that are not in any other hazard classification but are subject to DOT regulations.

OSH Act The Occupational Safety and Health Act of 1970. Effective April 28, 1971. Public Law 91-596. Found at 29 CFR 1910, 1915, 1918, 1926. OSHA jurisdiction. The regulatory vehicle to ensure the safety and health of workers in firms larger than 10 employees. Its goal is to set standards of safety that prevent injury and illness among the workers. Regulating employee exposure and informing employees of the dangers of materials are key factors. This act established the Hazard Communication Rule (29 CFR 1910.1200). See Hazard Communication Rule for details.

OSHA The Occupational Safety and Health Administration. Part of the U.S. Dept of Labor. The regulatory and enforcement agency for safety and health in most U.S. industrial sectors. (Documents are available from the OSHA Technical Data Center Docket Office, Rm N-3670, 200 Constitution Ave, NW, Washington, DC 20210; [202] 219-7500.)

OSHA Flammable/Combustible Liquid Classification (29 CFR 1910.106). Flammable/combustible liquid is a standard classification used to identify the risks of fire or explosion associated with a liquid.

Flammable, or Class I, liquids (flash point below 38 °C [100 °F]) are divided into: Class IA -- flash point below 22.8 °C (73 °F), boiling point below 38 °C (100 °F); Class IB -- flash point below 22.8 °C (73 °F), boiling point at or above 38 °C (100 °F); and Class IC -- flash point at or above 22.8 °C (73 °F), boiling point below 38 °C (100 °F).

Combustible liquids (flash point at or above 38 °C [100 °F]) are divided into two classes: Class II, flash point at or above 38 °C (100 °F) and below 60 °C (140 °F), except any mixture having components with flash points of 93.3 °C (200 °F) or higher, the volume of which makes up 99% or more of the mixture's total volume; and Class III, flash point at or above 140 °F (60 °C).

Class III liquids are divided into two subclasses: Class IIIA, flash point at or above 60 °C (140 °F) and below 93.3 °C (200 °F), except any mixture having components with flash points of 93.3 °C (200 °F) or higher, the volume of which makes up 99% or more of the mixture's total volume; and Class IIIB, flash point at or above 93.3 °C (200 °F).

Other Body Fluids Fluids other than blood that can potentially spread BBP's; it generally means the same as OPIM.

Other Potentially Infectious Materials (OPIM) A term frequently used in the OSHA regulation on BBP's. It means blood, semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid, peritoneal fluid, amniotic fluid, saliva in dental procedures, any body fluid that is visibly contaminate with blood, and all body fluids when it is impossible to tell what the source of the body fluid is. OPIM also includes human tissues and organs, and tissues, organs, and body fluids of experimental animals infected with HIV or HBV.

Outer Packaging The outermost enclosure of a composite or combination packaging together with any absorbent materials, cushioning and any other components necessary to contain and protect inner receptacles or inner packagings.

Outlet A point on the wiring system at which current is taken to supply utilization equipment.

Outsole and Heel The bottom surface of footwear; the part that is exposed to wear.

Over-Use Syndrome Also known as "cumulative trauma disorder" or CTD. Repetitive motion is the primary cause of CTD.

Overdrive Any arrangement of gearing that produces more revolutions of driven shaft than driving shaft used at cruising speed to improve fuel economy.

Overexposure A high level of exposure to a chemical which may cause health effects.

Overpack . An enclosure that is used by a single consignor to provide protection or convenience in handling of a package or to consolidate two or more packages. "Overpack" does not include a freight container.

Oxidation A reaction in which a substance combines with oxygen or another oxidizer. In hazardous waste management, the process whereby a waste stream is treated with a strong oxidizing agent, chemically changing the waste to a less hazardous state.

Oxidation-Reduction Reaction A chemical reaction in which an atom or molecule loses electrons to another atom or molecule.

Oxide Pox Dermatitis caused by contact with metal oxides under poor personal hygienic conditions.

Oxides of Nitrogen Compounds of nitric acid and nitrogen dioxide produced by combustion process especially at high temperatures.

Oxidizer The DOT defines an oxidizer or oxidizing material as a substance that yields oxygen readily to cause or enhance the combustion (oxidation) of other materials. Many oxidizers, such as chlorate (ClO3), permanganate (MnO4), and nitrate (NO3) compounds contain large amounts of oxygen (O). Others, such as chlorine, do not.

Oxidizing Agent A chemical or substance that brings about an oxidation reaction. The agent may 1) provide the oxygen to the substance being oxidized (in which case the agent has to be oxygen or contain oxygen), or 2) receive electrons being transferred from the substance undergoing oxidation. (Chlorine is a good oxidizing agent for electron-transfer purposes, even though it contains no oxygen.) See Reducing Agent.

Oxygen Deficiency An atmosphere having less than the percentage of oxygen found in normal air (approximately 21%). According to the OSHA Confined Space Entry standard, oxygen deficiency is considered to exist at less than 19.5%.

Oxygen Deficient Atmosphere An atmosphere containing less than 19.5% oxygen by volume.

Oxygen Deficient Atmosphere *Proposed* As defined in the proposed respirator regulation, an atmosphere with an oxygen content of less than 19.5% by volume at altitudes of 8000 feet or below. See Oxygen Deficient IDLH atmosphere for altitudes above 8,000 feet.

Oxygen Deficient IDLH Atmosphere *Proposed* As defined in the proposed respirator regulation, an atmosphere with an oxygen content below 16% by volume at altitudes of 3,000 feet or below, or below the oxygen levels specified for altitudes up to 8,000 feet, or below 19.5% for altitudes of 8,001 to 14,000 feet.

Oxygen Enriched Atmosphere An atmosphere containing more than 23.5% oxygen by volume.

Ozone A very active form of oxygen that may be produced by corona, arcing, or ultraviolet rays.

Ozone Cutting and Checking. The cutting action produced by ozone on rubber under mechanical stress into a series of interlacing cracks.

Packaging A receptacle and any other components or materials necessary for the receptacle to perform its containment function in conformance with the minimum packing requirements of the DOT regulations for shippers, transporters, and manufacturers. For radioactive materials packaging, the assembly of components necessary to ensure compliance with the packaging requirements in 49 CFR 173 Subpart I. It may consist of one or more receptacles, absorbent materials, spacing structures, thermal insulation, radiation shielding, and devices for cooling or absorbing mechanical shocks. The conveyance, tie-down system, and auxiliary equipment may sometimes be designated as part of the packaging.

Packing Group A grouping according to the degree of danger presented by hazardous materials. Packing Group I indicates great danger; Packing Group II, medium danger; Packing Group III, minor danger. In the 49 CFR 172.101 HMT, column 5 specifies one or more packing groups assigned to a material corresponding to the proper shipping name and hazard class for that material. Classes 2 and 7 materials and ORM-D materials do not have packing groups. If more than one packing group is indicated for an entry, the packing group for the hazardous material is determined using the criteria for assignment of packing groups specified in subpart D of Part 173. See 49 CFR 172.101(f).

Pad Disc brake friction material molded or riveted to metal backing.

PAH See Polycyclic Aromatic Hydrocarbons.

Pallor Pale skin appearance.

Palpitations A sensation of fluttering of the heart, irregular heartbeat, or pounding of the heart.

Papule Pimple or other small, raised inflammation of the skin.

Paralysis Inability to move a part of the body.

Parasite An animal or plant (often microscopic size) that lives on or in the body of another animal or human from which it obtains its nourishment. Parasites often cause disease.

Parenteral Exposure resulting from piercing of mucous membranes or the skin barrier from needlesticks, human bites, cuts, and abrasions.

Paresthesias Altered sensations of the skin, often numbness and tingling, or "pins and needles" sensation.

Pars-Aminosalicylic Acid (PAS) A second line, oral antituberculosis drug used for drug resistant TB.

Partial Thickness Burn Second-degree burn into the dermis of the skin causing blistering and redness.

Particle A small discrete mass of solid or liquid matter.

Particle Concentration Concentration expressed in terms of number of particles per unit volume of air or other gas.

Particle Size The measured dimension of liquid or solid particles. Usually expressed as microns.

Particulate Small, separate pieces of an airborne material. Dusts, fumes, smokes, mists, and fogs are examples. Particulates may be organic or inorganic, and may either be visible or invisible.

Partition Coefficient See Coefficient of Water/ Oil Distribution.

Parts per Billion (ppb) Unit of concentration of an air contaminant; one part contaminant (by volume) per billion parts air (by volume).

Pasteurization The partial sterilization of a substance by heating for a period of time. It destroys unwanted organisms without changing the substance.

Pathogenesis The pathologic, physiologic, or biochemical process by which a disease develops.

Pathogenicity The quality of producing or the ability to produce pathologic changes or disease.

PCB Polychlorinated biphenyl. A family of compounds used as a heat-transfer medium. PCBs accumulate in tissue, are environmentally hazardous, and are believed harmful to human health. Their handling is regulated by law (40 CFR Part 761).

Peak As related to a helmet, an integral part of the shell extending forward over the eyes only.

PEL Permissible exposure limit. Established by OSHA. This may be expressed as a time-weighted average (TWA) limit, a short-term exposure limit (STEL), or as a ceiling exposure limit. A ceiling limit must never be exceeded instantaneously even if the TWA exposure limit is not violated. OSHA PELs have the force of law. OSHA has established an Action Level for many substances, which is usually one-half of the PEL set for that compound. Exposure at or above the Action Level triggers additional employee protection measures, such as air analysis of the workplace, additional employee training, medical surveillance of affected employees, and record keeping. Note that ACGIH TLVs and NIOSH RELs are recommended exposure limits that OSHA may or may not enact into law.

Pensky-Martens Closed Cup or Closed Tester See PMCC.

Percent Volatile Percent volatile by volume. The percentage of a liquid or solid (by volume) that evaporates at an ambient temperature of 70 °F (20 °C) unless another temperature is stated. E.g., gasoline and paint thinner (mineral spirits) are 100% volatile; their individual evaporation rates vary, but over a period of time each evaporates completely. This physical characteristic reflects the potential for releasing harmful vapor into the air.

Percolation The movement, flow, or infiltration of water through the pores or spaces of rock or soil.

Percutaneous Through the skin; often referring to absorption of a chemical.

Pericardial Fluid Fluid found in a sac around the heart.

Peripheral Nervous System (PNS) Nerves outside of the brain and spinal cord, including motor nerves to control the function of muscles, sensory nerves to carry sensations to the brain, and autonomic nerves to control a variety of organ functions.

Permeable Open to passage or penetration; used especially for a substance that allows the passage of fluids.

Permissible Exposure Limit See PEL.

Permit Required Confined Space (PRCS) A confined space that has one or more of the following characteristics: 1) contains or has the potential to contain a hazardous atmosphere; 2) contains a material that has the potential for engulfing an entrant; 3) has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section; and 4) contains any other recognized serious safety or health hazard.

Permit Required Confined Space Program The employer's overall program for controlling, and, where appropriate, for protecting employees from permit space hazards and for regulating employee entry into permit spaces.

Permit System The employer's written procedure for preparing and issuing permits for entry and for returning the permit space to service following termination of entry.

Person An individual, firm, co-partnership, corporation, company, association, joint-stock association, including any trustee, receiver, assignee, or similar representative thereof, or government, Indian tribe, or agency or instrumentality of any government or Indian tribe when it offers hazardous materials for transportation in commerce or transports hazardous materials in furtherance of a commercial enterprise, but such term does not include:

(1) The United States Postal Service; or

(2) For the purposes of sections 110 and 111 of the Hazardous Materials Transportation Act (49 App. U.S.C. 1809-1810), any agency or instrumentality of the Federal Government.

Personal Hygiene Precautionary measures taken to maintain good health when exposed to potentially harmful materials. This includes keeping hands, and other parts of the body, work clothing, and equipment free of a material's residue, as well as not eating, drinking, applying makeup, or using toilet facilities where a material is in use.

Personal Protective Equipment See PPE.

Pesticides Chemicals designed to kill pests such as insects, rodents, weeds, etc.; most are toxic to humans.

pH Hydrogen ion exponent, a measure of hydrogen ion concentration of a solution. A scale (0 to 14) representing an aqueous solution's acidity or alkalinity. Low pH values indicate acidity and high values, alkalinity. The scale's mid-point, 7, is neutral. Some substances in aqueous solution ionize to various extents giving different concentrations of H and OH ions. Strong acids have excess H ions and a pH of 1 to 3 (HCl, pH = 1). Strong bases have excess OH ions and a pH of 11 to 13 (NaOH, pH = 12).

PHA Process Hazard Analysis. One of the important components of the Process Safety Management standard.

Pharyngitis Inflammation of the throat; may be caused by chemical irritation, a cold virus, or a bacterial infection.

Phlegm Thick mucous from respiratory passage.

Photochromic Lens A lens which darkens when exposed to sunlight and which fades when removed from the sunlight.

Photophobia Pain or discomfort around bright light.

Photosensitivity Sensitivity to light.

Physical Hazard A substance for which there is valid evidence that it is a combustible liquid, compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive), or water reactive. In the general safety sense, a hazard of physical origin, such as a fall, a heat burn, etc, and not a chemical or infective disease hazard.

Physical State Condition of a material; i.e., solid, liquid, or gas, at room temperature.

Physiological Stress A stimulus that effects the normal balanced functioning of a living organism.

Phytotoxic Poisonous to plants.

Pictograph A pictorial representation used to identify a hazardous condition or to convey a safety instruction.

PIN Product identification number. A four-digit number, prefaced by UN or NA, used in Canada under the Transportation of Dangerous Goods Regulation for use by emergency personnel to identify a material in the event of an accident. See DOT identification number, the same numbering system used in the U.S.

Pinch Grip Grasping an object with just the thumb and fingertips, causing strain to the fingers, palms, and wrists.

Pinging Sound produced when either preignition or detonation occurs.

Piston A cylindrical part, closed at one end, that is connected to the crankshaft through a connecting rod. Force of explosion from fuel mixture in cylinder exerted against top of piston forces piston and connecting rod to move, causing crankshaft to rotate.

Pleura The mucous sack which surrounds the lungs.

Pleural Relating to the lining around the lungs.

Pleural Effusion Fluid which builds up between the lungs and the pleura, reducing the ability to exchange air or breath. This may be life-threatening.

Pleuritis An inflammation of the pleura.

PMCC Pensky-Martens Closed Cup. One of several types of apparatus for determining flash points. The Pensky-Martens closed tester (ASTM D93-79) is used for liquids that: have a viscosity of 45 SUS (Saybolt universal seconds) or more at 38 °C (100 °F), have flash points of 93.6 °C (200 °F) or higher, contain suspended solids, or form surface films.

Pneumoconiosis A respiratory tract and lung condition caused by inhalation and retention of irritant mineral or metallic particles. An X-ray can detect changes, which include fibrosis, emphysema.

Pneumonia or Pneumonitis Inflammation of the lungs. May be caused by chemical irritation, bacteria or viruses.

PNOC An ACGIH term for "particulates not otherwise classified." See Nuisance Particulates.

PNOR An OSHA term for "particulates not otherwise regulated." (TWA: 15 mg/m3, total dust; 5 mg/m3, respirable fraction).

PNS See Peripheral Nervous System.

Point Source A discernible, confined, and discrete conveyance. Examples include: pipe; ditch; channel; tunnel; conduit; well; discrete fissure; container; rolling stock; concentrated animal feeding operation; and vessel or other floating craft from which pollutants may be discharged. Does not include return flow from irrigated agriculture.

Poison A substance which may cause adverse health effects or death.

Poison Control Center A regional center staffed 24 hours a day to answer inquiries and to assist in the proper management of poisoning; usually associated with a major hospital's emergency department.

Poison, Class A A DOT term for an extremely dangerous poison such as a poisonous gas or liquid of such a nature that a very small amount of the gas or vapor of the liquid mixed with air is dangerous to life. E.g., phosgene, cyanogen, hydrocyanic acid, and nitrogen peroxide.

Poison, Class B A DOT term for liquid, solid, paste, or semi-solid substances other than class A poisons or irritating materials known or presumed, on the basis of animal tests, to be so toxic to man as to afford a hazard to health during transportation.

Poisonous Material A material, other than a gas, which is known (on the basis of animal tests) to be so toxic to humans or causes such extreme irritation as to afford a hazard to health during transportation, or which, in the absence of adequate data on human toxicity, meet toxicity testing criteria detailed in 49 CFR 173.132(a).

Polar Solvents Solvents, such as alcohols and ketones, that contain oxygen, and have high dielectric constants.

Polycyclic Aromatic Hydrocarbons (PAH) A family of chemical compounds containing only carbon and hydrogen, in which molecules consist of three or more carbon ring structures fused so that some carbon atoms are common to two or three rings. A large number of this chemical family's members are carcinogens, or are converted to carcinogens when metabolized by animals or humans. PAHs are formed during incomplete combustion of hydrocarbons. They are common in smoke, such as that of vehicle exhaust or tobacco, and are also important industrial contaminants in coal gas or coke manufacture and other processes involving heating of coal tar and pitch.

Polymer A high molecular weight material formed by the joining together of many simple molecules (monomers).

Polymerization A chemical reaction in which one or more small molecules combine to form larger molecules. Hazardous polymerization takes place at a rate that releases large amounts of energy that can cause fires or explosions or burst containers. Materials that can polymerize usually contain inhibitors that can delay reactions. If hazardous polymerization can occur with a given material, the MSDS will usually list conditions that could start the reaction and, since the material usually contains a polymerization inhibitor, the length of time during which the inhibitor will be effective.

Poor Warning Properties A substance that has odor, taste, or irritation effects that are not detectable or persistent at concentrations at or below the exposure limit.

Portable Filtration Units Portable devices that reduce airborne TB infection by recirculating air within a room through a HEPA filter.

Portable Room-Air HEPA Recirculation Units Free-standing portable devices that remove airborne contaminants by recirculating air through a HEPA filter.

Portable Tank A bulk packaging (except a cylinder having a water capacity of 1000 lb or less) designed primarily to be loaded onto, or on, or temporarily attached to a transport vehicle or ship and equipped with skids, mountings, or accessories to facilitate handling of the tank by mechanical means. It does not include a cargo tank, tank car, multi-unit tank car tank, or trailer carrying 3AX, 3AAX, or 3T cylinders.

Positive PPD Reaction A reaction to the purified protein derivative (PPD) tuberculin skin test that suggests the person tested is infected with M. tuberculosis. The person interpreting the skin test reaction determines whether it is positive on the basis of the size of the induration and the medical history and risk factors of the person being tested.

Positive Pressure Respirator A respirator in which the pressure inside the respiratory inlet covering is normally positive with respect to ambient air pressure.

Pour Point The temperature at which a liquid either congeals or ceases to flow.

Power Brakes Hydraulic, vacuum, air, or electrohydraulic boost designed to increase braking performance.

Power Grip Making a fist around a handle or an object. This assures that the large muscles and structures in the arms are used to supply power along with the hands and wrists.

Power Steering Application of hydraulic or mechanical power in addition to manual power in steering of an automobile.

Power Train Group of components working in conjunction to transmit power to wheels, i.e. clutch, transmission, universal joints, drive shaft, rear axle, etc.

Powered Air-purifying Respirator An air-purifying respirator which uses an electrically-driven blower to deliver air through the air-purifying element to the wearer's breathing zone.

PO x A general term for the several oxides of phosphorus.

ppb Parts per billion. The concentration of a gas or vapor in air; part (by volume) of the gas or vapor in a billion parts of air. Usually used to express extremely low concentrations of unusually toxic gases or vapors; also the concentration of a particular substance in a liquid or solid.

PPD See Purified Protein Derivative.

PPE Personal protective equipment. Specialized clothing or equipment worn to help isolate a worker from direct exposure to hazardous materials. Examples include goggles, gloves, respirators, safety glasses, or ear plugs. General work clothes (e.g., uniforms, pants, shirts or blouses) not intended to function as protection against a hazard are not considered to be personal protective equipment.

ppm Parts per million. "Parts of vapor or gas per million parts of air by volume at 25 °C and 1 atm pressure" (ACGIH). At 25 °C, ppm = (mg/m3 x 24.45) divided by molecular weight. Usually used to express measurements of extremely low concentrations of unusually toxic gases or vapors; also used to indicate the concentration of a particular substance in a liquid or solid.

ppt Parts per trillion.

Precordial In front of the heart, stomach.

Pressure Demand A mode of operation for atmosphere-supplying respirators in which the air pressure inside the respirator is substantially maintained at a specific positive pressure differential with respect to the ambient air pressure. To maintain this pressure differential, additional air is admitted on demand to the facepiece when the wearer inhales.

Pressure-generating Material A substance or mixture that may spontaneously polymerize with an increase in pressure unless protected by the addition of an inhibitor or by refrigeration or other thermal control; decompose to release gas in its container; or comprise the contents of a self-pressurized container.

Preventive Therapy Treatment of latent TB infection, primarily used to prevent the progression of latent infection to clinically active disease.

Primary Back Pain Injury to the spine itself.

Primary Drug Resistance (PDR) A resistance to one or more antituberculosis drugs that exists before a patient is treated with drugs. Primary resistance occurs in persons exposed to and infected with a drug resistant strain of M. tuberculosis.

Primary Hazard The hazard class of a material assigned in the 49 CFR 172.101 HMT.

Primary Protector A device which may be worn alone or in conjunction with a secondary protector.

Process Any activity involving a highly hazardous chemical including any use, storage, manufacturing, handling, or the on-site movement of such chemicals, or combination of these activities; any groups of vessels which are interconnected and separate vessels that are located so that a highly hazardous chemical could be involved in a potential release shall be considered a single process.

Product Identification Number See PIN.

Prohibited Conditions Any condition in a permit space that is not allowed by the permit during the period when entry is authorized.

Prophylaxis Medical treatment to prevent infection or disease.

Proper Shipping Name The name of the hazardous material shown in Roman print (not italics) in the 49 CFR 172.101 HMT.

Prostration A state of total mental or physical exhaustion.

Protective Laboratory Practices & Equipment As defined by OSHA 1910.1450 Lab Standard, those laboratory procedures, practices, and equipment that laboratory health and safety experts accept as effective, or that the employer can show are effective, in minimizing the potential for employee exposure to hazardous chemicals.

Protective Padding A material used to absorb the kinetic energy of impact.

Proteinuria Presence of protein in the urine; sometimes may be a sign of kidney damage.

Protocol A documented plan of action.

psi Pounds per square inch (for MSDS purposes). The pressure a material exerts on the walls of a confining vessel or enclosure. For technical accuracy, pressure must be expressed as psig (pounds per square inch gauge) or psia (pounds per square inch absolute) - gauge pressure plus sea level atmospheric pressure, or psig plus approximately 14.7 pounds psi.

psia Pounds per square inch absolute.

psig Pounds per square inch gauge (i.e., above atmospheric pressure).

PSM The Process Safety Management standard, 29 CFR 1910.119, promulgated by OSHA, effective May 26, 1992.

Psychotropic, PSY Acting on the mind.

PUL Pulmonary systems effects. Effects on respiration and respiratory pathology.

Pulmonary Relating to the lungs.

Pulmonary Edema Filling of the lungs with fluid; can be caused by lung damage, excessive fluid in the body, or congestive heart failure.

Pupils An opening in the center of the eye that constricts and dilates, depending on the amount of available light.

Purge To clean, clear, or empty of material; a bleed of air or inert gas into a vessel to remove or exclude contaminants.

Purified Protein Derivative (PPD) A purified tuberculin preparation developed in the 1930's and that was derived from old tuberculin. The standard Mantoux test uses 0.1 mL of PPD standardized to 5 tuberculin units.

Purified Protein Derivative (PPD) Test A method used to evaluate the likelihood that a person is infected with Mycobacterium tuberculosis. A small dose of tuberculin (PPD) is injected just beneath the surface of the skin, and the area is examined 48-72 hours after the injection. A reaction is measured according to the size of the induration. The classification of a reaction as positive or negative depends on the patient's medical history and various risk factors. See Mantoux Test.

Purified Protein Derivative (PPD) Test Conversion A change in PPD test results from negative to positive. A conversion within a 2-year period is usually interpreted as new M. tuberculosis infection, which carries an increased risk for progression to active disease. A booster reaction may be misinterpreted as a new infection. See Booster Phenomenon; Two-step Testing.

Pyrazinamide (PZA) A first line, antituberculosis drug used in treatment regimens.

Pyrolysis Chemical decomposition or breaking apart of molecules produced by heating.

Pyrophoric A substance which can ignite spontaneously when exposed to air at temperatures below 54 °C (130 °F), even without an ignition source.

Pyrophoric Liquid A liquid or solid that, even in small quantities and without an external ignition source, can ignite within five (5) minutes after coming in contact with air when tested according to paragraph 3.a.(1) or 3.a.(2), as appropriate, of 49 CFR 173 Appendix E.

Qualitative Fit Test (QLFT) An assessment of the adequacy of respirator fit accomplished by determining whether or not the wearer of the respirator can detect the odor, taste, or irritation of a contaminant introduced into the vicinity of the wearer's head.

Quality Assurance Methods used to assess and ensure that quality control measures are applied.

Quality Control Methods implemented to ensure that the samples, analyses, or work in general, conforms to described techniques, methodologies, or specifications.

Quantitative Fit Test (QNFT) An assessment of the adequacy of respirator fit by numerically measuring concentrations of a challenge agent inside and outside the facepiece. The ratio of the two measurements is an index of leakage of the seal between the respirator facepiece and the wearer's face.

Rad A unit of absorbed dose. The word comes from the acronym Radiation Absorbed Dose and is equivalent to 100 ergs per gram. It does not take into account the biological effect resulting from the absorbed dose.

Radioactive A property of a material which emits ionizing radiation.

Radioactive Materials See 49 CFR 173.403 for detailed definitions relating to radioactive materials.

Radiography A method of viewing the respiratory system by using radiation to transmit an image of the respiratory system to film. A chest radiograph is taken to view the respiratory system of a person who is being evaluated for pulmonary TB. Abnormalities (e.g., lesions or cavities in the lungs and enlarged lymph nodes) may indicate TB.

Radiometric Methods A method for culturing a specimen that allows for rapid detection of bacterial TB growth by measuring production of carbon dioxide by viable organisms; also a method of rapidly performing susceptibility testing of M. tuberculosis.

Radionuclide An atom that spontaneously emits particles, gamma, or x-radiation.

RADS See Reactive Airways Dysfunction Syndrome.

Rail Freight Car A car designed to carry freight or non-passenger personnel by rail, including a box car, flat car, gondola car, hopper car, tank car, and occupied caboose.

RBC See Red Blood Cell.

RCRA Resource Conservation and Recovery Act, PL 94-580. Found at 40 CFR 240-271. EPA has jurisdiction. Enacted November 21, 1976, and amended since. RCRA's major emphasis is the control of hazardous waste disposal. It controls all solid-waste disposal and encourages recycling and alternative energy sources.

RCRA Hazardous Waste A material designated by RCRA as a hazardous waste and assigned a number to be used in record keeping and reporting compliance (e.g., D003, F001, U169).

Reaction A chemical transformation or change. The interaction of two or more substances to form new substances.

Reactivation Development of active TB in someone who had been exposed in the past, but then remained in the latent phase until reactivation occurred.

Reactive See Unstable.

Reactive Airways Dysfunction Syndrome (RADS) An asthma-like condition caused by a severe acute exposure to a pulmonary irritant.

Reactive Flammable Material A material which is a fire hazard because it reacts readily with air or water. Included are materials which: 1) spontaneously ignite in air or water; 2) react vigorously with air; and 3) give off flammable gas on reaction with water. Keep these materials dry and away from oxidizers. They are often stored in an all-nitrogen or argon environment.

Reactive Material explosive material - a substance or mixture that causes sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden adverse conditions; 2) organic peroxide - an organic compound that contains the bivalent -O-O- structure, which can be considered a structural derivative of hydrogen peroxide, in which one or both of the hydrogen atoms has been replaced by an organic radical; 3) pressure-generating material - a substance or mixture that spontaneously polymerizes with an increase in pressure unless protected by the addition of an inhibitor or by refrigeration or other thermal control; decomposes to release gas in its container, or comprises the contents of a self-pressurized container; 4) water-reactive material - a substance or mixture that reacts with water releasing heat or flammable, toxic gas.

Reactivity A substance's tendency to undergo chemical reaction either by itself or with other materials with the release of energy. Undesirable effects such as pressure buildup; temperature increase; or formation of noxious, toxic, or corrosive by-products may occur because of the substance's reactivity to heating, burning, direct contact with other materials, or other conditions in use or in storage. A solid waste that exhibits a "characteristic of reactivity," as defined by RCRA, may be regulated (by the EPA) as a hazardous waste and assigned the number D003.

Reagent Substance used in a chemical reaction to aid in qualitative or quantitative analysis of another substance.

Rebreather Respirator See Closed Circuit Respirator.

Recap Adding top strip of synthetic or reclaimed rubber to surface of a worn tire.

Receptacle A receptacle is a contact device installed at the outlet for the connection of a single attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is a single device containing two or more receptacles.

Receptacle Outlet An outlet where one or more receptacles are installed.

Recirculation Ventilation in which all or most of the air that is exhausted from an area is returned to the same area or other areas of the facility.

RECOMBIVAX One of the commercially available vaccines for HBV. It is derived from genetically modified yeast.

Recommended Exposure Limit See REL.

Red Blood Cell (RBC) Blood cells that look red and carry oxygen around the body.

Reducing Agent In a reduction reaction (which always occurs simultaneously with an oxidation reaction), the reducing agent is the chemical or substance that 1) combines with oxygen or 2) loses electrons to the reaction. See Oxidation; Oxidizing Agent.

Reduction Addition of one or more electrons to an atom through chemical change.

Regimen Any particular TB treatment that specifies which drugs are used, in what doses, according to what schedule, and for how long.

Registry A record keeping method for collecting clinical, laboratory, and radiographic data concerning TB patients so that the data can be organized and made available for epidemiologic study.

Regulated Waste Liquid or semi-liquid blood or other potentially infectious materials; contaminated items that may release blood or other potentially infectious materials in a liquid or semi-liquid state if compressed; items that are caked with dried blood or other potentially infectious materials and may release these materials during handling; contaminated sharps; and pathological and microbiological wastes containing blood or other potentially infectious materials.

REL The NIOSH REL (Recommended Exposure Limit) is the highest allowable airborne concentration that is not expected to injure a worker. It may be expressed as a ceiling limit or as a time-weighted average (TWA), usually for 10-hr work shifts.

Relative Humidity The ratio of the quantity of water vapor present in air to the quantity which would saturate it at any specific temperature.

Rem A unit of dose equivalent. The word comes from the acronym, Roentgen Equivalent Medical and takes into account the biological effect from an absorbed dose of radiation.

Renal Relating to the kidneys.

Replacement in Kind A replacement which satisfies the design specification (i.e. replacement with identical equipment).

Reportable Quantity (RQ) (for the purposes of the DOT regulations for shippers, transporters, and manufacturers). The quantity specified in Column 3 of Appendix A of 49 CFR 172.101 for any material identified in Column 1 of the Appendix.

Reproductive Health Hazard/Toxin Any agent with a harmful effect on the adult male or female reproductive systems or on the developing fetus or child. Such hazards affect people in many ways, including loss of sexual drive, impotence, infertility, sterility, mutagenic effects on germ cells, teratogenic effects on the fetus, and transplacental carcinogenesis.

Rescue Services The personnel designated to rescue employees from permit required confined spaces.

Residual Waste Garbage, refuse, discarded material, or other waste including solid, liquid, semi-solid, or contained gaseous materials resulting from industrial, mining, and agricultural operations and sewage from an industrial, mining, agriculture water supply treatment facility, waste water treatment facility, or air pollution control facility, provided that it is not hazardous.

Residue Solid or semi-solid materials such as ash, ceramics, glass, metal, and organic substances remaining after incineration or processing.

As used in the transporation of hazardous materials, residue means the hazardous material remaining in a packaging, including a tank car, after its contents have been unloaded to the maximum extent practicable and before the packaging is either refilled or cleaned of hazardous material and purged to remove any hazardous vapors.

Resistance The ability of some strains of bacteria (including M. tuberculosis) to grow and multiply in the presence of certain drugs which normally kill them. (Such strains are referred to as "drug resistant strains.")

Resource Conservation and Recovery Act See RCRA.

Respirator A variety of devices that limit inhalation of toxic materials. They range from disposable dust masks to self-contained breathing apparatus (SCBA). All have specific uses and limitations. Their use is covered by OSHA, 29 CFR 1910.134. See SCBA, Chemical Cartridge Respirator.

Respiratory Relating to the lungs, airways, nose, mouth, or throat.

Respiratory Distress Severe difficulty breathing.

Respiratory Protection Program A comprehensive program required by OSHA for the safe and effective use of respiratory protective devices in the workplace.

Respiratory System The breathing system, including the lungs and air passages (trachea or windpipe, larynx, mouth, and nose).

Resting Height Knuckle level, when your arms are relaxed and hanging down at your sides. Lifting from the resting height position creates less stress on the back than lifting directly from the floor.

Retread Used tire with new rubber bonded to worn surface from shoulder to shoulder.

Retrieval System The equipment, including a retrieval line, chest or full body harness, wristlets (if appropriate), and a lifting device or anchor, used for non entry rescue of persons from permit required confined spaces.

Rhinorrhea Runny nose.

Rifampin A first line, oral antituberculosis drug that, when used concomitantly with isoniazid and pyrazinamide, provides the basis for short-course therapy.

Right Angle Position When sitting, upper arms are against the body and forearms are extended at right angles. The right angle position is the most efficient and least stressful way for employees to perform work when seated.

Risk Assessment Evaluation of the threat to public health and the environment posed by hazardous waste, considering probability of incident and its effects.

Room-Air HEPA Recirculation Systems and Units Devices (either fixed or portable) that remove airborne contaminants by recirculating air through a HEPA filter.

Route of Entry Route of Exposure. The way a chemical enters the body; inhalation, skin contact, eye contact, and ingestion.

Routes of Entry To do bodily damage, a material must contact the body. The method of bodily contact is called the route of entry. The routes of entry are 1) absorption (eye or skin contact), 2) ingestion, and 3) inhalation.

RPM Revolutions per minute.

RQ Reportable Quantity. The amount of a material that, when spilled, must be reported to the DOT (Section 311 of the Clean Water Act).

RSI Repetitive stress injury. Injury to the body from performing a repetitive motion task, such as typing. Injuries generally occur in tendons, muscles, or nerves.

RSPA The Research and Special Programs Administration, US Department of Transportation, Washington, DC 20590.

RTECS Registry of Toxic Effects of Chemical Substances, published by NIOSH. Presents basic toxicity data on thousands of materials. Its objective is to identify all known toxic substances and to reference the original studies.

Rubber A generic term that includes elastomers and elastomeric compounds, regardless of origin.

Sacroiliac A joint in the lower back which joins the sacrum and the ileum.

SADT, Self-Accelerating Decomposition Temperature A test that determines an organic peroxide's minimum unsafe storage temperature. This test describes an organic peroxide's tendency to decompose as it warms. Since organic peroxides are oxygen-containing organic compounds, they are both a fuel and an oxidizer. Decomposition can be violent. A related term is MSST, the Maximum Safe Storage Temperature.

SAE Society of Automotive Engineers. As seen on motor oil containers, i.e., SAE 10W30.

Safe Sex Sexual intercourse in which semen or vaginal secretions do not enter the vagina, anus, tip of the penis, or mouth of either partner.

Saint Andrew's Cross. X Used in packaging for transport; means harmful - stow away from foodstuffs. (IMO, Material Class 6.1, Group III).

Saline A solution of salt and water that is the same concentration as the fluids in the human body. Saline is used in medical treatments to wash delicate tissues such as mucous membranes and the interior of wounds. Saline can also be used to replace body fluids in cases of excessive bleeding or dehydration.

SARA Superfund Amendments and Reauthorization Act. Signed into law October 17, 1986. Title III of SARA is known as the Emergency Planning and Community Right-to-Know Act of 1986. A revision and extension of CERCLA, SARA is intended to encourage and support local and state emergency planning efforts. It provides citizens and local governments with information about potential chemical hazards in their communities. SARA calls for facilities that store hazardous materials to provide officials and citizens with data on the types (flammables, corrosives, etc.); amounts on hand (daily, yearly); and their specific locations. Facilities are to prepare and submit inventory lists, MSDSs, and tier 1 and 2 inventory forms. The 1987 disaster in Bhopal, India, added impetus to this law's passage.

Sarcoma A type of cancer.

Saturation The maximum concentration of matter that can be dissolved in a solution at a given temperature.

Saturation Pressure The pressure at which a vapor combined with its liquid will be in stable equilibrium. Below the saturation pressure, some of the liquid will become vapor; above the saturation pressure, some of the vapor will condense to liquid.

SCBA See Self-Contained Breathing Apparatus.

SCC See SETA, SETAFLASH Closed Tester.

Sclera The tough, white, fibrous covering of the eyeball.

Seamed Gloves Gloves constructed by some mechanical process such as stitching or sewing.

Seamless Gloves Gloves made from a seamless process such as molding or dipping.

Seat Belt Passenger restraint system, usually consisting of a lap belt and a shoulder belt.

Second-hand Smoke By-products of burning tobacco. Second-hand smoke contains 3,000 substances, including carbon monoxide, ammonia, formaldehyde, benzene, and methane. The Surgeon General has declared second-hand smoke a serious health hazard.

Secondary Back Pain Injury to the muscles and soft tissue surrounding the spine.

Secondary Line Drugs Antituberculosis drugs used when first line drugs cannot be used (e.g., for drug resistant TB or because of adverse reactions to the first line drugs). Examples are cycloserine, ethionamide, and capreomycin.

Secondary Protector A device which shall be worn only in conjunction with a primary protector.

Sedentary Remaining in one position, such as sitting, for a long period of time.

Sedimentation Hazardous waste physical treatment method which separates and removes suspended particles that are heavier than the liquid in which they are present by gravitational setting.

Seizure An episode of fits or convulsions, such as in an epileptic, characterized by violent body spasms.

Select Carcinogen See Carcinogen.

Self-Accelerating Decomposition Temperature See SADT.

Self-Contained Breathing Apparatus (SCBA) A respirator which contains its own air supply that the user carries, usually in a tank on his or her back (very similar to scuba gear).

Self-Heating Material A material that, when in contact with air and without an energy supply, is liable to self-heat. A material of this type which exhibits spontaneous ignition, or if the temperature of the sample exceeds 200 °C (392 °F) during the 24-hour test period when tested in accordance with paragraph 3.b.(1) of 49 CFR 173 Appendix E, is classed as a Division 4.2 material.

Semen The fluid ejaculated by men during sex. It contains sperm and other fluids.

Sensitivity Testing The ability of an organism to change or respond to an agent, such as drugs, in determining those that are most effective against TB.

Sensitization A state of immune-response reaction in which exposure to a material elicits an immune or allergic response.

Sensitizer A material that on first exposure causes little or no reaction in humans or test animals, but upon repeated exposure may cause a marked response not necessarily limited to the contact site. Skin sensitization is the most common form. Respiratory sensitization to a few chemicals also occurs.

Sensor A device which mechanically, electrically, or thermally senses a state of change and activates an adjusting mechanism.

Service The conductors and equipment for delivering energy from the electricity supply system to the wiring system of the premises served.

Service Life A term that describes the period of time it takes for a specified concentration of a specific substance to break through the chemical or organic vapor cartridge or canister. This concentration is determined by the manufacturer for each type of cartridge or canister for specific substances.

Servicing and/or Maintenance Workplace activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment. These activities include lubrication, cleaning, or unjamming of machines or equipment and making adjustments or tool changes where the employee may be exposed to the unexpected energization or startup of the equipment or release of hazardous energy.

SETA, SETAFLASH Closed Tester Apparatus used to measure flash points in liquids in the 0 °C to 110 °C (32 °F to 230 °F) range (ASTM D 3278-82).

Setting Up Any work done to prepare a machine or equipment to perform its normal production operation.

Sharps Container See Sharps disposal unit.

Sharps Disposal Unit A container made of puncture-resistant plastic or other tough material; used to collect and store used needles, scalpels, broken glass, or other materials capable of breaking the skin. The sharps disposal unit must be located in an area in which sharps are used or generated. It must not overflow and must be leakproof. It must be labelled or color-coded to indicate that it contains contaminated material.

Shell A helmet less its harness, accessories, and fittings.

Shimmy In automobile steering, a wobbling or vibration of front wheels.

Shipping Paper A shipping order, bill of lading, manifest or other shipping document serving a similar purpose and containing the information required by §172.202, §172.203 and §172.204.

Shock A state of reduced blood pressure and/or blood volume resulting in depression of bodily functions; may be caused by injuries involving loss of blood, burns, or crushing of a body part; often is associated with pale, cool skin and a thready pulse.

Shock Absorber A device to provide hydraulic resistance to control excessive deflection of automobile springs.

Shoring Braced walls that will support the side of an excavation or trench from collapsing.

Siderosis Pneumoconiosis caused by inhalation of iron particles. Also, tissue pigmentation caused by contact with iron.

Sideshield A device, commonly attached to spectacles, that provides side exposure protection to the eyes.

Signal Word That portion of a tag's inscription that contains the word or words that are intended to capture the employee's immediate attention.

Silicosis A condition of massive fibrosis of the lungs causing shortness of breath because of prolonged inhalation of silica dusts.

Single Packaging A non-bulk packaging other than a combination packaging.

Single Pass Ventilation Ventilation in which 100% of the air supplied to an area is exhausted to the outside.

Six-Foot Rule General rule calling for workers to wear fall protection harness or use other accepted fall protection means whenever it is necessary to work over six feet above the level one would fall to.

Size The length and breadth measurement of footwear based on the American system of grading.

Skin A notation (sometimes used with PEL or TLV exposure data) which indicates that the stated substance may be absorbed by the skin, mucous membranes, and eyes, either airborne or by direct contact, and that this additional exposure must be considered part of the total exposure to avoid exceeding the PEL or TLV for that substance.

SKN Skin effects; e.g., erythema, rash, sensitization of skin.

Sludge Solid, semi-solid, or liquid waste generated from a municipal, commercial, or industrial waste treatment plant or air pollution control facility, exclusive of treated effluent from a waste water treatment plant.

As applied to motor vehicles, sludge means a viscous composition of contaminated engine oil and other products of incomplete combustion that eventually clogs oil passages resulting in engine failure.

Slurry A pourable mixture of solid and liquid.

Small Quantity Generators Facilities generating or accumulating less than 1,000 kg/month of identified hazardous waste or specific quantities of acutely hazardous wastes. Small quantity generators are exempt from RCRA.

Smear (AFB Smear) A laboratory technique for visualizing mycobacteria. The specimen is smeared onto a slide and stained, then examined using a microscope. Smear results should be available within 24 hours. In TB, a large number of mycobacteria seen on an AFB smear usually indicates infectiousness. However, a "positive" result is not diagnostic of TB because organisms other than M. tuberculosis may be seen on an AFB smear (e.g., nontuberculosis mycobacteria).

Smoke Dry particles and droplets (usually carbon or soot) generated by incomplete combustion of an organic material combined with and suspended in gases from combustion.

Smoke Inhalation Breathing smoke-filled air reduces the amount of oxygen in the body. Symptoms of smoke inhalation include headache, vomiting, nausea, dizziness, and muscular weakness. In severe cases, victims become unconscious and stop breathing.

Solid Waste Municipal, residual, or hazardous waste, including solid, liquid, semi-solid, or contained gaseous materials.

Solidification The process of stabilizing waste into a solid with high structural integrity. Solidified waste is less likely than untreated waste to leach out of a land disposal site, even though the physical and chemical characteristics of the constituents of the waste may not be changed by the process.

Soln See solution.

Solubility in Water A term expressing the percentage of a material (by weight) that dissolves in water at ambient temperature. Solubility information is useful in determining cleanup methods for spills and fire-extinguishing methods for a material. Solubility may be expressed as negligible, less than 0.1%; slight, 0.1 to 1.0%; moderate, 1 to 10%; appreciable, more than 10%; complete, soluble in all proportions. Alternatively, and more usually, it may be expressed as a percentage by weight in a solution, as grams of solute per liter of solution, or as grams of solute dissolved in 100 g of water.

Solution, Soln Mixture in which the components lose their identities and are uniformly dispersed. All solutions contain a solvent (fluid), and the substance dissolved, known as the solute. True solutions are homogeneous.

As used in the transportation of hazardous materials, solution means any homogeneous liquid mixture of two or more chemical compounds or elements that will not undergo any segregation under normal transportation conditions.

Solvent A material that can dissolve other materials to form a uniform single-phase mixture. Water is the most common solvent.

Somnolence Sleepiness.

Soot Fine particles, usually black, formed by combustion (complete or incomplete) and consisting chiefly of carbon. Soot gives smoke its color.

Sorbent A material that is contained in a cartridge or canister and removes specific gases and vapors from the inhaled air.

Source Case A disease (such as TB) in an infectious person who has transmitted the disease to another person or persons.

Source Control Controlling a contaminant at the source of its generation which prevents the spread of the contaminant to the general work space.

Source Individual Person who potentially exposes another person to disease. For example, the blood or other body fluids of a source individual may infect another person with BBP's.

SO x Oxides of sulfur where x equals the number of oxygen atoms.

Spark An electric current possessing sufficient voltage to jump through air (gap) from one conductor to another.

Spark Plug A device, inserted in combustion chamber of an engine, containing a side electrode and insulated center electrode spaced to provide a gap for firing an electrical spark to ignite air-fuel mixture.

Spasm An involuntary, abnormal, convulsive muscular contraction.

SPCC Spill Prevention, Control, and Counter-measure plan.

Specification Packaging A packaging conforming to one of the specifications or standards for packagings in Part 178 or Part 179.

Specific Chemical Identity The chemical name, Chemical Abstracts Service (CAS) Registry Number, or any unique chemical designation of a substance.

Specific Gravity The ratio of the density of a substance to the density of a reference substance, at a specified temperature. Specific gravity is a dimensionless number. Water (density 1 kg/l, or 1 g/mL, or 1 g/cm3 at 4 °C) is the reference for solids and liquids, while air (density 1.29 g/l at 0 °C and 760 mm Hg pressure) is the reference for gases. If a volume of a material weighs 8 g, and an equal volume of water weighs 10 g, the material has a specific gravity of 0.8 (8 ÷ 10 = 0.8). Insoluble materials with specific gravity greater than 1.0 will sink (or go to the bottom) in water. Specific gravity is an important fire suppression and spill cleanup consideration since most (but not all) flammable liquids have a specific gravity less than 1.0 and, if insoluble, float on water.

Specific Volume The volume occupied by a unit mass of a substance under specified conditions of temperature and pressure.

Specific Weight The weight per unit volume of a substance; corresponds to density.

Specimen Any body fluid, secretion, or tissue sent to a laboratory where smears and cultures will be performed (e.g., sputum, urine, spinal fluid, material obtained from a biopsy).

Spectacle A protective device to shield the wearer's eyes from a variety of hazards, depending on spectacle type.

Speedometer A device for measuring and indicating speed of a vehicle in miles per hour and/or kilometers per hour.

Spelunking To explore caves or underground caverns.

Spinal Column The backbone of the body consisting of vertebrae; a cord-like structure of nerve tissue.

Spontaneous Developing without an apparent cause.

Spontaneously Combustible Material A material which undergoes self-heating to the point of ignition without requiring heat from another source.

Spotter A worker, in direct communication with the operator, who watches the movement of heavy equipment, a moving load, or other moving device or material when the operator does not have clear vision.

Sprain Injury to the soft tissue surrounding a joint. A sprain usually causes immediate swelling and pain, and for this reason, X-rays are often needed to distinguish this injury from a fracture. Most sprains are treated by applying ice for 24 hours and resting the affected limb for several days.

Springs Suspension devices including leaf, coil, air type, or torsion bars.

Sputum Phlegm coughed up from deep within the lungs. If a patient has a pulmonary disease, an examination of the sputum by smear and culture can be helpful in evaluating the organism responsible for the infection. Sputum should not be confused with saliva or with nasal secretions.

Sputum Induction A method used to obtain sputum from a patient who is unable to cough up a specimen spontaneously. The patient inhales a saline mist, which stimulates a cough from deep within the lungs.

Sputum Smear Positive AFB (Acid Fast Bacilli) are visible on the sputum smear when viewed under a microscope. Persons with a sputum smear positive for AFB are considered more infectious than those with smear-negative sputum.

Stability The ability of a material to remain unchanged. For MSDS purposes a material is stable if it remains in the same form under expected and reasonable conditions of storage or use. Conditions such as temperatures above 66 °C (150 °F) or shock from being dropped that may cause instability (dangerous change) are stated on the MSDS. See Unstable.

Static Exertions Prevention of movement.

Static Loading A condition that results when the body is not involved in active exertion. Prolonged sitting or standing places repetitive pressure on various areas of the body and can cause pain and injury.

STEL Short-term exposure limit; ACGIH terminology. See TLV-STEL.

Sterilize The use of a physical or chemical procedure to destroy BBP's.

STEV Short-term exposure value. See TLV.

Stomatitis Inflammation of the mucous membrane of the mouth.

Storage The containment of waste on a temporary basis that does not constitute disposal of waste. Containment of waste for over a year constitutes disposal.

Storage Facility Any facility which stores wastes, except generators who store their own wastes, less than 90 days for subsequent transport off-site.

Streptomycin (SM) A first line injectable antituberculosis drug.

Stress Physical or mental tension. Everyone's stress threshold is different. Stress is an individual reaction to outside circumstances.

Strong Outside Container The outermost enclosure that provides protection against the unintentional release of its contents under conditions normally incident to transportation.

Stupor Partial or near complete unconsciousness.

Subacute Toxicity Adverse health effects resulting from exposure to a chemical for weeks or several months.

Subcutaneous Beneath the skin.

Sublime To change from the solid to the vapor phase without passing through the liquid phase. Dry ice exhibits sublimation.

Subpart Z See Z List.

Subsidiary Hazard A hazard of a material other than the primary hazard. See Primary Hazard.

Superficial Burn First-degree burn affecting the top layers of skin (epidermis) and characterized by redness and irritation or pain.

Superfund The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 provides the Federal government with the mechanism to take emergency or remedial action to clean up both abandoned and existing disposal sites when there is a release or threat of a release of a hazardous substance which may present imminent and substantial danger to public health and welfare. Funds for these clean-up actions come from a $1.6 billion trust fund called the Response Trust Fund.

Superfund Amendments and Reauthorization Act See SARA, CERCLA.

Supplied-air Respirator A respirator which receives breathing air through an airline or hose from a portable or stationary source of compressed air.

Surface Area The area of a material's surface exposed to air.

SUS Saybolt Universal Seconds. A unit measure of viscosity determined by the number of seconds required for an oil heated to 54 °C (130 °F) (lighter oils) and 99 °C (210 °F) (heavier oils) to flow through a standard orifice and fill a 60-ml flask.

Susceptibility An individual's sensitivity to a hazardous substance's effects (see also Individual Susceptibility).

Suspension The portion of the harness that is designed to act as an energy-absorbing mechanism. It may consist of crown straps, protective padding, or a similar mechanism.

As applied to motor vehicles, suspension refers to the use of front and rear springs to suspend a vehicle's frame, body or unitized body, above wheels.

Sweatband The part of the headband, whether integral or replaceable, that comes in contact with at least the wearer's forehead.

Swing Radius The circular area around heavy equipment that the equipment may traverse in the normal course of its work. Persons should not be in this area to avoid accidental impact by the equipment.

Symptomatic Having symptoms that may indicate the presence of a disease. See Asymptomatic.

Syncope Fainting; an episode of temporary unconsciousness.

Synergism A combined action of two or more toxic substances to give an effect greater than the sum of their activity when each toxic substance is alone. For example, both smoking and exposure to asbestos can cause lung cancer; however, if a smoker is also exposed to asbestos, the danger of lung cancer is far greater than just adding together the separate risks from the two exposures.

Synonyms Alternative names by which a material may be known.

Synovial Fluid A thin film of liquid surrounding a joint which cushions adjoined bones against each other.

SYS Systemic effects. Effects on the entire body.

Systemic Toxicity Toxicity resulting from absorption of a chemical substance into the body, and acting somewhere other than the point of entry.

Tachometer A device for measuring and indicating speed of an engine in revolutions per minute.

Tachycardia Fast heartbeat (over 100 beats per minute).

Tachypnea Fast breathing rate.

Tag Closed Cup See TCC or TCT.

Tag Open Cup See TOC.

Tag Open Tester An open-tank tester for liquids with low flash points. See TCC or TCT.

Tagout The placement of a tagout device on an energy-isolating device, in accordance with an established procedure, to indicate that the energy isolating device and the equipment being controlled may not be operated until the tagout device is removed.

Tagout Device A prominent warning device, such as a tag and a means of attachment, that can be securely fastened to an energy-isolating device in accordance with an established procedure, to indicate that the energy-isolating device and the equipment being controlled may not be operated until the tagout device is removed.

Tank Container, consisting of a shell and heads, that forms a pressure-tight vessel having openings designed to accept pressure-tight fittings or closures, but excluding any appurtenances, reinforcements, fittings, or closures. For tank specification purposes, "tank" means inner vessel and "jacket" means either the outer shell or insulation cover.

Target Organ The organ where a chemical exerts its toxic effects.

Target Organ Effects Chemically caused effects from exposure to a material on specific listed organs and systems, i.e. liver, kidneys, nervous system, lungs, skin, and eyes.

TCC TCT. Tag (Tagliabue) closed cup or Tag closed tester. One of several types of apparatus for determining flash points. The Tag closed tester, per ASTM D56-79, is intended for testing liquids with a viscosity of less than 45 SUS at 38 °C (100 °F) and a flash point below 93.4 °C (200 °F). Liquids should not have suspended solids or form surface films.

TCLo Toxic concentration low. The lowest concentration of a substance in air to which humans or animals have been exposed for any given period of time that has produced any toxic effect in humans or produced a tumorigenic or reproductive effect in animals or humans.

TCPL Toxic Contaminant Leaching Procedure. A method that assesses the concentration of 8 heavy metals, 6 pesticides, and 25 other organic compounds in a sample of waste. Values which exceed established limits (usually 100 times the maximum concentration level in the Safe Drinking Water Act) require that the waste be characterized as hazardous.

TDL Toxic dose level.

TDLo The lowest dose of a substance introduced by any route other than inhalation over any given period of time and reported to produce any toxic effect in humans or to produce tumorigenic or reproductive effects in animals or humans.

Technical Name A recognized chemical name or microbiological name currently used in scientific and technical handbooks, journals, and texts. Generic descriptions are authorized for use as technical names provided they readily identify the general chemical group, or microbiological group. Examples of acceptable generic descriptions are organic phosphate compounds, petroleum aliphatic hydrocarbons, and tertiary amines. For proficiency testing only, generic microbiological descriptions such as bacteria, mycobacteria, fungus, and viral samples may be used. Except for names that appear in 49 CFR 172 Subpart B, trade names may not be used as technical names.

Temp Temperature.

Temple That part of a spectacle commonly attached to the front and generally extending behind the ear of the wearer.

Tenderness Pain with pressure on the tender spot.

Tendon A hard, rigid cord or bundle of connective tissue by which a muscle is attached to a bone.

Teratogen, TER An agent or material causing physical defects in a developing embryo or fetus.

Testing The process by which the hazards that may confront entrants of a permit space are identified and evaluated. Testing includes specifying the tests that are to be performed in the permit space.

Tetanus A severe infection caused by a bacteria commonly found in soil. Tetanus, which is a possible complication of a wound, causes extremely painful muscular contractions which can result in death. Tetanus is very difficult to treat, but can be easily prevented by a vaccination given every ten years.

TFX Toxic effects. Used to introduce the principle organ system affected as reported or its pathology. Used especially in RTECS.

Thermal Pertaining to heat.

Thermal Burn A heat-caused burn.

Thermal Decomposition The breakdown of a material when heated.

Thermal Treatment Process by which hazardous waste is rendered non-hazardous or is reduced in volume by exposing the waste to high temperatures. The organic materials are oxidized and converted to carbon dioxide and water.

Thermostat A heat-activated valve used in cooling system of engine to regulate flow of water between cylinder block and radiator.

Three-Point Stance Of two hands and two feet, workers must at all times have three in contact with a ladder or when entering or exiting a piece of heavy equipment. To maintain a three-point stance, it is not possible to climb and at the same time carry something.

Threshold Limit Value See TLV.

Threshold Planning Quantity (TPQ) Per 40 CFR 302. The amount of material at a facility that requires emergency planning and notification per CERCLA.

Threshold TLV The level where the first effects occur.

Tight-fitting Facepiece A respiratory inlet covering designed to form a complete seal with the face. A half facepiece (includes quarter mask, disposable mask, or mask with an elastomeric facepiece) covers the nose and mouth. A full facepiece covers the nose, mouth, and eyes.

Time-Weighted Average See TLV.

Tine Test An older form of the TB skin test using multiple punctures. This has been replaced by the Mantoux test at most clinics.

Tinnitus A ringing sound in the ears.

TLm Median tolerance limit. Designates a toxic material's concentration at which 50% of the test organisms, usually aquatic, survive. For example, a conservation authority may limit pollution to TL90 (at which 90% survival is required), to protect fish.

TLV TLV-TWA, allowable time-weighted average concentration for a normal 8-hr workday or 40-hr week; TLV-STEL, short-term exposure limit or maximum concentration for a continuous exposure period of 15 min (with a maximum of four such periods per day, with at least 60 min between exposure periods, and provided that the daily TLV-TWA is not exceeded); and Ceiling (C), concentration not to exceed at any time.

TLV-Ceiling Limit See TLV.

TLV-Skin See Skin.

TOC Tag open-cup test method.

Toe Box A stiffener designed to provide toe protection for the wearer as required by the PPE standard, 29 CFR 1910.132.

Toluene The primary chemical in rubber cement. Toluene is a powerful narcotic and, if inhaled for a prolonged period of time, can cause brain damage.

torr A unit of pressure, equal to 1 mm Hg. See atm (atmosphere).

Total Suspended Particles Particles found in the atmosphere composed of substances such as dust, soot, organic matter, and compounds containing sulfur, nitrogen, and metals.

Toxic Poisonous; having properties of causing adverse health effects when the body is exposed. Having 1) an LD50 of 50 to 500 mg/kg when administered orally to albino rats weighing 200 to 300 g each; 2) an LD50 of 200 to 1000 mg/kg when administered by continuous contact for 24 hr to the bare skin of albino rabbits weighing 2 to 3 kg each; or 3) an LC50 of 200 to 2000 ppm (gas or vapor) or 2 to 20 mg/l (mist, fume, or dust) when administered by continuous inhalation for 1 hour to albino rats weighing 200 to 300 g each. See Acute Toxicity.

Toxic Substance Any chemical or material that 1) has evidence of an acute or chronic health hazard and 2) is listed in the NIOSH Registry of Toxic Effects of Chemical Substances (RTECS), provided that the substance causes harm at any dose level; causes cancer or reproductive effects in animals at any dose level; has a median lethal dose (LD50) of less than 500 mg/kg of body weight when administered orally to rats; has a median LD50 of less than 1000 mg/kg of body weight when administered by continuous contact to the bare skin of albino rabbits; or has a median lethal concentration (LC50) in air of less than 2000 ppm by volume of gas or vapor, or less than 20 mg/L of mist, fume, or dust when administered to albino rats.

Toxic Substances Control Act See TSCA.

Toxic Waste A waste that poses a substantial present or potential hazard to human health or the environment, when improperly managed, includes wastes which are toxic (poisonous), carcinogenic, mutagenic, teratogenic, phytotoxic, or toxic to aquatic species.

Toxicity A chemical's intrinsic ability to cause adverse health effects when exposure is excessive.

Toxicology The study of the nature, effects, and detection of poisons in living organisms. Also, substances that are otherwise harmless but prove toxic under particular conditions. The basic assumption of toxicology is that there is a relationship among the dose (amount), the concentration at the affected site, and the resulting effects.

TPQ See Threshold Planning Quantity.

TQ Threshold Quantity in pounds. The amount necessary to be covered by the Process Safety Management standard.

Trachea Windpipe.

Trade Name A name, usually not the chemical name, given to a product by the manufacturer or supplier and usually protected as a Registered Trademark. The same or similar products can be marketed under different trade names by different companies.

Trade Secret Confidential information (formula, process, device, etc.) that gives the owner an advantage over competitors. Manufacturers may choose to withhold proprietary data from an MSDS. Typically these would be ingredients of a formulated product. OSHA permits this provided 1) the trade secret claim can be substantiated; 2) the MSDS indicates that data is being withheld, and 3) the properties and health effects are included. State laws vary on this practice; some states require a trade secret registration number to be assigned to a material. There are procedures to obtain necessary trade secret information in emergency situations.

Transmission The spread of an infectious agent from one person to another. The likelihood of transmission is directly related to the duration and intensity of exposure. See Exposure.

Transport Vehicle A cargo-carrying vehicle such as an automobile, van, tractor, truck, semitrailer, tank car or rail car used for the transportation of cargo by any mode. Each cargo-carrying body (trailer, rail car, etc.) is a separate transport vehicle.

Trauma An injury from any cause, but usually mechanical (cut, broken bone).

Tread Wear Indicators Crosswire strips molded into tire that, when exposed, indicate the need for tire replacement.

Treatment Failures Disease in patients who do not respond to chemotherapy and in patients whose disease worsens after having improved initially.

Tremor Vibratory movement, shaking or trembling, usually of the hands.

1,1,1 Trichloroethane The primary chemical component in an older formula of typing correction fluid ("white out"). Inhaling its fumes for a prolonged period of time can injure your liver.

Trigger Finger A condition in which the finger that holds a tool trigger in the "on" position is locked in a bent position.

TSCA Toxic Substances Control Act. Public Law PL 94-469. Found in 40 CFR 700-799. EPA has jurisdiction. Effective Jan. 1, 1977. Controls the exposure to and use of raw industrial chemicals not subject to other laws. Chemicals are to be evaluated prior to use and can be controlled based on risk. The act provides for a listing of all chemicals that are to be evaluated prior to manufacture or use in the U.S. (EPA, Industry Assistance Office, [202] 554-1404.)

TSDF A treatment, storage, and disposal facility for hazardous waste.

Tubercle Bacilli Mycobacterium tuberculosis organism.

Tuberculin Skin Test A method used to evaluate the likelihood that a person is infected with Mycobacterium tuberculosis. A small dose of PPD-tuberculin is injected just beneath the surface of the skin and the area is examined 48-72 hours after the injection. A reaction is measured according to the size of the induration. The classification of a reaction as positive or negative depends on the patient's medical history and various risk factors. See Mantoux Test; PPD Test.

Tuberculosis (TB) A clinically active, symptomatic disease caused by Mycobacterium tuberculosis complex (usually M. tuberculosis or, rarely, M. bovis or M. africanum).

Tuberculosis (TB) Isolation Precautions Infection control procedures that should be used when persons with known or suspected infectious TB are hospitalized or residing in other in-patient facilities. These precautions include the use of a private room with negative pressure in relation to the surrounding air and removal of air from the room directly to the outside. Not the same as "respiratory isolation," which calls for a private room but does not require negative pressure and exhaust of room air to the outside.

Tuberculosis Case A particular episode of clinically active TB. It is sometimes used incorrectly to designate the individual with the disease. This term should be used only to refer to the disease itself, not the patient with the disease. By law, cases of TB must be reported to the local health department.

Tuberculosis Infection A condition in which living tubercle bacilli are present in the body, but the disease is not clinically active. Infected persons usually have positive tuberculin reactions, but they have no symptoms related to the infection and are not infectious. However, the infected persons remain at lifelong risk for developing disease unless preventive therapy is given.

Tumor A growth of tissue without physiological function. May be benign (noninvasive) or cancerous. See Cancer, Neoplasm.

Tune-up A process of accurate and careful adjustments and parts replacements.

TWA Time-weighted average. See TLV.

TWA-C Time-Weighted Average-Ceiling Limit. The limit placed on fast acting substances that restricts all exposures to a level below the applicable "C" limit. All time-weighted average concentrations and "peak" exposures must be less than this limit.

Two-Step Testing A procedure used for the baseline testing of persons who will periodically receive tuberculin skin tests (e.g., health care workers) to reduce the likelihood of mistaking a boosted reaction for a new infection. If the initial tuberculin test result is classified as negative, a second test is repeated 1-3 weeks later. If the reaction to the second test is positive, it probably represents a boosted reaction. If the second test result is also negative, the person is classified as not infected. A positive reaction to a subsequent test would indicate new infection (i.e., a skin test conversion).

Type 1 Helmet Headwear having a full brim.

Type 2 Helmet. Headwear having no brim but may include a peak.

UEL See Upper Explosive Limit, Upper Flammable Limit.

UFL See Upper Flammable Limit, Upper Explosive Limit.

Ulcer Ulceration. Loss or death of tissue resulting in an open sore on the skin or on a surface of an internal organ, such as the stomach.

Ultraviolet (UV) Lamps Lamps that destroy germs by emitting radiation predominantly at a wavelength of 254 nanometers (intermediate between visible light and X-Rays). They can be used in ceiling or wall fixtures or within air ducts of ventilation systems. The effectiveness in killing tubercle bacilli for infection control in health care facilities is not yet proven.

Ultraviolet Germicidal Irradiation (UVGI) The use of ultraviolet radiation to kill or inactivate microorganisms.

UN United Nations.

UN Number See DOT Identification Numbers; PIN.

Unattended Operations An experiment is considered unattended if it is operating without continuous human observation by a person capable of performing emergency response, in physical proximity to, and knowledgeable of the experiment's control parameters.

United States (US) A State of the United States, the District of Columbia, the Commonwealth of Puerto Rico, the Commonwealth of the Northern Mariana Islands, the Virgin Islands, American Samoa, Guam, or any other territory or possession of the US designated by the Secretary of State.

Unibody Design that incorporated body and frame of vehicle in a single structure.

United States Public Health Service A branch of the Federal Health and Human Services Department. Includes both NIOSH and CDC.

Unit Load Device Any type of freight container, aircraft container, aircraft pallet with a net, or aircraft pallet with a net over an igloo.

Universal Joint A connection for transmitting torque - rotational force from one shaft to another at fixed or varying angles.

Universal Precautions An approach to infection control in which all human blood and certain human body fluids are treated as if infected with HIV, HBV, or other BBP's.

Unleaded Gasoline Motor fuel containing no tetraethyl lead additive.

Unsafe Sex Sex in which semen or vaginal secretions enter the vagina, anus, tip of the penis, or mouth of either partner.

Unstable Tending toward decomposition or other unwanted chemical change during normal handling or storage. An unstable chemical in its pure state, or as commonly produced or transported, polymerizes vigorously, decomposes, condenses, or becomes self-reactive under conditions of shock, pressure, or temperature. See Stability, Reactive Material.

Unstable Reactive A chemical that, in the pure state, or as produced or transported, will vigorously polymerize, decompose, condense, or become self-reactive under conditions of shock, pressure, or temperature.

UN Standard Packaging A specification packaging conforming to the requirements in 49 CFR 178 Subparts L and M.

Upper The upper parts of the footwear, including the outside and the lining.

Upper Explosive Limit, Upper Flammable Limit UEL, UFL. The highest concentration of a material in air that produces an explosion or fire or that ignites when it contacts an ignition source (high heat, electric arc, spark, or flame). Any concentration above the UEL in air is too rich to be ignited. See Flammable Limits.

URT Upper respiratory tract.

Urticaria Hives caused by a systemic allergic reaction.

UV Ultraviolet (light).

Vaccination The process of administering a vaccine.

Vaccine A preparation administered to produce immunity against a specific infection; usually given by injection into a muscle or under the skin.

Vapor The gaseous state of a material normally encountered as liquid or solid at room temperature. Vapors of organic liquids are loosely called fumes; however, it is not technically appropriate to use the term fume for vapors of organic liquids.

Vapor Density The ratio of the formula mass (FM) of the compound to the average formula mass of the gases in air (29 grams per mole). This formula mass ratio is correct for a pure gas at room temperature. However, this ratio does not accurately express the vapor density of a liquid solvent. A liquid cannot liberate vapors more concentrated than its saturated vapor concentration. The saturated vapor concentration of a liquid is the ratio of its vapor pressure at a given temperature to the atmospheric pressure. Using this ratio, the % of the compound in air and the remaining % of air at saturation (for example, 19.7% hexane and 80.3% air) can be calculated. The saturated vapor density is then determined by multiplying the % of the compound in air by its FM and the % of air by its FM; adding this air/liquid vapor mixture at saturation; and dividing the sum by 29 and multiplying by the density of pure air (1.2 kg/m3, 0.075 lbs/ft3). Saturated air/liquid vapor mixtures may be heavier than air, but not as heavy as formula mass ratios indicate. Temperature differences and turbulence create density differences between volumes of air and often have a greater influence on the movement of contaminated air than the actual saturated vapor density of the chemical.

Vapor Lock A condition in which fuel "boils" in fuel system, forming air pockets that retard or stop flow of fuel to carburetor.

Vapor Pressure The pressure a saturated vapor exerts above its own liquid in a closed container. Vapor pressures reported on MSDSs are usually stated in millimeters of mercury (mm Hg) at 20°C (68°F). The lower a substance's boiling point, the higher its vapor pressure; and the higher the vapor pressure, the greater the material's tendency to evaporate into the atmosphere. Vapor pressures are useful (with evaporation rates) in learning how quickly a material becomes airborne within the workplace and thus how quickly a worker is exposed to it.

Vascular Relating to the blood vessels (arteries, veins, or capillaries).

VDT Video Display Terminal. Another name for computer monitors and screens. Glare and eyestrain are two problems associated with VDT use.

Vectors Invertebrates which transmit infectious agents by biting through the skin or depositing infective materials on skin or food; any animal involved directly in the transmission of communicable disease.

Vehicle The means of transmitting an agent or a carrier.

Ventilation Circulation of air within an environment.

Vertebrae Separate bones of the back stacked one on top of the other, cushioned by discs, and held together by ligaments.

Vertigo A type of dizziness in which the room feels like it is spinning.

Vesicant A chemical which causes a blistering rash.

Vesicular Blistered.

Vesiculation Blistering of the skin.

Vibration Rapid back and forth motion. In the hands, repeated use of vibrating tools can lead to numbness and a loss of control in the hands.

Virulence The degree of pathogenicity of a microorganism as indicated by the severity of the disease produced and its ability to invade the tissues of a host. M. tuberculosis is a virulent organism.

Virus Extremely small infectious agent capable of reproducing itself only inside living cells of a human or animal. There are thousands of virus types. Viruses cause diseases ranging from the common cold to severe infections resulting from HIV and HBV.

Viscosity Measurement of a fluid's thickness or resistance to flow. Unit of measurement, usually centipoise (cP), and temperature are included.

VOC Volatile organic compounds. Used in coatings and paint because they evaporate very rapidly. Regulated by the EPA per the Clean Water Act.

Volatile Evaporating readily at normal temperature and pressure.

Volatile Organic Compounds Any compound containing carbon and hydrogen in combination with any other element which has a vapor pressure of 1.5 pounds per square inch absolute (77.6 mm Hg) or greater.

Volatility The tendency or ability of a liquid to vaporize or evaporate at ambient routine conditions. Liquids, such as alcohol, gasoline, and ether, are described as volatile liquids because they evaporate readily.

Voluntary Muscles The muscles that you can control to create body movement.

VP See Vapor Pressure.

Warning Properties Odor or irritation signaling the presence of a chemical at airborne concentrations below those which are considered toxic.

Water Reactive Describes a substance or mixture that reacts with water to release heat or a flammable, toxic gas, or to otherwise present a health hazard.

Water Reactive Material A material that, by contact with water, is liable to become spontaneously flammable or to give off flammable or toxic gas at a rate greater than 1 liter per kilogram of the material, per hour, when tested in accordance with paragraph 4 of Appendix E in 49 CFR 173.

WBC See White Blood Cell.

Welding Helmet A protective device intended to shield the eyes and face from optical radiation and impact. Welding helmets are secondary protectors and shall be used only in conjunction with primary protectors.

What-if For relatively uncomplicated processes, a review of the process from raw materials to product. At each handling or processing step, "what if " questions are formulated and answered to evaluate the effects of component failures or procedural errors on the process.

What-if/Checklist The what-if/checklist is a broad-based hazard assessment technique that combines the creative thinking of a selected team of specialists with the methodical focus of a prepared checklist.

Wheelbase Distance between centerlines of front and rear axles.

Wheezing Breathing that sounds somewhat like bagpipes due to airway constriction; shortness of breath may be associated with wheezing; commonly occurs in asthma.

White Blood Cell (WBC) Blood cells that look white under the microscope and function to fight infection.

White Noise A low-level hum in a workplace that is emitted from office machinery. White noise is not loud enough to damage hearing, but it can affect the nervous system and cause stress.

WHMIS Workplace Hazardous Materials Information System. A nationwide Canadian system providing information to workers on hazardous materials in the workplace. This is accomplished through labels, MSDSs, and worker education. It is similar to the United States' OSHA Hazard Communication Standard.

Wilson RISK Scale An acute hazard rating scale unique to Genium's MSDS Collection. This scale was developed by a certified industrial hygienist for compliance with the OSHA Labeling Standard (29 CFR 1910.1200). This numbering system (of 0-4) & four hazard categories - reactivity (R), inhalation (I), skin contact (S), and kindling (K) - represents a material's degree of hazard based on documented values and/or the best judgments of certified industrial hygienists. The higher numbers indicate an increased hazard.

Window That portion of a faceshield through which the wearer views the work.

Window, Non-removable A window and holder that are homogeneous and continuous.

Wing Position Performing work with arms raised above the head.

Winter Liner A snug-fitting cover worn under the helmet to protect the head, ears, and neck from cold.

Work Practice Controls Changes in the way tasks are performed so that exposure to BBP's is reduced or eliminated.

Work Surface Height The optimal height necessary to effectively perform work. The height of the work surface is determined by the work involved.

Working Alone Performance of any work by an individual out of audio or visual range of another individual for more than a few minutes. No other person is aware of the individual working alone, the nature of the work being done, or the time period the individual expects to work. A worker alone in a lab should not undertake experiments known to be hazardous. Always work under conditions where the availability of emergency aid is compatible with the nature of the hazard and the degree of exposure.

Working Area Finger and thumb crotches; the palm (area between wrist and base of finger and thumb) and the area of the finger and thumb facing the palm not extending beyond the center line of the crotch.

Z List OSHA's Toxic and Hazardous Substances Tables Z-1, Z-2, and Z-3 of air contaminants, (29 CFR 1910.1000). These tables record TWAs, STELs, and ceiling concentrations for the materials listed. Any material on these tables is considered hazardous.

ZDV See Zidovudine.

Zidovudine (ZDV; also known as AZT) A medication that can delay the start of the complications of AIDS. ZDV can help a person with AIDS live longer, but it is not a cure. ZDV is often given to workers who have received a needlestick injury which is considered risky for the transmission of HIV infection. It is not yet known if ZDV can help prevent initial infection by HIV.

Zinc Fume Fever. Caused by inhalation of zinc oxide fume and characterized by flu-like symptoms: metallic taste in mouth, coughing, weakness, fatigue, muscular pain, and nausea, followed by fever and chills. Symptoms occur 4 to 12 hr after exposure.