EMTEnvironmental Monitoring Technology

Our Products
Our Services
Chemical Information

Dictionary
About Us
Contact Us
Coffee Break
Home
Environmental and Safety Services for Healthcare Organizations

Dictionary

Safety and Health Terms & Abbreviations

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A    Top

Abatement. Generally refers to a reduction in pollution either partially or completely.

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.

Acclimatization. The physiological and behavioral adjustments of an organism to changes in its environment.

Acetylcholine. A compound formed in the body and released at nerve endings to transmit nerve impulses.

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, Cincinnati, OH 45240; [513] 742-2020.)

Acid. An inorganic or organic compound that: 1) is usually corrosive to human tissue and must be handled with care; 2) has a pH of less than 7.0; 3) neutralizes bases (alkalis) to form salts; 4) dissociates in water yielding hydrogen or hydronium ions; 5) may react with metals to yield hydrogen; and 6) turns litmus paper red.

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.

Acrid. Irritating and bitter (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 (20 CFR 1910.1001.1052); 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.

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.

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

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).

ADI. Acceptable Daily Intake.

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.

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

Adulterants. Legally prohibited impurities in food or pesticides.

Aerosol. A fine suspension in air or other gas of liquid (mist, fog) or solid (dust, fume, smoke) particles small enough to stay suspended. See Smoke; Fog; Mist.

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

AICE. American Institute of Chemical Engineers (800-242-4363, Website: www.aiche.org).

AIHC. American Industrial Health Council (202-833-2131).

AICS. Abbreviation for 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.

Airborne Release. Release of any chemical (gas, vapor, mist, dust) into the air.

ALA. 8-Aminolevulinic Acid. A biological marker excreted in urine which may be indicative of lead poisoning.

ALARA. Acronym for "as low as reasonably achievable."

Alkali. An inorganic or organic chemical that: 1) is usually corrosive to human tissue and must be handled with care; 2) has pH of more than 7.0; 3) neutralizes acids to form salts; 4) dissociates with water yielding hydroxide ions; 5) turns litmus paper blue, and  6) may also be called a base or caustic. Examples are oxides of hydroxides of certain metals belonging to group IA of the periodic table (Li, Na, K, Rh, Cs, Fr). Ammonia and amines may also be alkaline. 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.

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, sneezing and skin eruptions are common. In more serious instances the throat swells, leading to respiratory distress.

Alopecia. Loss of hair.

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

Amenorrhea. Stoppage of menstruation (period).

Analgesia. Reduced sensitivity to pain.

Anemia. Blood is deficient in red blood cells, hemoglobin, or volume.

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

Anhydride. A compound derived from another compound (e.g., 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 or crystallization.

Annual Report on Carcinogens. Published annually by the National Toxicology Program (NTP) and available from NTIS, this report list substances either known or anticipated to be carcinogens.

Anorexia. Loss of appetite.

Anosmia. Loss of the sense of smell.

Anoxia. A lack of oxygen in the 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.

Antibodies. A blood serum protein produced by the immune system in response to antigens for purpose of fighting infection.

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

Antigen. Usually a protein or carbohydrate substance that enters the body as an infective organism and causes production of antibodies and an immune response.

Anuria. Absence or defective excretion of urine.

APHA. American Public Health Association (202-789-5600 Website: http://www.apha.org).

API. American Petroleum Institute (202-682-8000, Website: www.api.org).

Aplastic Anemia. Failure of bone marrow to produce red blood cells.

Apnea. Temporary stoppage of breathing.

Appearance. A material's physical state (solid, gas, or liquid), its color, and other visual attributes. If there is a difference between a material's appearance and that listed on the MSDS, contact your supervisor.

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.

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

Arrhythmia. Irregular heartbeat.

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 their use.

Arthralgia. Joint pain.

Asbestos. A group of impure magnesium silicate minerals typically used for their heat-insulating properties that when friable present a health hazard if airborne and inhaled. Their use is now banned or severely restricted by the EPA.

Asbestosis. Chronic lung disease caused by inhaling airborne asbestos fibers.

Ash. The mineral content remaining after complete combustion of a substance.

Asphyxia. Lack of oxygen or inability of cells to use oxygen; simple asphyxia is suffocation caused by a lack of oxygen in the inhaled air (e.g. displacement by nitrogen); chemical asphyxia poisons the blood's ability to carry oxygen (carbon monoxide) or the cell's ability to use oxygen (cyanide).

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

Asthenia. Loss of strength or energy.

Asthma. A medical disorder which causes attacks of wheezing, chest tightness, shortness of breath, and/or coughing due to spasmodic contraction of the air passages.

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

Asymptomatic. Not exhibiting symptoms.

Ataxia. A loss of muscular coordination of gait or movement.

atm. Atmosphere. A unit of pressure equal to the average pressure that air exerts at sea level. 1 atm =1.013 x 10 5 N/m2, or 14.7 lb/in. 2, or 760 mm Hg or 101 kPa. Generally used in connection with high pressures.

Atomize. To break up a liquid into very fine droplets by forcing it through a small orifice.

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

ATSDR. Agency for Toxic Substances and Disease Registry (800-447-1544, Website: http://www.atsdr.cdc.gov)

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.

B    Top

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

BaP. Benzo(a)Pyrene.

Base. An alkali. See Alkali.

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

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. Harmless.

Beryllium. A metal that can be hazardous to health, typically when inhaled as airborne particles. A human carcinogen (IARC).

Beta particle. A charged particle from radioactive decay that may cause skin burns when directly exposed and is harmful within the body.

Bilirubin. Red bile pigment, formed from hemoglobin during normal and abnormal destruction of red blood cells.

Bioaccumulate. The accumulation of a substance, such as a pesticide, in a living organism.

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.

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

Black Lung. Name given to the lung disease caused by the inhalation and prolonged retention of abnormal amounts of coal dust in the lungs. Also known as coalworkers' pneumoconiosis.

Blasting Agent. Any material or mixture, consisting of a fuel and oxidizer, intended for blasting, not otherwise classified as an explosive.

Blepharitis. Eyelid inflammation.

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.

BLS. Bureau of Labor Statistics (202-219-5000, Website: www.bls.org).

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.

BP. See Boiling Point.

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

British Anti-Lewisite. See BAL.

Bronchitis. An inflammatory condition of the air ways (bronchial tubes) resulting in coughing up of sputum.

Btu. British thermal unit. The quantity of heat required to raise the temperature of 1 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/ft 3 or g/cm 3.

BUN. Blood Urea Nitrogen.

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.

By-product. Material, other than the intended main product, that is created from an industrial process.

C    Top

c, ca. Circa, about, approximately.

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.

CAA. Clean Air Act. Public Law PL 91-604, 40 CFR 50-80. EPA has jurisdiction. Effective Dec.31, 1970, and subsequently amended several times. This regulatory vehicle sets the 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.

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

Cancer. An abnormal multiplication of cells that tends to infiltrate other tissues 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.

CAR, CARC. Carcinogen or carcinogenic.

Carbon Dioxide. See CO2.

Carbon Monoxide. See CO.

Carboxyhemoglobin. A compound formed when carbon monoxide is inhaled and results in the inability of the blood to combine with 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.

Carcinogenic. Cancer-producing.

Carcinoma. A malignant tumor or cancerous growth.

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

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.

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

Cathodic Protection. Prevention of metallic corrosion by making the subject metal act as the cathode of an electrochemical cell.

Caustic. See Alkali.

Caustic Soda. Sodium hydroxide. Strong alkaline substance used in cleaning products, detergents.

Caustic Lime. Calcium hydroxide.

Caustic Potash. Potassium hydroxide.

CBC. Complete blood count.

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

cc, cm3. Cubic centimeter.

CDC. Centers for Disease Control.

CDD. Chlorinated Dibenzo-p-dioxin.

CDF. Chlorinated Dibenzofurane.

Ceiling Limit, C. The concentration 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.

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

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

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

Central Nervous System (CNS). The brain and spinal cord.

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.

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 the land and 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 problems that arose from the release of hazardous materials in the Love Canal area near Niagara Falls, New York, Aug.1978.

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

CFM. Chlorofluoromethanes.

CFM. Cubic feet per minute.

CFR. Code of Federal Regulations. 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) 512-1800.

CFR 29 Section 1910.1200. The OSHA regulation known as the Hazard Communication Standard.

CFS. Cubic feet per second.

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

Cheilitis. Lip inflammation.

Chelating Agent. 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.

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 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; OSRA 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 Inventory. List of hazardous materials in a workplace, reflected by a collection of matching MSDSs, generally for compliance with OSHA and SARA.

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

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

Chemical-protective Clothing (CPC). Personal protective clothing, suit, apron, gloves, etc. that is manufactured to be resistant to penetration by specific chemicals for a certain period of time known as the breakthrough time.

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.

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

CHEMTREC. Chemical Transportation Emergency Center. Established in Washington, DC, by the Chemical Manufacturers Assoc. (CMA) to provide emergency information on materials involved in transportation accidents. 24-hr No.: (800) 424-9300.

Chest Roentgenogram. A photograph made through the process of x-raying, of the chest, to aid in diagnosis and therapy.

Cheyne Stokes Breathing. Cyclic breathing characterized by alternating periods of increased respiration, followed by decreased respiration, and not breathing.

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

Chlorinated Hydrocarbons. A class of hazardous chemicals, many highly toxic, that persist in the environment and may accumulate in the food chain. Includes many insecticides and industrial solvents.

Chlorinated Solvent. Organic solvent with chlorine atoms, used in fast-drying paints and aerosol sprays.

Chlorination. Disinfection of public water supplies, wastewater, or industrial effluent through addition of chlorine.

Chlorofluorocarbons (CFCs). Any of several compounds composed of carbon, fluorine, chlorine, and hydrogen, used mostly in refrigeration systems and as solvents and aerosol propellants. Blamed for loss of ozone layer of the atmosphere. Except for a few specialized items, their use was prohibited in 1979.

Cholinesterase. An enzyme that helps regulate the activity of nerve impulses by hydrolyzing acetylcholine.

Cholinesterase Inhibitor. A chemical compound such as an organophosphate, a carbamate, or a pesticide that deactivates the enzyme cholinesterase resulting in the buildup of the highly toxic acetylcholine at nerve endings producing symptoms such as salivation, sweating, abdominal cramps, diarrhea, visual disturbances, difficulty breathing, muscle twitching, and confusion.

CHP, Chemical Hygiene Plan. Per 29 CER 1910.1450, OSHA standard; "Occupational Exposures to Hazardous Chemicals in Laboratories." Effective May 1, 1990 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 chemical, in use in their work area. This OSHA standard provide for training, employee access to information, medical consultations, examinations, hazard identification procedures, respirator use, and record keeping practices. See paragraph E of the Standard.

Chromium. Heavy metal. Hexavalent chromium compounds are human carcinogens and corrosive.

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).

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

Closed Cup. See CC.

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

CLP. Contract Laboratory Program.

cm. centimeter.

CMA. Chemical Manufacturers Association (703-741-5000, Website: CMA.)

CNS. See Central Nervous System.

CNS Depression. See Central Nervous System Depression.

CO, Carbon Monoxide. 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.

CO2, Carbon Dioxide. A dense, colorless, gas produced by combustion and decomposition of organic substances 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 crate 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.

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 if pollution in domestic and industrial waters.

Code of Federal Regulations. See CFR.

Coefficient of Water/Oil Distribution. Also called the 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.

Colic. Acute abdominal pain.

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

Combustible. A materials 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). NFPA and OSHA generally define combustible liquid as a liquid with a flash point at or above 100 F (38 C) but below 200 F (93.3 C).

Combustion. An exothermic chemical reaction due to rapid oxidation or burning, which releases heat and light. A source of air pollution.

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].

Compliance. Meeting the requirements of law and regulations.

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.

Conc. Concentration.

Confined Space. Generally refers to spaces which are dangerous for a worker or occupant due to limited means for escape combined with other possible hazards such as exposure to dangerous air contaminants, suffocation, or asphyxiation.

Conjunctivitis. Irritation and inflammation of the lining of the eye and eyelids.

Consumer Products. Products regulated by the Consumer Product Safety Act. They are not required to carry label information.

Consumer Product Safety Commission. See CPSC.

Contingency Plan. Documented plan for the course of action to be taken in the event of a fire, spill or other emergency involving the potential for exposure of humans to health-threatening conditions.

Containment. To hold back a spilled material with dikes or absorbent material so as to prevent further spillage and contamination.

Convulsions. Violent body spasms; fits or seizures.

Coolant. A liquid or gas used to reduce the heat generated by power production.

Cornea. Transparent structure of the eyeball's external layer.

Corrosion. The degradation of metals or alloys by chemical reaction with their environment (moisture, oxidation); by contact with other chemical substances (acids, bases) or dissimilar metals.

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.

cP. See Centipoise.

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

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.

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

CSMA. Chemical Specialties Manufacturing Association. (202-872-8110, Web site: www.csma.org)

CTARC. Chemical Testing and Assessment Research Commission.

Cubic Feet per Minute (CFM). Means of quantifying the volume of air exchanged in a workplace in a period of time.

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

cu m, m3. Cubic meter. m3 is preferred.

Curie. Unit of measure for radioactivity. Equal to 3.7 x 10 10 disintegrations per second.

Cutaneous. Pertaining to the skin (dermal).

Cutaneous Hazards. A chemical that affects the skin by causing rashes, irritation, or defatting. Examples include ketones and chlorinated compounds.

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 Nov.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 types of control equipment and discharges for facilities.

CWTC. Chemical Waste Transportation Council.

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

D    Top

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.

dB. See decibel.

DDT. Dichlorodiphenyltrichloroethane. Most widely used contact insecticide until it was banned in 1972 because of its persistence and potential for bioaccumulation in the environment. Toxic.

Decibel (dB). Unit of measurement for sound loudness. Sound generally doubles in loudness for every 10 decibel increase.

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

Defatting Agent. A material, that upon repeated exposure or skin contact can remove fat causing in some instances drying, irritation and/or redness.

Degradation. Generally refers to the destruction or decomposition of material through the corrosive effects of chemicals, oxidation, heat, ultraviolet exposure, abrasion, etc.

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.

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.

Derivation. The process by which a chemical substance is obtained actually or theoretically from parent substance(s).

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.

Designated Area. An area of (or device within) a 1ab 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.

DFG (Germany) MAK. Deutsche Forschungsgemeinschaft (DFG), Federal Republic of German, Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area establishes MAK (maximum concentration values) for substances found in the workplace. MAKs are expressed as time weighted averages (TWAs) and peak exposures.

Diaphoresis. Perspiration, especially profuse.

Dike. A low wall that acts as a barrier to contain and prevent a spill from spreading.

Dilution Ventilation. See General Ventilation.

Dioxin. Common name for 2,3,7,8-tetrachlorodi-benzo-p-dioxin (TCDD). Contaminant in defoliants (Agent Orange) in Vietnam. Highly toxic. Possible human carcinogen.

Diplopia. Double vision.

Disinfectant. A chemical that kills pathogenic organisms. Chlorine is often used as a disinfectant.

Dispersant. Chemical agent with the property of separating concentrations of organic material, e.g., detergent on oil.

Distilled Spirits. As defined in the Federal Alcohol Administration Act (FAAA), are not subject to the label requirements of the Hazard Communication Standard when they are subject to the labeling requirements of the FAAA.

DNA. Deoxyribonucleic Acid. Carrier of the genetic information for most living cells.

Documentation. The record of compliance that a company should maintain in accordance with the Hazard Communication Standard. It includes employee information and training, a written program, MSDS maintenance, hazard determination, and quality assurance audits.

Dose. A measured and consistent amount used in toxicological testing.

Dosimeter. Instrument for measuring dose or exposure to radiation.

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. (202-366-9191 or   202-366-3282, Website: www.dot.gov)

DOT Identification Numbers. Four-digit numbers used to identify particular materials for regulation of their transportation. See DOT publications that describe the regulations (49 CFR 172.101). These numbers are called product identification numbers (PINs) under the Canadian Transportation of Dangerous Goods Regulations. Those numbers used internationally may carry an UN prefix (e.g., UN 1170, ethyl alcohol), but those used only in North America have an NA prefix (e.g., NA 9163, zirconium sulfate).

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.

Dysarthia. Difficulty in speaking clearly.

Dysosmia. Impaired sense of smell.

Dysphagia. Difficulty in swallowing.

Dysplasia. Abnormal growth or development of organs or cells.

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

Dysuria. Difficult or painful urination.

E    Top

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

Ecotoxicity. The capability of a chemical substance to have deleterious effects on animals, plants, fish, invertebrates, microorganisms, and the surrounding ecosystem.

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 tissues.

EDTA. Ethylene Diamine Triacetic Acid.

EEG. Electroencephalogram.

EEC. European Economic Community.

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 January 11971 and September 18, 1981.

ELINICS. A list of approximately 400 chemicals identified by EINECS numbers, established with the European Community from September 18, 1981 to June 30,1990. The list was published on May 29, 1991 and is a supplement to EINECS. Additional supplements will be added as necessary.

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.

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.

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.

Emergency Overview. A brief summary usually found in Sec. 3 of a MSDS that describes a material's appearance and gives an overview of the most significant immediate concerns for emergency personnel.

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

Encephalopathy. Degenerative brain disease.

Endothermic. A chemical reaction that absorbs heat.

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.

Environmental Fate. A summary describing the ultimate environmental effects a chemical substance may have when released to air, soil, or water, based on its chemical behavior and affinity.

Environmental Response Team. EPA trained for quick round-the-clock response to hazardous waste and spills emergencies.

EO. See Ethylene oxide.

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, Website: www.epa.gov).

Epidemic. Widespread outbreak of a disease, or a large number of cases of a disease in a single community or relatively small area.

Epidemiology. The study of the relationships between diseases and the various factors that could determine their frequency and distribution in populations.

Epiphora. Excessive flow of tears.

Epistaxis. Nosebleed.

Equilibrium. The state at which a (chemical) concentration is neither increasing nor decreasing.

Ergonomics. The study of human characteristics for appropriate design of living and work environments.

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

Ethylene Dibromide (EDB). Toxic chemical use an agricultural fumigant (generally banned in the U.S.) and for some industrial processes. Probable human carcinogen.

Ethylene Oxide. A highly reactive, flammable, explosive, colorless gas used as an industrial sterilant and chemical intermediate. Irritant. Probable human carcinogen.

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

Eutrophication. Accelerated aging of lakes caused by the addition of phosphorus in the form of (PO43-). Excessive phosphorus concentrations cause increased algae "blooms"; algae decay causes oxygen depletion.

Evaporation Rate. The rate at which a material vaporizes (volatilizes, evaporates) from the liquid 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.

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. See Flammable Limits.

Exposure Limits. The concentration in workplace air of a chemical deemed the maximum acceptable. Meaning 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).

Exposed. Refers to an employee possibly endangered by a chemical because the chemical may have been permitted to enter that employee through some route of entry.

Extremely Hazardous Substances. Chemicals specifically identified as "extremely hazardous" and if released into the air would have a potentially disastrous effect. Listed under SARA, Title III, and are subject to special emergency planning and reporting requirements.

Exothermic. A chemical reaction that gives off heat.

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.

Eye Hazards. Chemicals that affect the eye or visual capacity. Examples include acids and organic solvents.

F    Top

F or F. Degrees Fahrenheit. See C.

f/cc. Fibers per cubic centimeter of air.

Fasciculation. Muscular twitching.

FDA. See Food and Drug Administration.

Federal Register (U.S.). See FR.

FEMA. Federal Emergency Management Agency (800-480-2520, Website: www.fema.gov).

FEV 1. Forced expiratory volume in 1 sec (L). A measurement of lung function.

FFDCA. Federal Food, Drug, and Cosmetic Act.

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. Scarring; scarring in the lungs may affect oxygenation of blood.

FIFRA. The Federal Insecticide, Fungicide, and Rodenticide Act. Enacted on October 21, 1972, this act provides the regulatory authority for registration and use of pesticides and similar products intended to kill or control insects, rodents, and weeds.

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 that 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 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 in order to reduce or eliminate the potential effects of a chemical exposure or other injury.

Flammability Classification. Per OSHA 29 CFR 1910.106, criteria to classify combustible and flammable liquids.

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

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 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 an explosive or blasting agent, that ignites readily and continues to burn so vigorously and persistently that it creates a serious hazard. Flammable solids are liable to cause fires under ordinary conditions or during transportation, through friction, as a result of spontaneous chemical change, or from retained heat from manufacturing or processing, or moisture absorption.

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. Combustion does not continue. FP is determined by laboratory tests in cups. See Fire Point.

Flash Point Method. The means by which a flash point is obtained. If possible, flash point temperature is to be based on a closed cup (CC) method; see TCC, TCT, Setaflash Closed Tester, and Pensky-Martens closed cup (PMCC). Any flash point based on the Tag Open Tester (TOC) or the Cleveland Open Cup (COC) will be identified by (OC).

Fluorides. Compounds containing fluorine. May be gaseous, dissolved, or solid.

Fluorocarbons (FCs). Organic compounds similar to hydrocarbons in which hydrogen atoms are replaced by fluorine. Once commonly used as refrigerants and aerosol propellants, but are being replaced because of their role in ozone depletion.

Fluorosis. Excessive intake of fluorine causing abnormalities, chiefly mottling of the teeth.

Fly Ash. Ash from combustion process carried by the flue gasses.

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.

Food and Drug Administration (FDA). Branch of the federal government responsible for enforcing the Food, Drug and Cosmetic Act, including matters of consumer safety involving related products. Those products subject to the Act are not subject to labeling requirements of hazardous materials. (800-532-4440, Website: www.fda.gov).

Forseeable Emergency. Generally used by OSHA to refer to potential workplace emergencies that can expose workers to a hazardous substance.

Formaldehyde. Colorless, intensely irritating, flammable gas with pungent smell, used as a preservative and chemical feedstock. Probable human carcinogens.

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

FP. See Flash Point.

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

Freezing Point (FP). 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.

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).

Fumes. Tiny solid particles formed by the vaporization of a solid which then condenses in air; particles are usually of a size which readily reach the air sac (alveoli) of the lungs.

Fungicide. Chemical compounds used to prevent or destroy fungi.

FVC. Forced vital capacity. A measurement of lung function.

G    Top

g, gm. Gram. Metric unit of weight. See kg.

gal. gallon.

Gamma Radiation. Electromagnetic radiation of intensely high energy and extremely short wavelength. The most tissue-penetrating of waves of radiant nuclear energy. Exposure may be lethal.

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.

Gas, flammable. See flammable gas.

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.

Gavage. Feeding by means of a stomach tube.

GC. Gas Chromatograph.

GC/MS. Gas Chromatograph/Mass Spectometer.

Geiger Counter. Sensing device for detecting the presence and amount of radioactivity.

Germicide. Any compound that kills disease-causing microorganisms.

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.

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(Tm) 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).

GI, GIT. See Gastrointestinal Tract.

Gingivitis. Inflammation of the gums.

GLC. Gas Liquid Chromatography.

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

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

H    Top

h, hr(s). Hour(s).

Half-life. The time required for an existing concentration to fall to half its original value.

Halogen. Family of related nonmetallic elements that includes bromine, fluorine, chlorine, iodine, and astatine.

Halon. Chemical used in gas form to smother fires, generally no longer used due to ozone depletion.

Harmful. A material is defined as harmful (defined as a chemical with a low degree of toxicity) if it falls into any of the following two categories: 1) Has a median lethal dose (LD50) of more than 500 mg/kg but no more than 2000 milligrams per kilogram of body weight, when administered orally to albino rats; 2) Has a median lethal dose (LD50) of more than 1000 mg/kg, but no more than 2000 mg/kg of body weight, when administered by continuous contact for 24 hours with bare skin of albino rabbits.

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.

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 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 normal operations, may produce dusts, gases, fume, 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 Combustion Products. Hazardous products released when a material is burned.

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 used to make plastics, releases poisonous hydrogen chloride, carbon monoxide, and phosgene gases when burned.

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

Hazardous Waste Number. An identification number assigned by the EPA, per the RCRA law (40 CFR 261.33, 40 CFR 302.4), to identify and track wastes.

Health Hazard. For OSHA purposes refers to a material considered hazardous to human health due to at least one statistically significant study conducted in accordance with scientific principles.

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.

Heavy Metals. Any of several metallic elements with high atomic weights, e.g., mercury, chromium, cadmium, arsenic, lead. Exposure, even at low concentrations, can be hazardous.

Hematopoietic. Pertaining to the formation of blood in the body.

Hematuria. Blood in the urine.

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

Hemorrhage. Profuse bleeding.

Henry's Law Constant (H). The equilibrium ratio of concentrations of a material in air and in water. Materials with a high H are more volatile.

HEPA. High-efficiency particulate air filter. Also called absolute. Has a 99.97% removal efficiency for 0.3-micron particles.

Hepatic. Pertaining to the liver.

Hepatitis. Inflammation of the liver.

Hepatomegaly. Enlargement of the liver.

Hepatotoxins. Chemicals such as nitrosamines and carbon tetrachloride that can cause liver damage.

Highly Toxic. A material is classified as highly toxic (a poison) if it falls into any of the following four categories: 1) Has a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight when administered orally to albino rats. 2) Has a median lethal dose (LD50) of 200 milligrams or less per kilogram of body weight when administered by continuous contact for 24 hours with the bare skin of albino rabbits. 3) Has a median lethal concentration (LC50) of gas or vapor in air of 200 parts per million (ppm) or less by volume, or 2 milligrams per liter or less of mist, fume, or dust, when administered by continuous inhalation for 1 hour to albino rats. 4) Is a liquid having a saturated vapor concentration (ppm) at 68 F (20 C) equal to or greater than its LC50 (vapor) value (ppm), if the LC50 value is 3000 parts per million (ppm) or less when administered by continuous inhalation for 1 hour to albino rats.

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.

HOC. Halogenated Organic Carbons.

Hood Capture Efficiency. A measure of emissions that are captured by a lab hood, expressed as a percent of all emissions.

HSDB. Hazardous Substance Data Bank. A data bank focusing upon the toxicology of potentially hazardous chemicals. Built, maintained, reviewed, and updated by the National Library of Medicine.

Hydrocarbons (HCs). Chemical compounds - most often combustible fuels - that contain only hydrogen and carbon.

Hydrogen Sulfide (HS). A by-product of oil refining, and natural emission from rotting organic matter. Smells like rotten eggs. Highly flammable. Highly toxic by inhalation and strong irritant to eyes and mucous membranes.

Hydrolysis. Process by which chemical compounds are 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.

Hyperemia. 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.

Hyperkalemia. Abnormal elevation of potassium in the blood.

Hypocalcemia. Calcium deficiency of the blood.

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

I    Top

I. Intermittent.

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 Ave., Albany, NY 12210 [518] 436-9686.)

ID. Inside Diameter.

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

Ignitable. Capable of burning or causing a fire.

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

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

Impotence. Loss of sexual ability.

Incontinence. Inability to control excretory functions (e.g., urination).

Incineration. Intentional, controlled burning for the purpose of destroying waste. Typically performed at high temperatures and with controlled emissions to result in a landfillable ash.

Incinerator. A furnace for burning wastes under controlled conditions.

Incompatible. Describes materials that could cause dangerous reactions and the release of energy from direct contact with one another.

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.

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.

INGAA. The Interstate Natural Gas Association of America (202-216-5900, Website: www.ingaa.org).

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

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.

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.

Interstitial Fibrosis. Scarring of the lungs.

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

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.

Ion. An electrically charged atom or radical.

Ionizing Radiation. Radiation (e.g., alpha, beta, and gamma radiation) that has the effect of removing electrons from atoms leading to the formation of free radicals.

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

Irritant. A substance capable of causing a reversible or irreversible inflammatory effect on living tissue by chemical action at the site of contact as a function of concentration or duration of exposure.

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

Isotope. A variant of an element characterized by having the same atomic number but a different mass because of its neutrons.

IV. Intravenous. Injection of a substance into a vein.

J    Top

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 Hazard Analysis. A process by which work place hazards are determined and safe work practices are instituted to adequately protect workers.

K    Top

Keratosis. Horny growths on skin.

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

kg, kilogram. 1000 gram.

L    Top

L, l. Liter. Basic metric unit of volume. One liter a 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 l910.1450, a facility where 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-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.

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.

Lacrimation. Secretion and discharge of tears.

Lacrimator. A material that upon exposure to it causes tears.

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.

Lassitude. Sense of weariness.

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

Lavage. Rinse with water.

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

LC. Liquid Chromatograph.

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 (ug/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. 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 less than 24 hr (acute) or greater than 24 hr (subacute and chronic).

LD 0. The highest concentration of a toxic substance at which none of the test organisms die.

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.

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.

Lead (Pb). Heavy metal formerly used widely in paints, gasoline, and plumbing solder that is now sharply restricted in use because of its health hazards. A cumulative poison that may affect the kidneys and the nervous, blood, and reproductive systems. Possible human carcinogen.

LEL. See Lower Explosive Limit, Lower Flammable Limit.

Lesion. An abnormal change, injury, or damage to tissue or to an organ.

Lethargy. A sense of fatigue, drowsiness, and laziness.

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

Leukocyte. A white blood cell.

Leukocytosis. A temporary increase of leukocytes in the blood.

Leukopenia. A decrease in leukocytes cells in the blood.

LFL. See Lower Flammable Limit, Lower Explosive Limit.

LFM or lfm. Linear feet per minute.

Limiting factor. A condition or element, whose absence, or excessive concentration, is incompatible with the needs or tolerance of a species or population.

Limits of Flammability. See Flammable Limits.

Liner. A relatively impermeable barrier (e.g., plastic or dense clay) designed to prevent leachate from leaking from a landfill.

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.

Lipid Solubility. Measure of the maximum concentration of a chemical that will dissolve in fatty substances. Lipid-soluble substances will disperse through the environment via living tissue.

Liquefaction. Changing a solid into a liquid.

LOAEL. Lowest Observed Adverse Effect Level.

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.

LOEL. Lowest Observed Effect Level.

LPG. Liquified Petroleum Gas.

Lung Agent. Chemicals that irritate and/or damage lung tissue. Examples include silica and asbestos.

M    Top

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

m3 or Cu m. Cubic meter; m3 is preferred.

Malaise. A vague, generalized, ill feeling.

Malignant. Cancerous.

Material Safety Data Sheet. See MSDS.

Maximum Contaminant Level (MCL). The maximum permissible level of a contaminant in a public water system. MCLs are enforceable standards per the Safe Drinking Water Act.

MDA. Methylenedianiline.

Medical Surveillance. Regular medical testing of employees for early detection of overexposure to hazardous chemicals. Required when working with chemicals specified in 29 CFR 1910.1001 through 1910.1052.

MEK. Methyl Ethyl Ketone.

Melting Point (MP). 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].

Mercury. A highly toxic, heavy metal that can accumulate in the environment and in body tissues. Chronic exposure may result in permanent nervous system damage.

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

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

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

Methane. Colorless, nonpoisonous, flammable gas from the anaerobic decomposition of organic compounds. A simple asphyxiant.

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 (III)ion instead of iron (II) and is unable to combine reversibly with molecular oxygen.

mg. Milligram (1/1000, l0-3 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.

MIBK. Methyl Isobutyl Ketone.

MIC. Methyl Isocyanate.

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

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

Micron (u). See micrometer.

Milliliter (mL). 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.

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

min. Minute.

Mine Safety and Health Administration. See MSHA.

Miosis. Pupil contraction.

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.

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.

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. "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" (OSHA CPL 23-02.38A).

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.

MOD. Moderate irritation effects.

Mole or 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. See Formula Mass.

Molecule. Smallest representative particle of a covalently bonded chemical compound.

Momentary Value (DFG). A level which the concentration should never exceed.

Monitoring. Periodic determination or continuous surveillance of pollutant levels in the environment or biological exposure indices in humans for purposes of determining compliance with statutory limitations.

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

MS. Mass Spectrometry.

MSDS. 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 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 Hazard Communication Rule, 29 CFR, Part 1910.1200, as amended, Sec. g. See also Schedule I, Sec. 12, of the Canadian Hazardous Products Act. The CMA has recently drawn up a set of guidelines for developing a consistent MSDS format. This standard format has been accepted by ANSI.

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 (703-235-1452, Website: www.msha.gov).

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

MTBE. Methyl Tertiary Butyl Ether.

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

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.

Myalgia. Tenderness or pain in the muscles.

Mydriasis. Pupil dilation.

N    Top

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.

Narcosis. Sleepiness or a state of unconsciousness caused by a chemical.

National Fire Protection Association. See NFPA.

National Toxicology Program. See NTP.

Natural Gas. A combination of mostly methane and ethane that occurs naturally within the earth.

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

NCRIC. National Chemical Response and Information Center.

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

Necrosis. Localized death of tissue.

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

Nephrotoxic. Poisonous to the kidney.

Neuritis. Inflammation of the nerves.

Neurotoxins. Substances whose primary harmful effect on the body is to affect the central nervous system.

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 and 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. (Batterymarch Park, Quincy, MA 02269; [800] 344-3555, [617] 770-3000, Website: www.nfpa.org). NFPA Hazard Rating. See Fire Diamond.

NFPA 704 System. See NFPA.

ng. Nanogram. One billionth, l0-9, of a gram.

NICS. National Institute for Chemical Studies.

NIH. National Institutes of Health (Website: www.nih.gov)

NIOSH. National Institute of Occupational Safety and Health. The agency of the Public Health Service that tests and certifies respiratory and air-sampling devices. It recommends exposure limits to OSHA for substances, investigates incidents, and researches occupational safety. (NIOSH, 4676 Columbia Parkway, Cincinnati, OH 45226; [513] 533-8328.)

Nitrate. A compound containing (NO3~). The nitrate ion present in drinking water may cause severe illness (methemoglobinemia) in young children. Agricultural use of manure and fertilizer is usually the major source of this contaminant.

Nitrilotriacetic Acid (NTA). Compound generally used as a substitute for phosphates in detergents.

Nitrite. A compound containing (NO2~). The nitrite ion is toxic because it can combine with hemoglobin, and deprive the tissues of oxygen; a condition known as methemoglobinemia.

NLM. National Library of Medicine. A government library in Bethesda, ME containing medical documents (l-888-FINDNLM, Website: www.nlm.nih.gov).

NOAEL. No Observed Adverse Effect Level.

NOC. Not otherwise classified.

NOEL. No observed effect level.

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.

Nonionizing Electromagnetic Radiation. Radiation that does not change atom structure (e.g., micro waves, radiowaves, or low-frequency electromagnetic fields.)

NOR. Not otherwise regulated.

NOS. Not otherwise specified.

NOx. 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. Chronic exposure to low levels can cause irritation, cough, headache, and tooth corrosion. Commonly produced by combustion processes, including motor vehicle engines. Nitrogen oxides contribute to photochemical smog and acid deposition in the environment.

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

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

NTIS. National Technical Information Service (703-487-4600, Website: www.ntis.gov).

NTP. National Toxicology Program. Federal activity overseen by the Dept. 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 B2-04 , Box 12233, Research Triangle Park, NC 27709.)

Nuclear Power Plant. A facility that convents atomic energy into usable power; heat produced by a reactor makes steam to drive turbines which produce electricity.

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.

O    Top

Occupational Exposure. See Action Level.

Occupational Safety and Health Act. See OSH Act.

Occupational Safety and Health Administration. See OSHA.

Ochronosis. Dark spots on skin.

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.

OD. Outside Diameter.

OEL. Occupational Exposure Limit. See Exposure Limits.

Oliguria. Scanty or low volume of urine.

Oncogenic. Tumor (benign or malignant) inducing substance.

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 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.

Oral. An exposure route "through the mouth."

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.

Organochlorine Pesticide. Synthetic organic pesticide containing chlorine. May be highly toxic and exposure may affect the central nervous system.

Organometallic Compounds. An organic compound consisting of a metal directly attached to carbon. Some are highly toxic or flammable. Many of them are powerful catalysts used as coordination compounds.

Organophosphates. Synthetic organic compound containing phosphorus used as insecticides, plasticizers, flame-retardants, and in fertilizers. Many are highly toxic; insecticides affect the central nervous system by causing cholinesterase inhibition.

Organotins. Highly toxic, alkyl tin compounds widely used as stabilizers for plastics (rigid vinyl polymers) and some as catalysts.

ORM. Other Regulated material. DOT hazard classification of a particular hazardous material to label in transport.

ORM-D: materials such as consumer commodities that present limited hazards during transportation due to their form, quantity, and packaging.

OSHA. The Occupational Safety and Health Administration. Pant 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, Website: www.osha.gov).

OSH Act. The Occupational Safety and Health Act of 1970. Effective April 28, 1971. Public Law 91-596. Found at 29 CEP 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 CFP 1910.1200). See Hazard Communication Rule for details.

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), bboiling 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).

Osmosis. The passage of a fluid through a semi-permeable membrane to equalize the concentrations on both sides of the membrane.

OX. An abbreviation for oxidizer.

Oxidation. A reaction in which a substance combines with oxygen or another oxidizer.

Oxide Pox. Dermatitis caused by contact with metal oxides under poor personal hygienic conditions.

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 (C1O3), 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.

P    Top

PAH. See Polycyclic Aromatic Hydrocarbons.

Palpitation. Irregular, rapid heartbeat.

Paresthesias. Altered sensations of the skin, often numbness and tingling, or "pins and needles" sensation.

Particulates. Solid or liquid particles suspended in air; aerosol.

Partition Coefficient. See Coefficient of Water/Oil Distribution.

Pathogenic. Capable of causing disease.

PBB. Polybromated Biphenyls.

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).

PCDD. Polychlorinated Dibenzodioxin.

PCDF. Polychlorinated Dibenzofuran.

PCP. Pentachlorophenyl. Used as herbicide, fungicide, bactericide, aligicide, and wood preservative (as sodium pentachlorophenate). Toxic; abuse may be fatal.

Peak Exposure Limit (DFG). A short-term exposure level established for a certain duration and frequency per shift.

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. Note that ACGIH TLVs and NIOSH RELs are recommended exposure limits that OSHA may or may not enact into law.

Penetration. The passage of a chemical through an opening in a protective material. Holes and rips can allow penetration as can space between zipper teeth stitch holes, and open jacket and pant cuffs. See also chemical-protective clothing.

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.

Percutaneous. Through the skin; often referring to absorption of a chemical.

Peripheral Nervous System (PNS). Nerves outside of the brain and spinal cord, including motor nerves control the function of muscles, sensory nerves to carry sensations to the brain, and autonomic nerves to control a variety of organ functions.

Peripheral Neuropathy. An abnormal or degenerative state involving the nerves of the extremities (hands, feet, arms, legs).

Permeable. Allows passage of water through soil or rock or other fluids such as solvents through gloves. Permeation through protective clothing occurs on a molecular level and may occur even if there are no signs of degradation.

Permissible Exposure Limit. See PEL.

Personal Hygiene. Precautionary measures taken 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.

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 (HC1, pH = 1). Strong bases have excess OH ions and a pH of 11 to 13 (NaOH, pH = 12).

PHC. Principle Hazardous Constituent.

Phenols. Aromatic organic compounds with one or more hydroxy groups directly attached to the benzene ring. Toxic; strong tissue irritants.

Phlegm. Thick mucous from respiratory passage.

Phosphates. Compounds containing (P043-) Major cause of eutrophication of lakes and ponds. Two chief sources of phosphates in the environment are agricultural run-off carrying phosphate fertilizers and sewage.

Photolysis. Breaking up of a compound into simpler units by the absorption of one or more quanta of radiation (for example by direct exposure to sun's ultraviolet light).

Photophobia. Intolerance to light.

PHS. (U.S.) Public Health Service.

Physical Hazard. A substance for which there is valid evidence that it is a combustible liquid, compressed gas, explosive, flammable, organic peroxide, oxidizer, pyrophoric, unstable (reactive), or water reactive. In the general safety sense, a hazard of physical origin, such as a fall, 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.

Pickling. Immersion of metals in inorganic acids such as hydrochloric, sulfuric, or phosphoric to remove impurities from the surfaces.

Picocurie. A measurement of radiation intensity. A picocurie is one trillionth (10-12), of a curie.

Picocuries per Liter (pCi/L). A unit of measure used for expressing levels of radon gas.

Pig. A container, usually lead, used to store or ship radioactive materials.

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.

Placard. A diamond-shaped marker required by the DOT on vehicles transporting hazardous materials. It displays DOT identification number and applicable warning symbols (for ex., flammable, corrosive, or explosive).

Plastics. Man-made materials comprised of large molecules (polymers) and modifying agents such as fillers, colorants, and stabilizers that can be molded or shaped.

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.

PNA. Polynuclear Aromatic Hydrocarbons; also PAH.

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. Inflammatory lung disease caused by microorganisms, virus, and chemical or physical irritants.

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).

POHC. Principal Organic Hazardous Constituent.

Poison Control Center. Provides medical information on a 24-hr basis for accidents involving ingestion of potentially poisonous materials. Call your area's largest hospital to find the one nearest you.

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.

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.

Polyelectrolytes. A natural or synthetic high-polymer substance containing ionic constituents. Major uses include treatment of paper-mill wastewater and flocculation (clumping) of solids in potable water.

Polymer. A large molecule formed by the union of five or more identical combining units (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.

Polyvinyl Chloride (PVC). A tough, environmentally indestructible plastic that when burned releases hydrochloric acid.

Pour Point. The temperature at which a liquid either congeals or ceases to flow.

POx. A general term for the several oxides of phosphorus.

ppb. Parts per billion.

PPE. Personal protective equipment. Devices or clothing worn to help isolate a worker from direct exposure to hazardous materials. Examples include gloves, respirators, safety glasses, or ear plugs.

pph. Parts per hundred.

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.

ppt. Parts per trillion.

ppth. Parts per thousand.

Precordial. In front of the heart, stomach.

Product Identification Number. See PIN.

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.

Proteinuria. Presence of protein in the urine.

psia. Pounds per square inch absolute.

psig. Pounds per square inch gauge (i.e., above atmospheric pressure).

Psychotropic, PSY. Acting on the mind.

Pulmonary edema. Fluid in the lungs.

Purge. To clean, clear, or empty of material; a bleed of air or inert gas into a vessel to remove or exclude contaminants.

Pyrolysis. Chemical decomposition or breaking apart of molecules produced by heating.

Pyrophoric. Describes materials that ignite spontaneously in air below 54 C (130 F).

Q    Top

QA. Quality Assurance.

QC. Quality Control.

R    Top

Radiation. Any form of energy propagated as electromagnetic waves.

Radiation Absorbed Dose (RAD). A unit of absorbed dose of ionizing radiation; the absorption of 100 ergs of radiation energy per gram of irradiated material.

Radon. A colorless, naturally occurring, radioactive gas formed by radioactive decay of radium in soil or rocks.

RBC. Red blood cell.

RCRA. Resource Conservation and Recovery Act, PL 94-580. Found at 40 CFR 240-271. EPA has jurisdiction. Enacted Nov.21, 1976, and amended since. RCRA's major emphasis is the control of hazardous waste disposal. It controls all solid-waste disposal a encourages recycling and alternative energy sources.

RCRA Hazardous Waste. A material designated RCRA as a hazardous waste and assigned a number to be used in record keeping and reporting compliance (e.g., D003, F00l, U169).

Reactive Flammable Material. A material which 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 oxidizer. They are often stored in an all-nitrogen or argon environment.

Reactive Material. A chemical substance or mixture that vigorously polymerizes, decomposes, condenses, or becomes self-reactive due to shock, pressure, or temperature. Includes materials or mixtures within any of these categories: 1) 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.

Recommended Exposure Limit. See REL.

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.

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.

REM. Radiation Equivalent Man. The dosage in rads multiplied by a factor that takes into account the different effects of various types of radiation.

Reportable Quantity. See RQ.

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.

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 System. The breathing system, including the lungs and air passages (trachea or windpipe, larynx, mouth, and nose).

Rhinorrhea. Excessive nasal discharge.

Ribonucleic Acid (RNA). Universally present in living cells; carries genetic information.

Right-to-Know. A term applied to a variety of laws and regulations enacted by local, state, and federal governments to make information on chemical hazards readily available to workers and communities. Also includes the OSHA Hazard Communication Standard and SARA Title III, Community Right-to-Know. See also Hazard Communication.

Rodenticide. A chemical or agent used to destroy rats or other rodent pests.

Route of Entry or Route of Exposure. The way a chemical enters the body; inhalation, skin contact, eye contact, and ingestion.

RQ. Reportable Quantity. The amount of a material that, when spilled, must be reported to the DOT (Section 311 of the Clean Water Act).

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.

S    Top

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.

Saint Andrew's Cross. X. Used in packaging for transport; means harmful - stow away from foodstuffs. (IMO, Material Class 6.1, Group III).

SARA. Superfund Amendments and Reauthorization Act. Signed into law Oct.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.

SCBA. See Self-Contained Breathing Apparatus.

SCC. See SETA, SETAFLASH Closed Tester.

Sclera. The tough, white, fibrous covering of the eyeball.

Select Carcinogen. See Carcinogen.

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).

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.

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).

Siderosis. Pneumoconiosis caused by inhalation of iron particles. Also, tissue pigmentation caused by contact with iron.

Silicosis. A condition of massive fibrosis of the lungs causing shortness of breath because of prolonged inhalation of silica dusts.

Skin. A notation to exposure limits (TLVs) indicating possible significant contribution to overall exposure to a material by way of absorption through the skin, mucous membranes, and eyes by direct or airborne contact.

Slurry. A pourable mixture of solid and liquid.

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.

SOC. See Synthetic Organic Chemicals.

Soil Adsorption/Mobility. A chemical substance's ability to travel through soil and potentially contaminate groundwater, determined by the substance's organic carbon-water partitioning coefficient. A high Koc indicates low mobility in soil whereas a low Koc indicates high mobility.

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. A uniformly dispersed single-phase mixture of a solvent (water or other fluid) and a dissolved substance, called the solute.

Solvent. A material that can dissolve other materials to form a uniform single-phase mixture. Water is the most common solvent.

Somnolence. Prolonged sleepiness.

Soot. Fine particles, usually black, formed by combustion (complete or incomplete) and consisting chiefly of carbon. Soot gives smoke its color.

SOx. Oxides of sulfur where x equals the number of oxygen atoms.

SOP. Standard Operating Procedure.

Sorption. Action of soaking up or attracting substances.

Spasm. An involuntary, convulsive muscular contraction.

SPCC. Spill Prevention, Control, and Counter-measure plan.

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/1, 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 divided by 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.

Spontaneously Combustible Material. A material which undergoes self-heating to the point of ignition without requiring heat from another source.

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.

Standards. Prescriptive norms that govern actual limits of airborne contaminants in the workplace and the amount of pollutants or emissions produced by industry.

STEL. Short-term exposure limit; ACGIH terminology. See TLV-STEL.

Stomatitis. Inflammation of the mucous membrane of the mouth.

STP. Standard Temperature and Pressure. For a gas 0 C and 1 atm pressure; for a solid element ordinary temperature and 1 atm pressure.

Stupor. Partial or near complete unconsciousness.

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.

Sulfur Dioxide (S02). A heavy, pungent, colorless, nonflammable gas formed primarily by the combustion of fossil plants. It is a constituent of smog and partially responsible for acid rain. Toxic by inhalation and a severe eye, skin, respiratory tract irritant.

Sump. A pit or tank to contain an accumulation of hazardous waste for drainage or disposal.

Superfund Amendments and Reauthorization Act. See SARA, CERCLA.

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.

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.

Synthetic Organic Chemicals (SOCs). Man-made organic chemicals including products manufactured from coal, crude petroleum, natural gas, and certain natural substances such as fats, protein, carbohydrates, vegetable oils, rosin, grain, and their derivatives.

Systemic Toxicity. Adverse effects induced by a substance which affects the body in a general manner rather than locally. For example, a substance absorbed through the skin of the hands may result in kidney damage.

T    Top

Tachycardia. Excessively rapid heartbeat, usually with a pulse rate above 100 beats per minute.

Tachypnea. Increased rate of respiration.

Tag Closed Cup. See TCC or TCT.

Tag Open Cup. See TOC.

Tag Open Tester. Open-tank tester for liquids with low flash points. See TCC or TCT.

Target Organ Effects. Chemically caused effects from exposure to a material on specific listed organs and systems, i.e. liver, kidneys, nervous system, lung skin, and eyes.

TCC or 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 no have suspended solids or form surface films.

TCDD. Dioxin (Tetrachlorodibenzo-p-dioxin).

TCE. See Trichloroethylene.

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.

TCRI. Toxic Chemical Release Inventory.

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.

TCE. See Trichloroethylene.

Temp. Temperature.

Teratogen. An agent or material causing physical defects in a developing embryo or fetus.

Tetany. Intermittent muscle spasms.

Threshold Limit Value. See TLV.

Threshold Planning Quantity (TPQ). Per 40 CFR 302. The amount of material at a facility that require emergency planning and notification per CERCLA.

THM. See Trihalomethane.

Time-Weighted Average. See TLV.

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 (a which 90% survival is required), to protect fish.

TLV. Threshold limit value. A term ACGIH uses to express the maximum airborne concentration of a material to which most workers can be exposed during a normal daily and weekly work schedule without adverse effects. "Workers" means healthy individuals, "healthy" is defined as a 150 lb. male, age 25 to 44. The young, old, ill, or naturally susceptible have lower tolerances and need to take additional precautions. ACGIH expresses TLVs in three ways:
TLV-TWA, allowable time-weighted average concentration for a normal 8-hour workday or 40-hour week;
TLV-STEL, short-term exposure limit or maximum concentration for a continuous exposure period of 15 minutes (with a maximum of four such periods per day, with at least 60 minutes 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. TLV-C. The ceiling exposure limit or concentration not to exceed at any time, even for very brief times. The ACGIH publishes a book annually that explains and lists TLVs called: Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Copies are available from ACGIH (q.v.).

TLV-Skin. See Skin.

TOC. Tag open-cup test method.

torr. A unit of pressure, equal to 1 mm Hg. See atm (atmosphere).

Toxic. A material is defined as toxic if it falls into any of the following four categories: 1) Has a median lethal dose (LD50) of more than 50 mg/kg, but no more than 500 mg/kg of body weight, when administered orally to albino rats. 2) Has a median lethal dose (LD50) of more than 200 mg/kg, but no more than 1000 mg/kg of body weight, when administered by continuous contact for 24 hours with the bare skin of albino rabbits. 3) Has a median lethal concentration (LC50) in air of more than 200 (parts per million (ppm), but no more than 2000 ppm of gas or vapor by volume, or more than 2 milligrams per liter (mg/L), but no more than 20 mg/L, of fume, mist, or dust, when administered by continuous inhalation for 1 hour to albino rats. 4) Is a liquid having a saturated vapor concentration (ppm) at 68 F (20 C) for more than one-fifth its LC50 (vapor) value (ppm), if the LC50 value is not more than 5000 mL/m3 (ppm) when administered by continuous inhalation for 1 hour to albino rats.

Toxicant. An agent capable of being toxic.

Toxic Chemical Release Reporting Form. A form required to be submitted by facilities that manufacture, process, or use toxic chemicals listed under SARA Title III.

Toxicity. The degree of a chemical substance's ability to produce deleterious effects. See also Acute Toxicity; Chronic Toxicity.

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.

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.

TPQ. See Threshold Planning Quantity.

TPTH. Triphenyltinhydroxide. Used as a fungicide and insect chemisterilant. Skin irritant.

Trace Impurities. Small amounts of impure substances present due to natural occurrences or formation or contamination during the derivation process.

Tradename. 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 tradenames 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.

Trichoroethylene (TCE). A colorless, mobile liquid used as a degreasing solvent in electronics and dry cleaning and a diluent in paint and adhesives. Irritating and toxic to the central nervous system.

Trihalomethane (THM). Substances formed as a result of the chlorination of drinking water containing organic materials such as plants. Public health concerns have been expressed about their presence as contaminants.

TSCA. Toxic Substances Control Act. Public Law PL 94-469. Found in 40 CFR 700-799. EPA has jurisdiction. Effective January 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.)

Tumor. A growth of tissue without physiological function. May be benign (noninvasive) or cancerous. See Cancer, Neoplasm.

TWA. Time-weighted average. See TLV-TWA.

U    Top

UEL. See Upper Explosive Limit, Upper Flammable Limit.

UFL. See Upper Flammable Limit, Upper Explosive Limit.

UL. Underwriters' Laboratories.

Ulcer. 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.

Underground Storage Tank (UST). A tank or combination of tanks, including connecting pipes, located substantially or totally underground that is designed to store hazardous substances. May be potential sources of groundwater contamination.

UN Number. See DOT Identification Numbers; PIN.

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.

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.

Urticaria. Hives caused by a systemic allergic reaction.

USDA. United States Department of Agriculture. (202-720-2791, Website: www.usda.gov)

USPHS. United States Public Health Service.

UST. See Underground Storage Tank.

UV. Ultraviolet (light).

V    Top

Vapor. Gases given off by a substance normally encountered as liquid or solid at standard temperature and pressure.

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 (i.e., 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, 0.075lbs/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 the chemical.

Vaporization. The charge of a substance from a liquid to a gas.

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.

VCM. Vinyl Chloride Monomer.

Vertigo. A feeling of revolving in space; dizziness, giddiness.

Vesiculation. Blisters.

Vinyl Chloride. A chemical compound, used in producing some plastics. Toxic, flammable and reactive (polymerizes) material. A human carcinogen.

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.

Volatility. Measure of a material's tendency to vaporize or evaporate at ambient routine conditions.

VP. See Vapor Pressure.

W    Top

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.

Water Reactive. Describes a material that reacts with water to release a flammable gas or to present a health hazard.

WBC. White blood cell.

WEEL. Workplace Environmental Exposure Level. Guides established by the American Industrial Hygiene Association for certain substances which do not have exposure guidelines (such as TLVs) established.

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.

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.

XYZ    Top


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.

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.

Chemical Vapor Monitors

Cylinder-Safe Cylinder Security Racks
graph