Safety and Health Terms & Abbreviations
X Y Z
Abatement. Generally refers to a reduction in pollution either partially or completely.
Absolute. A chemical substance relatively free of impurities, e.g.,
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;  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; 
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
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;
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
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
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
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;  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
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
Asbestosis. Chronic lung disease caused by inhaling airborne asbestos
Ash. The mineral content remaining after complete combustion of a
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
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;  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,
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.
BAL. British Anti-Lewisite. A name for the drug dimercaprol,
a treatment for inhalation or ingestion of specific toxic metal compounds.
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
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
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
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
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
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, ca. Circa, about,
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.
Carcinoma. A malignant tumor or cancerous growth.
Cardiovascular. System of the human body involving the heart and blood
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; 
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
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
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
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
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
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)
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
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
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
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.
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
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
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.
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
Conjunctivitis. Irritation and inflammation of the lining of the eye and
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
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
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.
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
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
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
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
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
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.
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
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.
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
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.
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
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;  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
Epiphora. Excessive flow of tears.
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
Ethylene Dibromide (EDB). Toxic chemical use an agricultural fumigant
(generally banned in the U.S.) and for some industrial processes. Probable human
Ethylene Oxide. A highly reactive, flammable, explosive, colorless gas
used as an industrial sterilant and chemical intermediate. Irritant. Probable
Etiology. All factors that contribute to the cause of a disease or an
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
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 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:
FEV 1. Forced expiratory volume in 1 sec (L). A measurement of lung
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
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"
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
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
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
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
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,
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
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, gm. Gram. Metric unit of weight. See kg.
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
Gastroenteritis. Stomach and intestine inflammation.
Gastrointestinal Tract (GI tract). The stomach and intestine as a
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
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, 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
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;  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
Hygroscopic. Readily adsorbing available moisture in any form. See
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
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  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
Inflammable. Capable of being easily set on fire and continue burning,
especially violently. Do not confuse with nonflammable. See Combustible
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,
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;
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).
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
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
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.
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.
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, 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
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
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
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. 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.
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.
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
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 (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
Millimeter (mm). 1/1000 (10-3) of a meter.
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
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
Momentary Value (DFG). A level which the concentration should never
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
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
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
MW. See Molecular Weight.
Myalgia. Tenderness or pain in the muscles.
Mydriasis. Pupil dilation.
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
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;  344-3555,
 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;  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
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
Nonionizing Electromagnetic Radiation. Radiation that does not change
atom structure (e.g., micro waves, radiowaves, or low-frequency electromagnetic
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;  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
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.
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
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
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;  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
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.
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
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
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
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
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
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
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
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
Pyrophoric. Describes materials that ignite spontaneously in air below 54
C (130 F).
QA. Quality Assurance.
QC. Quality Control.
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
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
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
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.
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
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
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
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
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
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
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.
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
TCE. See Trichloroethylene.
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
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
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
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, 
Tumor. A growth of tissue without physiological function. May be benign
(noninvasive) or cancerous. See Cancer, Neoplasm.
TWA. Time-weighted average. See TLV-TWA.
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
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
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).
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
VCM. Vinyl Chloride Monomer.
Vertigo. A feeling of revolving in space; dizziness, giddiness.
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.
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.
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