ECS_a-g_onECS Trail

The following glossary presents brief explanations of common terms frequently used by chemical manufacturers on their Safety Data Sheets (SDS).

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.

Acid - A substance that produces hydrogen ions (H+) in aqueous solutions. An acid will destroy human tissue on contact. The pH values of acids are between 0 and 6. Strong acids have a lower pH and are more corrosive than weak acids. Examples of strong acids include hydrochloric acid, nitric acid, and phosphoric acid. See also pH, Bases, Corrosive.

Action Levels - Action levels are used by OSHA and NIOSH to express an increased level of health or physical hazard. They indicate the level of a harmful or toxic substance that requires a medical surveillance program, increased industrial hygiene monitoring, or biological monitoring. Action levels are generally set at one half of the permissible exposure limit (PEL), but the actual level may vary from standard to standard.

Acute Effects - Adverse symptoms that occur immediately or shortly after an exposure to a chemical. Common symptoms of acute exposure include headache, dizziness, or nausea.

Acute Toxicity - Acute effects resulting from a single dose of, or exposure to, a substance.

"Acute Toxins" - A subset of Particularly Hazardous Substances as defined by the OSHA Laboratory Standard. These are defined as chemicals which may be fatal as a result of a single exposure or exposure of a short duration. 

Adenocarcinoma - A tumor with glandular (secreting) elements.

Adenosis - Any disease of a gland.

Adhesion - A union of two surfaces that are normally separate.

Administrative Controls - Policies intended to reduce exposure to hazardous chemicals or other forms of hazards.

Aerosol - A fine suspension in the air of small particles (e.g., smoke or fog).

AIHA - American Industrial Hygiene Association, AIHA, "promotes, protects, and enhances industrial hygienists and other occupational health, safety, and environmental professionals in their efforts to improve the health and well being of workers, the community, and the environment." The AIHA is a global organization that is not limited solely to industrial hygiene. Their web site is  Industrial hygiene deals with the protection of the health of those involved in industry. This classifies it as a form of preventative medicine.

Air-Line Respirator - A respirator that is connected to a compressed breathable air source by a hose of small inside diameter. The air is delivered continuously or intermittently in a sufficient volume to meet the wearer's breathing requirements. Respirators are to be considered a last resort after considering engineering or administrative controls.  Respirators may only be used as part of a respiratory protection program.  Contact the EC & S Office if considering respirator use. (

Air-Purifying Respirator - A respirator that uses chemicals to remove specific gases and vapors from the air or that uses a mechanical filter to remove particulate matter. An air-purifying respirator must only be used when there is sufficient oxygen to sustain life and the air contaminant level is below the concentration limits of the device. Respirators are to be considered a last resort after considering engineering or administrative controls.  Respirators may only be used as part of a respiratory protection program.  Contact the EC & S Office if considering respirator use. (

Alkali - See Base.

Allergic Reaction - An abnormal response by the body to chemical or physical stimuli (e.g., hives, sneezing).

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

ANSI - This organization, formerly known as American National Standards Institute, is a privately funded, voluntary membership organization that identifies industrial and public needs for national consensus standards and coordinates development of such standards.

Antidote - A remedy to relieve, prevent, or counteract the effects of a poison.

Appearance - A description of a substance at normal room temperature and normal atmospheric conditions. Appearance includes the color, size, and consistency of a material.

Aquatic Toxicity - The adverse effects to marine life that result from being exposed to a toxic substance.

Asphyxiant - A vapor or gas that can cause unconsciousness or death by suffocation due to lack of oxygen. Most simple asphyxiants are harmful to the body only when they become so concentrated that they reduce oxygen in the air to dangerous levels of 18 percent or lower. The normal level of oxygen in the air is about 21 percent. Asphyxiation is one of the principal potential hazards of working in confined and enclosed spaces.

ASTM - American Society for Testing and Materials is the world's largest source of voluntary consensus standards for materials, products, systems and services. ASTM is a resource for sampling and testing methods, health and safety aspects of materials, safe performance guidelines, effects of physical and biological agents and chemicals.

Asymptomatic - Showing no symptoms.

Atm - Atmosphere, a unit of pressure equal to 760 mmHg (millimeters of mercury) at sea level.

Atmosphere-Supplying Respirator - A respirator that provides breathable air from a source independent of the surrounding atmosphere. There are two types: air-line and self-contained breathing apparatus.  Respirators may only be used as part of a respiratory protection program.  Contact the EC & S Office if considering respirator use. (

Auto-Ignition Temperature - The minimum temperature at which a substance can ignite without a spark or a flame. Some examples: acetone 538°C (1000°F), ethyl ether 180°C (356°F), phenol 715°C (1319°F).

BAL - British Anti-Lewisite - A name for the drug dimecaprol - a treatment for toxic inhalations.

Base - A substance that produces hydroxide ions (OH-) in aqueous solution. The pH values of bases are between 8 and 14. Strong bases have a higher pH and are more corrosive than weak bases. Examples of strong bases include sodium hydroxide, and ammonium hydroxide. See also pH, Acid, Corrosive.

BCM - Blood-clotting mechanism effects.

Benign - Not recurrent or not tending to progress. Not cancerous.

Biodegradable - Capable of being broken down into non harmful products by the action of living things.

Biopsy - Removal and examination of tissue from the living body.

BLD - Blood effects.

Boiling Points—BP - The temperature at which a liquid changes to a vapor state at a given pressure. The boiling point is usually expressed in degrees Fahrenheit at sea level pressure (760 mmHg, or one atmosphere).

Some examples of boiling points:

      Propane     -42°C (-44°F)
      Butane      -0.5°C (31°F)
      Gasoline     38°C (100°F)
      Water       100°C (212°F)
      Ethylene Glycol (Antifreeze)    197°C (387°F)

Bonding - The interconnecting of two objects by means of a clamp and bare wire. Its purpose is to equalize the electrical potential between the objects to prevent a static discharge when transferring a flammable liquid from one container to another. The conductive path is provided by clamps that make contact with the charged object and a low resistance flexible cable which allows the charge to equalize.

Bulk Density - Mass of powdered or granulated solid material per unit of volume.

C - Celsius or Centigrade: a unit of temperature.

CAA - Clean Air Act was enacted to regulate/reduce air pollution. CAA is administered by the U.S. Environmental Protection Agency (EPA).

Ceiling Limit - When noted as a type of PEL (Permissible Exposure Limit) or TLV (Threshold Limit Value) it is the maximum allowable human exposure limit for an airborne substance which is not to be exceeded even momentarily.

Carcinogen - A substance or agent that has been demonstrated to cause or produce cancer in mammals, including humans.  "Select Carcinogens" are a subset of Particularly Hazardous Substances as defined by the OSHA Laboratory Standard.  A chemical is included in this category if:

(a) It has been evaluated by the International Agency for Research on Cancer (IARC) and found to be a carcinogen or potential carcinogen; or

(b) It is listed as a carcinogen or potential carcinogen in the Annual Report on Carcinogens published by the National Toxicology Program (NTP) (latest edition); or

(c) It is regulated by OSHA as a carcinogen. 

CAS - Chemical Abstracts Service is an organization under the American Chemical Society. CAS abstracts and indexes chemical literature from all over the world in "Chemical Abstracts." "CAS Numbers" are used to identify specific chemicals or mixtures.

Caustic - See Base.

cc - Cubic centimeter is a volume measurement in the metric system that is equal in capacity to one milliliter (ml). One quart is about 946 cubic centimeters (0.946L).

Ceiling Limit (PEL or TLV) - The maximum allowable human exposure limit for an airborne substance which is not to be exceeded even momentarily. See also PEL and TLV.

Centigrade - Centigrade, a unit of temperature. To convert from centigrade to Fahrenheit, multiply the temperature given in centigrade degrees by 9, divide that number by 5, then add 32.

Central Nervous System - The brain and spinal cord. These organs supervise and coordinate the activity of the entire nervous system.

CERCLA  - Comprehensive Environmental Response, Compensation, and Liability Act of 1980. The Act requires that the Coast Guard National Response Center be notified in the event of a hazardous substance release. The Act also provides for a fund (the Superfund) to be used for the cleanup of abandoned hazardous waste disposal sites.

CFR - Code of Federal Regulations. A collection of the regulations that have been promulgated under United States Law.

Chemical Cartridge Respirator - A respirator that uses various chemical substances to purify inhaled air of certain gases and vapors. This type respirator is effective for concentrations ten times or more times (depending on the type of respirator) the TLV of the contaminant, if the contaminant has warning properties (odor or irritation) below the TLV. See also Air-Purifying Respirator. Respirators may only be used as part of a respiratory protection program.  Contact the EC & S Office if considering respirator use. (

Chemical Family - A group of single elements or compounds with a common general name. Example: acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) are of the "Ketone" family.

Chemical Name - The name given to a chemical in the nomenclature system developed by the International Union of Pure and Applied Chemistry (IUPAC) or the Chemical Abstracts Service (CAS). This is the scientific designation of a chemical or a name that will clearly identify the chemical for hazard evaluation purposes.

Chemical Pneumonitis - Inflammation of the lungs caused by accumulation of fluids due to chemical irritation.

CHEMTREC - Chemical Transportation Emergency Center is a national center established by the Chemical Manufacturers Association (CMA) to relay pertinent emergency information concerning specific chemicals on requests from individuals. CHEMTREC has a 24-hour toll-free telephone number (800-424-9300) to help respond to chemical transportation emergencies.

Chronic Effect - Adverse symptoms of chemical exposure that develop slowly over a long period of time (weeks, months or years) due to repeated long-term exposure to a
substance. Examples include cancer or damage to certain internal organs. Also see Acute Effect.

Chronic Exposure - Repeated long-term contact with a substance.

Chronic Toxicity - Adverse effects resulting from repeated doses of, or exposures to, a substance over a long period of time.

Clean Air Act - Clean Air Act was enacted to regulate/reduce air pollution. CAA is administered by the U.S. Environmental Protection Agency.

Clean Water Act - Federal law enacted to regulate/reduce water pollution. CWA is administered by the U.S. Environmental Protection Agency.

CMA - Chemical Manufactures Association. See CHEMTREC.

CNS - Central Nervous System

Combustible - For liquids, a liquid with a flash point above 100°F (37.8°C) but below 200°F (93.3°C). Non-liquid substances such as wood and paper are classified as "ordinary combustibles" by NFPA. Also see Flammable Liquid.

Common Name - A name used to identify a chemical other than its chemical name (e.g., code name, code number, trade name, brand name, or generic name). See Generic.

Compressed Gas   -    

a. A gas or mixture of gases having, in a container, an absolute pressure exceeding 40 pounds per square inch (psi) at 70°F (21.1°C); or

b. A gas or mixture of gases having, in a container, an absolute pressure exceeding 104 psi at 130°F (54.4°C) regardless of the pressure at 70°F (21.1°C); or

c. A liquid having a vapor pressure exceeding 40 psi at 100°F (37.8°C) as determined by ASTM D-323-72.

Conc. - Concentration.

Concentration - The relative amount of a substance when combined or mixed with other substances. Examples: 2 ppm hydrogen sulfide in air, or a 50 percent caustic     solution.

Conditions to Avoid - Conditions encountered during handling or storage that could cause a substance to become unstable.
Confined Space - Any area that has limited openings for entry and exit that would make escape difficult in an emergency, has a lack of ventilation, contains known and potential hazards and is not intended nor designated for continuous human occupancy.

Conjunctivitis - Inflammation of the conjunctiva, the delicate membrane that lines the eyelids and covers the eyeballs.

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

Corrosive - Any solid, liquid, or gas that burns, irritates, or destroys organic tissues such as the skin, lungs, and stomach. Corrosives can also destroy metal and other materials. The term corrosive includes both acids and bases.

CPSC - Consumer Products Safety Commission has responsibility for regulating hazardous materials when they appear in consumer goods. For CPSC purposes, hazards are defined in the Hazardous Substances Act and the Poison Prevention Packaging Act of 1970.

Curettage - Cleansing of a diseased surface.

Cutaneous Toxicity - See "Dermal Toxicity."

CWA - Clean Water Act was enacted to regulate/reduce water pollution. It is administered by the Environmental Protection Agency (EPA).

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

Density - The mass (weight) per unit volume of a substance. Usually given in pounds per gallon or grams per milliliter. See also Specific Gravity.

Depressant - A substance that reduces a bodily functional activity or an instinctive desire, such as appetite.

Dermal - Relating to skin.

Dermal Toxicity - Adverse effects resulting from skin exposure to a substance.

Dike - A barrier constructed to control or confine hazardous substances and prevent them from entering sewers, ditches, streams, or other flowing waters.

DOL - U.S. Department of Labor, OSHA is a part of DOL.

DOT - U.S. Department of Transportation regulates transportation of chemicals and other substances.

Dry Chemical - A powdered fire-extinguishing agent usually composed of sodium bicarbonate, potassium bicarbonate, etc.

Dysmenorrhea - Painful menstruation.

Dsyplasia - An abnormality of development.

Dyspnea - A sense of difficulty in breathing; shortness of breath.
Edema - An abnormal accumulation of clear watery fluid in the tissues.

Endocrine glands - Glands that regulate body activity by secreting hormones.

Environmental Toxicity - Information obtained as a result of conducting environmental testing designed to study the effects on aquatic and plant life.

EPA - U.S. Environmental Protection Agency.
Epidemiology - Science concerned with the study of disease in a general population. Determination of the incidence (rate of occurrence) and distribution of a particular disease (as by age, sex or occupation) which may provide information about the cause of the disease.

Epithelium - The covering of internal and external surfaces of the body.

Evaporation Rate - The rate at which a material will vaporize (evaporate) when compared to the known rate of vaporization of a standard material. The evaporation rate can  be useful in evaluating the health and fire hazards of a material. The designated standard material is usually normal butyl acetate (NBUAC or n-BuAc), with a vaporization rate designated as 1.0. Vaporization rates of other solvents or materials are then classified as:

FAST evaporating if greater than 3.0.


         Methyl Ethyl Ketone = 3.8
         Acetone = 5.6
         Hexane = 8.3

MEDIUM evaporating if 0.8 to 3.0.


         190 proof (95%) Ethyl Alcohol = 1.4
         VM&P Naphtha = 1.4
         MIBK = 1.6

SLOW evaporating if less than 0.8.


         Xylene = 0.6
         Isobutyl Alcohol = 0.6
         Normal Butyl Alcohol = 0.4
         Water = 0.3
         Mineral Spirits = 0.1

Explosive - A chemical that causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden shock, pressure, or high temperature.

Exposure or Exposed - Exposure to a chemical occurs when the chemical is taken into the body through inhalation, ingestion, skin absorption, or any other means.

Exposure Limits - The concentration in workplace air of a chemical deemed the maximum acceptable. This means that most workers can be exposed at given levels or lower without harmful effects.

Exposure limits in common use are:

1. TLV-TWA: Threshold limit value—time-weighted average.  An ACGIH term for its 8 hour day/ 40 hour week exposure limit.

2. STEL: Short-term exposure limit.

3. C: Ceiling value.

Extinguishing Media - The firefighting substance to be used to control a material in the event of a fire. It is usually identified by its generic name, such as fog, foam, water, etc.

Eye Protection - Recommended safety glasses, chemical splash goggles, or face shields to be used when handling a hazardous material.

F Fahrenheit - A scale for measuring temperature. On the Fahrenheit scale, water boils at 212°F and freezes at 32°F. To convert a temperature from degrees Fahrenheit to degrees Centigrade, subtract 32 from the temperature, multiply that number by five, then divide by 9.

f/cc - Fibers per cubic centimeter of air. A measure used for exposure limits to fiber forming minerals such as asbestos.

FDA - U.S. Food and Drug Administration.

Fetus - The developing young in the uterus from the seventh week of gestation until birth.

FIFRA - Federal Insecticide, Fungicide, and Rodenticide Act requires that certain useful poisons, such as chemical pesticides, sold to the public contain labels that carry health hazard warnings to protect users. It is administered by EPA.

First Aid - Emergency measures to be taken when a person is suffering from overexposure to a hazardous material, before regular medical help can be obtained.

Flammable - A chemical that falls into one of the following categories:

a. Liquid—A liquid with a flashpoint below 100°F (37.8°C).

b. Solid—A solid, other than a blasting agent or explosive, that is able to cause fire through friction, absorption of moisture, spontaneous chemical change, or retained heat from manufacturing or processing, or which can be ignited readily and when ignited burns so vigorously and persistently as to create a  hazard.

c. Gas—A gas that, at ambient temperature and pressure, forms a flammable mixture with air at a concentration of 13 percent by volume or less.

d. Aerosol—A chemical substance or mixture dispensed from its container as a spray or mist by a propellant under pressure that, when tested by the method described in 16 CFR 1500.45, yields a flame projection exceeding 18 inches at full valve opening, or a flashback at any degree of valve opening.

Flammability Range - The lower and upper concentrations of a chemical vapor in air that will ignite if an ignition source is present. The lower concentration range is called the lower explosive limit (LEL), and the upper concentration range is called the upper explosive limit (UEL).

     Some examples of the LEL and UEL for some common chemicals:

      acetylene 2.5-80%
      acetone 2.6-12.8%
      propane 2.4-9.5%
      toluene 1.27-7%
      diesel fuel 1-5%

Flashback - A flashback occurs when flame from a torch burns back into the tip, the torch, or the hose. It is often accompanied by a hissing or squealing sound with a smoky or sharp-pointed flame.

Flashpoint - The minimum temperature at which a liquid gives off vapor in sufficient concentration to ignite. Used to determine how flammable a liquid is.

Foreseeable Emergency - Any potential occurrence such as, but not limited to, equipment failure, rupture of containers, or failure of control equipment which could result in an uncontrolled release of a hazardous chemical into the workplace.

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

Fume - A solid condensation particle of extremely small diameter, commonly generated from molten metal as metal fume.

g - Gram is a metric unit of weight. One U.S. ounce is about 28.4 grams.

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

Generic Name - A designation or identification used to identify a chemical by other than its chemical name (e.g., code name, code number, trade name, brand name).

Genetic - Pertaining to or carried by genes. Hereditary

Gestation - The development of the fetus in the uterus from conception to birth; pregnancy.

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

Grounding - The procedure used to carry an electrical charge to ground through a conductive path. A typical ground may be connected directly to a conductive water pipe or to a grounding bus and ground rod. See Bonding.