Environmental, Health and Safety Services


ACGIH - American Conference of Governmental Industrial Hygienists

Acrid - irritating and bitter

Action level - the exposure level (the material's concentration in air) at which OSHA regulations to protect employees take effect.

Active ingredient - the ingredient of a product that actually does what the product is designed to do. The remaining ingredients my be "inert".

Acute health effect - an adverse effect on a human or animal body, with symptoms developing rapidly.

Anhydrous - without water. A substance in which no water molecules are present in the form of a hydrate or as water of crystallization.

Anoxia - a lack of oxygen from inspired air.

Article - a manufactured item, other than a fluid or particle, which (1) is formed to a specific shape or design during manufacture, (2) has end use function(s) dependent in whole or in part upon its shape or design during end use, and (3) under normal conditions of use does not release more than very small quantities (e.g. minute or trace amounts of a hazardous chemical) and does not pose a physical hazard or health risk to personnel.

Asphyxiant - a vapor or gas that can cause unconsciousness or death by suffocation.

Boiling point, BP - the temperature at which the vapor pressure of a liquid equals the surrounding atmospheric pressure so that the liquid rapidly becomes a vapor.

Carcinogen - cancer-causing. A chemical is legally considered to be a carcinogen if it has been evaluated and determined to cause cancer by IARC or NFP, or is regulated by OSHA as such.

Chemical - any element, chemical compound, or mixture of elements and/or compounds.

Chemical formula - gives the number and kind of atoms that comprise a molecule of a material. The chemical formula for water is H2O. Each molecule of water is made up of 2 atoms of hydrogen and 1 of oxygen.

Chemical name - the scientific designation of a chemical in accordance with the nomenclature system developed by the International Union of Pure and Applied Chemistry (IUPAC), or the Chemical Abstracts Service (CAS) rules of nomenclature, or a name which will clearly identify the chemical for the purpose of conducting a hazard evaluation.

CHO - Chemical Hygiene Officer

CHP - Chemical Hygiene Plan

Chronic health effect - an adverse effect on a human or animal body with symptoms that develop slowly over a long period of time or that recur frequently.

CNS, central nervous system - indicates effects on the CNS by the material, including headache, tremors, drowsiness, convulsions, hypnosis, anesthesia, nervousness, irritability, narcosis, dizziness, fatigue, lethargy, peripheral memopathy, memory loss, impaired concentration, sleep disturbance, etc.

Combustible liquid - any liquid having a flashpoint at or above 100° F (37.8° C) but below 200° F (93.3° C), except any mixture having components with flashpoints of 200° F (93.3° C), or higher, the total volume of which makes up 99% or more of the total volume of the mixture.

Class II Liquids having flashpoints at or above 100° F (37.8° C) and below 140° F (60° C).
Class III Liquids having flashpoints at or above 140° F (60° C) are subdivided into two subclasses.
Class III A Liquids having flashpoints at or above 140° F (60° C) and below 200° F (93.3° C).
Class III B Liquids with flashpoints at or above 200° F (93.3° C).

Common name - any designation or identification, such as code name, code number, trade name, brand name, or generic name used to identify a chemical other than by its chemical name.

Compressed gas - a gas, or mixture of gases, having (in a container) an absolute pressure exceeding 40 psig at 70° F (21.1° C); or exceeding 104 psig at 130° F (54.4° C) regardless of the pressure at 70° F (21.1° C); or a liquid having a vapor pressure exceeding 40 psig at 100° F (37.8° C) as determined by ASTM D-323-72.

Consumer products - (as defined by the Consumer Product Safety Act) any article, or component part thereof, produced or distributed (i) for sale to a consumer for use in or around a permanent or temporary household or residence, a school, in recreation, or otherwise, or (ii) for the personal use, consumptions or enjoyment of a consumer in or around a permanent or temporary household or residence, a school, in recreation, or otherwise. This definition does not include certain products such as tobacco products, motor vehicles, pesticides, aircraft, boats, etc.

Control area - as defined by the 2003 International Fire Code, spaces within a building which are enclosed and bounded by exterior walls, fire walls, fire barriers, and roofs, or a combination thereof, where quantities of hazardous materials not exceeding the maximum allowable quantities per control area are stored, dispensed, used, or handled.

Controlled substances - those substances listed on Drug Enforcement Agency (DEA) schedules I - V.

Corrosive - a chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact.

Engineering controls - systems that reduce potential hazards by isolating the worker from the hazard, or by removing the hazard from the work environment. Methods include ventilation, isolation, and enclosure.

Essential chemical - a chemical that, in additional to legitimate uses, may be used as a solvent, reagent, or catalyst in manufacturing of controlled substances.

Evaporation rate - the rate at which a material vaporizes (volatizes, evaporates) from the liquid or solid state when compared to a known material's vaporization rate.

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

Flammable liquid - any liquid with a flashpoint below 100° F (37.8° C), except any mixture having components with flashpoints of 100° F (37.8° C), or higher, the total of which make up 99% or more of the total volume of the mixture. Check the Material Safety Data Sheet for characteristics or classification of a particular liquid.

Class I A Liquids having flashpoints below 73° F (22.8° C) and having a boiling point below 100° F (37.8° C).
Class I B Liquids having flashpoints below 73° F (22.8° C) and having a boiling point at or above 100° F (37.8° C).
Class I C Liquids having flashpoints at or above 73° F (22.8° C) and below 100° F (37.8° C).

Flash point, FP - the 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.

Foreseeable emergency - examples include equipment failure, container rupture, uncontrolled releases, etc.

Hazardous chemical - any chemical or product which poses a physical or health hazard. It can include liquids in containers, substances in pipes, chemicals generated in work operations (ex. welding fumes or exhaust fumes), solids, gases, or vapors.

Hazard warning - any words, pictures, symbols, or combination thereof appearing on a label or other appropriate form of warning which convey the specific physical and health hazard(s), including target organ effects, of the chemical(s) in the container(s).

Health hazard - a chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed employees, including chemicals which are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents which act on the hematopoietic system and agents that damage the lungs, skin, eyes, or mucous membranes. Appendix A and B of 29 CFR 1910.1200 provides further definitions, explanations, and criteria, if needed.

Highly toxic - a chemical that falls into any of these categories: 1) has a median lethal dose (LD50) of 50 mg or less per kg of body weight when administered to albino rats orally, 2) has a LD50 of 200 mg or less per kg of body weight when in continuous skin contact, or 3) has a lethal concentration (LC50) of 200 ppm or less of volume air on continuous inhalation.

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.

IARC - International Agency for Research on Cancer

IDLH - "immediately dangerous to life and health".

Immediate use - the hazardous chemical will be under the control of, and used only by, the person who transfers it from a labeled container into an unlabeled container, and only within the work shift in which it is transferred.

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

Inflammable - capable of being easily set on fire and continuing to burn, especially violently

Inhibitor - a material added to another to prevent an unwanted reaction, e.g. polymerization.

Irritant - a chemical which is not corrosive, but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact.

Laboratory - a facility where:

  • chemical manipulations are carried out on a "laboratory scale",
  • multiple chemical procedures are used,
  • procedures are not part of a production process, and
  • practices and equipment exist to protect employees from exposure to hazardous chemicals.

Laboratory scale - work with substances in which the containers used for reactions, transfers, and other handling of substances are designed to be easily and safely manipulated by one person. "Laboratory scale" excludes those workplaces whose function is to produce commercial quantities of materials.

Laboratory unit - a single lab, a group of research labs under the direction of the same Principle Investigator, or a group of instructional laboratories within a single department.

Latency period - the time that elapses between exposure and the first manifestations of disease or illness. Periods can range from minutes to decades, depending on the material.

LCHO - Laboratory Chemical Hygiene Officer

LC50 - the concentration of a material in air that will kill 50% of a group of test animals with a single exposure (usually 1-4 hours). The LC50 expressed as parts per million (ppm) of air, by volume, for gases and vapors. It is expressed as micrograms of material per cubic meter of air (mg/m3) for dusts and mists.

LD50 - a single dose of a material expected to kill 50% of a group of test animals. The LD50 does is usually expressed as milligrams or grams of material per kilogram of animal body weight (mg/kg or g/kg). The materials may be administered by mouth or applied to the skin.

LEL, LFL - lower explosive or flammable limit. Refers to the lowest concentration of gas or vapor (% by volume in air) that burns or explodes if an ignition source is present at ambient temperatures.

Listed chemical - any Drug Enforcement Agency (DEA) listed drug precursor or listed essential chemical.

Listed precursor - a chemical that, in addition to legitimate uses, can be used in illegal manufacture of a controlled substance.

Material Safety Data Sheet (MSDS) - written or printed material concerning a hazardous chemical that communicates hazard information to employers, employees, physicians, other health professionals, and emergency personnel.

Non-laboratory personnel - a facility where chemical manipulations are not carried out on a "laboratory scale".

NTP - National Toxicology Program

Physical Hazard - a chemical for which there is scientifically valid evidence that it is a combustible liquid, a compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive), or water-reactive.

P-listed Waste - waste that is considered "acutely hazardous" when discarded and is subject to more stringent regulation.

Pyrophoric - a chemical that will ignite spontaneously in air at a temperature of 130° F (54.4° C) or below.

Reactive material - a chemical substance or mixture that vigorously polymerizes, decomposes, condenses, or becomes self-reactive due to shock, pressure, or temperature.

Respirator - a device that protects the user from inhaling contaminated air and air with low oxygen content. Contact EHSS (231-2509) for guidance on respirator selection and associated mandatory services. Dust masks are a class of respirators.

Sensitizer - a chemical that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure.

Special waste - includes radioactive waste, asbestos waste, and infectious waste.

STEL - short-term exposure limit. The maximum concentration for a continuous exposure period of 15 minutes.

Unstable (reactive) - a chemical which in the pure state, or as produced or transported, will vigorously polymerize, decompose, condense, or will become self-reactive under conditions of shocks, pressure, or temperature.

TLV - threshold limit value (term used by ACGIH)

Toxic - A chemical that falls into one of the following categories: 1) has an LD50 of 50 - 500 mg per kg body weight (oral exposure), 2) has an LD50 of 200-1000 mg/kg (skin exposure, or 3) has a LC50 or 200-2000 ppm (inhalation exposure).

TWA - time weighted average. The allowable time-weighted average concentration for a normal 8-hour workday or 40-hour week.

UEL, UFL - upper explosion/flammable limit. The highest concentration of a material in air that produces an explosion in fire or ignites when it contacts an ignition source.

Water-reactive - a chemical that reacts with water to release a gas that is either flammable or presents a health hazard.