This glossary shows brief explanations of common terms and acronyms frequently used by chemical manufacturers in their MSDS's.
| Absorption: | Penetration of a chemical into the body through the skin, respiratory tract, or other route of entry. |
| Aerosol: | Liquid droplets or solid particles small enough to remain dispersed in air for a long period of time. |
| ACGIH: | American Conference of Governmental Industrial Hygienists; an organization of professional personnel in governmental agencies or educational institutions engaged in occupational safety and health programs. ACGIH develops and publishes recommended occupational exposure limits (see "TLV") for many chemicals. These are considered reliable indicators of toxicity since they are not subject to any industry bias. |
| Acid: | A corrosive material whose water solution contains hydrogen ions (H+). Acids can burn, irritate or destroy organic tissues such as skin and lungs. |
| Acute Effect: | An adverse effect on a person which develops rapidly. An example would be a burn from acid or dizziness from solvent vapors. See also "chronic effects". |
| ANSI: | American National Standards Institute. A privately funded, voluntary membership organization which develops consensus standards based on industrial and public needs. Among them is a standardized format for MSDS preparation. |
| Article: | These are exempted from the Hazard Communications Rule. They are defined as manufactured items formed to a specific shape or design during manufacture which have end use functions dependent in whole or in part upon shape or design; and which do not release, or otherwise result in exposure to a hazardous chemical under normal conditions of use. |
| Asphyxiant: | A vapor or gas which can cause unconsciousness or death by suffocation (lack of oxygen). |
| Auto-ignition Temperature: | Temperature at which a gas or vapor can burst into flames or explode with no other source of ignition present. |
| Base: | A corrosive material whose water solution contains hydroxyl ions (-OH). Bases can burn, irritate or destroy organic tissues such as skin and lungs. Many bases are more difficult to wash off than acids. |
| Boiling Point: | Temperature at which a liquid changes to a vapor state at a given pressure (usually sea level pressure of 760 mm of Hg). Mixtures may have a boiling range. The boiling point of water is 212oF (100oC). |
| "C" or Ceiling: | The maximum allowable human exposure limit for an airborne substance, not to be exceeded even momentarily. See also "TLV". |
| CAA: | Clean Air Act administered by EPA. |
| Carcinogen: | A chemical capable of causing or producing cancer in animals. Chemicals are generally considered carcinogens if regulated as such by OSHA, or listed as such by the ACGIH, the IARC, or the NTP. |
| C.A.S.: | Chemical Abstracts Service Number, used to identify specific chemicals. Allows for easy indexing of chemicals and can be used for positive identifications since the same chemical can have several names. |
| cc: | Cubic centimeter, measurement of volume equal to one milliliter (ml). One quart is about 946 cc. |
| Chemical Family: | A group of single elements or compounds with a common name and similar characteristics. 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. |
| CHEMTREC: | Chemical Transportation Emergency Center. A national center established by the Chemical Manufacturers Assn. to relay emergency information concerning specific chemicals on request. It is intended for use primarily for use by responders to transportation emergencies. |
| Chronic Effect: | Adverse effect on a person resulting from repeated doses or exposure to a substance over a relatively prolonged period of time. Examples might be development of cancer from benzene exposure, liver damage from repeated ingestion of alcohol. |
| Combustible Liquid:. | Material with a flashpoint at or above 100oF, but below 200oF |
| Compressed Gas: | Any substance which, when enclosed in a container, gives a pressure reading of at least: 25 psig (pounds per square inch, gauge pressure) at 70oF, or over 89 psig at 130oF, or over 25 psig at 100oF for flammable materials. |
| Corrosive: | Any solid, liquid, or gas that destructively attacks organic tissues such as the skin, lungs, and stomach. May also dissolve metal, concrete, and other materials. |
| Concentration: | The relative amount of a substance when combined or mixed in another. Usually expressed in parts per million, percentage, or mg/m3. |
| CPSC: | Consumer Products Safety Commission. Federal agency which regulates hazardous materials when they appear in consumer goods. |
| CWA: | Clean Water Act administered by EPA to reduce water pollution. |
| Decomposition: | Breakdown of a material or substance (by heat, chemical reaction, decay or other process) into parts, elements or simpler compounds. Decomposition products may be hazardous (e.g., ammonia, carbon monoxide, chlorides) or non-hazardous (e.g., carbon dioxide, water, nitrogen). |
| Dermal Toxicity: | Adverse effects resulting from skin exposure to a substance. |
| DOT: | U.S. Department of Transportation; regulates the transportation of chemicals and other substances for the protection of the public. DOT has a chemical classification system, label and placard requirements. |
| EPA: | U.S. Environmental Protection Agency. |
| Epidemiology: | The science which deals with the study of disease in a general population. Determination of rate of occurrence and distribution may provide information about the cause. |
| Evaporation Rate: | Rate at which a product will vaporize when compared to the rate of vaporization of a known material. Butyl Acetate is usually used as the standard and assigned an evaporation rate of 1.0. Evaporation rate can be useful in evaluating health and fire hazards of a material. Rates are generally classified as fast (greater than 3.0), medium (0.8 to 3.0), and slow (less than 0.8). Evaporation rate of water is 0.3. |
| Explosive: | A chemical that causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden shock, pressure, or high temperature. |
| Explosive Range: | The range of concentration of a flammable gas or vapor (% by volume in air) in which explosion can occur upon ignition in a confined area. See also L.E.L. and U.E.L. |
| Flammable Gas: | A gas that forms a flammable mixture with air at a concentration of 13% by volume or less, or a gas that forms a flammable mixture with air with a range wider than 12% by volume regardless of the lower limit. |
| Flammable Liquid: | A liquid with a flash point below 100o F (37.8o C). Note that there are current proposals to change definition to include those flashpoints up to 141o F. |
| Flammable Solid: | A solid other than a blasting agent or explosive which burns or ignites easily through friction, absorption of moisture, spontaneous chemical change, or retained heat from manufacturing or processing, or which can be ignited readily and when ignited burns so vigorously and persistently as to create a serious hazard. |
| Flash point: | Temperature at which a liquid will give off enough vapor to create an ignitable mixture. Vapors will not auto-ignite at the flash point. An ignition source must be present for a fire to occur. The lower the flashpoint, the greater the fire danger. Flash point values are most important when dealing with hydrocarbon solvents. The flashpoint of a material may vary depending on the method used for testing, therefore methods are usually listed. Common test methods include Tag (Tagliabue) Closed Cup (TCC), Tag open Cup (TOC), and Pensky-Martens Closed Cup (PMCC). |
| Fume: | Airborne dispersion of minute solid particles arising from heating solids as in welding. Odorous gases and vapors are often incorrectly called fumes. |
| g.: | Gram; a metric unit of weight. One ounce is about 28.4 grams. |
| g/kg.: | Grams per kilogram; an expression of dose used in oral and dermal toxicity testing to indicate the grams of substance dosed per kilogram of animal body weight. (1000 grams = 1 kilogram) |
| General Exhaust: | A system for exhausting air containing contaminants from a general work area. This is essentially dilution ventilation and should be used only with contaminants of low toxicity. |
| Hazardous Chemical: | As defined under the OSHA Hazard Communications rules, any chemical which has a physical or health hazard. Physical hazards are defined as being flammable, combustible, a compressed gas, an explosive, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive), or water-reactive. |
| IARC: | International Agency for Research on Cancer. Publishes a list of known and potential carcinogens. |
| IDLH: | Immediately Dangerous to Life or Health. The concentration representing a maximum airborne concentration from which, in the event of a respirator failure, a person could escape within 30 minutes without any escape-impairing symptoms or any irreversible health effects. Unlike the TLV/PEL and STEL values, it is not a "safe" level of exposure. |
| Ignitable: | Capable of being set on fire. |
| Incompatible: | Materials which could cause a dangerous reaction from direct contact with one another. |
| Inert Gas: | A gas which does not normally chemically combine with other substances, i.e., argon and nitrogen |
| Ingestion: | Taking a substance in through the mouth (eating or drinking). |
| Inhalation: | Breathing a substance into the lungs in the form of a gas, vapor, fume, mist, or dust. |
| Inhibitor: | A chemical which is added to another substance to prevent an unwanted chemical change from occurring. |
| Irritant: | A chemical which is not a corrosive but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact. |
| kg: | Kilogram; a metric unit of weight, about 2.2 pounds. |
| L: | Liter; a metric unit of volume. A quart is about 9/10 of a liter. |
| LC50: | Lethal concentration that will kill 50% of test animals. |
| LD50: | Dose which is required to produce death in 50% of exposed species. |
| LEL: | Lower Explosive Limit, also referred to as LFL, Lower Flammable Limit. The lowest concentration in air that a gas or vapor will burn. Mixtures below the LEL are commonly called "too lean" to burn. |
| Local Exhaust: | A system for capturing and exhausting contaminants from the air at the point where they are produced. |
| mg/kg: | see also g/kg. A measure of toxic dose. 1000 mg = 1 g. |
| mg/m3: | Milligrams per cubic meter. Most often used as a measure of concentration of dusts and mists in air. (1000 milligrams = 1 gram; a cubic meter is about 1.3 cubic yards.) |
| ml: | Milliliter; a metric unit of volume. There are 1000 milliliters in a liter. |
| mmHg: | Millimeters of mercury (Hg); a unit of measurement for low pressures or partial vacuums, or vapor pressures. |
| mppcf: | Million particles per cubic foot. A unit for measuring dust contaminants. This has now largely been replaced by mg/m3. |
| Mutagen: | Chemical which can alter the genetic material in a living cell or cause birth defects through damage of chromosomes. |
| NFPA: | National Fire Protection Association. They have a diamond safety label. The NFPA health hazard code refers only to acute exposures to emergency personnel. Tektronix health code is often a higher number since it also accounts for chronic effects. |
| NIOSH: | National Institute for Occupational Safety and Health. Part of the Public Health Service. They recommend exposure limits to OSHA, certify respirators and sampling devices, and assist in health investigations. |
| NTP: | National Toxicology Program. Publishes a list of known and suspect carcinogens. |
| Olfactory: | Relating to sense of smell. |
| Oral toxicity: | Adverse effects resulting from taking a substance into the body via ingestion. Ordinarily used to denote effects on experimental animals. |
| Organic Material: | Term used to designate chemicals which contain carbon. |
| OSHA: | U.S. Occupational Safety and Health Administration. |
| Oxidizer: | A chemical other than a blasting agent or explosive that initiates or promotes combustion in other materials. These chemicals can react with organic material or combustible liquids to cause or intensify fires. |
| P.E.L.: | Permissible Exposure Limit. The maximum permitted 8-hour time-weighted average concentration of an airborne contaminant established by the U.S. OSHA. See also "C" and "STEL". |
| Percent Volatile: | The percentage of a material that will evaporate at a temperature of 70o F (unless some other temperature is specified). Many solvents are 100% volatile and completely evaporate over a period of time. Materials such as paints are less than 100% volatile and will leave a solid residue. |
| pH: | A value used to represent the strength of an acid or base. pH values of 1 to 6 indicate acids, with 1 being a very strong acid and 6 being a very weak acid. Neutral materials such as pure water have a pH of 7. Bases have pH values of 8 to 14, with 8 being a very weak base and 13 being a very strong base. |
| Poison, Class A: | A DOT term for extremely dangerous poisonous liquids and gases where a very small amount is dangerous to life. Examples: phosgene, cyanogen, hydrocyanic acid, nitrogen peroxide. |
| Poison, Class B: | A DOT term for liquid and solid substances known or presumed to be so toxic to man as to afford a hazard to health during transportation. These are less dangerous than Class A Poisons. |
| Polymerization: | A chemical reaction in which two or more small molecules combine to form larger molecules at a rate which releases large amounts of energy. |
| ppm: | Parts Per Million. Used as a volume concentration of airborne gas and vapor contaminants. ppb is parts per billion. One part per million is the equivalent of 1/2 of a dissolved aspirin tablet in a full bathtub of water (50 gallons). One part per billion is equivalent to 1/2 of a dissolved aspirin tablet in 1,000 bathtubs of water (50,000 gallons). |
| psi: | Pounds per square inch. Normal atmospheric pressure is about 14.7 psi. |
| Pyrophoric: | A chemical that will ignite spontaneously in air at temperature less than or equal to 130oF (54.4oC). |
| Reactive Chemical: | Unstable chemicals or those that can become hazardous in contact with other chemicals or water, will vigorously polymerize, decompose or become self-reactive under conditions of shocks, pressure or temperature. |
| SARA Section 313: | Toxic Chemical Release Reporting required under the Superfund Amendment and Re-authorization Act. The chemicals on this list are reported by users on an emissions inventory to inform government officials and the public about the release of toxic chemicals into the environment. The MSDS often gives information as to whether any components are on this list. |
| Sensitizer: | A chemical that causes a substantial proportion of exposed people or animals to develop allergic reaction in normal tissue after repeated exposure to the chemical. |
| "Skin": | A notation sometimes used with PEL or TLV exposure data to indicate that the substance may be absorbed through the skin. |
| Solubility in Water: | Expresses the percentage of a material by weight that will dissolve in water at room temperature. This information is important in determining spill cleanup or fire extinguishing methods. Terms used to express solubility are: Negligible - less than 0.1%, Slight - 0.1 to 1.0% , Moderate - 1 to 10%, Appreciable - more than 10%, Complete - soluble in all proportions |
| Solvent: | Solvent is commonly used to refer to most organic liquids. A solvent is any substance capable of dissolving another substance to form a uniformly dispersed mixture at the molecular or ionic size level. Water is the most common solvent. |
| Specific Gravity: | The weight of a material compared to the weight of an equal volume of water; an expression of the density (heaviness) of the material. Insoluble materials with specific gravity of less than 1.0 will float on water - an important consideration for fire suppression and spill cleanup. |
| Stability: | The ability of a material to remain unchanged under expected and reasonable conditions of storage or use. |
| STEL: | Short-Term Exposure Limit. Maximum average concentration for a continuous 15-minute exposure period (maximum of four such periods each day, with at least one hour between exposure periods, and provided that the daily TWA is not exceeded). |
| Teratogen: | Chemicals which can cause malformations of a fetus (developing unborn baby) when a pregnant female is exposed. |
| TCLP: | Toxicity Characteristic Leaching Procedure. This is used as a measure of whether a material can be placed in a landfill, and this information is often contained on the MSDS. A description of the test procedure is contained in 40 CFR 261; Appendix II; Method 1311. |
| TLV: | Threshold Limit Value; a term used by the ACGIH to express the airborne concentration of a material to which nearly all persons can be exposed day after day without adverse health effects. |
| Toxicity: | Relative property of a chemical agent referring to harmful effect on some biologic mechanism. |
| TSCA: | Toxic Substances Control Act administered by U.S. Environmental Protection Agency. Regulates manufacture, handling, and use of materials classified as "Hazardous Substances". A key provision is maintenance of a registry of all chemicals manufactured or imported for use in commerce. A certification that all components are on this registry will often be included on the MSDS. |
| TWA: | Time Weighted Average; the average exposure level allowable for a normal 8-hour workday or 40-hour workweek. |
| UEL: | Upper Explosive Limit, or UFL, Upper Flammable Limit. The maximum concentration of a material in air which can be ignited. Mixtures at this concentration are commonly called "too rich to burn". |
| ug/m3: | Micrograms per cubic meter. Used as a measure of highly toxic airborne concentrations of dusts and mists. 1 milligram = 1000 micrograms. |
| Unstable: | See "Reactive". |
| Vapor: | The gaseous form of a material which is normally in the liquid or solid state at standard temperature and pressure. |
| Vapor Density: | The weight of a vapor or gas compared to the weight of an equal volume of air; an expression of the density of the vapor or gas. Materials lighter than air have values less than 1.0, and those heavier than air have values greater than 1.0. Heavy vapors and gases are likely to concentrate in low places where they can create fire or health hazards. Heavy vapors can displace oxygen in sumps or pits. Lighter vapors usually dissipate unless confined. |
| Vapor Pressure: | The pressure exerted by a saturated vapor (maximum concentration) above its own liquid in a closed container. Values are reported at a given temperature (usually 20oC/68oF). The lower the boiling point of a substance, the higher its vapor pressure. As the temperature of a product increases, its vapor pressure also increases. Vapor pressure relates to speed of evaporation. |
| Volatile: | That which will evaporate. |
| Water Reactive: | A chemical that reacts with water to release a gas that is either flammable or presents a health hazard.
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