The following glossary presents brief explanations of common terms frequently used by chemical manufacturers in their Material Safety Data Sheets (MSDS).
A B C
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.
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.
Adverse symptoms that occur immediately or shortly after an exposure to a chemical. Common symptoms of acute exposure include headache, dizziness, or nausea.
Acute effects resulting from a single dose of, or exposure to, a substance.
A fine suspension in the air of small particles (e.g., smoke or fog).
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. See also Chemical Cartridge Respirator.
An abnormal response by the body to chemical or physical stimuli (e.g., hives, sneezing).
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 alcohol, paint remover, and degreasers.
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.
A remedy to relieve, prevent, or counteract the effects of a poison.
A description of a substance at normal room temperature and normal atmospheric conditions. Appearance includes the color, size, and consistency of a material.
The adverse effects to marine life that result from being exposed to a toxic substance.
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.
Showing no symptoms.
Atmosphere, a unit of pressure equal to 760 mmHg (mercury) at sea level.
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).
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.
Capable of being broken down into non harmful products by the action of living things.
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:
|Ethylene Glycol (Antifreeze)||197°C (387°F)|
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.
Clean Air Act was enacted to regulate/reduce air pollution. CAA is administered by the U.S. Environmental Protection Agency (EPA).
A substance or agent that has been demonstrated to cause or produce cancer in mammals, including humans. Carcinogens are regulated by OSHA and are listed in the National Toxicology Program Annual Report of Carcinogens.
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.
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, 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.
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.
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.
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; acrolein, furfural, and acetaldehyde are of the "aldehyde" family.
Inflammation of the lungs caused by accumulation of fluids due to chemical irritation.
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.
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.
Repeated long-term contact with a substance.
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.
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.
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.
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.
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.
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 building materials. The term corrosive includes both acids and bases.
Clean Water Act was enacted to regulate/reduce water pollution. It is administered by the Environmental Protection Agency (EPA).
D E F
The mass (weight) per unit volume of a substance. Usually given in pounds per gallon or grams per milliliter. See also Specific Gravity.
A substance that reduces a bodily functional activity or an instinctive desire, such as appetite.
Relating to skin.
Adverse effects resulting from skin exposure to a substance.
A barrier constructed to control or confine hazardous substances and prevent them from entering sewers, ditches, streams, or other flowing waters.
U.S. Department of Transportation regulates transportation of chemicals and other substances.
A powdered fire-extinguishing agent usually composed of sodium bicarbonate, potassium bicarbonate, etc.
Information obtained as a result of conducting environmental testing designed to study the effects on aquatic and plant life.
U.S. Environmental Protection Agency.
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
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.
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 valuetime-weighted average.
2. STEL: Short-term exposure limit.
3. C: Ceiling value.
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.
Recommended safety glasses, chemical splash goggles, or face shields to be used when handling a hazardous material.
is 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.
U.S. Food and Drug Administration.
The developing young in the uterus from the seventh week of gestation until birth.
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.
Emergency measures to be taken when a person is suffering from overexposure to a hazardous material, before regular medical help can be obtained.
A chemical that falls into one of the following categories:
a. LiquidA liquid with a flashpoint below 100°F (37.8°C).
b. SolidA 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. GasA gas that, at ambient temperature and pressure, forms a flammable mixture with air at a concentration of 13 percent by volume or less.
d. AerosolA 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.
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:
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.
The minimum temperature at which a liquid gives off vapor in sufficient concentration to ignite. Used to determine how flammable a liquid is.
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.
The scientific expression of the chemical composition of a material (e.g., water is H2O, sulfuric acid is H2SO4, sulfur dioxide is SO2).
The particulate, smoke-like emanation from the surface of heated metals.
G H I
Gram is a metric unit of weight. One U.S. ounce is about 28.4 grams.
A system for exhausting air containing contaminants from a general work area. Also see Local Exhaust.
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).
The development of the fetus in the uterus from conception to birth; pregnancy.
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).
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.
Specific type of gloves or other hand protection required to prevent harmful exposure to hazardous materials.
Any chemical whose presence or use is a physical hazard or health hazard.
Words, pictures, or symbols, presented on a label to inform of the dangers of a chemical.
Hazard Communication Standard is an OSHA regulation issued under 29 CFR Part 1910.1200. Also known as HazCom or Right-to-Know.
A chemical for which there is 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. The term "health hazard" includes chemicals that are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents that act on the hematopoietic system, and agents that damage the lungs, skin, eyes, or mucous membranes.
A chemical in any of the following categories:
a. A chemical with a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each. (ORL-RAT LD50)
b. A chemical with a median lethal dose (LD50) of 200 milligrams or less per kilogram of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between 2 and 3 kilograms each. (SKN-RBT LD50)
c. A chemical that has a median lethal concentration (LC50) in air of 200 parts per million by volume or less of gas or vapor, or 2 milligrams per liter or less of mist, fume, or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 grams each. (IHL-RAT LC50)
Act as chemical messengers to body organs.
International Agency for Research on Cancer.
Capable of being set on fire.
A material that does not allow another substance to pass through or penetrate it.
Materials that could cause dangerous reactions by direct contact with one another. Reactions between incompatible chemicals can cause an explosion, a fire, or the release of a toxic gas.
Taking in by the mouth.
Breathing in of a substance in the form of a gas, vapor, fume, mist, or dust.
A chemical added to another substance to prevent an unwanted chemical change.
Not capable of being dissolved in a liquid.
A chemical, which is not corrosive, that causes a reversible inflammatory effect on living tissue by chemical action at the site of contact.
J K L
Kilogram is a metric unit of weight. One kilogram is about 2.2 U.S. pounds. Also see "g/kg," "g," and "mg."
Liter is a metric unit of capacity. A U.S. quart is about 9/10 of a liter.
Secretion and discharge of tears.
Notice attached to a container, bearing information concerning its contents.
Lethal concentration is the concentration of a substance being tested that will kill.
Lethal concentration, low, lowest concentration of a gas or vapor capable of killing a specified species over a specified time.
The concentration of a material in air that will kill 50 percent of a group of test animals with a single exposure (usually 1 to 4 hours). The LC50 is expressed as parts of material per million parts of air, by volume (ppm) for gases and vapors, or as micrograms of material per liter of air (µg/l) or milligrams of material per cubic meter of air (mg/m3) for dusts and mists, as well as for gases and vapors. See also Highly Toxic and Toxic.
Lethal dose is the quantity of a substance being tested that will kill.
Lethal dose low, lowest administered dose of a material capable of killing a specified test species.
A single dose of a material expected to kill 50 percent of a group of test animals. The LD50 dose is usually expressed as milligrams or grams of material per kilogram of animal body weight (mg/kg or g/kg). The material may be administered by mouth or applied to the skin. See also Highly Toxic and Toxic.
LEL, or LFL
Lower explosive limit, or lower flammable limit, of a vapor or gas; the lowest concentration (lowest percentage of the substance in air) that will produce a flash of fire when an ignition source is present. At concentrations lower than the LEL, the mixture is too "lean" to burn. Also see UEL and Flammability Range.
A system for capturing and exhausting contaminants from the air at the point where the contaminants are produced (welding, grinding, sanding, or other processes or operations). Also see General Exhaust.