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Hazard Communication: An Employee's Right to Know
Glossary

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A

acute
An adverse health effect on a human or animal body characterized by severe symptoms that develop rapidly and occur immediately upon exposure.
asphyxiant
A chemical that displaces oxygen in the air (simple asphyxiant) or prevents bodily absorption of oxygen to cause suffocation (chemical asphyxiant) causing a person to suffocate. Examples include nitrogen and carbon monoxide.

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B

boiling point
The temperature at which a liquid begins to turn to a vapor or gas.

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C

carcinogen
Substance or agent capable of causing or producing cancer in mammals.
chemical
Any element, (chemical) compound, or mixture of elements or compounds.
chemical formula
The scientific description of a chemical's physical properties or structure.
chemical name
The scientific designation of a chemical or the name that will clearly identify the chemical for the purpose of conducting a hazard evaluation.
chronic
Adverse effect resulting from repeated doses of, or exposure to, a substance over a relatively prolonged period of time (sometimes years).
combustible liquid
Capable of igniting and burning. Combustible liquids have a flash point that is at or above 100° Fahrenheit but below 200° Fahrenheit.
compressed gas
Gas under greater than atmospheric pressure. Usually stored in high-pressure cylinders.
concentration
The relative amount of a substance when combined or mixed with other substances (for example, PPM).
corrosive
A liquid or solid that causes visible destruction or irreversible alterations in human skin tissue at the site of contact or has a severe corrosion rate on steel.

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D

decomposition
The process of decaying or breaking down (for example, by heat, chemical reaction, electrolysis, or decay). Some materials will decompose into parts or elements of simpler compounds.
dosimeter
A device for measuring air quality.

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E

environmental monitoring
Monitoring the area in which an employee works.
epidemiology
The branch of medical science dealing with the transmission and control of disease.
evaporation rate
The rate at which a particular material will vaporize, or evaporate, when compared with the rate of vaporization of a known material.
explosive
A chemical that causes a sudden, almost instantaneous release of energy, pressure, gas, and heat when subjected to sudden pressure, shock, or high temperature.

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F

flammable liquid
Liquid with a flash point below 100° Fahrenheit which will ignite 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 flammable vapor near the surface of the liquid to ignite
formula
The conventional scientific designation for a material.
freezing point
The temperature at which a liquid turns to a solid.

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G

gram, or g
Unit of weight in the metric system; 28.4 grams = 1 ounce.
grams per kilogram, or g/Kg
In toxicology, an expression of dose that indicates grams of a substance dosed per kilogram of animal body weight.

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H

hazardous chemical
Any chemical which is a physical hazard or a health hazard, or a chemical for which there's evidence that acute or chronic health effects may occur in exposed employees.
hazardous polymerization
A chemical reaction in which two or more molecules combine to form a larger molecule, causing a rapid release of energy.
health hazard
A chemical for which there's evidence that acute or chronic health effects may occur in exposed employees. Includes chemicals that are carcinogens, toxic, irritants, corrosives, or sensitizers.

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I

ignitable
Capable of being set on fire.
incompatible
Materials that could cause dangerous reactions from direct contact with one another.
irritant
A substance which by contact can cause an inflammatory response or reaction of the skin or respiratory system.

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K

kilogram, or Kg
Metric unit of weight; 1 Kg = 2.2 pounds.

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L

LC-50
See lethal concentration – fifty percent.
LD-50
See lethal dose – fifty percent.
LEL/LFL
See lower explosive/flammable limit.
lethal concentration – fifty percent
The concentration of a substance in air that kills 50% of a group of test animals; usually expressed as PPM or mg/m3.
lethal dose – fifty percent
Abbreviated LD-50, a single dose of a substance that kills 50% of a group of test animals; usually expressed as mg/Kg.
liter, or L
A metric unit of capacity; 1 quart = 9/10 liter.
lower explosive/flammable limit
Abbreviated as LEL/LFL, the lowest percentage of a gas or vapor in air that will produce a flash of fire when heat, spark, or flame is present.

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M

medical monitoring
Monitoring a worker's response and biological changes after exposure to a hazardous chemical.
melting point
The temperature at which a solid turns to liquid.
milligram, or mg
Metric unit of weight; 1000mg = 1 Kg or 2.2 pounds.
milliliter, or ml
Metric unit of capacity; 1000ml = 1L.
molecular weight
The average mass of a molecule of a compound compared to 1/12 the mass of carbon 12 and calculated as the sum of the atomic weights of the constituent atoms.
mutagen
A substance of agent capable of altering the genetic material in a living cell.

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N

National Fire Protection Association
Abbreviated NFPA, an organization that promotes fire protection and prevention.
National Institute for Occupational Safety and Health
Abbreviated as NIOSH, an organization that is part of the US Department of Health and Human Services.
NFPA
See National Fire Protection Association.
NIOSH
See National Institute for Occupational Safety and Health.

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O

Occupational Safety and Health Administration
Abbreviated as OSHA, a regulatory and enforcement safety and health organization that is part of the US Department of Labor.
odorant
An odorous substance added to a dangerous odorless substance to warn of its presence.
oral toxicity
Adverse effects resulting from taking a substance into the body via the mouth.
organic peroxide
An organic oxidizer that can be shock- and heat-sensitive, flammable, and potentially explosive.
OSHA
See Occupational Safety and Health Administration.
oxidizer
A substance which yields oxygen readily to stimulate the combustion, or oxidation, of organic matter.

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P

parts per million
Abbreviated PPM, one part of a gas or vapor in a million parts of air.
PEL
See permissible exposure limit.
percent volatile
The percentage of a liquid or solid, by volume, that will evaporate at an ambient temperature of 70° Fahrenheit.
permissible exposure limit
Abbreviated PEL, an exposure limit established by OSHA to indicate the maximum airborne concentration of a contaminant to which an employee may be exposed over a specified duration of time.
personal monitoring
Monitoring the area immediately next to an employee's body.
personal protective equipment
Abbreviated as PPE, the last line of defense between a worker and a hazard. Examples include hard hats, gloves, earplugs, and face shields.
physical hazards
A chemical which is classified as a combustible liquid, a compressed gas, explosive, flammable, an organic peroxide, and oxidizer, pyrophoric, unstable, or water reactive. A chemical for which there's evidence that it can harm both people and property.
PPE
See personal protective equipment.
PPM
See parts per million.
pyrophoric
A chemical that will ignite spontaneously in air at a temperature of 130° Fahrenheit or lower.

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R

reactive
The tendency of a substance to undergo chemical reaction with the release of energy.

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S

short term exposure limit
Abbreviated as STEL, the maximum exposure limit for a period no longer than 15 minutes.
solubility in water
A term expressing the percentage of a material that will dissolve in water.
specific gravity
The weight of a material compared to the weight of an equal volume of water.
stability
The ability of a material to remain unchanged. A material is considered stable if it remains in the same form under expected and reasonable conditions of storage or use.
STEL
See short term exposure limit.
synonym
Another name for which a material is known.
systemic
Affecting the entire body or an entire organism.

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T

target organ/system
Organ or system which a specific or class of chemicals seeks, regardless of the site of entry. Examples vinyl chloride (liver), halogenated hydrocarbons (kidneys), and methyl mercury (nervous system).
teratogen
A substance or agent to which exposure of a pregnant female can result in malformations in the fetus.
threshold limit value
Abbreviated as TLV, the exposure amount considered safe by the American Conference of Governmental Industrial Hygienists (ACGIH) for continued exposure for the entire working life. Exposures above this increase the risk of having a response to the exposure.
time weighted average
Abbreviated as TWA, the exposure amount averaged over an eight-hour period.
TLV
See threshold limit value.
toxic agent/material
A chemical or substance that produces harmful health effects.
toxicity
The capacity of a material to produce harmful health effects.
trade secret
The chemical manufacturer, importer, or employer may withhold the specific chemical identity, including the chemical name of a hazardous chemical, from the Safety Data Sheet. For this to happen, the information must be classified as a trade secret.
TWA
See time weighted average.

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U

UFL/UEL
See upper flammability/explosive limit.
upper flammability/explosive limit
Abbreviated as UFL/UEL, the highest concentration of a chemical that will burn if an ignition source is provided.

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V

vapor density
The relative weight of gases and vapors as compared to a standard, like air. A material with a vapor density greater than 1 will gather along the floor. A material with a vapor density less than 1 will float off.
vapor pressure
The pressure exerted by a vapor on the walls of its container. The higher the vapor pressure, the stronger the container must be.
ventilation systems
Systems used to improve the quality of air by circulating fresh air.

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W

water reactive
A chemical that reacts violently when it contacts water.

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