Acute Effect - An adverse effect
with severe symptoms occurring very quickly, as a result of a single
excessive overexposure to a substance.
Acute Toxicity - The adverse effects
resulting from a single excessive overexposure to a substance. Usually
a figure denoting relative toxicity.
Asphyxiant - A vapor or gas that
can cause unconsciousness or death by suffocation. Most are associated
with a lack of sufficient oxygen to promote life.
Boiling Point - A temperature at
which a liquid turns to a vapor state. This term is usually associated
with the temperature at sea level pressure when a flammable liquid gives
off sufficient vapors to promote combustion.
Ceiling or "C" - In terms of exposure
concentrations, this is the number that should never be exceeded even
for a short period, for a substance.
Carcinogen - A substance or agent
capable of producing cancer in mammals.
Cubic centimeter - cc - A volume
measurement usually associated with small quantities of a liquid. One
quart has 946 cubic centimeters.
Chronic Effect - An adverse effect
with symptoms that develop or recur very slowly, or over long periods
of time.
Chronic Toxicity - The adverse
effects resulting from prolonged or repeated exposures to a substance,
usually used as an indicator of relative toxicity for exposure over
great lengths of time.
Combustible - A term used to classify
liquids, gases, or solids that will burn readily. This term is often
associated with "flash point", which is a temperature at which a given
material will generate sufficient vapors to promote combustion.
Concentration - A figure used to
define relative quantity of a particular material. Corrosive - A material
with the characteristics of causing irreversible harm to human skin,
or steel by contact. Many acids are classified as corrosives.
Decomposition - The breakdown of
materials or substances into other substances or parts of compounds.
Usually associated with heat or chemical reactions.
Dermal - Used on or applied to
the skin.
Dermal Toxicity - The adverse effects
resulting from exposure of a material to the skin. Determined from tests
on lab animals.
Evaporation Rate - The rate at
which a liquid material is known to evaporate, usually associated with
flammable materials. The faster a material will evaporate, the sooner
it will become concentrated in the air, possibly creating an explosive
mixture or toxic concentration.
Flash Point - The temperature at
which a liquid will generate sufficient vapors to promote combustion.
Generally, the lower the flash point, the greater the danger of combustion.
Flammable - Any liquid that has
a flash point of 100 degrees F. or below. Also, any solid which can
ignite readily and sustain fire.
General Exhaust - A term used to
define a system for exhausting or ventilating air from a general work
area. Not as site specific as localized exhaust.
Gram "g" - A unit of weight. One
ounce equals about 28.4 grams.
Hazardous Chemical - Any chemical
which is either a physical or health hazard or both.
Ignitable - A term used to define
any liquid, gas or solid which has the ability to be "ignited" which
means having a flash point of 140 degrees F., or less.
Incompatible - Materials which
could cause dangerous reactions from direct contact with one another.
Ingestion - Taking in of a substance
through the mouth.
Inhalation - The breathing in of
a substance in the form of a gas, liquid, vapor, dust, mist, or fume.
Inhibitor - A chemical added to
another substance to prevent an unwanted change from occurring.
Irritant - A chemical that causes
a reversible inflammatory effect on the site of contact; however, is
not considered a corrosive. Normally, irritants affect the eyes, skin,
nose, mouth, and respiratory system.
Oxidizer - A substance that yields
oxygen readily to stimulate the combustion of an organic material.
Oxidizing Agent - A chemical or
substance that brings on oxidation reaction by providing the oxygen
to promote oxidation.
Permissible Exposure Limit PEL
- An exposure concentration established by the Occupational Safety and
Health Community which indicates the maximum concentration for which
no adverse effects will follow.
Parts Per Million PPM - A unit
of measurement for the concentration of a gas or vapor in air. Usually
expressed as number of parts per million parts of air.
Parts Per Billion PPB - As above,
only expressed as number of parts per billion parts of air.
Reactivity - The term which describes
the tendency of a substance to undergo a chemical change with the release
of energy, often as heat.
Reducing Agent - In an oxidation
reaction, this is the material that combines with oxygen.
Respiratory System - The breathing
system, including the lungs, and air passages, plus their associated
nervous and circulatory components.
Sensitizer - A substance that on
first exposure causes little or no reaction; however, with repeated
exposure will induce a marked response not necessarily limited to the
exposure site. Usually associated with skin sensitization.
Specific Gravity - The weight of
a material compared to the weight of an equal volume of water. Usually
expressed as material's heaviness. A material with a specific gravity
greater than l.0 will sink in water, whereas a material with a specific
gravity less than l.0 will float in water.
Short Term Exposure Limit STEL -
The maximum allowable concentration of a substance that one can be exposed
to for less than 15 minutes and not produce adverse health effects.
Teratogen - A substance or agent
that may cause malformation of the fetus in pregnant women. Determined
from lab animal tests.
Threshold Limit Value TLV - A term
used by the occupational safety and health community to describe the
airborne concentration of a material to which nearly all persons can
be exposed day in and day out, and not develop adverse health effects.
Toxicity - The sum of adverse effects
of exposure to materials, generally by mouth, skin, or respiratory tract.
Time Weighted Average TWA - The
airborne concentration of a material to which a person can be exposed
over an 8-hour workday without adverse effects.
Upper Explosive Limit UEL - The
highest concentration of a gas or vapor in air that will sustain or
support combustion, when an ignition source is present.
Vapor Density - A term used to
define the weight of a vapor or gas as compared to the weight of an
equal volume of air. Gases lighter than air have a vapor density of
less than l.0 whereas gases heavier than air have a vapor density greater
than l.0.
Vapor Pressure - A number used
to describe the pressure that a saturated vapor will exert on top of
its own liquid in a closed container. Usually, the higher the vapor
pressure, the lower the boiling point, and therefore the more dangerous
the material can be, if flammable.
