GLOSSARY OF COMMONLY USED MSDS TERMS
Acid
Action level
Acute effect
Allergy
Asphyxiant
Base
C
Carcinogen
CAS
Chronic
Combustible
Compressed
gas
Corrosive
Decomposition
Dose
Edema
Flammable
Flashpoint
Hazardous
chemical
HEPA
IDLH
Incompatible
Irritant
LC50
LD50
A substance which dissolves in water and releases hydrogen ions (H+);
strength determined by pH [0<acid<7]; acidity increases as pH
decreases; can cause irritation, burns, or more serious tissue damage
One half of the PEL; if exceeded necessitates certain activities such as
exposure monitoring and medical surveillance
Adverse effects with severe symptoms developing rapidly and coming
quickly to a crisis; usually reversible
An abnormal response of a hypersensitive individual to chemical or
physical stimuli; same as hypersensitivity
A vapor or gas which can cause unconsciousness or death by suffocation
(Aame as alkali/caustic) A substance which dissolves in water and
releases a hydroxyl ion (OH-); measured in pH, [7<base<14];
strength increases as pH increases; irritates and can cause tissue
damage
Ceiling limit; the maximum concentration of a material, in air, that must
never be exceeded, even for an instant
A chemical or physical agent capable of causing cancer
Chemical Abstract Service registry number
An adverse effect with symptoms which develop over a long period of
time (months or years)
Material which can burn, but not as easily as a flammable material;
flashpoint at or above 100oF
A gas or mixture of gases in a container having an absolute pressure
exceeding 40 psi (at 70oF)
A liquid or solid that causes visible destruction or irreversible alterations
in skin tissue at the place where it touches the skin; splash-proof
goggles and skin protection must be worn when handling these
materials
Breakdown of chemicals into simpler parts, compounds, or elements
The amount of a chemical that enters or is absorbed by the body;
usually expressed in milligrams of a chemical per kilogram of body
weight (mg/kg)
A swelling of body tissue due to water or fluid accumulation in tissues
Material which catches fire easily and burns rapidly; flashpoint below
100oF
Lowest temperature at which a liquid gives off enough flammable vapor
to ignite and produce a flame when an ignition source is present
Any chemical which is a physical hazard or a health hazard
High Efficiency Particulate Aerosol filter; by definition it is 99.97%
effective against particles > 0.3 microns
Immediately Dangerous to Life and Health; air concentration at this
level can cause death very quickly; can be caused by toxic chemicals,
insufficient oxygen, or both
Materials which could cause dangerous reactions from direct contact
with one another
A substance which can cause an inflammatory response or reaction of
the eye, skin, or respiratory system
Lethal Concentration 50%; a concentration of chemical in the air that
will kill 50% of the test animals inhaling it
Lethal Dose 50%; the dose of a chemical that will kill 50% of the test
animals receiving it; Oral; Skin; parenteral; it is a rough measure of
acute toxicity
mg/m3
MSDS
Mutagen
NFPA
NIOSH
PEL
pH
Polymerization
ppb
ppm
psi
Pyrophoric
Oxidizer
Reactivity
Respirator
Route of
entry/exposure
STEL
Teratogen
TLV
TWA
A way of expressing dose; milligrams of a substance per cubic meter of
air
Material Safety Data Sheets; a form that lists the properties and hazards
of a product or a substance
A chemical or physical agent able to change the genetic material in the
cells
National Fire Protection Agency
National Institute for Occupational Safety and Health
Permissible Exposure Limit; legal limit of chemical exposure a worker
can be exposed to based on an 8 hour work day for 40 hours per week
based on 30 years of employment
Expresses how acidic or alkaline a solution or chemical is; range is from
0 to 14; water is neutral at pH=7; see acid/base
A chemical reaction in which small molecules (monomers) combine to
form much larger molecules (polymers); hazardous when this takes
place at a fast rate with large amounts of energy released
Parts per billion; a measure of concentration
Parts per million; a measure of concentration
Pound per square inch; a unit of pressure
A chemical that will ignite spontaneously in air at a temperature of
130oF or below
Any substance which will react chemically either by supplying oxygen or
removing electrons; oxidizers must not be stored near flammable or
reactive materials
The ability of a substance to undergo a chemical reaction (such as
combining with another substance)
A device worn to prevent inhalation of hazardous substances; UCSD has
an official program in which all respirator users must be enrolled
The way in which a chemical enters the body; ingestion, inhalation, skin
absorption or injection
Short Term Exposure Limit; indicates the maximum average
concentration allowed for a continuous 15 minute exposure
A chemical or physical agent which can lead to malformations in the
fetus and birth defects in children (live born offspring)
Threshold Limit Value; suggested chemical exposure limit as determined
by the American Conference of Governmental Industrial Hygienists
[ACGIH])
Time-Weighted Average; the average concentration of a chemical in the
air over the total exposure time- usually a 8-hour work day