Chemical Hygiene Plan - Queensborough Community College ...

are the effects of exposure at hazardous levels. Most chemicals are safe in normal use
and the vast majority of workers never suffer toxic effects. However, any chemical can
be toxic in high concentrations, and the precautions outlined in the MSDS should be
followed.
The health hazards section often contains information on the toxicity of the substance.
The data most often presented are the results of animal experiments. For example,
"LD50 (mouse) = 250 mg/kg." The usual measure of toxicity is dose level expressed as
weight of chemical per unit body weight of the animal-usually milligrams of chemical
per kilogram of body weight (mg/kg). The LD50 describes the amount of chemical
ingested or absorbed by the skin in test animals that causes death in 50% of test animals
used during a toxicity test study. Another common term is LC50, which describes the
amount of chemical inhaled by test animals that causes death in 50% of test animals used
during a toxicity test study. The LD50 and LC50 values are then used to infer what dose
is required to show a toxic effect on humans.
As a general rule of thumb, the lower the LD50 or LC50 number, the more toxic the
chemical. Note there are other factors (concentration of the chemical, frequency of
exposure, etc.) that contribute to the toxicity of a chemical, including other hazards the
chemical may possess.
Health hazard information may also distinguish the effects of acute and chronic exposure.
Acute toxicity is generally thought of as a single, short-term exposure where effects
appear immediately and the effects are often reversible. Chronic toxicity is generally
thought of as frequent exposures where effects may be delayed (even for years), and the
effects are generally irreversible. Chronic toxicity can also result in acute exposures,
with long term chronic effects.
SECTION VI - REACTIVITY DATA
Stability Unstable Conditions to avoid
Stable
Incompatibility (Materials to Avoid)
Hazardous Decomposition Products
Hazardous Polymerization
May Occur Will Not Occur
Conditions to Avoid
This section gives information on the reactivity of the chemical – with other chemicals,
air, or water which is important when responding to a spill or fire. Chemical substances
may be not only hazardous by themselves, but may also be hazardous when they
decompose (break down into other substances) or when they react with other chemicals.
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