Step
2.2 Comparing Exposure Doses to Health Guidelines (Observed Effect Levels)
Introduction
Once the site-specific exposure doses have been estimated, they are compared
to human health guidelines, such as ATSDR's minimal risk levels (MRLs).
If the estimated dose for a chemical is at or above the health guideline,
then the exposure will be further evaluated.
The health assessor must keep in mind what health guidelines are and
what they are not.
Health guidelines are doses
at which harmful health effects are not expected. They are based on toxicologic
and epidemiologic studies, and they are conservative estimates with built-in
safety and uncertainty factors.
Health guidelines are not
used to predict adverse health effects. They are based on site-specific
data. Health guidelines are not clean-up levels.
Environmental guidelines versus health guidelines
An environmental guideline is a level (concentration) of a chemical in air,
soil, or water that is considered safe for human contact. A health guideline
is the dose (amount) of the chemical entering the human body that is not
expected to cause harm.
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