Key Links for Risk Assessors
What is bioavailability?
Bioavailability is a measure of how much of a contaminant is absorbed when people are exposed to that contaminant through inhalation, skin contact or food intake.
What is relative bioavailability?
Relative bioavailability of a contaminant in soil is how much of a contaminant is absorbed from soil as compared to how much of that contaminant is absorbed from a reference exposure medium (e.g., food, water) that relates back to the toxicity value of the contaminant.
For the general public
Relative bioavailability is how much of a contaminant is absorbed from soil as compared to how much of that contaminant is absorbed from food or water.
For site assessors
Specifically, oral relative bioavailability is the fraction of an ingested dose that crosses the lining of the intestines and becomes available for distribution to human tissues and organs relative to an experimentally reported absorption value. As defined above, relative bioavailability and oral absorption fraction are equivalent terms.
EPA is providing information to allow site assessors to use bioavailability data to make more informed cleanup decisions.This definition does not consider the case of metals that may act directly upon the lining of the intestines (e.g., irritants and corrosives).
Other resources (including non-EPA Web sites) are provided on the Related Links Page