EPA-Expo-Box (A Toolbox for Exposure Assessors)
When a contaminant is taken into the body by ingestion, the amount that gets into the body in a biologically available form is called the dose. There are a few different ways to measure dose (U.S. EPA, 1992):
- Potential dose is the amount of contaminant ingested (i.e., amount that gets in the mouth), not all of which is actually absorbed.
- Applied dose is the amount of contaminant at the absorption barrier (e.g., gastrointestinal [GI] tract) that can be absorbed by the body. The applied dose might be smaller than the potential dose if the contaminant is only partially bioavailable.
- Internal dose is the amount of contaminant that gets past the exchange boundary (GI tract) and into the blood, or the amount of the contaminant that can interact with organs and tissues to cause biological effects.
- Biologically effective dose is the amount of contaminant that interacts with the internal target tissue or organ.
The following general equation may be used to estimate the average daily dose (ADD) from intake of food, water, soil, dust, or other non-dietary exposure from hand- or object-to-mouth contact.
Average Daily Dose = Concentration x Intake Rate / Body Weight
Algorithms for specific ingestion pathways are provided in the Calculations tab of this module.