Step 2.1 Estimating Exposure Doses

The level of a chemical that is present at the point an individual comes in contact with it.

The amount of the chemical taken into a person's body during the time of contact with the chemical. Intake rates are calculated separately for each way that a chemical enters a person's body.

How often a person comes in contact with the chemical.

How long people have been contacting the chemical.

Demographic and social characteristics of people in the community.

Types of site-specific information that can be used for evaluating exposures are

Community interviews
Historical maps of the area
Observations made during the site
Contacts who are knowledgeable about the site
Voter registration records

A health assessor must use all information about a site and the characteristics of the population when estimating exposure doses. For example, a health assessor evaluating health conditions in a community near rivers where fish had been found to contain harmful levels of chemicals would estimate exposure doses for people in the community depending on the amount of fish in their diets.

ATSDR's Public Health Assessment Guidance Manual provides health assessors with guidelines for conducting public health assessment activities.

The manual is available online at http://www.atsdr.cdc.gov/HAC/PHAManual/. (Information about doses and health guidelines can be found in Appendix G.)

The U.S. Environmental Protection Agency's Exposure Factors Handbook

EPA's Exposure Factors Handbook summarizes the available statistical data on various types of information used in estimating human exposure doses. The exposure factors provided in the handbook should only be used if no site-specific information is available.

The Exposure Factors Handbook and updates to the handbook are available online at https://hero.epa.gov/hero/index.cfm/project/page/project_id/1854