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Step 2.1 Estimating Exposure Doses

Site-Specific Exposure Information

The types of information needed to estimate an exposure dose are referred to as exposure factors. That information is based on site-specific conditions.

To see an explanation of each type of information, click on the list entries that follow.

Exposure point level

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

Intake rate

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.

Exposure frequency

How often a person comes in contact with the chemical.

Exposure duration

How long people have been contacting the chemical.

Population characteristics

Demographic and social characteristics of people in the community.

From the following list, select three items that a health assessor can use to evaluate exposure. Then click on the View Correct Selections link to check your answers.

Community interviews

Historical maps of  the area

Observations made during the site

Contacts who are knowledgeable about the site

Voter registration records

View Correct Solutions

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

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

What information does an assessor use when estimating exposure doses?

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

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

The manual is available online at (Information about doses and health guidelines can be found in Appendix G.)

Where does a health assessor find information on exposure factors when site-specific information is not available?

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