Step 2. Characterizing the Limitations of Health Data

• Biologic and Biomonitoring Studies

One of the biggest limitations in conducting a health outcome data review is the difficulty in identifying "exposed" people. Simply living near a facility is a poor indicator of exposure. Individual biological measurements or individual environmental measurements are much better indicators of exposure than residence or employment near a site or facility or distance or duration of residence in the area.

In some cases, biomonitoring data might be available to specifically define or quantify exposures to site contaminants. However, in using biologic or biomonitoring data, it will be important to consider the following:

• biologic data, like environmental data, need to be collected by trained professionals and analyzed in a standard way
• detected levels might not be the result of site-related exposures (e.g., increased blood lead levels could be the result of lead paint exposures or traditional medicines)
• for chemicals with short biological half-lives, results will likely only represent recent exposures
• the correlation between detected levels and clinical effects might not be understood
• the people tested might not be representative of the exposed population (i.e., results from a small sample group may not reflect the range in exposures across the entire exposed population)

Although biomonitoring is the best indicator of exposure, because of such limitations it is seldom done

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