Physiology biomarker approach

Chapter 5 describes a variety of approaches for interpreting biomonitoring results, ranging from direct application of biomarker-response relationships found in epidemiologic studies to physiologically based phar-mokinetic (PBPK) modeling based on animal data. Although Chapter 5 provides several chemical examples of the approaches described, the additional case studies discussed in this appendix are useful to illustrate the data needs and limitations. 

Another approach to evaluating exposure uses chemical, biochemical, or physiological evidence (e.g., biomarkers) of a previous exposure. This approach has been used primarily for assessing chemical exposures and is particularly useful when a residue or biomarker is diagnostic of exposure to a particular chemical. These types of measurements are most useful for exposure characterization when they can be quantitatively linked to the amount of stressor originally contacted by the organism. Pharmacokinetic models are sometimes used to provide this linkage. 

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