Overview of Exposure Assessment Techniques

P-130 Abstract: Exposure assessment is an integral part of epidemiologic studies and the risk assessment process. Unfortunately, exposure can be poorly defined in these studies resulting in biased results. Biomonitoring, measuring a chemical, its metabolites or reaction products in biological media, is one of the most important exposure assessment techniques. However, biomonitoring techniques differ in their degree of sensitivity and selectivity and may be difficult to implement given the life stage during which the exposure is to be assessed. We have developed highly sensitive and selective methods for biomonitoring using state-of-the-art technologies. But with each method, advantages and limitations exist. Sometimes the biomarker measured is difficult to interpret because of coexposures to similar compounds. Some biomarkers are difficult to measure because of their stability or low concentrations. Further, some biomarkers are subject to contamination issues because of their ubiquitous presence in our environment. Biomonitoring measurements are further complicated in large-scale studies requiring multiple chemical measurements from a limited amount of sample. In addition, monitoring exposure during critical life stages such as the fetal and early childhood period can be difficult. We will present the advantages and limitations of biomonitoring as an exposure assessment method for many applications including epidemiologic studies, trend evaluations, and risk assessment. We will further present innovative strategies to evaluate exposures during critical life stages by maximizing the use of alternative matrices or using surrogates of exposure.