Arsenic (As) is a widely occurring environmental contaminant. To assess human exposures to As, public health officials and researchers often conduct biomonitoring. Samples of urine, hair, nails, or blood are collected from potentially exposed people and are analyzed for As compounds and their metabolites. When analyzing for As exposure, it is useful to distinguish between As species, since they differ in their origin and toxicity. Urine is the most frequently used biological medium for biomonitoring. Measuring the urinary concentration of As is useful in assessing recent exposure to As, and high-quality reference ranges are available for urinary As concentrations in the U.S. population. Biomonitoring for As in hair and nails has been used in many studies and is particularly useful in evaluating chronic exposures to As. Interpreting the health implications of As concentrations in biological samples is limited by the small number of studies that provide information on the correlation and dose-response relationship between biomonitoring test results and adverse health effects. This study discusses the advantages and limitations of biomonitoring for As in biological samples and provides illustrative case studies.

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Biomonitoring is a valuable tool for assessing human exposures to chemical contaminants in the environment. Biomonitoring tests can be divided into biomarkers of exposure, effect, and susceptibility. In studies of community exposure to an environmental contaminant, biomarkers of exposure are most often used. The ideal biomarker should be sensitive, specific, biologically relevant, practical, inexpensive, and available. Seldom does a biomarker meet all of these criteria--most biomarkers represent a compromise of these criteria. In designing a community exposure study, consideration should also be given to the selection of the test population, the practicality of collecting biological samples, temporal or seasonal variations in exposure, the availability of background comparison ranges, and interpretation of the test results. Biomonitoring tests provide unequivocal evidence of exposure, but they do not typically identify the source of exposure. Furthermore, rarely do the test results predict a health outcome. For many chemicals, testing must be conducted soon after exposure has occurred. In spite of these limitations, the use of biomonitoring is finding wider application in many scientific disciplines. Recent advances in analytical techniques are expanding the utility of biomarker testing in public health investigations.

Blood serum concentrations of polychlorinated biphenyls (PCBs) were measured in members of a residential community who lived near a chemical plant that formerly manufactured PCBs. Elevated blood serum PCB concentrations were detected in some of the older adults who were long-term residents of the community. Congener-specific analyses indicated that PCB congeners 153, 138/158, 180, 118, and 187 contributed 60-67% of the total PCBs detected in blood from adults and children. Blood PCB concentrations correlated strongly with age and length of residency in the neighborhood. However, blood PCB concentrations did not correlate with PCB concentrations in soil or house dust samples from the homes. Past exposures to PCBs may be a significant contributor to the elevated PCB concentrations detected in some adult members of the community.