IMPROVING EXPOSURE ASSESSMENT BY MONITORING HUMAN TISSUES FOR TOXIC-CHEMICALS

Typically, the availability of appropriate data to estimate human expo sures to toxic chemicals is scarce. Consequently exposure assessments are often based on indirect surrogates of exposure, such as a combinat ion of questionnaire data on time-activities and concentrations of tox ic chemicals measured in environmental media (e.g., air, water, food, soil, dust). Recent advances, however, make it technically feasible an d relatively affordable to measure low levels of multiple toxic chemic als in accessible human tissues (e.g., blood, urine). The increasing a vailability of biological markers far exposure, along with improvement s in pharmacokinetic understanding, present new opportunities to estim ate exposure from human tissue measurements and from knowledge of inta ke and uptake parameters. Biological monitoring provides exposure info rmation that is usually complementary to the type of exposure informat ion obtained from environmental monitoring. Biological and environment al monitoring can be used separately or together in order to meet desi red objectives. We present here a discussion of the value of biologica l monitoring far improving exposure assessment. We emphasize the role of biological monitoring in identifying high-priority exposures, evalu ating the effectiveness of intervention and prevention efforts, identi fying at-risk subpopulations, recognizing time trends in population ex posures, establishing reference ranges of tissue concentrations, and p roviding integrated dose measurements.