ROLE OF BIOMARKERS OF EXPOSURE IN THE ASSESSMENT OF HEALTH RISKS

Biomarkers of exposure can be used as part of an exposure assessment t o assess potential health risks when exposure measurements and health effects occur during the same period of time. Exposure assessment is t he determination of the concentration of a chemical in an environmenta l medium coupled with the presence of the human in that environment. A biomarker of exposure gives an assessment of absorbed dose in the wor ker. A biomarker of effect, often referred to as a biomarker, is used in the assessment of health risk. A biomarker of effect gives an asses sment of the effect of a chemical on a physiological process and is an indicator of a possible adverse health effect. For example, biomarker s of exposure give an assessment of a worker's current exposure to sol vents and some metals. Biomarkers of exposure for chronic health effec ts with long latent periods, such as carcinogens, are more problematic al. These exposure indicators, however, can be used to help reconstruc t past exposures. Selected biomarkers of exposure can also be predicto rs of adverse health effects. Examples include the use of 2,5-hexanedi one and 2-ethoxyacetic acid in urine as indicators of exposure to n-he xane and 2-ethoxyethanol, respectively. These two urinary metabolites are 'active' metabolites responsible for observed neurotoxic and repro ductive effects. Biomarkers of exposure are particularly useful for th e objective assessment of current systemic exposure to chemicals that are readily absorbed through the skin. Exposure assessments, including the use of biomarkers of exposure, are necessary to postulate a cause of observed adverse health effects seen in epidemiological investigat ions and to determine the bioavailability of the chemicals present in the workplace.