ABSTRACT
Two components of risk assessment are hazard identification and exposure assessment. The total exposure assessment methodology, or The Total Exposure Assessment Methodology study, and the National Ambient Volatile Organic Compounds data base provide some information on indoor and ambient air concentrations for many organic compounds. This chapter presents two studies of air contaminant exposure in a school and in apartments to demonstrate that there may be significant temporal variation in exposure. It shows the variation in methylene chloride concentrations in ambient air, in the school crawl space, and in the school rooms. Characterizing human health risks from chemical exposure requires consideration of both exposure and toxicity data. Exposure assessments have improved. As the exposure data improve, additional methods of combining the exposure and toxicologic data, e.g., pharmacokinetic modeling, will have to be developed to estimate the effects of highly variable exposure data.
