RISK ASSESSMENT OF OXIDANT GASES AND PARTICULATE AIR-POLLUTANTS - UNCERTAINTIES AND RESEARCH NEEDS

The assessment of risks to human health associated with exposure to ox idant air pollutants has not received adequate attention despite the r ecognized public health threat posed by the ubiquitous presence of the se compounds in the environment. In this article, research needs and u ncertainties at each of the steps in the risk assessment oi oxidant ai r pollutants are identified: hazard identification, dose-response asse ssment, exposure assessment, and risk characterization. Many of these limitations and uncertainties arise at the interface between the labor atory and the regulatory arenas. Therefore, as a case study, relevant methodologic problems associated with the application of experimental findings to the risk assessment of respirable dusts are also discussed . These issues include the extrapolation of animal data to the human c ase and extrapolation from high-dose to environmentally relevant, low- level exposures.