Screening-level assessment of airborne carcinogen risks from uncontrolled waste sites

This report presents screening-level estimates of the general level of cancer risks arising from air emission from uncontrolled waste sites. Twenty-five National Priorities List sites were chosen randomly and airborne cancer risks estimated for each site in terms of risk to the maximally exposed individual (MEI risk), average individual risk (AEI risk), and population incidence. The estimates were developed using the EPA Human Exposure Model using assumptions on the rate and toxicity of site emissions. MEI risks ranged from 4 X 10(-9) to 1 X 10(-6) with an average of about 5 X 10(-7). AEI risks for individuals residing within four miles of the sites average about 10(-8), declining significantly for individuals residing at longer distances. Population incidence was low at all sites ranging from 2 X 10(-4) to 1 X 10(-2) cancer cases expected within 60 miles of the sites. Due to the uncertainties in this type of analysis and the underlying study assumptions, these results must be viewed with caution. Nonetheless, some preliminary conclusions can be drawn from the analysis, principally that airborne cancer risks from uncontrolled waste sites are likely to be small in most cases, with the greatest concern being maximally exposed individuals rather than the number of cancer cases expected in the exposed population.