Development and use of asbestos risk estimates

Several groups of researchers, at the request of government agencies in various countries, have reviewed the literature on the health effects of asbestos exposure and derived quantitative estimates of the risks from such exposures. Because of differences in the area of responsibility of the different agencies, these estimates have inevitably been based on different assumptions concerning exposure (concentration, number of years of exposure, initial age, and number of hours per week). The lifetime cancer risk estimates derived in 6 reports are compared here, after adjustment to a common set of exposure assumptions appropriate for students attending schools containing asbestos products. Estimates are found to be reasonably similar, remaining differences being primarily due to differences in assumptions concerning parameter values of the models and the background risk of lung cancer. The various administrative processes used by the US agencies are also compared, and recommendations made for US government agencies involved in the derivation of risk estimates for exposures of general public concern.