Evidence for silica's neoplastic risk among workers and derivation of cancer risk assessment.

Although there has been debate in the medical community about silica's carcinogenicity since the 1930s, only in the past decade have there emerged scientific data supporting a causal association between industrial silica exposure and lung cancer. This paper examines the evidence for the association, with a particular focus on those studies appropriate for cancer risk assessment. The cancer risk extrapolations from epidemiology studies suggest that the levels of risks are approximately two factors less than that derived from animal studies. Additional research is needed to provide a stronger basis for the extrapolations so that policy makers can have more confidence in their estimates.