Background To investigate exposure-response relationships for silica, silicosis, and lung cancer. Methods Quantitative review of the literature identified in a computerized literature search. Results The risk of silicosis (ILO category 1/1 or more) following a lifetime of exposure at the current OSHA standard of 0.1 mg/m3 is likely to be at least 5-10% and lung cancer risk is likely to be increased by 30% or more. The exposure-response relation for silicosis is nonlinear and reduction of dust exposures would have a greater than linear benefit in terms of risk reduction. Available data suggests that 30 years exposure at 0.1 mg/m3 might lead to a lifetime silicosis risk of about 25%, whereas reduction of the exposure to 0.05 mg/m3 might reduce the risk to under 5%. Conclusions The lifetime risk of silicosis and lung cancer at an exposure level of 0.1 mg/m3 is high. Lowering exposures to the NIOSH recommended limit if 0.05 mg/m3 may have substantial benefit.

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