O3B.3 Estimating the impact of changes to occupational standards for silica exposure on lung cancer mortality

BackgroundRespiratory exposure to silica is associated with the risk of death due to malignant and non-malignant disease. 2.3 million U.S. workers are exposed to silica. Occupational exposure limits for silica are derived from a number of lines of evidence, including observational studies. Observational studies may be subject to healthy worker survivor bias, which could result in underestimates of silica’s impact on worker mortality and, in turn, bias risk estimates for occupational exposure limits.MethodsUsing data on 65 999 workers pooled across multiple industries, we estimate the impacts of several hypothetical occupational exposure limits on silica exposure on lung cancer and all-cause mortality. We use the parametric g-formula, which can account for healthy worker survivor bias.ResultsAssuming we could eliminate occupational exposure, we estimate that there would be 20.7 fewer deaths per 1000 workers in our pooled study by age 80 (95% confidence interval: 14.5, 26.8), including 3.91 fewer deaths due to lung cancer (95% CI: 1.53, 6.30). Less restrictive interventions demonstrated smaller, but still substantial risk reductions.ConclusionsOur results suggest that occupational exposure limits for silica can be further strengthened to reduce silica-associated mortality and illustrate how current risk analysis for occupational limits can be improved.