Estimating the Impact of Changes to Occupational Standards for Silica Exposure on Lung Cancer Mortality

• Type of Material: Article
• Authors: Alexander P Keil, University of North Carolina; David B Richardson, University of North Carolina; Daniel Westreich, University of North Carolina; Nelson Steenland, Emory University
• Language: English
• Date: 2018-09-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.
• Final Published Version (URL): http://dx.doi.org/10.1097/EDE.0000000000000867
• Title of Journal or Parent Work: Epidemiology
• ISSN: 1044-3983
• Volume: 29
• Issue: 5
• Start Page: 658
• End Page: 665
• Grant/Funding Information: National Institutes of Environmental Health Sciences (DP2-HD-08-4070, T32 HD057833-07)
• Keywords: QUANTITATIVE RISK ASSESSMENT; Life Sciences & Biomedicine; lung cancer; RESPONSE ANALYSES; MARGINAL STRUCTURAL MODELS; HEART-DISEASE; WORKER SURVIVOR BIAS; causal inference; AFRICAN GOLD MINERS; CRYSTALLINE SILICA; DIATOMACEOUS-EARTH INDUSTRY; occupational limits; Public, Environmental & Occupational Health; Science & Technology; silica; PARAMETRIC-G-FORMULA; g-computation; CAUSAL INFERENCE
• Research Categories: Environmental Sciences; Health Sciences, Epidemiology

Abstract

BACKGROUND: Respiratory exposure to silica is associated with the risk of death owing to malignant and nonmalignant disease. 2.3 million US 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. METHODS: Using 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. RESULTS: Assuming we could eliminate occupational exposure, we estimate that there would be 20.7 fewer deaths per 1,000 workers in our pooled study by age 80 (95% confidence interval = 14.5, 26.8), including 3.91 fewer deaths owing to lung cancer (95% CI = 1.53, 6.30). Less restrictive interventions demonstrated smaller but still substantial risk reductions. CONCLUSIONS: Our 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.