Crystalline Silica Dust and Lung Cancer: A Systematic Review and Meta-Analysis Protocol

Abstract

Background: Crystalline silica dust is prevalent in mining, construction, and manufacturing. Prolonged exposure is linked to silicosis, COPD, and lung cancer; the International Agency for Research on Cancer classifies crystalline silica as a Group 1 human carcinogen. Yet epidemiological findings vary by region, design, and exposure level. A rigorous synthesis is needed to clarify lung cancer risk.

Objective: To conduct a systematic review and meta-analysis quantifying the association between occupational crystalline silica exposure and lung cancer incidence, and to examine heterogeneity by study characteristics, geographic region, and exposure assessment methods.

Methods: Following PRISMA, we will search PubMed, Scopus, Web of Science, Embase, and Cochrane Library without date limits. Eligible designs include cohort, case-control, and cross-sectional studies reporting quantitative associations between crystalline silica exposure and lung cancer. Two reviewers will independently screen, extract data, and resolve discrepancies by consensus. Study quality and risk of bias will be appraised using Joanna Briggs Institute tools. Random-effects models will generate pooled effect estimates. Between-study heterogeneity will be assessed using the I² statistic and Cochran’s Q. Prespecified subgroup and sensitivity analyses will evaluate sources of variation, including exposure metrics, industry, sex, smoking adjustment, and confounding by co-exposures. Small-study effects and publication bias will be examined via funnel plots, Egger’s regression, Begg’s test, and Galbraith plots, with trim-and-fill applied where appropriate. Findings will be reported witforest plots, descriptive tables, and narrative synthesis when pooling is infeasible.

Discussion: This review will consolidate the best available evidence on silica-related lung cancer risk, contextualized by mechanistic insights (e.g., inflammation, genotoxicity) and international regulatory standards. Anticipated limitations include exposure misclassification, residual confounding (notably smoking), and variability in study design and adjustment strategies. By providing robust pooled estimates and transparent exploration of heterogeneity, this work aims to inform occupational health policy, risk assessment, and targeted prevention strategies across diverse workplaces.