Global Prevalence of Silicosis and Associated Risk Factors: A Systematic Review and Evidence Synthesis

Abstract

Context: Silicosis is a preventable occupational lung disease caused by the inhalation of crystalline silica dust. Despite existing control regulations, it remains a major public health concern worldwide. This systematic review aimed to estimate the global prevalence of silicosis, identify key risk factors, and compare epidemiological patterns across geographical regions. Evidence Acquisition: PubMed, Scopus, Web of Science, and Magiran were systematically searched. Studies published between 1988 and 2024 were included in the final analysis. The analysis comprised two phases: a proportional meta-analysis of 24 studies to estimate the pooled prevalence of silicosis and a vote-counting synthesis of all 32 studies to identify significant risk factors. The pooled prevalence was estimated using a random-effects meta-analysis of single proportions to account for heterogeneity. Factors significantly associated with silicosis were classified into three categories: workplace conditions; social, economic, and demographic status; and health status. Factors associated with silicosis prevalence were identified using vote counting, which tallied the frequency and direction of associations reported for each factor across studies to determine those supported by significant evidence. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Results: In total, 32 studies from 25 countries, including more than 140,000 workers, were reviewed. Of these, 24 were included in the random-effects meta-analysis, and the remaining 8 provided qualitative data on risk factors. The weighted global average prevalence of silicosis was 22% (95% confidence interval [CI]: 19% to 25%), with considerable heterogeneity (I2 = 99.57%, Cochran's Q = 5301.05, df = 23, P < 0.001). The highest prevalence was observed among workers in Asia. The main risk factors included longer exposure duration, older age, smoking, and employment in high-risk occupations. Conclusions: Silicosis remains a common occupational disease and requires stronger preventive interventions and regular screening of at-risk workers. Prolonged exposure, older age, smoking, and unsafe working conditions were the most consistent risk factors. These findings support urgent policy interventions, including mandatory annual chest radiographic screening for workers with ≥ 5 years of silica exposure; a regulatory ban on dry cutting and grinding of engineered stone; enforcement of local exhaust ventilation and wet methods; and targeted health education and the provision of personal protective equipment for small-scale and artisanal mining sectors in low- and middle-income countries.