Silicosis and silica dust sampling in mineral mining across 30 countries: a systematic review and meta-analysis

Silicosis is an irreversible scarring lung disease caused by occupational respirable crystalline silica (RCS) dust exposure. Mineral (noncoal) miners who extract metal, nonmetal, stone, and sand/gravel commodities are at risk for silicosis, but disease prevalence and exposures in these heterogeneous mining sectors are poorly understood. We assessed the global burden of silicosis and existing RCS dust sampling practices in mineral mining. We conducted a systematic review of studies published through March 2025 from five online databases, without geographic/language restrictions (PROSPERO CRD420250524573). Studies of mineral miners that reported prevalence or incidence of silicosis on chest imaging were included. We performed meta-analyses using random-effects models for pooled prevalence and subgroup analyses based on commodity, Social-demographic Index (SDI), study period (pre/post-1970), and mine type (underground/surface). We also reviewed published reports on existing RCS sampling practices. The search yielded 2,408 potential articles. We included 85 studies (95 publications) for systematic review comprising 57 prevalence studies, six cumulative incidence studies, and 28 studies that reported on RCS sampling in mineral mines. The pooled prevalence of silicosis in 162,449 mineral miners from 26 countries was 17% (95% CI [13%, 22%]), based on low certainty due to high study heterogeneity (I2 = 99.6%). Silicosis prevalence was highest in stone (20%; n = 12 studies), nonmetal (20%; n = 6), and metal (18%; n = 36) miners, with lower prevalence in sand/gravel (3%; n = 2) and mixed commodity miners (6%; n = 3), though studies were few and differences non-significant (p = 0.27). Silicosis was significantly less prevalent in contemporary miners and countries with higher SDI, likely related to improved mining conditions and regulations. In 43,282 miners from four countries, the cumulative incidence of silicosis ranged from 2 to 26%. RCS sampling data from 11 countries included area and personal dust samples using different measurement devices and methodologies, performed under national mandates spanning the 1950s-1990s. Despite differences based on country SDI and mining era, silicosis prevalence among mineral miners worldwide is considerable. Country-specific variability in silica dust regulation and control likely contributes to prevalence, and future efforts should focus on linking exposure monitoring with policy and medical surveillance to reduce rates of this disabling but preventable disease.