Silicosis Prevalence and Associated Occupational Risk Factors Among Cassiterite (Tin Ore) Miners in Eastern Rwanda: A Cross-Sectional Analysis of Mining Practice and Risk in an Active and Retired Mining Cohort

Abstract

Abstract Background Silicosis is one of the most common forms of pneumoconiosis worldwide. In Rwanda - there is paucity of data on the silicosis burden and occupational risk among underground miners. Methods We conducted a cross-sectional study among all miners from 8 cassiterite (tin ore) mining sites in Kayonza district, Eastern Rwanda. Questionnaire data and chest radiography were collected at Rwinkwavu District Hospital. Two radiologists reviewed all the chest radiography using ILO criteria, with a third radiologist reviewing films with ILO rating discrepancies and serving as an arbiter. Logistic regression was performed to investigate risk factors associated with radiographic silicosis. Findings In total, 1,021 mine workers were included in the primary outcome (risk) analysis. The median age was 32 years (IQR 26-40), and 948 participants (93%) were male. Of all participants, 94 (9%) were diagnosed with silicosis. Increased odds of silicosis were associated with working in a blasting station (aOR 3·30; 95% CI 1·68-6·45), excavation station (aOR 2·77; 95% CI 1·09-7·04), drilling station (aOR 2·51; 95% CI 1· 34-4· 70), exposure to tobacco (aOR 1·92; 95% CI 1· 14-3· 24), and increased time of working in mining (aOR 1·05; 95% CI 1·01-1·09). Interpretation Almost 1 in 10 Cassiterite miners in an occupational cohort of active and retired miners in the Eastern Province of Rwanda were found to have Silicosis. Tobacco use, certain mining tasks and duration of mining employment were significantly associated with increased risk of having a silicosis diagnosis. Our results indicate that screening and preliminary occupational risk analysis in a rural mining cohort is technically feasible. Funding All funding was provided by internal grants through the Non-Communicable Diseases program through Partners in Health/Inshuti Mu Buzima Research In Context What is Already Known on this Topic Silicosis is recognized as a “Disease of Concern” for Low- and Middle-Income countries (LMICs) and is resurgent in parts of the United States and Australia. While the pathophysiology and preventative interventions necessary to address the development of silicosis, Little is known about the risk of mining related lung disease in Eastern Africa and no studies have been done in cassiterite miners in areas under conflict minerals regulation in our review of the literature. What this Study Adds The objectives of this study were threefold. First, to determine the radiographic prevalence of silicosis in a mining cohort in Eastern Rwanda. Second, to identify risk factors associated with the development of silicosis present in cassiterite mining in semi-formal mines. Third, to develop a methodology for identifying and tracking mining-related disease in a rural community reliant on the mining economy. How this study might affect research, practice or policy Our paper, in combination with available evidence, supports that silicosis continues to be a significant cause of morbidity and mortality in underground mining populations. It elucidates mechanisms within mining practice in Eastern Africa likely contributing to a high rate of advanced and accelerated silicosis in a region typically difficult to access for clinical surveillance programs. It also adds evidence of occupational risk associated with a pervasive and common mineral, cassiterite. Finally, it calls into question epidemiologic data on the true rates of silicosis in mining communities in Eastern Africa.