Prevalence and determinants of evidence of silicosis and impaired lung function, among small scale tanzanite miners and the peri-mining community in northern Tanzania

Among mining communities in Tanzania, the limited data available suggests the prevalence of silicosis, obstructive lung diseases (OLD) and restrictive lung disease (RLD) to be around 1.6%, 1.9% and 8.8% respectively. Our study therefore aimed to determine the prevalence and factors associated with evidence of silicosis and ILF among tanzanite mining community in northern Tanzania. We conducted a cross-sectional study, involving 330 randomly selected miners and 330 conveniently selected non-mine workers from the peri-mining community (PMC) in Mererani mines, northern Tanzania. Evidence of silicosis was defined based on study participants’ history of exposure to mining dust and digital chest radiological findings with reference to the 2011 ILO classification of pneumoconiosis. Impaired lung function was determined by spirometry using American Thoracic Society (ATS)/European Respiratory Society (ERS) recommended system 3. Association between evidence of silicosis/impaired lung function and presumed risk factors were determined using binary logistic regression analyses. The study found that 99/330 (30.0%) of miners had evidence of silicosis, of whom 97.0% had accelerated silicosis. Among miners and community members, 75 (11.4%) had ILF, of whom 30 (4.5%) had COPD, 9 (1.4%) had asthma, 29 (4.4%) had restrictive lung disease and 7 (1.1%) had mixed pattern of both obstructive and restrictive lung disease. We found that having a daily income of more than USD 4.3 was associated with lower odds of silicosis (aOR 0.57, 95% CI 0.37-0.89, p<0.05) while ILF was associated with being a miner (aOR 2.06, CI=1.38-3.07, p<0.001). We found a concerningly high prevalence of evidence of silicosis despite short durations of exposure among small scale tanzanite miners. Immediate dust control measures including deployment of wet drilling, wearing of personal protective equipment (PPE) and regular monitoring of dust exposure need to be enforced by the OSHA (Tanzania).