Purpose: In Democratic Republic of the Congo (DRC), informal coltan mining has been expanding amidst increased insecurity due to armed conflicts. We investigated the impact of occupational dust-exposure on the respiratory health of Congolese coltan miners.
Methods: In total, 441 Congolese workers participated in this study, including 199 informal coltan miners and 242 office workers (controls). Information on respiratory complaints was collected using two standardized questionnaires. Physical examination (vital signs, auscultation) and lung function test (Peak Flow meter) were performed. In addition, workplace airborne PM2.5 and volatile organic compounds (VOC) concentrations were measured.
Results: Higher airborne PM2.5 (range 180-210 µg/m3) and VOC (range 1.4-2.3 µg/m3) levels were detected at coltan mining work stations as compared with control sites (19-44 and 0.5-0.8 µg/m3, respectively). All respiratory complaints and disorders were more prevalent in informal coltan miners than in controls. Additionally, a markedly lower mean PEFR was observed in coltan miners than in controls (347.93 ± 6.88 vs. 493.23 ± 67.38 L/min, respectively). Moreover, positive associations between informal coltan mining and almost all respiratory complaints were observed, except wheezing at effort and night cough. On the other hand, an inverse association was observed between lung function (PEFR) and PM2.5 exposure, between PEFR and VOC exposure, and also between PEFR and current smoking.
Conclusions: This study showed high prevalence of respiratory complaints in Congolese informal coltan miners, suggesting the necessity to implement efficient occupational safety measures and regulate this informal mining business.
Keywords: Dust exposure; Informal coltan mining; Lung function; Respiratory health.