Silica exposure and disease in semi‐precious stone craftsmen, Minas Gerais, Brazil

Abstract

Brazil is an exporter of precious stones and craftsmen often work in poor conditions. We assessed silica-related diseases among crystal craftsmen and the complexity of its control. Case-series including 118 subjects evaluated from 2006 to 2015, based on medical interviews, chest X-rays, spirometry, and respirable silica samples. Median age and length of exposure were 32 and 13 years, respectively. Silicosis, with 1/0 as a threshold, was diagnosed radiologically in 57 individuals (48.3%). Respirable silica concentrations were 0.9-29.3 times greater than the Brazilian occupational exposure limit. A Receiver Operating Characteristic (ROC) curve with the same diagnosis threshold showed best discrimination at a cut point of 12.5 years of exposure, corresponding to 4.85 mg-y/m3 of cumulative silica exposure. There was a significant decline in FEV1 across radiological and cumulative silica exposure categories. Eleven individuals (9.3%) had mycobacterial diseases at baseline or follow-up. Crystal craftsmen continue to suffer from silicosis, lung function impairment, comorbidity, and death due to silicosis. To date collective protection in some work sheds has not diminished silica levels. Long-term follow-up is needed to evaluate further improvements in preventive measures. Am. J. Ind. Med. 60:239-247, 2017. © 2017 Wiley Periodicals, Inc.