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Workers in artisanal gold mines at increased risk for TB

Individuals working in artisanal small-scale gold mines in Tanzania were exposed to airborne crystalline silica levels that were 337 times greater than the recommended limit set by U.S. safety standards, according to study results.

“Silica dust hazards are being ignored while thousands of miners die each year due to silicosis and the alarmingly high rates of tuberculosis in these mining communities,” Perry Gottesfeld, MPH, executive director of Occupational Knowledge International in San Francisco, said in a press release. “A recent global treaty has emphasized reducing mercury exposures among these gold miners, while silica dust hazards are overlooked although they are likely to cause much more death and disease.”

TB rates among miners in Sub-Saharan Africa are fivefold to sixfold greater than that of the general population, Gottesfeld and colleagues wrote in the Journal of Occupational and Environmental Hygiene.

The investigators collected air samples from an artisanal small-scale gold mine (ASGM) in Tanzania in July 2014 to measure the amount of respirable crystalline silica exposures among workers. Air monitoring occurred during drilling, hammering, loading, crushing and miscellaneous processing operations in five villages.

Workers also clipped battery-operated pumps to their clothing to collect personal samples for 85 minutes to 7 hours of exposure.

Results indicated 97% of the 32 air samples collected exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit. The mean concentration of respirable crystalline silica during above-ground operations was 0.19 mg/m³, four times the safe level recognized by NIOSH. Sample results in below-ground drilling were 16.85 mg/m³, or 337 times more than the NIOSH standard.

Gottesfeld said while the study was limited to one location, the results are far-reaching.

“While we did the study in Tanzania, the risk for TB and silicosis is similar in artisanal mining around the world.” Gottesfeld said. “Many times more people work in artisanal mining than in formal sector mines.” – by Ryan McDonald

Disclosure: The researchers report no relevant financial disclosures