Inhaled Mercury Exposure From Artisanal Gold Mining and Processing — Nome, Alaska, 2012

BACKGROUND:  Mercury, a potent toxin that can cause brain and kidney damage, has long been used by miners to bind and thus extract gold. Consequently, gold unearthed in heavily mined areas is commonly amalgamated to mercury, which can be released through heating. In June 2012, we responded to concerns relayed by Alaska’s Department of Environmental Conservation that artisanal miners in Nome were potentially inhaling mercury vapor while heating gold.

METHODS:  Through press release, radio, and newspaper advertisements, we targeted persons exposed to gold mining or processing. We surveyed a convenience sample to assess risk factors. We analyzed urine to determine creatinine-normalized mercury levels, using a literature-derived reference (20 µg/g creatinine) to assess potential health risk.

RESULTS:  Of 40­–50 people approached, 18 participants completed surveys and submitted urine.  Seventeen (94%) were male; 14 (78%) were miners. No miner heated gold ≥15 minutes/week. Participants’ urine mercury levels ranged from 0.2 to 106.1 µg/g (median: 0.9 µg/g). Subject A, the only participant whose urine mercury concentration exceeded the health-risk level, was a processor who heated gold inside his home 2–3 hours/day. His two neighbors — nonminers concerned about frequent unpleasant fumes from subject A’s home — had the next highest levels (6.4 and 5.4 µg/g). Subject A denied symptoms, and his urine mercury level decreased to 50 µg/g after the summer gold-processing season ended. Safe practice recommendations were distributed to miners and posted throughout Nome.

CONCLUSIONS:  Subject A was exposed to potentially toxic mercury levels while heat-processing gold indoors. His neighbors were likely exposed through fumes released from his home. Artisanal miners and processors need education about safe purification practices to limit personal and community exposure.