Abstract
Mercury is a toxic metal and is used in small scale gold mining. In Portovelo, Ecuador, mercury has been an environmental and health problem for decades. The target of this study was to assess the mercury concentration in the urine of miners from Portovelo/Zaruma to establish a prevalence of high values. Eight hundred and sixty-five (865) urine samples were collected and analysed for their mercury content, using cold vapor atom absorption spectroscopy. The prevalence of high mercury values (>25 μg/L) was estimated. Forty-four (44) miners with mercury levels >15 μg/L filled in a questionnaire for characteristics and possible confounders, and were examined for intoxication symptoms to establish the ten points medical score sum. The median urine value was 1.8 μg/L; 78.3% of miners were below 7 μg/L and were not at risk of an intoxication, whereas 5.9% of miners exceeded the limit of 25 μg/L and were probable to experience intoxication symptoms. The medical score sum had a range of 2 to 8 points with a median of 6. The low prevalence of high mercury concentrations shows that the politics and techniques to eliminate the use of mercury are being successfully implemented. Further studies are needed to identify factors enabling this process.
Highlights
All around the world, gold is one of the most precious and most wanted metals, there is a high economic interest in producing it
Testing results revealed that 78.3% (n = 677) of the miner population was below the Human Biomonitoring (HBM)-I threshold (7 μg/L) and not at risk of an intoxication
In another study, where 200 Ecuadorian gold miners of coastal areas were examined, Harari et al found that about 5.1% had urine values above 35 μg/L, whereas we found that only 3.4% of the miners exceeded that value [28]
Summary
Gold is one of the most precious and most wanted metals, there is a high economic interest in producing it. Most of the production is done mechanically and on an industrial scale, there is a significant portion that is carried out by manual labour. About 15% of gold (~400 tons) is mined manually by 10 to 15 million miners in 70 countries who work in artisanal and small scale gold mining (ASGM), including about 3 million women and children [1]. In ASGM, mercury is commonly used to extract the gold from the ore [3,4]. Once the ore is obtained from underground or open pit deposits, it needs to be crushed and ground into a fine powder. This is done mechanically by using constructed ball mills.
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