title: Exposure and toxic effects of elemental mercury in gold-mining activities in Ecuador.
abstract: Traditional gold mining, using metallic mercury (Hg(0)) to form gold amalgam, followed by burning to remove the Hg(0), is widely used in South America, Africa and Asia. The gold is sold to merchants who burn it again to eliminate remaining Hg(0). In Ecuador, 200 gold miners, 37 gold merchants and 72 referents were studied. The median Hg concentrations in urine (U-Hg) were 3.3 (range 0.23-170), 37 (3.2-420), and 1.6 (0.2-13)μg/g creatinine, respectively, and in whole blood (B-Hg) were 5.2, 30, and 5.0 μg/L, respectively. Biomarker concentrations among merchants were statistically significantly higher than among miners and referents; also the miners differed from the referents. Burning of gold amalgam among miners was intermittent; U-Hg decreased in the burning-free period. In computerized neuromotor examinations, B-Hg and U-Hg concentrations were associated with increases in the centre frequency of the tremor, as well as in reaction time and postural stability.Retention of Hg (B-Hg), and the elimination rate (U-Hg) appears to be modified by polymorphism in a gene of an enzyme in the glutathione synthesis (GCLM), but there were no significant genetic modifications for the associations between exposure and neurotoxicity.Thus, the gold merchants have a much higher exposure and risk than the miners, in whom the exposure varies over time. The metabolism of Hg is modified by genetic traits. The present exposure to Hg had limited neurotoxic effects.
authors.affiliation: Corporación Para el Desarrollo de la Producción y el Medio Ambiente Laboral (Institute for the Development of Production and the Work Environment), P.O. Box 17-08-8386, Domingo de Brieva N38-107 y Villalengua, Urbanización Granda Centeno, Quito, Ecuador.
authors.forename: Raúl
authors.initials: R
authors.lastname: Harari
authors.forename: Florencia
authors.initials: F
authors.lastname: Harari
authors.forename: Lars
authors.initials: L
authors.lastname: Gerhardsson
authors.forename: Thomas
authors.initials: T
authors.lastname: Lundh
authors.forename: Staffan
authors.initials: S
authors.lastname: Skerfving
authors.forename: Ulf
authors.initials: U
authors.lastname: Strömberg
authors.forename: Karin
authors.initials: K
authors.lastname: Broberg
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D004484:Ecuador; D005721:Glutamate-Cysteine Ligase / Q000235:genetics; D006046:Gold; D006801:Humans; D008297:Male; D008628:Mercury / Q000633:toxicity* / Q000652:urine; D008906:Mining; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects; D014202:Tremor / Q000139:chemically induced
chemical_list: D015415:Biomarkers; D006046:Gold; C546365:GCLM protein, human; D005721:Glutamate-Cysteine Ligase; D008628:Mercury