Biomonitoring of metal in children living in a mine tailings zone in Southern Mexico: A pilot study

Accumulation of metals in soil represents a health risk for individuals living near mining areas, especially for children who have a higher susceptibility to metal related diseases. The Taxco mining district in Southern Mexico was one of the largest Mexican metal producers of silver and gold, among other metals. The aim of this pilot study was to evaluate metal exposure on children aged 6–11 years living in and around the Taxco mine tailings zone. Lead in blood (PbB) was measured by graphite furnace atomic absorption spectrophotometry (AAS). Urine arsenic (AsU) was measured by hydride generation AAS, urinary Hg (HgU) by flow injection cold vapor atomic absorption, and urinary concentration of other metals such as chromium (Cr), nickel (Ni), cadmium (Cd), barium (Ba), cobalt (Co), copper (Cu), zinc (Zn), manganese (Mn), molybdenum (Mo), strontium (Sr), and iron (Fe) were determined by inductively coupled plasma optical emission spectrometry. Fifty samples were analyzed for PbB, AsU, and HgU, and 35 samples for the other metals. The mean concentration ± SD for each metal was: PbB, 9.4 ± 3.3 μg/dL; NiU, 75.4 ± 30.7 μg/L; BaU, 18.4 ± 4.1 μg/L; MnU, 5.2 ± 0.7 μg/L; CuU, 29.6 ± 6.8 μg/L; AsU, 16.5 ± 8.3 μg/L; HgU, 0.7 ± 0.86 μg/L; CdU, 4.7 ± 2.7 μg/L; CrU, 15.1 ± 4.45 μg/L; CoU, 18.3 ± 9.7 μg/L; SrU, 49.2 ± 30.7 μg/L; ZnU, 628.4 ± 438.9 μg/L; FeU, 30.5 ± 17.7 μg/L; and MoU, 52.1 ± 29.3 μg/L. Results of this exploratory study show that children residing in the mining area of Taxco were environmentally exposed to several metals and a high percentage of these children had levels of Ni, Ba, Mn, Cr, Co, Cd, As, Hg, and Pb above reference values. Thus, further studies are needed to assess the effects of simultaneous exposure to toxic metals in children residing in mining areas.