Elevated blood mercury and neuro-otological observations in children of the ecuadorian gold mines

The prevalence of mercury (Hg) intoxication was investigated in 114 Andean Saraguro and non-Saraguro (Mestizo) children living in remote gold-mining settlements in Nambija and Portovelo, Ecuador. Venous blood samples showed a mean total blood mercury (B-Hg) level of 18.2 μg/L (SD 15.5; range 2-89.) for 77 Saraguro and non-Saraguro children in the Nambija settlement, which was significantly higher than that of children in the Portovelo and reference groups. Comparison of groups showed mean B-Hg levels of 26.4 μg/L (range 4-89 μg/L) for 32 indigenous/Saraguro children; 12.3 μg/L (range 2-33 μg/L) for 45 non-Saraguro children; 4.9 μg/L (range 1-10 μg/L) for 37 children in Portovelo; and 2.4 μg/L (range 1-6 μg/L) for a reference group of 15 children. Fisher's post hoc analysis revealed significant differences among groups, except between the Portovelo and the reference groups. Neuro-otological symptoms and abnormalities were observed in Saraguro, non-Saraguro, and Portovelo children. Samples of soil collected at sites near the local school were found to contain Hg levels ranging from 0.1 to 38 ppm, cadmium (Cd) levels from 0.07 to 0.82 ppm and arsenic (As) levels from <1 to 3.9 ppm. In conclusion, the children of Nambija, particularly the Saraguro "Amer-Indians," exhibited elevated B-Hg levels from exposure to Hg used in the gold-mining process, and are at risk for neurological impairment. The children of Portovelo who reported neuro-otological symptoms but had low B-Hg levels (<10 μg/L) may be affected by exposure to sodium cyanide, which is used extensively in the local gold-mining operations.