Exposure of children to heavy metals from artisanal gold mining in Nigeria: evidences from bio-monitoring of hairs and nails

Abstract

In recent times, there had been reported cases of Pb poisoning in Anka gold mining area, Northwest Nigeria. Therefore, this study was carried out to determine the extent of bioaccumulation of heavy metals in the hairs and nails of children in the area. Forty samples (twenty nails and twenty hairs) samples were collected from ten boys and ten girls of ages 5–9 residing in the area. To ascertain the sources of heavy metals in children, 15 soils samples, 15 groundwater samples, 5 samples of mine tailings, and 5 plants samples were collected. Hair and nails of the subjects were collected using internationally acceptable techniques. All samples were kept in uncontaminated ziplock bags prior to laboratory preparation and analysis. The samples were cleaned using nonionic detergent (triton X-100) and deionized water. The hairs and nails were digested with 10 mL of 6:1 mixture of nitric acid and perchloric acid. The soils, mine tailings, and plants were air-dried at room temperature, sieved, and chemically digested using the aqua regia method. The concentrations of metals in all the samples were determined using high-performance liquid chromatography–inductively coupled plasma–mass spectrometry. Statistical analysis was employed to unravel potential sources of metals in the media. Results showed that heavy metals in children of the area are above results from similar studies and pathological ranges for heavy metals in hairs and nails. Also, heavy metals in environmental media are above the recommended standards. Multivariate analysis showed that the metals are mainly from mining and other anthropogenic sources. Results of correlation between heavy metals in hairs and nails with those in geological samples revealed that heavy metal that bioaccumulates in the children of this area are mostly from contaminated environmental media. It is recommended that complete remediation and effective health education be carried out in the area.