Using human hair and nails as biomarkers to assess exposure of potentially harmful elements to populations living near mine waste dumps

Abstract

Potentially harmful elements (PHEs) manganese (Mn), cobalt (Co), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) were measured in human hair/nails, staple crops and drinking water to ascertain the level of exposure to dust transference via wind and rain erosion for members of the Mugala community living near a mine waste dump in the Zambian Copperbelt. The mean PHE concentrations of hair in decreasing order were Zn (137 ± 21 mg/kg), Cu (38 ± 7 mg/kg), Mn (16 ± 2 mg/kg), Pb (4.3 ± 1.9 mg/kg), Ni (1.3 ± 0.2 mg/kg) and Cr (1.2 ± 0.2 mg/kg), Co (0.9 ± 0.2 mg/kg) and Cd (0.30 ± 0.02 mg/kg). Whilst for toenails the decreasing order of mean concentrations was Zn (172 ± 27 mg/kg), Cu (30 ± 5 mg/kg), Mn (12 ± 2 mg/kg), Pb (4.8 ± 0.5 mg/kg), Ni (1.7 ± 0.14 mg/kg) and Co (1.0 ± 0.02 mg/kg), Cr (0.6 ± 0.1 mg/kg) and Cd (0.1 ± 0.002 mg/kg). The concentration of these potentially harmful elements (PHEs) varied greatly among different age groups. The results showed that Mn, Co, Pb, Cd and Zn were above the interval values (Biolab in Nutritional and environmental medicine, Hair Mineral Analysis, London, 2012) at 0.2–2.0 mg/kg for Mn, 0.01–0.20 mg/kg for Co, < 2.00 mg/kg for Pb, < 0.10 mg/kg for Cd and 0.2–2.00 mg/kg for Zn, whilst Ni, Cu and Cr concentrations were within the normal range concentrations of < 1.40 mg/kg, 10–100 mg/kg and 0.1–1.5 mg/kg, respectively. Dietary intake of PHEs was assessed from the ingestion of vegetables grown in Mugala village, with estimated PHE intakes expressed on a daily basis calculated for Mn (255), Pb (48), Ni (149) and Cd (33) µg/kg bw/day. For these metals, DI via vegetables was above the proposed limits of the provisional tolerable daily intakes (PTDIs) (WHO in Evaluation of certain food additive and contaminants, Seventy-third report of the Joint FAO/WHO Expert Committee on Food Additives, 2011) for Mn at 70 µg/kg bw/day, Pb at 3 µg/kg bw/day, Ni and Cd 5 µg/kg bw/day and 1 µg/kg bw/day, respectively. The rest of the PHEs listed were within the PTDIs limits. Therefore, Mugala inhabitants are at imminent health risk due to lead, nickel and cadmium ingestion of vegetables and drinking water at this location.