Heavy metal residues in hair sample of residents around metal recycling factories in Ikorodu, Lagos State, Nigeria

Abstract

There is increasing global concern over the public health impacts attributed to heavy metal exposure. The analysis of human hair has been valuable in screening for such exposures. This research was conducted to determine residues of Pb, Cd and As in hair samples of residents around scrap metal recycling factories in Odonguyan, Ikorodu, Lagos state. The study area was divided into three units P1, P2 and P3, each having an active recycling factory located ≤50 metres to a populated area. Control samples were collected from a remotely located area (approximately 2 km) from study area (P4). Samples were collected three times from 20 volunteers per location at 4 weeks interval. Volunteers were non-smoking adult males (18-35 years) with at least 7 years residency history in each sample area. Collected hair samples from each location were bulked, recut, thoroughly mixed and taken in 5 replicates for laboratory analysis. Sample preparation was conducted using standard procedures. Concentration of heavy metals in samples was determined using the Atomic Absorption Spectrophotometer (AAS; UNICAM 929 London). Data obtained were analysed using ANOVA. Mean separation was by LSD (p≤0.01). Results showed that mean concentrations of Pb, Cd and As were significantly higher (p≥0.01) in all exposed groups compared to the control group. Mean concentration (mg/kg) ranges were: 2.25 (P2) - 3.93 (P1) for Pb, 1.18x10^-2 (P2) -7.10x10^-2 (P1) for Cd and 6.00 x10^-4 (P1, P2,) - 7.40x10^-4 (P3) for As. Mean values (mg/kg) for control group were 0.49, 6.40x10^-3 and 2.00x10^-4 for Pb, Cd and As respectively. All parameters were lower than maximum permissible limits for England, Italy and Japan except for Pb whose mean values were higher than safe limits for Japan in all study locations except the control. Thus, residents in the study area are exposed to toxic heavy metals resulting from poorly regulated activities of recycling industries.

Keywords: Heavy metals, Hair samples, Metal recycling factory, Residential area