Health risk assessment of heavy metals in soil samples from an abandoned industrial waste dumpsite in Ibadan, Nigeria.

Abstract

This study was carried out to determine the concentrations of heavy metals in the soil samples collected from an abandoned lead acid battery (LAB) industrial waste dumpsite in Ibadan, southwestern Nigeria. This was to assess the potential risks of the heavy metals on human due to exposure among local residents (children and adults) of the area. Forty (40) soil samples were collected over the entire dumpsite at 0-20 cm depth. The elemental concentrations of Pb, Cr, Cd, Zn, Cu, and Ni were measured using an atomic absorption spectrophotometer (AAS) technique. The contamination load was estimated by employing index of geoaccumulation (I) and potential human health risks due to multiple exposure pathways (inhalation, dermal absorption, and ingestion) were estimated using the risk-based equations and exposure parameters developed by the United States Environmental Protection Agency (USEPA). The average concentrations (± standard deviation) of Pb, Cr, Cu, Mn, Cd, Ni, and Zn were 3.79 ± 2.16, 8.36 ± 3.90, 7.77 ± 2.70, 7.75 ± 3.10, 4.31 ± 0.82, 3.09 ± 2.29, and 3.07 ± 1.74 μg/g, respectively. The mean values of I follow the order of Mn < Cr < Pb = Ni < Zn < Cu < Cd. The dermal contact with the heavy metals appeared to be the major route of exposure to children followed by inhalation and ingestion. Inhalation is the main route of exposure for the adults. The hazard quotients (HQ) of all the heavy metals are lower than 1, implying that the adverse health impact on the children and adult exposed to heavy metals from the dumpsite was relatively moderate. The hazard index (HI) values of Cd were 2.0 and 1.2 for exposed adults and children, respectively. The carcinogen risks for inhalation exposure ranged from 2.3 × 10 to 6.4 × 10, which falls within the acceptable limit of 10 to 10. There is concern over the potential health risk of the local residents, most especially the children living in the vicinity of the dumpsite due to the possibility of dispersal of heavy metals to the entire community, leading to long-life exposure and residents' detrimental health.