Health risk assessment of heavy metals in drinking water leaching through improperly managed dumpsite waste in Kurata, Ijoko, Sango area of Ogun State, Nigeria

Groundwater contamination by leachate from dumpsites is a major health issue of public concern in developing nations of the world. The present study assessed the health risk of the scavengers and residents exposed to different heavy metals (HMs) in drinking water contaminated through leaching from improperly managed dumpsite waste in Kurata, Ijoko, Sango area of Ogun State, Nigeria. The data of groundwater parameters and biological (nails and urine) samples of scavengers and the residents around the dumpsite were evaluated for descriptive and inferential statistics. The HMs observed in samples varied significantly (p < 0.05) across the sampling sites. However, 74 and 63% of the nail samples had Pb and Co levels below the detection limit (BDL) of the analytical instrument, respectively, The HM concentrations (mg/L) in groundwater followed the decreasing order of Fe (16.66 ± 13.98) > Zn (2.46 ± 1.80) > Pb (0.55 ± 0.59) > Cu (0.03 ± 0.01) > Cd (0.01 ± 0.01). Positive correlations were observed for Cu and Pb, and Cu and Cd at p < 0.05 in groundwater. The distribution patterns of HMs followed the decreasing trends of Zn > Ni > Mn > Cu > Pb > Co for nails; and Ni > Zn > Mn > Co > Cr > Pb > Cd for urine. The hazard quotient values estimated for HMs (except Zn and Pb) in groundwater consumed by adults were greater than the permissible limit of 1.0, indicating adverse health effects. The cancer risk data for Cd and Pb were generally higher than the acceptable limit of 1.0 × 10⁻⁴; suggesting the possible development of cancer on exposure to groundwater through ingestion. The ∑CRs of HMs in groundwater samples were 114, 76, and 14 times higher than the acceptable limit of 1.0 × 10⁻⁴ for infants, children, and adults, respectively. Cd (94%) was the major contributor to the total cancer burden of HMs in the groundwater. The HMs were observed at higher concentrations in biological samples than in groundwater. This study, therefore, established the deleterious health effects of the dumpsite on the vicinity groundwater and the scavengers.