Assessment of quality and health risk of peri-urban groundwater supply from selected areas of Abeokuta, Ogun State, Southwestern Nigeria.

Groundwater is an important source of drinking water. However, pollution of groundwater resource could initiate serious health damage to the consumers. The present study aimed at assessing the quality and health risk of groundwater samples collected from the peri-urban areas of Abeokuta. Twelve (12) fresh ditch cuttings from wells sites and forty (40) well water samples were collected between August and September, 2018. Samples were analysed for important physical and chemical parameters using the standard procedure. Groundwater data were subjected to statistical manipulation of descriptive and inferential statistics. The health risk assessment was conducted for non-carcinogenic effect {hazard quotient (HQ), hazard index (HI)} and cancer risk (CR). Results showed the pH of groundwater ranged from 7.65 to 8.48. The electrical conductivity varied from 266.5 to 461.5 µS/cm, while the total dissolved solids ranged from 90.0 to 348.2 mg/L. The concentrations of Pb (1.58-14.5 µg/L), Mn (11.10-836 µg/L), Al (64-2000 µg/L) and Fe (30-5070 µg/L) in groundwater were higher than the permissible limits of the World Health Organization in drinking water. The levels of metals/metalloids in the well cuttings were: Pb (8.9-27.6 µg/kg), As (0.8-8.6 µg/kg), Cr (14.0-98.0 µg/kg) and Mn (138.0-1080 µg/kg). The HQs of Cr (infants and children) and Ba (infants, children and adults) were greater than 1.0 indicating adverse health effects. The CRs of Cr, Co and Ni in water consumed by infants, children and adults were greater than the acceptable limit of 1.0 × 10 suggesting possible development of cancer. The health risk data of metals in groundwater indicated deleterious health effects on consumers.