Human health risks of metals contamination in Shallow Wells around waste dumpsites in Abeokuta Metropolis, Southwestern, Nigeria

Metals contamination in shallow wells through solid waste leaching is a serious environmental problem with potential contribution to the global cancer cases. This paper evaluated the health risks of metals in shallow wells around dumpsites in Abeokuta Metropolis, Nigeria. Five dumpsites were purposively selected to sample twenty-five shallow wells. In-situ and laboratory analysis for pH and Electrical conductivity, copper, lead, Cadmium, Iron, and Chromium were conducted following the APHA standard procedure. Carcinogenic and non-carcinogenic risks for oral and dermal routes were evaluated for adult male and female, children, and infant. Findings show that all wells are highly acidic (pH = 4.08–5.24), with Fe and Cd concentration above the established limits. Wells around Obada, Obantoko, and Saje dumpsites have high EC (upto 1200µS/cm), Cu, and Pb concentration above the permissible limits. Non-carcinogenic risks for oral ingestion were significant (HI > 1) for all age groups, and the significance level across dumping area increases in the order: Saje > Obantoko > Obada > Idi-aba > Lafenwa. All wells assessed in Saje and Obantoko recorded significant HI of dermal exposure for children and infants. Cancer risks were significant (CR > 1.0E-04) for all age groups, and metal contributions followed: Cd > Cr > Pb. Overall trend of significant risks for non-carcinogenic and carcinogenic via oral and dermal routes are in the order: infant > children > adult female > adult male. This show that groundwater users within the studied areas may experience diverse illnesses or cancer in their lifetime, particularly children and infant.