Assessment of Radiological Indices and Heavy Metals in Well Water Around Lapite Dumpsite, Ibadan, Southwestern Nigeria

Municipal solid-waste dumpsites can generate leachate containing heavy metals and naturally occurring radionuclides, which may migrate into groundwater and pose potential health risks to communities relying on well water for domestic purposes. Lapite dumpsite, Ibadan, is surrounded by communities that depend substantially on well water, while limited information exists on the combined radiological and heavy-metal quality of the well water. This study therefore assessed the radiological indices and heavy-metal concentrations in well water around Lapite dumpsite, determined the activity concentrations of U-238, Th-232 and K-40, quantified Cd, Pb, Fe, Cu and Zn, and evaluated associated radiological, carcinogenic and non-carcinogenic health risks. Forty well-water samples were collected from selected locations around the dumpsite, including a control sample. Samples were filtered and analysed for radionuclides using a gamma-ray spectrometer coupled with NaI(Tl) detector, while heavy metals concentration were determined using atomic absorption spectrophotometry. Descriptive statistics, radiological indices, chronic daily intake, hazard quotient, hazard index, lifetime average daily dose and cancer risk were evaluated. K-40, U-238 and Th-232 recorded mean activities of 45.00 ± 17.47, 4.49 ± 2.20 and 2.28 ± 1.20 Bq/L, respectively. Mean AEDE and ELCR were 1.50 ± 0.59 mSv/y and 0.0053 ± 0.0020, respectively, AEDE indicating elevated radiological exposure while ELCR fall below ICRP nominal cancer risk coefficient of 5.5 × 10-2 Sv-1. The combined non-carcinogenic risk of the investigated heavy metals remained below unity.