Vol.:(0123456789) 1 3 Environ Monit Assess (2021) 193:746 https://doi.org/10.1007/s10661-021-09466-4 Quality and human health risk assessment of uranium and other heavy metals in drinking water from Kwale County, Kenya Pamella Kageliza Kilavi · M. I. Kaniu · J. P. Patel · I. T. Usman  Received: 9 April 2021 / Accepted: 13 September 2021 © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2021 levels in drinking water. The concentration levels of Ni, Cu, As, and U in all samples from both study areas were within the recommended values in drinking water. Therefore, the quality of water from both study areas was unsuitable for human consumption due to Cd and Cr contamination. The non-carcinogenic risk assessment also showed that the hazard indices (HI) evaluated for both children and adults at the study areas were higher than unity. In addition, the esti- mated carcinogenic risks of both population groups were more than the recommended value of 10 –4 . This study shows that the residents near Mrima Hill and the Kwale heavy minerals sand deposit remain suscepti- ble to carcinogenic and non-carcinogenic health risks emanating from exposure to these heavy metals in drinking water. Keywords Heavy metals · Drinking water · Risk assessment · Deterministic · Monte Carlo simulation Introduction Drinking water sourced from either ground or sur- face naturally contain heavy metals such as chro- mium (Cr), nickel (Ni), copper (Cu), arsenic (As), cadmium (Cd), and uranium (U). The concentrations of these metals depend on geogenic and anthropo- genic activities. For instance, the high concentration of U detected in water samples from private wells in Greenville County was due to the interaction of Abstract Heavy metal contamination in drinking water is a global health concern. Anthropogenic and geogenic activities exacerbate the concentrations of these metals in surface and groundwater. In this study, we sampled drinking water sourced from surface and groundwater resources at the environs of Mrima Hill and the Kwale heavy minerals sand deposit, Kwale County, Kenya. The concentrations of Cr, Ni, Cu, As, Cd, Pb, and U were measured using the inductively coupled plasma mass spectrometer. The water quality indices were evaluated using the weighted arithme- tic index method, while the human health risks due to exposure to these heavy metals through the inges- tion pathway were assessed using deterministic and probabilistic techniques. The concentrations of Cr and Cd in samples from both study areas exceeded the national and international maximum contaminant Supplementary information The online version contains supplementary material available at https://doi. org/10.1007/s10661-021-09466-4. P. K. Kilavi  School of Physics, University of the Witwatersrand, Private Bag 3 – 2050, Johannesburg, South Africa P. K. Kilavi · M. I. Kaniu · J. P. Patel  Department of Physics, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya I. T. Usman (*)  School of Physics, University of the Witwatersrand, Private Bag X3, WITS 2050, Johannesburg, South Africa e-mail: iyabo.usman@wits.ac.za