Health Risk Assessment of Heavy Metal Contamination in Natron (Kanwa) Consumed in Selected Local Government Areas, Northwestern Kebbi State, Nigeria

ABSTRACT: The widespread consumption of Natron (“Kanwa”) in Northern Nigeria necessitates evaluation of its safety, particularly regarding heavy metal contamination. This study assessed the concentrations of selected heavy metals and associated health risks in Natron consumed across selected Local Government Areas (LGAs) in Northwestern Kebbi State, Nigeria. Three commonly consumed Natron varieties (Balma, Kanwa Jarinrai, and Kanwa Tuwo) were collected from Bunza, Birnin Kebbi, Kalgo, and Jega LGAs and analyzed for cadmium (Cd), lead (Pb), nickel (Ni), chromium (Cr), and manganese (Mn). Health risk assessment was performed using Daily Intake of Metals (DIM) and Health Risk Index (HRI) for adults and children. Results revealed detectable concentrations of all investigated metals, with marked spatial variations across locations. Cadmium DIM values ranged from 0.0041–0.0134 mg/person/day, lead from 0.006–0.020 mg/person/day, chromium from 0.009–0.027 mg/person/day, and manganese from 0.013–0.054 mg/person/day. Higher DIM values were generally observed in Birnin Kebbi and Bunza compared to Kalgo and Jega. HRI analysis showed significant health concerns, as cadmium and chromium exceeded the safety threshold (HRI > 1) in all samples, with maximum values of 13.37 and 9.07, respectively. Lead also presented elevated HRI values of up to 5.82, indicating potential non-carcinogenic risks. Conversely, nickel and manganese recorded HRI values below 1, suggesting minimal immediate risk. These findings indicate that regular Natron consumption may pose serious long-term health risks, emphasizing the need for routine monitoring, public awareness, and regulatory control of heavy metal contamination in food additives. Keywords: Heavy Metals, Toxicity, Environmental Exposure, Risk Assessment, Food Contamination