Fluoride and nitrate in groundwater: health risks and monitoring in the Vea catchment, Ghana

Abstract The Vea catchment, especially in the Bongo area, is among the first areas in Ghana where high fluoride levels in groundwater were reported leading to extensive hydrochemistry studies within the catchment. Although high fluoride (F − ) levels in groundwater are known to be one of the causes of waterborne diseases and have been studied extensively across the globe, the health risk of the established high levels of F − in the catchment and its spatial distribution is still an enigma. For the above reasons, F − and NO 3 − health risks assessment and spatial characterization were conducted in this study using indexical proxies and ArcGIS. The multilinear regress modeling at ρ < 0.05, has Ca 2+ , TDS, HCO 3 − , and NO 3 − as the controllers of F − while that of NO 3 − are Ca 2+ and Mg 2+ . From the concentration levels classification of F − , 10% and 57.1% of the area are prone to dental caries and skeletal fluorosis, respectively, while 65.7% of the area is at F − risk from the fluoride risk index (FRI) classification. The hazard quotient (HQ) values > 1 for F − are 68.6% and 57.1%, while that for NO 3 − is 11.4% and 4.3% for children and adults, respectively. The Vea catchment has a very high hazard index (HI) value of 95.7% and 82.9% for children and adults in the area. The carcinogenic risk (CR) of NO 3 − in the area is 75.7% for children and 87.1% for adults. From the percentages of the HI values, there is a need for urgent action toward providing fluoride-free drinking water to the people within the catchment by targeting uncontaminated aquifers for safe groundwater supply within the catchment while ensuring continuous monitoring of current boreholes.