Groundwater fluoride contamination, sources, hotspots, health hazards, and sustainable containment measures: A systematic review of the Ghanaian context

Groundwater quality is globally threatened by geogenic and human activities. These activities release high levels of potentially toxic elements, such as fluoride (F⁻), which pose significant threats to human health. This has become a global issue, especially in developing countries such as Ghana. Despite efforts to address this issue, knowledge gaps still need to be addressed to ensure safe and healthy drinking water for all Ghanaians. Moreover, Ghana has been reported to be a fluorosis-endemic country but the sources and exact hotspots of F⁻ enrichment in the aquifers on a countrywide scale are lacking in the available literature. Understanding the quality of water used for diverse purposes in Ghana is necessary to achieve the United Nations Sustainable Development Goals like good health and well-being (SDG 3) and clean water and sanitation (SDG 6), among others. Therefore, this study synthesized all previous studies on groundwater F⁻ contamination in Ghana, to identify the sources of F⁻ enrichment in groundwater, delineate the hotspots for fluorosis, assess the associated human health risks, identify the best sustainable defluoridation methods, and recommend policy intervention for high groundwater F⁻ threat to aquifers in Ghana. In the Ghanaian context, F⁻ contamination in groundwater is largely from geogenic sources like the weathering of fluoride-bearing rocks (granitoids and carbonate sedimentary lithologies) from the Birimian and Voltaian Supergroups and the dissolution of fluoride-rich minerals (fluorapatite, amphiboles, fluorite, biotite, and muscovite). Hotspots for high groundwater F⁻ in Ghana are mainly restricted to the Upper East Region (0.10–5.00 mg/L), North East Region (0.01–13.29 mg/L), Northern Region (0.1–11.6 mg/L), and the White Volta River Basin (0.04–3.79 mg/L). The mean and maximum values of F⁻ in these hotspots exceed the maximum permissible level (1.5 mg/L) set by the World Health Organization and Ghana Standards Authority. Most people in these areas suffer from dental fluorosis. Therefore, affordable and sustainable defluoridation technologies as well as community-based initiatives are recommended to deal with this menace.