Fluoride in groundwater in Nigeria: Origin and human health impact

Abstract: Until recently, the mottling and staining of teeth (dental caries) was believed to be an identity of certain ethnic groups or communities in Nigeria. Those born and reared locally within such communities had mottling teeth and fluoride as the causal factor was not known then. It was sooner discovered that dental caries extended beyond tribal or communal barriers. Even foreigners that came from far away Asia presented this disease condition. Records have shown that elsewhere in the world where dental caries was endemic, fluoridization of public water supplies was done and that reduced the prevalence of dental carries greatly. Dental caries is endemic and epidemic spread over a large range of superficial area mainly the north eastern half of Nigeria both in the crystalline basement and sedimentary areas. The few data available on fluoride in drinking water clearly establishes the relationship between dental caries and environmental fluoride in drinking water. With the failure of the water supply systems in most parts of Nigeria to meet the demand of the increasing human population, about 90 % of people use groundwater (well and borehole) for drinking and other domestic purposes. Studies have shown that, fluoride values (0.2 – 8 mg/l) above the 1.5 mg/l WHO admissible value have been recorded in the groundwater from the crystalline Basement rocks (consisting of granites, gneisses, and migmatites). In the sedimentary terrain especially that of the Benue Trough, fluoride value