Unsuitability of World Health Organisation guidelines for fluoride concentrations in drinking water in Senegal

A survey was done of the prevalence of dental fluorosis among children aged 7-16 years and the occurrence of skeletal fluorosis among adults aged 40-60 years living in regions in Senegal where fluoride concentrations in the drinking water ranged from less than 0.1 to 7.4 mg/l. In the area where the fluoride concentration in the drinking water was 1.1 mg/l milder forms of dental fluorosis were found, the prevalence being 68.5%. In areas where fluoride concentrations exceeded 4 mg/l the prevalence of dental fluorosis reached 100%. Kyphosis was very prevalent among a community whose drinking water contained 7.4 mg/l fluoride. Radiographs of the vertebral column, hand, and wrist of 3 adults with kyphosis confirmed the diagnosis of skeletal fluorosis. High sweat loss and a high intake of water because of the hot weather may account for the finding. The present World Health Organisation guideline for the upper limit of fluoride concentration in drinking water may be unsuitable for countries with a hot, dry climate.