Water quality fact sheet: Fluoride

Fluoride has been found to have a significant mitigating effect against dental caries and it is accepted that some fluoride presence in drinking water is beneficial. Optimal concentrations are around 1 mg/l. However, chronic ingestion of concentrations much greater than 1.5 mg/l (the WHO guideline value) is linked with development of dental fluorosis and, in extreme cases, skeletal fluorosis. High doses have also been linked to cancer. Health impacts from long-term use of fluoride-bearing water have been summarised (Dissanayake, 1991) as: <0.5 mg/l: dental caries 0.5-1.5 mg/l promotes dental health 1.5-4 mg/l dental fluorosis >4 mg/l dental, skeletal fluorosis >10 mg/l crippling fluorosis