Fluoride occurs naturally in soil, water, plants and animals in trace quantities. When fluoride is ingested, some is taken up by body tissues, with long-term deposition in teeth and bones. Following the demonstration of a significant reduction in dental caries in childhood within populations exposed to higher levels of fluoride in drinking water, between 1964 and 1975 several Local Authority water fluoridation schemes were introduced in England and Wales, whereby the fluoride content was artificially increased to a level of I ppm (I mg L-1). Although evidence continues to support the premise that fluoride in water helps protect children's teeth against caries, there are a number of potential adverse impacts, notably dental fluorosis (mottling of teeth). The situation is complicated by the fact that many individuals receive additional exposure to fluoride through the use of fluoride toothpaste, for example. Nonetheless, fluoridation of water continues to be generally regarded as a safe, simple and cost-effective public health measure to reach children most at risk and reduce the incidence of dental caries. Available evidence on risk of hip and other bone fractures suggests no effect of fluoride in water, although a small percentage change (in either direction) cannot be ruled out. There appears to be no link between water fluoridation and either cancer in general or any specific cancer type, but an updated analysis of UK data on fluoridation and cancer rates has nonetheless been recommended. Evidence for additional health outcomes suggested by some to be associated with fluoride ingestion, and on other concerns related to the chemicals that are added during the fluoridation process and indirect effects such as increased leaching of lead from pipes and aluminium from cooking utensils, is weak but the area deserves to be kept under review. (c) 2005 Elsevier B.V. All rights reserved.
