Fluoridation of Water and Cancer: A Review of the Epidemiological Evidence

PREFACE There is ample evidence, from many places and over many years, that fluoridation of the public water supply leads to a substantial reduction in dental caries, with all that means in prevention of suffering, inconvenience and unnecessary cost. It can be shown that the beneficial effect of fluoride is significant, whatever other measures are taken in relation to sound nutrition and preventive dental practice. There are several other ways in which fluoride can be used in the prevention of dental caries but each of the alternatives has substantial disadvantages compared with the fluoridation of water. The justification for such a measure as the addition of fluoride to the water supplies of entire communities must rely on strong scientific evidence pointing not only to its effectiveness but to its safety, even though the recommended level in the public water supply is similar to that yielded by many natural sources. From the first, therefore, the safety of the fluoridation of water to the optimum concentration (1 milligram per litre) has been a paramount consideration, and fluoridation programmes were both preceded and accompanied by investigations ofthe health of populations exposed to fluoride in water. Allegations that fluoridation causes cancer have naturally given rise to great public concern. The present Report of the Working Party on the Fluoridation ofWater and Cancer* draws together the many relevant epidemiological studies, including several analyses commissioned by the Working Party itself. The Report concludes that there is nothing in this extensive range of studies, covering altogether very large populations, to suggest that fluoride or fluoridation "is capable of inducing cancer or of increasing the mortality from cancer''. Indeed the Report goes further and states that in view of the very large human populations which have been observed it can be concluded that "in this respect the fluoridation of drinking water is safe". The opposite opinion is still voiced in some quarters but the Report demonstrates that elementary misinterpretations of the facts are responsible for that conclusion. The epidemiological studies reviewed by the Working Party provide the most direct evidence for the examination of the hypothesis that fluoridation causes cancer in man. Indeed, largely because of the extensive human data available on fluoride exposure, there has been relatively little work done on the effects of fluoride on cancer in animals. A more extensive body of research has been carried out using short-term animal tests, and tests with tissue …