Fluoridation of Water and Cancer: A Review ofthe Epidemiological Evidence Report of the Working Party

“We conclude that there is no substantiated evidence from studies of human populations that fluoride or fluoridation causes cancer, or increases mortality from cancer, whether for cancer as a whole or for cancer at individual sites. The notion that fluoridation and cancer were associated seems to have arisen as a result ofthe fact that, amongst the major cities ofthe United States, fluoridation was introduced earliest in those which were relatively disadvantaged in social and economic terms (as can be seen by the effects of the corrections for such factors in the paper of Erickson, 1978), which already had relatively high standardised cancer rates (Oldham and Newell, 1977) and which, because the proportion of the elderly was increasing particularly fast, had crude rates which were increasing particularly fast. Each of the epidemiological studies whose authors have concluded or implied that fluoridation causes cancer has been shown to be unsoundly based. The conclusions of those studies arose from elementary errors, most importantly a failure to use standard and well tried approaches which would allow properly for these important demographic and socioeconomic differences between populations. In addition these authors employed many inappropriate unvalidated methods; many of the types of error which we have described in Chapter 1 played a part in the false conclusions reached by Yiamouyiannis, Burk, Brady, Schatz and Schatz, and Cecilioni. Each of these authors has failed to ask the fundamental question proposed by Bradford Hill (1977): ”Is there any other answer which is more likely than cause and effect?”. Their repeated analyses, principally ofjust two basic sets of data, but with a variety of method and argument, may have given the impression of a complex body of evidence; on examination, however, each strand ofthat evidence is unsound and the conclusions drawn from it by the authors can be unreservedly dismissed. It has been left to other authors’ studies ofcancer rates in the same populations, and often ofthe same data, to show that there is in fact no evidence of an adverse effect when well-established and sound methods of analysis are used.”

Fluoridation of Water and Cancer: A Review of the Epidemiological Evidence Report of the Working Party Chairman: Professor E G Knox
London Her Majesty’s Stationery Office

Read Full Study