The Knox report: a review of the epidemiological evidence on fluoridation
of water and cancer (1985)
An expert Working Party convened by the UK Department of Health and Social Security and led by Professor George Knox reported in 1985 on its evaluation of analyses of cancer data available at that time .
Members of the Working Party included some of the country’s leading cancer epidemiology experts from the Institute of Cancer Research, supported by colleagues from the Medical Research Council, the University of Birmingham Cancer Epidemiology Research Unit and the Water Research Centre. They reviewed around 110 published papers and commissioned re-analyses of some of the most important data and results.
Naturally occurring and added fluoride are not linked to cancer, and fluoridation of drinking water is safe
In their report, Professor Knox and his team concluded: “We have found nothing in any of the major classes of epidemiological evidence which could lead us to conclude that either fluoride occurring naturally in water, or fluoride added to water supplies, is capable of inducing cancer, or of increasing the mortality from cancer.
“This statement applies both to cancer as a whole and to cancer at a large number of specific sites. In this we concur with the great majority of scientific investigators and commentators in this field. The only contrary conclusions are in our view attributable to errors in data, errors in analytical technique, and errors in scientific logic.
“The evidence permits us to comment positively on the safety of fluoridated water in this respect. The absence of demonstrable effects on cancer rates in the face of long-term exposures to naturally elevated levels of fluoride in water; the absence of any demonstrable effect on cancer rates following the artificial fluoridation of water supplies; the large human populations observed; the consistency of the findings from many different sources of data in many different countries; lead us to conclude that in this respect the fluoridation of drinking water is safe.”
They added: “The routine monitoring of public health has been an important feature of many fluoridation programmes, and has contributed to the confidence with which we can assert the safety of fluoridation with respect to cancer. We recommend that such monitoring should continue.”
1. Knox G: Fluoridation of water and cancer: a review of the epidemiological evidence. HMSO. (1985)
NO EVIDENCE LINKING FLUORIDATION TO CANCER
“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.”
“Each of the epidemiological studies whose authors have concluded or implied that fluoridation causes cancer has been shown to be unsoundly based. “
REASSURANCE ON SAFETY
“Standardised cancer rates have tended to be lower in the fluoridated areas, and in areas with high natural levels of fluoride, than in the areas with little or no fluoride in the drinking water. Although this is certainly not evidence that fluoride actually protects from cancer, it adds to the confidence with which it is possible to assert the safety of fluoridation.”