AbstractMany laboratory and other studies have shown that fluorides can cause genetic damage and cancer in plants and animals and their cells; this literature is reviewed. Studies on human populations have been undertaken in at least eight countries: this literature is also reviewed.Most studies on humans have compared cancer rates in fluoridated and non-fluoridated cities, and have concluded that fluoridation is safe. The authors point to serious weaknesses in these studies — poor control groups, too few people, too short a period being analysed, etc.The main conclusion is that fluoridation of drinking water is associated with increased cancer mortality rates.The policy implication is clear: stop water fluoridation.