SCIENCE / MEDICINE : Fluoridated Water and Rats

A small number of rats drinking fluoridated water developed both cancer of the mouth and bone irregularities unrelated to cancer, the National Toxicology Program announced last week. The findings, part of a federal study, came in addition to a report that some of the rats given fluoridated water had developed malignant bone tumors.

As with the bone tumors, however, the numbers of affected test animals were small and the results have not yet been interpreted by outside scientific experts. The rodents were given water with varying levels of fluoride many times higher than what most humans consume.

Five rats of both sexes consuming various doses of fluoride in water developed malignant tumors on the inside of their mouths, out of a total of 360 rats exposed to fluoride. Four of the cancer cases occurred in rats on the highest doses of fluoride. The finding was clouded, however, by the fact that one rat in a “control” group of 160 animals--which had no fluoride in its water--also developed cancer of the mouth.