Honorable Patrick Johnston
Senate Appropriations Committee
5066 Capitol Building
Dear Mr. Johnston and Committee Members:
I have learned that the credibility of a scientific paper that I co-authored (1) has been attacked during recent hearings on fluoridating the water supplies in California. I refer specifically to the statement by Assemblymember Speier on June 21, 1995: "For example, a study mentioned by opponents in the committee analysis refers to a 1992 JAMA study which observed three communities in Utah and concluded that fluoride caused an increase in hip fractures. But if you read the study in its entirety, the authors freely admit to looking at no other risk factors and, in fact relied solely on hospital discharge data."
Ms. Speier's statement that we examined no other risk factors is in error. We adjusted for differences in age between the fluoridated community and the two control communities, age being the strongest risk factor for hip fracture. We also chose the control communities to have similar proportions of members of the Church of Jesus Christ of Latter-day Saints (Mormons) as the fluoridated community to adjust for potential differences in cigarette and alcohol use, two other risk factors. The statement that we relied solely on hospital discharge data is not correct. We used hospital discharge data to identify patients with hip fractures, but combined this data with data on the exposure to fluoride, age smoking and alcohol usage in all three communities. Our study was prompted by increased risk of hip fractures observed in patients treated for osteoporosis with higher doses (as a prescribed medication) of fluoride. There was a biological mechanism whereby fluoride increased the brittleness of bone, and this was manifested by an increased incidence of hip fractures. We wondered if the same effect might be seen at fluoride levels introduced into public water supplies to protect against dental caries. That we found an association was a surprise to all of us. This association has been replicated by a group in France in a much larger population. (2) This raises the question of an unintended side effect of fluoridating public water supplies. Our group still stands by its conclusion, and suggests that a large study needs to be done to better address this issue.
Joseph L. Lyon, M.D., M.P.H.
1. Danielson C, Lyon JL, Egger ME, Goodenough J, Hip Fractures and Fluoridation in Utah's Elderly Population, Journal of the American Medical Association 1992; 268:746-748.
2. Jacqmin-Gedde H, Commangos O, Oartiques JF, Fluorine Concentration in Drinking Water in the Elderly, Journal of the American Medical Association 1995; 273:775-776.