1993; 26(2):79-82.


John R Lee MD
Sebastopol CA, USA

Guest Editorial

The NTP (National Toxicology Program) fluoride/cancer study of rats and mice (1) found a statistically significant dose-related increase of osteosarcoma incidence in male rats and, in addition, found fluoride correlations with thyroid follicular cell adenomas, oral and nasal squamous dysplasia, a rare type of liver cancer (hepatocholangiocarcinoma), and, as might have been expected, extensive osteosclerosis. Following this, the Public Health Service, under Dr Hoover et al, reviewed the limited SEER epidemiological data which also showed a significant association of water fluoridation with osteosarcoma incidence among males under 20 years of age (2). However, the meaning of this association was questioned by the PHS because of the apparent absence of a linear trend of a putative association over time of which water supplies were fluoridated. Despite this question, it is clear from the data that osteosarcoma in young men had increased over time and that this increase was greater in fluoridated areas. Also, a New York State study, excluding New York City, attempted to analyze its hospital and population data in regard to bone cancer incidence since the 1950s (3). However, due to a change in diagnostic classification from body site (ie., simply, "bone cancer") to cell type (osteochondroma, Ewing's sarcoma, and osteosarcoma) in the Mid-1970s, the true change in incidence of osteosarcoma cannot be calculated. Despite the fact that osteosarcoma is rare (2.9 cases per million people on average annually in New Jersey), it is the most common primary malignant tumor of bone and is one of the principal cancers of childhood. Dr Cohn therefore thought it appropriate to survey its incidence in New Jersey relative to water fluoridation (4).

In his executive summary, Dr Cohn reports his findings of a strong statistical association between water fluoridation and osteosarcoma in young men but points out that the total number of cases is small and that he obtained no data concerning individual residence history, average water ingestion, use of dental fluoride supplements, exposure to other carcinogens, or family cancer history. For these reasons Dr Cohn advises that the results be interpreted cautiously. However, health decisions most often must be made on data which, from the viewpoint of pure science, are in one way or another incomplete. This is inherent in the practice of medicine.

Tables of the study results are reproduced on the following pages.

It should be noted that twelve cases of osteosarcoma were diagnosed among males under 20 in a three county area with the greatest prevalence of fluoridation. Of these, 2 were of age 0-9 and 10 were of age 10-19 years. The rate ratio of incidence in fluoridated vs non-fluoridated municipalities in the three county area was 5.1 (95% CI 2.7-9.0)*. Among 10-19 year old males in those three counties, the ratio rate was 6.9 (95% CI 3.3-13). No other age/sex groups exhibited significant association with fluoride. Thus it can be seen that, for these populations, the chance of osteosarcoma for males age 10-19 years was 6.9 times higher in the fluoridated municipalities.

As noted by Dr Cohn, the etiology of osteosarcoma has not been established. The fact that rapidly growing bone in adolescent males is most susceptible to the development of osteosarcoma suggests that fluoride, which is known to be toxic to bones and a potent enzyme inhibitor, may act as a cancer promoter during this narrow window of susceptibility. Given this, the available SEER epidemiologic data may be more significant than appreciated by the PHS which discounted the observed fluoride/osteosarcoma correlation on the basis of the absence of a linear trend of association with duration of time the water supplies were fluoridated. However, if fluoride acts as a cancer promoter, rather than an initiator, the duration/latency assumption is not warranted.

In the context of the strong correlation of fluoride to osteosarcoma in male rats in the NTP study and the strong epiderniologic evidence of osteosarcoma incidence increase in young males in the US, especially in fluoridated communities, this report from New Jersey adds considerable weight to the probability that fluoride does indeed increase the risk of osteosarcoma among males.

Furthermore, fluoridation/caries studies of the past two decades (5-7), including the latest National Institute of Dental Research study (7), indicate that caries reduction in U.S. schoolchildren is not significantly correlated with fluoridation status. Therefore, given that osteosarcoma is potentially fatal and caries is not, and that other documented studies show fluoride-related increases in hip fractures, dental fluorosis, and other health damaging effects, it would be wise to cease all artificial fluoridation. Anyone who chooses to give their children additional fluoride in spite of all these risks would still be free to do so. I can think of no other agent with this degree of risk which is mandated by the PHS to be added to our food or water. The decision to use the agent should be left to the individual and his/her health advisor.


1. Maurer JY, Cheng MC, Boysen BG, Anderson RL. Two-year carcinogenicity study of sodium fluoride in rats. Journal, National Cancer Institute 82 111811261990.
2. Hoover RN, Devesa S, Cantor K, Fraurneni JF Jr. Time trends for bone and joint cancers and osteosarcomas in the Surveillance, Epidemiology and End Results (SEER) Program, National Cancer Institute. In: Review of Fluoride: Benefits and Risks, Report of the Ad Hoc Committee on Fluoride of the Committee to Coordinate Environmental Health and Related Programs. US Public Health Service, 1991 pp F 1 -177.
3. Mahoney MC, Nasca PC, Burnett WS, Mehus JM. Bone cancer incidence rates in New York State: Time trends and fluoridated drinking water. American Journal of Public Health 81475479 1990.
4. Cohn PD. A brief report on the association of drinking water fluoridation and the incidence of osteosarcoma among young males. New Jersey Department of Health, Trenton NJ November 8 1992.
5. Hildebolt CF, Elvin-Lewis H, Molnar S et al. Caries prevalences among geochemical regions of Missouri. American Journal of Physical Anthropology 78 79-92 1989.
6. Yiamouyiannis J A. Water fluoridation and tooth decay results from the 1986- 1987 national survey of US schoolchildren. Fluoride 23 55-67 1990
7. Brunelle JA, Carlos JP. Recent trends in dental caries in US children and the effect of water fluoridation. Journal of Dental research 69 (Special Issue) 7237281990.

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