Fluoride Action Network

Harvard/Bone Cancer Files

The documents that sparked national headlines and a year-long investigation into scientific misconduct by the Harvard dental professor who led NIH's ongoing study of fluoride and bone cancer. Plus, new documents obtained from under the Freedom of Information Act.

The Timeline

Douglass’ research on fluoride and osteosarcoma comprises two separate studies. The first study — a “retrospective study” — was initiated in 1992 and completed by 1995, while the second study — a “prospective study” — began soon thereafter. Douglass’ graduate student, Elise Bassin, conducted her analysis on Douglass’ first study. The following discussion focuses on Douglass’s retrospective study.


In 1992, Douglass submits a proposal to NIH to do a more comprehensive study of fluoride/osteosarcoma. In his proposal, Douglass expresses concern about the negative effects on fluoridation policy if fluoride is found to cause osteosarcoma. To quote:

“We will test the primary hypothesis that higher fluoride exposure is associated with the risk of osteosarcoma. An incorrect inference implicating systemic fluoride carcinogenicity and its removal from our water systems under the EPA Delaney clause would have significant oral health consequences for most Americans, particularly those who cannot afford to pay for increasingly expensive restorative dental care.”


 In a progress report to the NIH (obtained by FAN under the Freedom of Information Act), Douglass reports that some analyses of his retrospective dataset suggest an elevated risk of osteosarcoma from exposure to fluoridated water. To quote:

“The importance of the prospective study is further magnified if one considers point estimates of OR (Odds Ratio) using the assumption of 0 ppm fluoride in bottled water. All of those analyses have point estimates of the OR that are greater than one. However, all confidence intervals include one.”


In another document obtained by FAN under the Freedom of Information Act, Douglass expresses concern about the ramifications to water fluoridation if his team was to report that fluoridation is associated with an elevated, although not statistically significant, rate of bone cancer. To quote:

“Because of the importance of the question at hand, we think the policy implications of reporting that the relative risk maybe higher than 1.5 would have consequences for fluoridation health policies.”


Consistent with Douglass’s avowed hesitance to disrupt water fluoridation programs, he never publishes or discloses ANY of the analyses of the retrospective data (including his own and Bassin’s) that show an elevated rate of osteosarcoma from fluoride exposure. Indeed, in ALL four of Douglass’s public summaries of his retrospective dataset (in 19951998 & 2002), Douglass states that the retrospective data shows fluoridation has either no effect, or a slightly protective effect, on osteosarcoma rates.


Douglass acknowledges the importance of specifically investigating the relationship between fluoridation, osteosarcoma and growth spurts. According to a presentation before the American and European Musculoskeletal Tumor Society, Douglass notes:

“specific analysis of Fluoride ingestion during the childhood growth spurt periods will further test the consistency of reported findings.”

Douglass’s graduate student, Elise Bassin, is the one who conducts the age-specific analysis that Douglass references.


Bassin’s age-specific analysis finds a “remarkably robust” association between fluoridation and osteosarcoma in boys exposed to fluoridated water during their “mid-childhood growth spurt.” To quote:

“Among males, exposure to fluoride at or above the target level was associated with an increased risk of developing osteosarcoma. The association was most apparent between ages 5-10 with a peak at six to eight years of age.. [T]he results continue to demonstrate an effect after adjusting by zipcode, county population, ever use of bottled or well water, age, and any use of self-administered fluoride products. For males, the odds ratio for the high exposure group was 7.20 at 7 years of age with a 95 percent confidence interval of 1.73 to 30.01… All of our models are remarkably robust in showing this effect during the mid-childhood growth spurt, which, for boys, occurs at ages seven and eight years. For females, no clear association between fluoride in drinking water during growth and osteosarcoma is shown in this study… Our results are consistent with findings from the National Toxicology Program animal study which found ‘equivocal evidence’ for an association between fluoride and osteosarcoma for male, but not female, rats and from two ecological studies that found an association for males less than twenty years old.”

Douglass reviews and approves Bassin’s analysis, and the University awards her a PhD for her work.


One year after approving Bassin’s thesis, Douglass gives a presentation at a conference organized by the British Fluoridation Society and states that his retrospective study found a reduced risk of osteosarcoma among those living a greater percentage of their life in fluoridated areas. He makes no mention of Bassin’s findings.

January 2004:

In a submission to the National Research Council, Douglass again summarizes his retrospective study as showing no significant association between fluoridation and osteosarcoma. Although he cites Bassin’s study as one of two supporting references for this summary, Douglass makes no mention that Bassin found a strong age-specific relationship between fluoridation and osteosarcoma in boys.

March 2004:

In his Final Report to the NIH, Douglass again summarizes the results of the retrospective study as showing no significant association between fluoridation and osteosarcoma. Further, as with his report to the NRC, Douglass references Bassin’s thesis without mentioning the fact that her findings directly contradict his summary.


FAN researcher Michael Connett obtains a copy of Bassin’s PhD thesis (which, despite being finished in 2001, remains unpublished) as well as Douglass’s submission to NRC. Connett provides these documents to the Environmental Working Group (EWG), which sends a letter to get an explanation from Douglass about the apparent misrepresentation. After Douglass fails to respond, EWG files an ethic complaint with the NIH. In response to the complaint, the NIH asks Harvard to conduct an investigation.

march 2006:

A local tv station films Douglass carrying a draft copy of the Harvard investigation report, five months before the report is finished and released to the public. Douglass tells the journalist that the report would “speak directly to the issue of whether there’s any evidence of trying to cover something up.” EWG (the organization that filed the ethics complaint) was not provided similar treatment. Indeed, throughout the entire one-year investigation, Harvard did not contact EWG once.

April 2006:

Bassin’s study is published in the journal Cancer, Causes & Control. In the same issue that Bassin’s study is printed, Douglass publishes a letter stating that he has failed to corroborate Bassin’s findings. To support this, he states that he has been unable to find a relationship between osteosarcoma and bone fluoride content  in the prospective data set (Bassin’s analysis was based on the retrospective data set). A bone-fluoride analysis, however, cannot assess the age-specific risk of fluoride exposure (which is the risk that Bassin’s study identified). Douglass’s claim, therefore, that Bassin’s findings have not been corroborated is, at best, an overstatement.

Summer 2006:

In March, the National Research Council reports that Douglass’s study “is expected to be reported in the summer of 2006.” (NRC 2006, p. 280). The NRC bases this on a personal communication it received from Douglass on January 3, 2006. Douglass’s study, however, is not published. In September, Harvard’s Dean for Faculty and Research Integrity, states that Harvard expects the study to be published “in early 2007.”

August 2006:

The Harvard press office announces the conclusion of its investigation. The announcement, which is four paragraphs long and very short on detail, states the university’s position that Douglass did not “intentionally omit, misrepresent, or suppress” Bassin’s findings. Following the announcement, several Harvard alumni — including Robert Weissman (current President of Public Citizen) and Dr. Albert Burgstahler — write letters to Harvard’s President asking him to release the full report of the investigation. Harvard denies the request.

According to Dr. David Egilman, an alumnus of the Harvard School of Public Health, “While I was disturbed to read the well-documented ethics charges against Douglass, I was even more disturbed to read Harvard’s very brief, and completely inadequate, response on August 15, 2006.”

September 2006:

The Fluoride Action Network receives a tip that Chester Douglass had donated over one million dollars to Harvard University during the course of his tenure at the school. Harvard denies this had any bearing on the integrity of its investigation.


After Douglass failed to publish his study in the summer of 2006 (as he told the NRC he would), he claimed that he would be publishing the study “in early 2007.” However, at no point in 2007 is Douglass’s study published. Indeed, for some reason that has yet to be explained, the study is not published until 2011. (In a surprise to some, the study is not published in a cancer or epidemiology journal, but a dental journal — the Journal of Dental Research). Despite the five-year delay in publication, Douglass’s study focuses only on bone-fluoride levels and provides no analysis of the age-specific risk that Bassin identified. (Kim, et al. 2011). The omission of an age-specific analysis is not due to lack of data, as Douglass’s prospective data contains sufficient personal-history data to replicate the age-specific analysis that Bassin performed on the retrospective data. As discussed here, the study has other significant limitations. Thus, although billed as a refutation of Bassin’s study, the long-anticipated study does little to resolve the controversy.


In a March 6, 2012 interview with a California radio station, the chairman of NRC’s review on fluoride, Dr. John Doull, states in a radio interview that the “Kim study” (the name for the lead author of Douglass’s 2011 paper) is “not adequate” to answer the question of whether fluoride causes osteosarcoma. Doull expressed his hope, therefore, that further research would be conducted.

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