A Harvard professor’s testimony to the government on the effects of adding fluoride to tap water has inflamed a 60-year-long debate over the chemical’s safety and its place in the water supply—prompting a University investigation into his work that has garnered nationwide attention.

Chester Douglass, chair of the Oral Health Policy and Epidemiology Department at the Harvard School of Dental Medicine (HSDM), submitted written testimony to the National Research Council last year claiming that there was no significant link between fluoride and osteosarcoma, a rare but deadly form of bone cancer.

Since then, several environmental advocacy groups have questioned the validity of his research, claiming conflict of interest and outright deception.

“His conclusion that there is no link is a lie,” said Tim Kropp, the head toxicologist for the Environmental Working Group, the Washington-based organization that filed the initial ethics complaint with the National Institute of Environmental Health Sciences. “He cites work in his references, but directly contradicts it in his write-up.”

At the heart of the group’s claims lies the work of one of Douglass’ doctoral students, Elise B. Bassin. Using Douglass’ data, Bassin came up with a different set of conclusions—she found that fluoride makes the risk of osteosarcoma five to seven times higher.

Bassin’s work has never been published in a peer-reviewed journal, a gold standard for scientific authenticity. Select portions of her study, however, have been publicized by the Environmental Working Group.

While HSDM is investigating the allegations, several Harvard professors have spoken out in support of their colleague.

Myron Allukian Jr., a Harvard associate clinical professor and one of the foremost experts in oral health policy, called the environmental groups’ claims “ridiculous” and “illogical,” saying that Douglass is a world leader in the field and that the results of his seven-year study should be treated with respect.

“The claims don’t hold fluoridated water,” Allukian said. “If I was going to take every study done by a student and say that this should be public policy, then we’d be in very bad shape.”

Another group, the Fluoride Action Network, has accused Douglass of having a conflict of interest. Douglass edits the Colgate Oral Care Report, a newsletter subsidized by Colgate Palmolive, which looks at issues affecting oral health. Colgate uses fluoride in its popular toothpaste.

Claiming “ties to a company that profits from Fluoride,” the network asked the National Institute of Health, which has funded Douglass’ work, to remove Douglass from the study, eliminate all other conflicts of interest, and publish his data along with his conclusions.

But R. Bruce Donoff, dean of the HSDM, says that Douglass’ work with the journal “represents no conflict of interest” and has been reviewed by the University.

“He edits a newsletter that is part of a learning experience for dentists worldwide,” said Donoff, who expects the investigation to be completed in a month or two.

This is the first time Douglass has faced allegations of misconduct in his roughly 30 years working at Harvard, said Donoff.

But other groups are not waiting for the results of Harvard’s investigation. Unions from the Environmental Protection Agency (EPA), longtime opponents of water fluoridization, seized on the allegations against Douglass, writing a letter to the EPA administrator calling for a moratorium on programs that add fluoride to drinking water.

But Allukian, who is also the former chair of the U.S. Surgeon General’s Working Group on Fluoridation and Dental Health, says that the preponderance of evidence favors fluoridation, and that the groups criticizing Douglass’ work are probably fringe groups reminiscent of the movie Dr. Strangelove.

“When this was first implemented, a lot of people thought it was a communist plot,” he said. “The government started fluoridating communities in 1945...and by 1950 saw such a dramatic benefit that the government endorsed it for the entire country.”

Dr. Stephen A. Colchamiro, a professor in Douglass’ department, said that he does not think that any of his colleagues would support ending fluoridization programs.

“Fluoridization has worked so well,” he said. Fluoride strengthens teeth and lowers the decay rate, said Colchamiro.