The study, published online yesterday in a Harvard-affiliated journal, could intensify debate over fluoridation and mean more scrutiny for Harvard’s Dr. Chester Douglass,accused of fudging the findings to downplay a cancer link.

“It’s the best piece of work ever linking fluoride in tap water and bone cancer. It’s pretty damning for (Douglass),” said Richard Wiles of the Environmental Working Group, which filed a complaint with the National Institutes of Health against Douglass.

Douglass, an epidemiology professor at Harvard’s School of Dental Medicine, is paid as editor of the Colgate Oral Care Report, a newsletter supported by the toothpaste maker.

Harvard and the NIH are investigating whether Douglass misrepresented research findings last year when he said there was no link, despite extensive research to the contrary by one of his doctoral students. The NIH gave Douglass at least $1 million for the research.

That student, Dr. Elise Bassin, wrote in yesterday’s Cancer Causes and Control that boys who drink water with levels of fluoride considered safe by federal guidlines are five times more likely to develop osteosarcoma than boys who drink unfluoridated water. About 250 U.S. boys each year are diagnosed with osteosarcoma, the most common type of bone cancer and the sixth most common cancer in children. Bassin notes that more research is needed to “confirm or refute this observation.”

Douglass, in a letter to the editor published in the same issue, said Bassin’s study was a “partial view of this ongoing study,” and urged readers to be “especially cautious” when interpreting the findings.