Two scientific studies focusing on the safety of the chemicals for water fluoridation most commonly used by cities across the country — including Burlington — have become a part of the Burlington debate on whether to continue fluoridating the city’s water supply.
One study suggests there might be a link between use of the fluoridation chemical and heightened lead levels in blood. The other study criticizes the research methods of the first study and suggests it was conducted with a conclusion in mind.
The Burlington Board of Health is investigating whether the city should continue its 53-year practice of fluoridating its drinking water before making a recommendation to the City Council. According to a report provided by the state Department of Health, about 56 percent of Vermonters take their drinking water from fluoridated systems. Nationally, the figure is 66 percent for people “with access to community water systems.”
The 1999 study raises questions about the safety of silicofluorides, as the chemical is known. The study was headed by Dartmouth College research professor Roger Masters and Myron Coplan, a chemical engineer, and was partially funded by the U.S. Environmental Protection Agency’s Office of Criminal Enforcement, Forensics and Training.
Masters found that silicofluorides could double the chances of having high levels of lead in the blood. The study compared the blood lead levels of 280,000 children in 30 Massachusetts communities that use silicofluorides in their water supplies with 30 unfluoridated communities.
In subsequent research, Masters found that behavioral tendencies — “higher levels of learning disabilities, hyperactivity, substance abuse, violent crime, and other forms of anti-social behavior” — which previous research linked with exposure to lead were more pronounced in communities using silicofluorides. His research documented higher crime rates in Massachusetts in those communities, and found similar results in six other states, as well as higher rates of substance abuse.
The second study disputed Masters’ findings. It was performed by EPA researchers Edward Urbansky and Michael Schock of the EPA’s National Risk Management Research Laboratory, and published in 2000.
It argued that Masters’ methodology was faulty and that he was “intentionally biased towards what appears to be a preconceived conclusion.” The Vermont Department of Health included the Urbansky and Schock study in its fluoridation information packet.
The Masters and the Urbansky/Schock studies appeared in the International Journal of Environmental Studies.
Steve Arthur, head of the state health department’s division of oral health, said this week that given the different findings of the two studies, it might be feasible to use a different form of fluoride — sodium fluoride — rather than silicofluorides in communities across the state “until the scientific controversy is resolved.”
“It is certainly something that could be considered and something that warrants further investigation and research,” he said. He emphasized that he was speaking for himself rather than for the department.
He said a change in chemicals would pose no difficulties for small water departments but might be a technical challenge for larger departments such as Burlington. He said his office has requested information from the Centers for Disease Control and Prevention in Atlanta, Ga. “to check on the feasibility of a switch” to sodium fluoride use by larger systems.
“Such a change,” he wrote in an e-mail, emphasizing that the health department has not formally considered recommending a change in chemicals, “would take considerable discussion, work, evaluation and planning.” Arthur said he is unaware of any study other than Urbansky and Schock’s, which rebuts the Masters study on silicofluorides.
Recommending a change in chemicals would represent a marked shift in the health department’s position on water fluoridation, which proponents say reduces tooth decay. During a debate last week before Burlington’s Board of Health, Arthur, speaking for the health department, said emphatically that water fluoridation as practiced by Burlington and other communities across the state is “safe and effective.” The department in its defense of water fluoridation did not make a distinction between sodium fluoride and silicofluorides.
Michael Connett, project director of the anti-fluoride organization Fluoride Action Network, said that although Masters is correct about the lack of FDA testing on silicofluorides, “the more important point, in my view, is that the FDA has never approved any fluoride product, including sodium fluoride, when used for ingestion. The FDA has only approved topical fluorides, e.g. toothpaste.”
Masters argued in a 2005 guest editorial in the New Zealand journal Fluoride that silicofluorides are an “untested compound” which “should not be used until they have been scientifically demonstrated to be safe with the kind of extensive biological testing used for any new drug.”
In a Dartmouth news release announcing his study, Masters said, “The correlation with blood levels is especially serious because lead poisoning is associated with higher rates of learning disabilities, hyperactivity, substance abuse and crime.”
Masters said silicofluoride, unlike sodium fluoride, does not “come apart into its constituent elements when put in water. Our concern,” he said, “is with the residue of the silicofluorides” which “seems to have the effect of increasing the absorption of lead.”
“There should be a moratorium on this chemical until it’s demonstrated to be safe,” he said last week in a telephone interview from his home in White River Junction.
He noted that as a result of his research, silicofluorides were recommended for additional chemical studies and possible toxicology studies in 2002 to the National Toxicology Program of the Department of Health and Human Services. The recommendation was made by the toxicology program’s interagency committee because of a “lack of toxicity information,” and a lack of “experimental evidence” on the assumed chemical composition of silicofluorides in the drinking water.
In their 2000 study, Urbansky and Schock strongly criticized Masters’ and Coplan’s methodology, and concluded that the “sampling scheme employed in the studies is entirely unrelated to any credible statistically based study design to identify drinking water lead and fluoride exposure as a significant source of blood lead in the individuals.”
Masters and Coplan, Urbansky and Schock concluded, hadn’t established a link between silicofluorides and lead absorption. The authors, they write, “provide no credible evidence to suggest that the common practice of fluoridating drinking water has any untoward health impacts.”
Masters answered Urbansky and Schock’s criticisms in an e-mail to the Free Press. “In the situation of two widely used chemicals that had never been studied, we were doing epidemiology,” he wrote, “and the data they say we should have cited or used didn’t exist.”
Wednesday, Scott Presson, a dentist and public health specialist with the CDC, which supports fluoridation unreservedly, said that the “level of concern from the public because of the Masters study” had prompted the CDC to sponsor “a more in depth study under way to look at the same questions Masters did.”
That study by a University of Maryland epidemiologist, is in progress, he said.
Connett, whose organization opposes all water fluoridation, said Masters’ research suggests that silicofluorides “may present a unique risk, not seen with sodium fluoride, regarding its ability to increase lead exposure in the population.”
He said the Masters research demonstrates the risk of using silicofluorides as “a fluoridation chemical without any testing by government agencies to assure its safety for long term consumption.”
The EPA has jurisdiction in the United States over water safety, but spokesman Kit Owens of the EPA’s National Risk Management Research Laboratory said Monday that the agency has “not done a toxicity study on silicofluorides.”
Mike Herndon, a spokesman for the federal Food and Drug Administration, which tests drugs for safety, said the FDA has not studied the fluoride compounds used in water fluoridation across the country.
“The FDA doesn’t have jurisdiction over water that runs in your city,” he said. “That is overseen by the EPA. There has been no public call for the FDA to study fluoride in drinking water.”