Fluoride Action Network

Harvard scientists: Data on fluoride, IQ not applicable in U.S.

Source: The Wichita Eagle | September 11th, 2012 | By Dion Lefler
Location: United States, Kansas

Harvard University scientists say that Wichita voters shouldn’t depend on a research study they compiled to decide whether to put fluoride in the city’s drinking water to fight tooth decay.

While the studies the Harvard team reviewed did indicate that very high levels of fluoride could be linked to lower IQs among schoolchildren, the data is not particularly applicable here because it came from foreign sources where fluoride levels are multiple times higher than they are in American tap water.

Opponents of adding fluoride to Wichita’s drinking water have frequently cited the Harvard research in their efforts to persuade Wichitans to reject a ballot initiative that would require the water department to introduce the cavity-fighting chemical into the water supply.

Fluoride supporters gathered more than 11,000 signatures in favor of fluoridated water, forcing the City Council to put it to a vote on the Nov. 6 ballot.

Two of the scientists who compiled the Harvard study on fluoride said it really doesn’t address the safety of fluoridation levels typical of American drinking water.

“These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S.,” the researchers said in an e-mail response to questions from The Eagle. “On the other hand, neither can it be concluded that no risk is present.”

The researchers noted that the fluoride levels they studied were much higher than what is found in fluoridated water in the United States and recommended “further research to clarify what role fluoride exposure levels may play in possible adverse effects on brain development, so that future risk assessments can properly take into regard this possible hazard.”

The e-mail was jointly signed by the study’s primary authors, research scientist Anna Choi and Associate Professor Philippe Grandjean, of the Department of Environmental Health at the Harvard School of Public Health.

But the researchers’ acknowledgement that their study doesn’t draw conclusions about the safety of American fluoridated water won’t necessarily put the controversy to rest.

“The key takeaway for me in the study is one, they didn’t rule out the danger, and two, they said further research is necessary,” said Don Landis, a spokesman for the group Wichitans Opposed to Fluoridation. “That’s what we’re saying; the science is not settled.”

“No research is done on low-dosage fluoride,” he added. “The Harvard study is very valuable in pointing that out.”

Landis said he has looked for and been unable to find comprehensive research on the effect of fluoride, “not on just the so-called effect on teeth, but to the rest of the body.”

Larry Hund, a pediatrician and leader in the pro-fluoride group Wichitans for Healthy Teeth, said he had taken the Harvard study with a grain of salt even before the researchers acknowledged that it didn’t address American fluoridated water.

“They’re looking at fluoride levels 10 times what we see here in the U.S.,” he said. In addition, he pointed out that most of the studies were done in China and didn’t account for other factors that can influence IQ scores such as poverty, exposure to heavy metal pollution and dietary deficiencies.

He said fluoridated water has been used in the United States for about 65 years without causing noticeable problems.

“We have the best research hospitals in the world,” he said. “They’re in communities using fluoridated water. If something was wrong, these researchers would be waving a red flag.”

He said he’s passionate about the cause because he sees children in his practice – especially those whose parents can’t afford much dental treatment or fluoride supplements – go through unnecessary pain that could be prevented.

“The saddest ones you see are the kids with several cavities that need to be fixed and their parents can’t afford it,” he said. “I think it’s a shame we’re withholding this from our children.”

The Harvard scientists did not gather the original data for the paper they published in July, titled “Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis.”

The Harvard paper was a compilation of 27 other studies, 25 of which were done in China.

“On average, children with higher fluoride exposure showed poorer performance on IQ tests,” the Harvard researchers wrote. “Fluoride released into the ground water in China in some cases greatly exceeded levels that are typical in the U.S. In general, complete information was not available on these 27 studies, and some limitations were identified.”

One of the Chinese studies that has been translated into English, “Research on the intellectual abilities of 6- 14- year-old students in an area with endemic fluoride poisoning,” gave a glimpse of what the study limitations are.

The students in the study were drinking well water containing seven parts per million of fluoride – 10 times the amount proposed for Wichita water.

The study compared children in a control group with those whose water had high levels of fluoride.

The children in the control group were drinking water with up to .8 parts per million of fluoride, a slightly higher level than .7 parts per million that will be in Wichita water if the ballot issue passes.

The Chinese researchers found children using the high-fluoride water had IQs about a point lower than the control group.

But the researchers also found the IQ differential didn’t appear to last to adulthood.

“The IQs of adults in the area were also measured and the intellectual ability and even life expectancy of people in the (high-fluoride) endemic region appeared to be higher than the non-endemic region, indicating that the effect of fluoride poisoning on intellectual ability is negligible,” the study said.