Study linking fluoride to IQ dismissed as ‘misleading’
Canadian research
Several international experts have taken the unusual step of urging a Canadian university to arrange an independent investigation into research that controversially linked fluoride in drinking water to lower intelligence in children.
The academics and public health officials from six countries say studies by york university’s Christine Till have been widely criticized, yet are still influencing often-emotional debates over fluoridation in american and Canadian cities.
an arm’s-length review is needed to determine whether “ideology is being misrepresented as science,” the group says in a letter sent to york’s board monday.
The fact Till is using an animated video and public comments to advocate against pregnant women drinking fluoridated water, despite shortcomings in her research, makes this more than a simple scientific debate, said myron allukian Jr., one of the signatories.
“it’s bothersome that an academic goes around yelling ‘Fire, fire,’ when there’s no fire,” said allukian, former president of the american Public Health association and Harvard dental professor. “She is misleading the public and others by distorting the data and not doing the proper analyses.”
The letter is also signed by professors and other experts in the U.S., the U.K., Australia, New Zealand and Chile.
Till, a neuropsychologist, could not be reached for comment. but she has strenuously defended her work, saying that it’s in line with other research looking at the neurological effects of fluoride.
Her critics are simply unwilling to accept that fluoridation is anything but “unequivocally safe,” despite a number of studies suggesting it poses a risk to children, she said in a commentary published earlier this year.
Till described “the challenges of conducting fluoride research and the overt cognitive biases we have witnessed in the polarized fluoride debate.”
“The tendency to ignore new evidence that does not conform to widespread beliefs impedes the response to early warnings about fluoride as a potential developmental neurotoxin,” warned the scientist.
In fact, the prominent journal that published Till’s key study on fluoride and IQ said it subjected the paper to added scrutiny and peer review because of its implications. The JAMA Pediatrics editor has said he would tell his wife not to drink tap water if she were pregnant.
And separate studies from China, mexico and other places, though also criticized and generally considered less rigorous, have had similar findings.
Barbara Joy, a university spokeswoman, said york has policies in place to deal with such requests and “we will be responding fully once we have carefully reviewed the concerns.”
The u.s. Centers for disease Control has declared fluoridation of drinking water one of the 10 greatest public health achievements of the 20th Century, reducing cavities by an estimated 25 per cent.
But it has long been a contentious issue. Opposition once veered into conspiracy-theory territory, though now relies more on published research into possible harms. The movement still has links to the scientifically dubious anti-vaccination lobby.
Till’s study last year on IQ and fluoridation thrust her into the centre of the fray. It examined maternal consumption of the chemical, both by looking at fluoride in urine and mothers’ reports of their fluoridated-water consumption.
Of the 500 mothers from six Canadian cities included in the study, those with 1 part per million more fluoride in their urine had boys whose IQ was an average of 4.5 points lower between ages three and four. Their girls had slightly higher IQS, and there was no difference when the sexes were combined.
Those who reported higher fluoridated-water consumption had children of both sexes with an average 3.7 points lower IQ, the study concluded.
Till has also published a paper linking fluoridated water and Adhd, and one that concluded baby formula made with fluoridated water was associated with lower IQS.
The letter cites critiques that largely dismissed the results of the IQ paper on various grounds.
A detailed report by Canada’s CADTH, the independent, government-funded agency that evaluates new drugs and other health issues, said Till’s conclusions were simply “not supported by the data.”
The report cited “multiple weaknesses,” including potentially wrong estimation of the mothers’ fluoride exposure and variables like parental IQ and diet after birth that weren’t considered but could have skewed the results.
A review by Germany’s Leibniz research Centre for Working environment and Human Factors raised similar concerns and concluded the study did not justify calling fluoride a “human developmental neurotoxin.”
The letter also points to an animated video produced by Till and colleagues that leaves out much of the nuance in her findings. It states flatly that her study and one in mexico found “fluoride led to IQ deficits in children.” Till’s work suggested there was an association between the two, not a proven cause-and-effect relationship.
The review by an independent, international committee should look at whether the animation accurately represents her findings. If not, there should be a “forensic audit” into whether public research funds were used to produce it, the letter says.
Meanwhile, Till also wrote to the city council of Green bay, Wis., in July as it debated fluoridation, suggesting that, based on her results and others, pregnant women should decrease their fluoride intake.