Let's See That Fluoride Smile!

"So much is at stake. Hundreds of millions of people around the globe -- from Brazil to Australia -- live in homes that receive fluoridated drinking water."
"Hundreds of millions of people use toothpaste or other products with fluoride."
"Many millions of children receive topical fluoride treatments."
(signed) Chair Royal Society for Public Health, U.K. Timothy Caulfield, Canada Research Chair in Health Law, former chief dental officer for England, and more...

"We're scientists. We let the data tell us the story and still people don't believe it."
"As a neuropsychologist, I care about brain development. I care about effects that we cannot treat."
"At least with cavities you can treat them."
Christine Till, professor of psychology, York University, Toronto

"[Tooth decay is caused by numerous factors and water fluoridation alone] isn't a panacea."
"But [the Till study] said that this is a neurotoxin and that it will lower children's IQ and that, unfortunately, is undermining public health policy that has been widely advocated by the U.S. federal government, the United Nations, the World Health Organization and many others for decades."
Dr.Scott Tomar, professor, University of Florida School of Dentistry

"[I was taught during professional training that those opposed to fluoride] were a bunch of whack jobs and there's absolutely no science at all to suggest that fluoride is dangerous."
"[The York study] was sort of an eye-opener for me."
"[Proponents of fluoridation would] trash it, because they just don't want to believe the findings."
Dr.Dimitri Christakis, editor, JAMA Pediatrics

"We’re scientists. We let the data tell us the story and still people don’t believe it,” said the fluoridation study’s senior author, York psychology professor Christine Till.  Getty Images

As editor-in-chief of a world-renowned, highly reputable scientific journal out of the U.S. Dr. Christakis struggled with whether or not to publish a new study out of Canada that asserted the potential of pregnant women's imbibing of fluoridated water risks subtle damage to their child's brain. But he did publish the study, and then sat back in trepidation of what was most surely to follow; a storm of reaction from the medical-scientific community in defence of an additive to municipal drinking water sources meant to protect children's teeth from dental caries.

He envisaged anti-fluoridation advocates excitedly citing the study's findings as proof positive that their campaign to oppose the addition of fluoride to potable water is right on the money. Just as those within the world of science who are advocates of the use of fluoride as a preventive, and the municipal authorities wedded to its use, would slam the findings as harmfully inaccurate. The 'findings' have certainly added fuel to the anti-fluoride campaign whose activists are demanding a moratorium, an end to the "human experiment on millions of children".

For their part, respected and high-profile academics have launched their own protest by sending an appeal to the U.S. National Institute of Environmental Health Sciences, signed off by a in impressive number of highly-knowledgeable elite public figures and members of the scientific community. Their argument centers on forcing the release of the study's data to undergo independent review to either validate or to put to rest the conclusion leading to distrust of such a highly regarded health measure to prevent children's dental cavities and related dental disease.

The suggestion that children born to women exposed to higher levels of fluoride during pregnancy will be beset with lower IQs, according to the appeal, is full of inconsistencies and "incongruities", through focus on a significant portion of its text on boys as a "subgroup", failing to take into account the mother's own IQ scores, using invalid measures in determining just how much fluoride exposure relates to such an assumed outcome.

The confusion caused by the study's publication could, the group insists, influence public policy (which, presumably, it is meant to do). Proof enough seen in York psychology professor, Dr.Christine Till, senior author of the study, stating it to be a "no brainer" that pregnant women be advised to reduce fluoride intake during pregnancy to avoid an outcome of bearing a child with a slightly lowered intelligence, influenced by the effect of fluoride.

Studies show more cavities in Calgary children. Gavin Young / Postmedia

In Calgary, which has for years withheld fluoridation from its water system and which is in the process of reconsidering its eight-year moratorium on its use, the release of the study's data would most certainly have its intended negative effect. Dentists in Calgary have been exposed to more aggressive cavities in children's teeth since the phase-out of fluoride from the city's tap water in 2011. "The amount of decay that we're seeing is just startling", Calgary pediatric dentist Dr.Kari Badwi asserted.

And since untreated teeth can become abscessed and infected this is no slight matter of inconvenience. Dr.Badwi described treatment of a six-year-old recently who had half her teeth "just rotted down to the gums". Bacteria is able to "get into the brain, it can get into different organs and it can cause death", warned Calgary dentist Robert Barsky.

A case in point was a situation in Timmins, Ontario which does not fluoridate its tap water. In 2012 a case was reported in the Journal of the Canadian Dental Association, where an eleven-year-old Timmins boy suffered a brain abscess resulting from bacteria felt to have originated from an infected molar. Rushed to hospital when his mother discovered the boy screaming, lying on the floor in agony, he was airlifted to Toronto by helicopter, to undergo two brain surgeries followed by months of rehabilitation.


Dr.Christakis spoke of a four-point drop in a child's IQ not representing a significant impediment, yet taken in whole at a population level the total cognitive loss "would be a different story". When he first read the York study, "I was like, 'hold on a minute, is this Wakefield'?" in reference to the British physician who published a 1998 paper that claimed a link between the MMR vaccine and autism, proven to be hugely inaccurate, retracted, with Wakefield losing his licence.

Concentrations in fluoridated tap water are deemed safe. ALASTAIR PIKE/AFP

However, Professor Till refuses to release her study's raw data, arguing it doesn't belong to her, but rather to a Canadian biobank with over 200,000 biological samples from thousands of mothers who gave birth between 2008 and 2012.The data, she points out, is meant to remain in Canada, although it is available for study to researchers in Canada and outside as well as long as it is acknowledged it will remain within the country. A doctoral student was hired by Professor Till to run "every single diagnostic test she could" to validate the results, offering the student a bonus should she find an error.

"It has major drawbacks in terms of how the measurements have been made. The results are very borderline in terms of statistical significance."
"[The self-reported consumption was not linked directly to levels of fluoride measured in bodily fluids, and the sex difference in IQ — the drop observed for boys but not girls] makes no sense."
"If you see a gender difference claim for this type of association, it’s far more likely to be a spurious finding rather than something true."
John Ioannidis, Stanford University meta-scientist

Alerts and Reactions

"There are some pretty bizarre theories out there, such as the idea that fluoride is being used to sedate the population."
"I worry that this study -- which the authors note should be replicated, and they call for further analysis and research -- will be presented as definitive. It is not."
Tim Caulfield, health policy researcher, University of Alberta

"[In Mexico], not many people drink tap water. [Intake of fluorides takes place through fluoridation of salt.]"
"[Still], the urinary fluoride levels of these [Mexican] women were definitely not sky high."
"There still may be a level of fluoride exposure among both pregnant women and everybody else that can still preserve the beneficial effects on tooth decay, while avoiding any effects on intelligence [in the developing fetus]." 
"This is a very rigorous epidemiology study. You just can't deny it. It's directly related to whether fluoride is a risk for the neurodevelopment of children. So, to say it has no relevance to the folks in the U.S. seems disingenuous."
Dr. Howard Hu, principal investigator, dean, Dalla Lana School of Public Health, Toronto

"[The study's findings] are not applicable [to the United States] because it's not known how the subjects of the study ingested the fluoride -- whether through salt, water or both -- no conclusions can be drawn regarding the effects of community water fluoridation in the U.S."
American Dental Association statement

U of T research

Fierce debate over the safety of water fluoridation – particularly for children’s developing brains – has fuelled researchers to explore the issue and provide evidence to inform national drinking water standards (photo by Gullherme Jofill via Flickr)

Since fluoridation of the public potable water supply became a staple health intervention many decades ago when research showed that fluoride was hugely effective in protecting against dental caries, there have been reactions from the public, claiming that general fluoridation had deleterious effects, and some municipalities, sensitive to public criticism, have taken steps to reverse the procedure, no longer fluoridating the water supply in their jurisdictions.

Across Canada most cities remain devoted to fluoridation; Ottawa, Edmonton and Toronto, for example. In other cities, such as Calgary, Waterloo and Windsor, fluoridation is no longer used in those municipalities' systems. Opponents of fluoridation allow their imaginations to run amok, claiming among other things that fluoridation is responsible for an proliferation of heart disease, cancer, birth defects, kidney problems, goiters, ulcers, anemia and spontaneous abortions.

"However, these associations are not supported by the scientific literature", researchers from the University of Guelph concluded in a 2014 evidence review under the imprimatur of the National Collaborating Centre for Environmental Health. Now, however, with the publication of the first study of its kind and size to explore the issue of fluoride exposure and its effects on stages of brain development by researchers from the University of Toronto, the issue has been brought back to life.

Data from 287 mother-child pairs in Mexico City were analyzed by the Toronto researchers from 1994 to 2005 when pregnant women were recruited for a study that took in their children as well at ages six to twelve. Levels of fluoride in urine were examined to find how children were seen to score on intelligence and neurocognitive function tests at age four and then once more between ages six and twelve. For every 0.5 milligrams-per-litre increase in mother's urinary fluoride levels beyond 0.8 mg/l, children scored 2.5 to three points lower on IQ tests.

That the children's own urinary fluoride levels measured at the times of testing, appeared not to register a significant effect, appeared to suggest that whatever effect fluoride could have on brain development occurred while in the womb. Most fluoride exposure in both Canada and the United States results from drinking water being fluoridated in the prevention of cavities, as well as fluoride manufactured right into toothpaste.

There were adjustments made in reaching conclusions based on association, inclusive of the baby's weight at birth, whether the mother smoked, intelligence quotient, socioeconomic conditions, and possible exposure to lead. The Mexican study verified that the mothers on average had 0.90 milligrams-per-litre of fluoride in their urine, a number considered to represent the "general range of exposures" comparable to other populations.

On the other hand, a 2012-2013 survey taken in Canada pointed out mean urinary fluoride levels were roughly 0.43 milligrams-per-litre, representing about 50 percent of the Mexican levels. The Toronto research team took pains to emphasize that their findings, while important, require confirmation in similar studies of other populations. According to Dr. Hu, direct comparisons with women in the United States or Canada face difficulties, reflecting the fact that there have been no large population studies of maternal urinary fluoride loads.

In Canada and the U.S., most fluoride exposure comes from the fluoridation of drinking water to prevent cavities, and fluoride in toothpaste and other dental products.  Getty Images