Canada - If fluoride decreases children's IQ, are harder teeth worth the risk?

Corbella: If fluoride decreases children's IQ, are harder teeth worth the risk?
LICIA CORBELLA Updated: August 27, 2019

Calgary City council is again considering fluoride in Calgary's tap water after studies show more cavities in Calgary children. G
If you had to choose, would you rather have your child lose a permanent tooth or 4.5 points from their IQ?

Obviously, no parent would want either but if you faced that kind of rock-and-a-hard place choice for your child, what would you pick?

My guess is most parents would say that enhancing and protecting their child’s intelligence would take precedence over the loss of a molar.

A new Canadian research study that has garnered international interest should cause policymakers to ask themselves the above question before they consider adding fluoride to their community’s water supply or to consider removing the mineral from water where it is currently added.

The Journal of American Medical Association (JAMA Pediatrics) study published Aug. 19 exposes a link between exposure to fluoridated drinking water during pregnancy and lower IQs in children.

The study, entitled, Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada, measured the levels of fluoride in the urine of 512 pregnant women living in six major Canadian cities at three different times during pregnancy. It then tested their children once between the ages of three and four. All of the children were born between the years of 2008 and 2012.

Ultimately, for every 1 milligram-per-litre increase in fluoride in the women’s urine, a corresponding drop of 4.5 IQ points was found in boys but not girls.


A study published on August 19, 2019 links exposure to fluoridated tap water during pregnancy to lower IQ scores in infants, but several outside experts expressed concern over its methodology and questioned its findings. ALASTAIR PIKE/AFP/GETTY IMAGES

The study’s lead author, Christine Till, an associate professor in the faculty of health at York University in Toronto, told Postmedia that she is “concerned about anything that can negatively impact brain function.”

Reached Monday via email in the Netherlands, where she is attending the International Society of Environmental Epidemiology (ISEE) conference, Till said a 4.5 drop in IQ scores has an enormous negative impact on society.

“Most parents want to provide the most optimal development for their child,” said Till. “The question is whether the risk of decreasing a child’s IQ by three to four points is worth the benefits that ingestion of fluoride provides in pregnancy.”

Hardy Limeback, a retired University of Toronto professor of dentistry who once supported fluoridation but now is a leading advocate against “the mass medicating of our water supply,” says studies show that people who live in areas without fluoridated water suffer the loss of just one tooth over their lifetime than they would had they been exposed to fluoridated drinking water their entire lives.

“This study puts to bed the question about the risk versus the reward of water fluoridation,” he said from his home in Ontario. “This study essentially shows that fluoride is as toxic as lead to a developing brain and therefore shouldn’t be added to our water supply.”


Fluoride is applied directly to teeth with most toothpastes. ELAINE THOMPSON / AP

Till says a 4.5-point drop in IQ scores would lead “to 50 per cent more children falling in the range of having an intellectual disability and many fewer children falling into the gifted range.

“We are not talking about a small number of kids who are affected,” she added. “The loss of three to four IQ points gets magnified when we think about the hundreds of thousands of children who are exposed to fluoride when their brain is growing. A shift of that magnitude would have serious societal and economic implications,” added Till, who is giving a talk about the use of fluoridated water in infant formula in Utrecht on Tuesday.

In July, Calgary city council voted to delay the public presentation of a study, completed by the U of C’s O’Brien Institute for Public Health, until the fall.

The report listed the potential benefits of adding fluoride to Calgary’s drinking water, which was eliminated in 2011 following a vote by council that faced spending up to $6 million to replace the aging fluoridation equipment at the city’s water treatment facilities as well as about $750,000 annually to run the program. The O’Brien report found that water fluoridation could reduce cavities and decay in baby teeth by 44 per cent and a 37 per cent reduction in children’s permanent teeth but it also acknowledged that fluoride causes fluorosis (weakening of the enamel and bones), may have minor effects on thyroid function and that there is “more evidence needed for effect of fluoride on cognition.”

Well, the additional evidence needed is here. The JAMA study says that “the beneficial effects of fluoride predominantly occur at the tooth surface after the teeth have erupted. Therefore, there is no benefit of systemic exposure to fluoride during pregnancy for the prevention of caries in offspring.

“The evidence showing an association between fluoride exposure and lower IQ scores raises a possible new concern about cumulative exposures to fluoride during pregnancy, even among pregnant women exposed to optimally fluoridated water,” says the study.

It’s unrealistic to expect pregnant women to avoid drinking water from the tap during their entire pregnancy. It’s much easier for those who want their children to have fluoride to ensure that they get it in their toothpaste and even in their water.

This study further bolsters findings by Dr. Howard Hu in his 2017 University of Toronto study that led the researcher to conclude that: “The potential risks associated with fluoride should be further studied, particularly among vulnerable populations such as pregnant women and children, and more research on fluoride’s impact on the developing brain is clearly needed.”

No one doubts that fluoride, applied topically to teeth, improves dental health. However, if we believed that lead could solve dental issues, would we add it to our water supply? Of course not.

Calgary’s community and protective services committee needs to brush up on this latest study before it holds a public hearing into this divisive topic, as expected in October. Then, if it absorbs what the science says, it will pull from its roots the repeated demands to reintroduce fluoride into our water supply. After all, a good brain is worth more than a tooth.

Licia Corbella is a Postmedia opinion columnist. lcorbella@postmedia.com