Fluoride exposure during pregnancy tied to lower IQ scores

Pregnant women who drink fluoride-treated water may have children with lower IQs, study suggests

Pregnant women who drink fluoride-treated water may have children with lower IQs, study suggests

The study, revealed in the journal JAMA Pediatrics on Monday, found that elevated ranges of fluoride exposure during pregnancy had been related to declines in IQ in kids.

"It is important to recognize that this is one study with small sample sizes within the context of more than 40 years of other research on the safety and health benefits of fluoridated water".

The American Dental Association released a statement saying it "remains committed to fluoridation of public water supplies as the single most effective public health measure to help prevent tooth decay".

"Four and a half IQ points is of substantial societal and economic concern", said senior researcher Christine Till, an associate professor of psychology at York University in Toronto.

Critics of water fluoridation argue it is unnecessary because modern dental products like toothpaste contain fluoride, while 97% of European residents receive unfluoridated water without a major impact on their dental health.

He said it's something he sees all the time as a researcher: Academics who are doing great scientific work - really innovative, interesting, lovely work - and want to see it translated into policy right away.

For the Canadian study, the researchers gathered urine samples from pregnant women during each trimester and tested their fluoride levels. It did not examine whether drinking fluoridated water or getting the mineral from other sources after birth suppresses a child's intelligence.

The authors found that for each additional 1 milligram per liter in concentration of fluoride in a mother's urine, there was a 4.5-point drop in IQ in males.

A recent Report carried out by the O'Brien Institute of Public Health in Canada dismissed the New Zealand Broadbent study, the only epidemiological study that has found fluoridation does not reduce IQ, because of its poor quality. He reviewed the paper before it was published and wrote a commentary about it.

They also found the fluoride consumption during pregnancy from the levels in the public water supply and the recalled consumption of the participants in the study.

The fact that the more robust measure of fluoride intake - fluoride in the mothers' urine - was less convincingly associated with IQ suggests other factors are at play, he added. Given the sensitivity of the findings, he wrote, "we subjected it to additional scrutiny for its methods and the presentation of its findings".

"In my view, a strong case for a hypothesis is present when multiple studies conducted independently produce consistent results".

'The gender difference in the results make it hard to interpret.

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"When it comes to epidemiology, it is unwise to place too much emphasis on the results of any one study", Bellinger concluded, although he noted that Till and her colleagues produced a "very good environmental epidemiology study". "Not all women have the means to pay for bottled water and that is a concern to me as a public health dentist", Dr. Martinez-Mier said.

Urinary fluoride concentrations and total fluoride intakes were significantly greater in women living in areas with fluoridated drinking water, compared to the second group.

Adding fluoride to drinking water to promote dental health has been a fixture of municipal drinking water systems as far back as the 1950s. About 27% of this study population lived in areas where drinking water was fluoridated, and for the rest, it was not.

HARRIS: That gave her a sample with a whole spectrum of fluoride exposure.

There was complete data on urinary tests gathered from 512 pregnant women, and self-reported maternal daily fluoride intake from beverage consumption was available for 400 pregnant women.

TILL: Only boys were affected when we looked at urinary fluoride.

Girls didn't have a change in their IQs, but the research did not focus on why boys were affected and not girls. That's a small difference for any individual child. I'm shocked. (The effect on IQ) of lead exposure is of this magnitude.

Questions about water fluoridation have at times been considered 'fringe science, ' and the editorial board of JAMA Pediatrics recognized that publishing the paper could invite controversy.

Fluoride is a naturally occurring mineral that is present in almost all water sources and is associated with reduced tooth decay.

BELLINGER: And the people who - on the other side, who think that fluoride is quite toxic, are going to say, see.

"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, a Stanford University meta-scientist known for researching clinical research, told the Washington Post.

HARRIS: A previous study in Mexico found a similar link, she says, so this is not the first to suggest one.

Now, the majority of the US population has fluoride in their water, which according to the Centres for Disease Control and Prevention prevents cavities and the need for fillings, and causes "less pain and suffering because of tooth decay". Therefore, the conclusion would be, as Till says: "We recommend that women reduce their fluoride intake during pregnancy".

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