A study published Monday suggests that fluoride consumed by pregnant women can decrease the IQ of their children. No single study provides definitive answers, but the latest research on this controversial topic will no doubt stir debate.
The study, published in the journal JAMA Pediatrics on Monday, found that increased levels of fluoride exposure during pregnancy were associated with declines in IQ in children. Previous research has made similar findings, but this is the first such study to evaluate the effect of fluoride on populations receiving what the US Public Health Service considers optimal levels of 0.7 milligrams of fluoride per liter of drinking water, such as in the United States and Canada.
First added to an American water supply at the end of World War II, fluoride has been the subject of controversy, hysteria, conspiracy theories, reasoned argumentation, and bitter municipal friction since 1949.
There are reasons that European countries tend to avoid fluoride. The stuff really does have toxic effects at concentrations that aren’t that much higher than what crops up in our water.
The research was expected to be so controversial that JAMA Pediatrics included an editor’s note saying the decision to publish it was not easy and that it was subjected to “additional scrutiny.”
A handful of earlier studies have suggested that prenatal fluoride exposure could affect neurodevelopment, but many experts considered those to be substandard.
The new study, vetted by the premier medical publisher in the U.S., is seen as more rigorous, although some experts found it unconvincing, saying the results were statistically borderline and the methodology was flawed.
The researchers say that further investigation into whether boys are more vulnerable to fluoride neurotoxicity is needed, especially considering that boys have a higher prevalence of neurodevelopmental disorders such as autism and attention-deficit disorder.
“It’s actually very similar to the effect size that’s seen with childhood exposure to lead,” says David Bellinger, a professor of neurology at Harvard Medical School and Boston Children’s Hospital. He reviewed the paper before it was published and wrote a commentary about it.
“I think people are going to be shocked but I think people should realize that science is constantly evolving,” senior study author Till says. A previous study in Mexico found a similar link, she says, so this is not the first to suggest a connection. This finding is likely to spur more research on the topic.
The study was funded by the Canadian government and the U.S. National Institute of Environmental Health Science.