Fluoride and IQ

The U.S. government published a report this week linking high levels of fluoride with lower IQs in children. The report was a long time coming. NPR’s Pien Huang has this story.

PIEN HUANG, BYLINE: It’s hefty, it’s over 300 pages long and it comes from the National Toxicology Program, which is part of the National Institutes of Health. Ashley Malin studies toxic exposures at the University of Florida. She did not help write the report, but she does support it.

ASHLEY MALIN: I think it is the most comprehensive and rigorously conducted report of its kind and so important for our understanding of impacts of fluoride exposure on child IQ.

HUANG: The report addresses concerns that have been circulating for a while. Linda Birnbaum is a toxicologist and former head of the National Toxicology Program.

LINDA BIRNBAUM: The question was, is fluoride a developmental neurotoxicant? And the analysis clearly said it certainly has the potential to be.

HUANG: The authors of the report gathered animal and human studies from around the world and weighed the available evidence. They conclude with moderate confidence that there is an association between higher levels of fluoride and lower IQ in children. The report didn’t quantify the effects, but some of the studies they included showed a decrease of a few IQ points.

Now, by higher levels of fluoride, they mean 1.5 milligrams per liter or more. This applies to about 2 million people in the U.S. who live in places where high levels of fluoride naturally occur in the soil and rocks. That level is twice as high as what’s added to the public drinking water in many places to prevent cavities, and the report does not address whether lower fluoride exposures come with health risks. Still, Birnbaum says concerns from fluoride advocates delayed the report’s publication for several years.