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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.
BIRNBAUM: There was a great deal of concern raised, especially by the dental community, and they were concerned that this report would be misconstrued to say that any fluoridation of drinking water is a problem.
HUANG: The report kept getting sent between inside and outside committees for review. Howard Pollick is a dentist and spokesman for the American Dental Association. He critiqued earlier drafts of the report, and he says he's OK with the final version for now.
HOWARD POLLICK: This is not conclusive evidence. They didn't indicate it was conclusive evidence, and so more studies need to be done.
HUANG: The report itself calls for more research into how fluoride could affect brain development and whether it has an effect at lower levels. Some, like Birnbaum and Malin, think there's already reason to tell those who are pregnant or who care for babies to reduce their fluoride intake. Pollick thinks these calls are premature.
POLLICK: Especially when you've got a proven method of preventing a potentially very serious disease, tooth decay, you need a lot more evidence.
HUANG: Now that this report is finally out, it may open up more funding and research.
Pien Huang, NPR News. Transcript provided by NPR, Copyright NPR.
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