Health Agency Finalizes Fluoride Dose Harmful to Babies’ IQ

Fluoride concentrations in drinking water above public health guidelines may lower children’s IQ, according to a National Toxicology Program review published Wednesday.

The US health agency’s final, long-awaited report about fluoride’s hazards tackles the science debated for years in an ongoing federal trial about the mineral.

NTP concludes it has “moderate confidence” that exposures to fluoride concentrations in drinking water higher than the 1.5 milligrams per liter (mg/L) recommended by the World Health Organization are associated with lower IQ in children.

That’s more than double the federal government’s recommendation for fluoride concentrations in drinking water in the US, currently 0.7 mg/L, but significantly lower that the Environmental Protection Agency’s enforceable limit of 4 mg/L.

There aren’t enough studies for scientists to confidently conclude that exposure to fluoride in drinking water harms adults, according to the report.

The report’s authors caution that it doesn’t address whether the sole exposure to fluoride added to drinking water in the US and Canada is associated with a measurable effect on IQ. None of the studies focused on IQ that were included in the review were conducted in the US.

“The bodies of experimental animal studies and human mechanistic evidence do not provide clarity on the association between fluoride exposure and cognitive or neurodevelopmental human health effects,” the report says. “More studies are needed to fully understand the potential for lower fluoride exposure to affect children’s IQ.”

US children whose mothers drank fluoridated water while pregnant had an increased risk of neurobehavioral problems, according to an American Medical Association journal study published in May, after the NTP stopped looking for new studies.

“These findings suggest that there may be a need to establish recommendations for limiting fluoride exposure during the prenatal period,” the study’s authors wrote.

Unique Case

The question of fluoride’s risks has been central to litigation, Food & Water Watch Inc. v. EPA, before the US District Court for the Northern District of California in San Francisco that began in 2017. Arguments in that case wrapped up in a trial that ended in February, but the judge has yet to issue his ruling.

In the first-of-its kind case, Senior Judge Edward M. Chen has to make a decision without deference to the EPA about whether fluoride poses an unreasonable risk to human health. The section of Toxic Substances Control Act (TSCA) that’s central to this lawsuit, provides plaintiffs an opportunity for a “de novo” review by the court.

Complicating that decision, the EPA said and Chen agreed, that TSCA doesn’t allow him to consider the chemical’s benefits although fluoride’s been used since 1945 to fight cavities.

The Fluoride Action Network and other plaintiffs maintain fluoride in public drinking water supplies to prevent cavities is too risky. The groups challenged the EPA’s refusal to initiate a regulation banning fluoride in drinking water. The TSCA was the basis of the groups’ rulemaking petition, because that law requires the agency to take some kind of action against chemicals that pose unreasonable risks.

NTP’s final report largely reflects conclusions agency scientists released in draft versions of the document years ago, and one version of which was presented to the district court.

The NTP declined to comment on the report’s implications on the lawsuit, and the EPA didn’t immediately respond to comment.

Plaintiffs attorney Michael Connett, a partner with Siri & Glimstad LLP, said the release of the final report is very significant.

NTP’s scientists focused on fluoride’s hazards and concludes concentrations above 1.5 mg/L can be harmful, he said. But the EPA typically issues regulatory levels intended to keep human exposures well below levels that can cause harm and TSCA requires protections for vulnerable groups such as infants, Connett said.

Even the 0.7 mg/L level that health agencies recommend is only two times less than the concern level, and the EPA typically seeks a much larger margin of safety, he said.

Still, “many substances are healthy and beneficial when taken in small doses but may cause harm at high doses,” said NTP Director Rick Woychik in a statement about the report.

“More research is needed to better understand if there are health risks associated with low fluoride exposures,” he said. “This NTP monograph may provide important information to regulatory agencies that set standards for the safe use of fluoride. It does not, and was not intended to, assess the benefits of fluoride.”

Connett declined to comment on how Chen may respond to the report’s release or whether it would influence the judge’s ruling. But the plaintiffs will notify the court about the document’s availability, he said.

The NTP report is equivocal on the effect, if any, of low fluoride exposures, and saying more research is needed would seem to be unhelpful to Chen in making any dose-response determination in the case over which he is presiding, said Lynn Bergeson, managing partner of Bergeson & Campbell PC, which specializes in chemical laws and regulations.

Based strictly on the findings, Bergeson said she’d expect the government to argue the report’s conclusions don’t support a finding that 0.7 mg/L poses an unreasonable risk under TSCA. To the extent fluoride in water could contribute to other sources of the mineral that might pose a cumulative risk, “it is unclear if the record would support a judicial finding,” she said.