"Last May, the National Toxicology Program (NTP), a federal research agency, was set to release its eagerly awaited report into the cognitive and neurodevelopmental impacts on humans from fluoride exposure.
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The report was also set to play a key role in an ongoing lawsuit, filed by government accountability nonprofit Food & Water Watch, to get the Environmental Protection Agency to regulate water fluoridation because of fluoride's possible neurotoxic harm. More than two years ago, the judge put the case on hold in expectation of the NTP report's public release.

Before the NTP could release the report, however, "They were blocked," said Linda Birnbaum, NTP director until 2019.
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Some health experts believe this finding makes current water fluoridation levels potentially unsafe for developing fetuses and young children. Because many common foods and drinks contain fluoride, consuming them along with fluoridated water could amount to harmful exposure levels, these experts say.
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This January, Birnbaum issued a scathing legal declaration as part of the lawsuit, writing, "The decision to set aside the results of an external peer review process based on concerns expressed by agencies with strong policy interests on fluoride suggests the presence of political interference in what should be a strictly scientific endeavor." Birnbaum said she issued the legal declaration in part over concerns the report might never be publicly released.
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Birnbaum, however, remains adamant that the science proves there is "no real benefit" from ingesting fluoride. "The benefit from fluoride is from topical applications," she said."

https://www.salon.com/2023/03/16/health-officials-delayed-report-linking-fluoride-to-brain-harm_partner/