Miss a day, miss a lot. Subscribe to The Defender's Top News of the Day. It's free.

A team of pro-fluoride researchers led by California’s dental director intentionally omitted data from a study seeking to undermine the forthcoming National Toxicology Program (NTP) report linking fluoride exposure to neurodevelopmental damage in children, according to documents released last week.

The documents — obtained through a California public records search and posted in a press release by the Fluoride Action Network — show that the team, led by Dr. Jayanth V. Kumar, a dental surgeon, conducted a meta-analysis of the scientific literature on fluoride’s neurotoxicity and found a link between fluoride exposure and lowered IQ in children at low levels of exposure.

However, they omitted the data and wrote a paper concluding there was no evidence of a link.

Four rounds of peer review rejected Kumar’s manuscript as “poorly researched,” “internally inconsistent” and committing “unashamed exaggeration” before the journal Public Health finally published the study last month.

NTP report: ‘no obvious threshold’ at which fluoridating water is safe

Kumar et al.’s study was published online less than a week before the NTP’s May 4 Board of Scientific Counselors (BSC) meeting where advisors would finalize any recommended changes before the NTP publishes the final version of its report on fluoride’s neurotoxicity.

The NTP, an interagency program run by the U.S. Department of Health and Human Services that researches and reports on environmental toxins, conducted a six-year systematic review to assess scientific studies on fluoride exposure and potential neurodevelopmental and cognitive health effects in humans.

Its groundbreaking report on those findings — which consists of a “state of the science” monograph and meta-analysis surveying the literature on the links between fluoride exposure and cognitive health effects — concluded that prenatal and childhood exposure to higher levels of fluoride is associated with decreased IQ in children.

It also found that given that children are exposed to fluoride from multiple sources, there was “no obvious threshold” at which fluoridating water would be safe.

That means even when water is fluoridated at lower levels (typically 0.7 mg/L), studies found children had dangerous levels of fluoride in their systems.

The study’s findings contradict mainstream assumptions, the position of the dental industry, the sugar industry and the health regulatory agencies on the safety and benefits of fluoridating water to prevent cavities, despite substantial evidence to the contrary, including a series of studies funded by the National Institutes of Health (NIH).

At the BSC meeting, the American Dental Association (ADA), with whom Kumar is affiliated, used his meta-analysis as evidence there were problems with the NTP study and argued that the NTP report should therefore be postponed.

This was just the latest in a series of attempts by industry and regulatory agency officials to “weaken, delay, or kill” the report.

The report is a key document in the ongoing lawsuit filed by Food & Water Watch, the Fluoride Action Network, Moms Against Fluoridation and private individuals against the U.S. Environmental Protection Agency (EPA) seeking to end water fluoridation.

The lawsuit was put on hold for more than two years pending the finalization and publication of the report. After the NTP scientists finalized their draft in May 2022 — which they deemed ready for publication — U.S. District Judge Edward Chen ruled the EPA could no longer delay the trial.

The case is moving forward as the report goes through the final stages of review.

The plaintiffs hope the report will be published in final, rather than draft, form prior to the next phase of the trial in January 2024.

The report was subject to an unprecedented number of peer reviews and agency commentary, and as a direct attempt by the NIH to block its publication, internal Centers for Disease Control and Prevention emails obtained through the Freedom of Information Act (FOIA) revealed.

The final step in its publication will be for the NTP director to consider the BSC’s suggestions and make any amendments to the report prior to publication.

The BSC recommended the NTP include comment on the recently published meta-analyses, but they were not aware that Kumar et al. buried data in order to support their findings.

Plaintiffs’ attorney Michael Connett, partner at the law firm Waters Kraus & Paul, provided the evidentiary documents to the NTP last week so the agency can consider the omitted data in its long-awaited final review of fluoride’s neurodevelopmental toxicity.

Connett told The Defender:

“We felt it was important to make the NTP aware of the omitted data as it directly contradicts the paper’s conclusion, and further undermines the dental lobby’s main talking point that the neurotoxic hazards of fluoride only occur at high doses.”

How researchers manipulated ‘the science’

Email exchanges between Kumar and his co-authors and transcripts from Kumar’s deposition in the lawsuit show Kumar and his co-authors are professionally committed to water fluoridation.

Kumar is a member of the pro-fluoridation ADA’s National Fluoridation Advisory Committee and one of the nation’s leading promoters of fluoridation. He admitted in the deposition that his job is “to promote fluoridation.”

Dr. Susan Fisher-Owens, one of his co-authors, receives funding from Colgate, which also promotes water fluoridation.

Kumar also admitted that part of his job was to work with the ADA’s marketing consultant to come up “with the best messaging and strategies for how to best advocate for fluoridation,” including messaging to “inoculate policymakers” with pro-fluoride information before they speak with anyone questioning the policy.

The documents show the researchers set out to prove there was no link between low levels of fluoride and lowered IQ in children, specifically to undermine the NTP report.

In a presentation to the Association of State and Territorial Dental Directors in February 2021, Kumar told his colleagues he was hoping to pre-empt the NTP monograph by publishing his own meta-analysis and finding a “friendly editor” to publish it.

He reiterated this point in an email to his co-authors in July 2022, in which he emphasized there was “urgency” to get their paper published. “I wanted to publish the paper before the NTP report,” he wrote.

But publishing their desired results met a series of roadblocks as peer reviewers at the Journal of the American Dental Association rejected the study twice, finding the “discussion is unbalanced and misleading.”

One reviewer expressed concern that “the misinformation in this manuscript will fuel more controversy rather than stimulate prudent science-based decisions.”

Reviewers at Pediatrics Journal similarly rejected the study as marked by “fallacious” reasoning with conclusions that were “internally inconsistent.” Another reviewer said that a “facile style of citation increases concern about the balance of the work.”

But reviewers were unaware that Kumar also omitted data that contradicted his desired conclusions.

In an email to Kumar in February 2022, the study’s biostatistician Honghu Liu, Ph.D., told Kumar he thought the results of his analysis were “headed in the right direction.”

But on March 5, 2022, Liu wrote to Kumar explaining they had done analyses trying to find a safe threshold — ideally, around 1.5 mg/L — for fluoride in water, below which there is no association with reduced IQ in children. However, he wrote, “the results are opposite to what we hoped for.”

Liu told Kumar he would keep trying to produce different results. “Although hard, we can test more models to try to identify a threshold that can lead to a nonsignificant fluctuation in IQ before the threshold and a significant drop in IQ after the threshold,” he wrote.

But further analysis continued to show an association between low levels of fluoride exposure and decreased IQ. According to Liu, the dose-response analysis was “unfortunately not showing what we like to show.”

To resolve the problem, they eliminated the analysis from the study.

On March 24, 2022, Kumar sent his colleagues an email, quoting the particular parts of the NTP monograph that he sought to invalidate with their paper and raising concerns that reviewers would question their research if they included a certain figure that contradicted their conclusions.

When the team submitted the study to Public Health for publication, the analysis showing an association between low-level water fluoridation and IQ deficits had been removed.

The study concluded, “These meta-analyses show that fluoride exposure relevant to community water fluoridation is not associated with lower IQ scores in children.”

Connett sent the omitted analysis along with an explanation of how Kumar’s conflicts of interest influenced the outcome of his study in a letter to the NTP last week and urged them to take it into consideration as they evaluated the meta-analysis.

He wrote:

“The public counts on NTP to provide the best available science on the chemicals that impact their lives. I recognize this is a challenging task, particularly for chemicals with significant political interests at stake, but it is vital nonetheless.”

Through FOIA and public records requests, the plaintiffs revealed how high-level public health officials blocked the report’s publication after the NTP determined it was finalized.

They also showed how the ADA sought to influence the “independent” National Academies of Science, Engineering, and Mathematics to insist on further review.

Commenting on what else they might uncover about efforts to protect pro-fluoridation interests, Connett told The Defender:

“The only reason we were able to get Kumar’s emails is because he’s a government official who is subject to Freedom of Information requests. It raises the question of what else we would learn if the emails of private actors, like the PR strategists who Kumar works with, were also accessible.”