A new study led by a California public health official and long-time advocate of water fluoridation omitted data that contradicted its conclusion that fluoridated water is not associated with reduced IQ, according to documents obtained through Public Records Act requests. Attorney Michael Connett has provided the unearthed documents to the National Toxicology Program (NTP) so that the agency can consider the omitted data in its long awaited final review of fluoride’s neurodevelopmental toxicity.
In April, California’s State Dental Director, Dr. Jayanth Kumar, published a meta-analysis in the journal Public Health that purported to show that fluoridated water is not associated with reduced IQ. The American Dental Association (ADA), with whom Kumar works closely, has touted Kumar’s findings as a basis for the NTP to postpone publishing its report.
But Kumar is not an independent voice on the issue of fluoride’s safety. At a recent deposition, Kumar admitted his “job is to promote fluoridation” and that he is “literally being paid to promote fluoridation.”
Documents obtained under California’s Public Records Act show that Kumar’s desire to protect fluoridation influenced almost every aspect of the study. Before even conducting the study, Kumar told his colleagues that his aim was to “pre-empt” the NTP and show that fluoridated water is safe. In emails to co-authors, Kumar emphasized the “urgency” of the task.
Kumar’s biases caused the paper to be rejected four times prior to being published. One peer reviewer described the study as “superficial,” “unbalanced,” and “misleading” and cautioned, “I’m afraid that the misinformation in this manuscript will fuel more controversy rather than stimulate prudent science-based decisions.”
But the problems with Kumar’s study were worse than the peer reviewers realized. Emails obtained from California’s Department of Public Health show that Kumar omitted data that was contrary to the conclusion.
In an email from March 5, 2022, the study’s biostatistician, Honghu Liu, reported to Kumar that the results are “opposite to what we hoped for” as they failed to show a safe (aka “threshold”) level of fluoride in water below which there is no association with reduced IQ.
The failure to find the “hoped for” threshold was troubling to Kumar and his team.
Liu suggested trying different models to see if they could obtain different results: “although hard, we can test more models to try to identify a threshold that can lead to a non-significant fluctuation in IQ before the threshold and a significant drop in IQ after the threshold.”
But further analyses continued to show the same thing: an association between low-level fluoride and IQ deficits. According to Liu, the dose-response analysis “is unfortunately not showing what we like to show.”
Kumar’s response? Remove the analysis from the study.
In an email from March 24, 2022, Kumar suggested removing the analysis “because it appears to contradict other findings” and “I think the reviewers will have many questions.”
About a month later, Kumar submitted the study for publication. But the analysis showing an association between low-level fluoride and reduced IQ was gone. Stripped of this analysis, the study concludes, “These meta-analyses show that fluoride exposure relevant to community water fluoridation is not associated with lower IQ scores in children.”
In his letter to NTP, Connett disclosed the omitted analysis from Kumar’s study, and called on NTP to give due consideration to Kumar’s biases. According to Connett, a partner at the law firm Waters Kraus & Paul, “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.”