This latest study used urine samples from 2017 to 2020, and neurobehavioral data gathered from 2020 to 2023 as part of the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort. This dataset focused on pregnant Hispanic women in L.A. who were at least 18 years old.
As the researchers note, “it is widely established that exposure to high fluoride levels can adversely affect neurodevelopment”; however, the latest studies from Mexico and Canada indicate that fluoride exposure at lower levels — including those in the range recommended by the CDC — may also be associated with neurobehavioral issues.
“Specifically, higher prenatal fluoride exposure in Canada and/or Mexico has been associated with lower IQ among children aged 3 to 4 years in Canada and children aged 6 to 12 years in Mexico, increased symptoms of attention-deficit/hyperactivity disorder (ADHD) among children aged 6 to 12 years, poorer executive function among children aged 3 to 5 years, and poorer performance on measures of global cognition among 12- and 24-month-old boys.”
While acknowledging that there have been inconsistencies in the “global body of scientific literature” regarding fluoride — such as boys being impacted more than girls in some studies — the researchers also conclude that “the weight of the scientific literature supports an association of prenatal fluoride exposure with adverse child cognitive and neurobehavioral development in North America”.
The study also mentions the systematic review conducted by the National Toxicology Program (NTP) which has been the source of much controversy during the still ongoing fluoride lawsuit against the Environmental Protection Agency (EPA). It is this report which was blocked from release by leadership at the top levels of the Department of Health Human Services, including Assistant Secretary for Health Rachel Levine.
The research team notes that the NTP reported “with moderate confidence that higher fluoride exposure…is consistently associated with lower IQ in children.” They also note that the NTP highlighted a lack of studies based in the United States and stated that more US studies would be valuable.
Dr. Howard Hu and The Fluoride Lawsuit
Dr. Howard Hu was part of the team involved in the new JAMA study. He is also one of the expert witnesses who was called to testify during the second phase of the fluoride lawsuit in February. He has extensively studied fluoride’s toxicity, and has also been involved in research on lead toxicity and anti-social behavior.
“When you add this to all the other studies that have been done on this subject in the last few years, it creates a body of evidence, which — in conjunction with the basic science looking at how fluoride may be toxicologically active on the brain — suggests that the impact of fluoride on neurobehavioral development problems is causal,” Dr. Hu told Children’s Health Defense. “It’s not just an epidemiological association.”
These statements echo what Hu told me after his testimony at the fluoride lawsuit hearings in San Francisco.
“Yes. I would say that, in my view, the evidence is quite persuasive that there is a negative impact of fluoride exposure on the neurodevelopment of children, particularly the research that’s been coming out in prenatal exposure.”
Hu’s statements were part of an eight-year legal battle between the EPA and the Fluoride Action Network (FAN). The lawsuit began following the EPA’s 2016 decision to deny the plaintiff’s petition under the Toxic Substances Control Act (TSCA). The FAN is attempting to prove that fluoride is a neurotoxin and should be regulated or banned under the TSCA.
Dr. Hu was the principal investigator in the Mexico ELEMENT study, a pregnancy and birth cohort on fluoride’s impact on neurobehavioral development. The research was funded by the EPA and the National Institutes of Health.
During the hearings, FAN attorney Michael Connett asked Dr. Hu about the fact that some studies have found different associations for boys and girls, and whether or not these studies can all be true. Hu described various factors that can split the data in such a way, including different populations, life experiences, diet, and hormones.
“Would you expect a neurotoxicant, like fluoride, could have different impact on populations?” Connett asked Hu during his testimony. “Yes. We haven’t tried to account for differences with our colleagues in Canada, but there is a whole set of factors that we know could be in play.”
Dr. Hu was also one of the expert witnesses to testify to the increasing concentration of fluoride which could potentially pass from a pregnant mother to her child. Connett showed Hu a graph comparing the Canadian study, known as the MIREC cohort, and Hu’s more recent study in Mexico, known as the MADRES cohort, both of which indicated higher levels of fluoride within the urine of pregnant mothers in the 3rd trimester.
Hu explained a baby in the 3rd trimester typically pulls calcium from the mother’s bones as it develops its skeletal structure. If a mother is receiving fluoride this will be stored in her bones. When her child begins pulling minerals from the mother it will also receive fluoride via the placenta.
While testimony from the FAN and the EPA has concluded in the fluoride lawsuit, the public is still awaiting a decision from Judge Edward Chen.
