Fluoride Neurotoxicity

Fluoride Developmental Neurotoxicity

  • Approximately 100 developmental neurotoxicity test set chemicals have been  identified by US EPA. Of those chemicals, EPA has identified 22%, including fluoride, with both significant evidence of neurotoxicity in animal studies from multiple laboratories, and with significant documented human evidence of harm.
  • Because of evidence linking fluoride to impaired brain development, NTP plans an investigation into the developmental neurotoxicity of fluoride. In 2015, Dr. Kristina Thayer of the US NTP (National Toxicology Program of the National Institute of Health) outlined reasons for the studies that NTP seeks to conduct on fluoride. Those studies include a systematic review of the existing research on fluoride’s developmental neurotoxicity, including human, animal, and cellular studies, and  NTP’s own animal experiments, to clarify fluoride’s effects on learning and memory and the doses at which these effects can occur. (2, 3)
  • After promoting higher fluoride levels, encouraged as safe for decades, because at least 41% of young teenagers (ages 12 to 15) in the U.S. have visible dental fluorosis (damaged enamel presenting as permanent white, yellow, or brown marks on teeth, with pitted and flaking enamel in severe cases), US HHS now advises that water fluoride levels be lowered to 0.7 mg/L. Future evaluations would determine whether the new concentration level provides the desired outcomes, a decline in rates of visible dental fluorosis, with no increase in dental caries rates. (4, 5)
  • A new review by the Cochrane Collaboration finds no recent or high quality research proving fluoridation reduces tooth decay, but did find that 40% of children in fluoridated areas have dental fluorosis. (6)
  • A 2015 study, including subjects with lifetime exposures to fluoride levels overlapping the range of levels allowed in U.S. fluoridation programs, reports the results of a simple, specific mental development test: the child’s ability to repeat a sequence of numbers both forwards and backwards. Even children with very mild dental fluorosis performed less well than children without fluorosis. (7)
  • The first study to systemically examine the relationship between a behavioral disorder and fluoridation found that U.S. states with higher rates of artificially fluoridated water had a higher prevalence of ADHD, with water fluoridation rates “significantly positively correlated with state prevalence of ADHD for all but one year examined.” (8)

REFERENCES

(1) Expanding the test set: Chemicals with potential to disrupt mammalian brain development.” EPA Review article. Neurotoxicology and Teratology 52 (2015) 25 / William R. Mundy, et al. PDF. Building a Database of Developmental Neurotoxicants: Evidence from Human and Animal Studies.” EPA Chart. W. Mundy, et al. Neurotoxicology and Teratology. PDF. Both documents were approved by the National Health and Environmental Effects Research Laboratory (NHEERL), a division of EPA.

(2) Nominations to the Report on Carcinogens and Office of Health Assessment and Translation; Request for Information. “ A Notice by the National Institutes of Health. Federal Register, The Daily Journal of the United States Government (10/07/2015).

(3) Concept: Proposed NTP Evaluation on Fluoride Exposure and Potential for Developmental Neurobehavioral Effects.” Presentation by Dr. Kristina Thayer, NIEHS/DNTP. NTP Webinar (December 2, 2015). Conference Agenda.

(4) HHS issues final recommendation for community water fluoridation: Adjusted level seeks to maintain dental health benefits of fluoride.” HHS Press Office,  U.S. Dept. of Health and Human Services (April 27, 2015).

(5) U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries.” Reports and Recommendations. Public Health Reports (July–August 2015), Volume 130, page 10.

(6)Water fluoridation for the prevention of dental caries.” Z. Iheozor-Ejiofor, et al. Cochrane Oral Health Group. (June 18, 2015)

(7) Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study. Choi, et al. Neurotoxicology and Teratology (Jan-Feb. 2015)

(8) Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association.” Christine Till and Ashley Malin, York University, Toronto. Environmental Health (February 27, 2015).