A large US cohort study reveals no significant overall association between prenatal fluoride in public water and behavioural problems in children, though increased externalising symptoms at higher exposure levels warrant further research.
A large US cohort study has found no overall link between fluoride exposure in public drinking water during pregnancy and later emotional or behavioural problems in children, although a closer look at higher exposure levels suggested a possible increase in externalising symptoms that will need more research.
The study, published in JAMA Network Open, followed 5,520 children in the Environmental Influences on Child Health Outcomes cohort across 20 sites in 34 states. Researchers estimated fluoride exposure at the census-tract level from public water compliance records, then linked those estimates to each month of pregnancy using residential address histories. Child behaviour was later assessed with the Child Behaviour Checklist, a parent-completed questionnaire that measures internalising problems such as anxiety and sadness, and externalising problems such as aggression and rule-breaking.
Overall, the analysis did not find a statistically significant association between prenatal fluoride exposure and either type of behavioural problem. That result held when fluoride exposure was treated as a continuous measure and when the researchers compared women exposed to levels above the US Public Health Service’s recommended concentration of 700 micrograms per litre with those at or below it. Sensitivity analyses were also consistent with the main finding.
The authors did identify a model-based change point for externalising problems at 625 micrograms per litre. Above that level, scores rose modestly with increasing exposure, but the threshold was statistical rather than a recognised safety limit. A separate change point for internalising problems appeared at a much higher level, though too few children were exposed above it for the researchers to draw a firm conclusion. The paper also reported subgroup findings that were not statistically significant overall, including a negative association for internalising problems in multiracial children and a positive association for externalising problems among children aged six and older.
The findings add to a mixed but increasingly careful literature on fluoride and child development. A 2021 study in Environmental Research that used maternal urine samples found no significant link between prenatal fluoride exposure and early childhood neurodevelopment. More recently, a 2026 Environmental Health Perspectives study using the MIREC cohort likewise reported no meaningful association between prenatal fluoride exposure and autistic traits in preschool children, while a separate US study published in the American Journal of Epidemiology found no adverse effect on cognition.
That picture differs from some work on other fluoride-related chemicals and exposure measures. Studies of per- and polyfluoroalkyl substances, or PFAS, a separate class of man-made chemicals, have reported links between prenatal exposure and children’s behaviour in some cohorts, including higher externalising and aggressive behaviour in certain analyses. The fluoride paper’s authors said the contrast may reflect differences in how exposure was measured, since their study focused on drinking water rather than urine biomarkers, which capture fluoride from multiple sources.
The researchers also noted important limits. They could not account for fluoride exposure after birth, detailed water-drinking habits, or non-residential sources of water, and the study population was mostly White, non-Hispanic and college educated, which may restrict how widely the findings can be applied. Even so, the authors said the study does not support an overall association between prenatal fluoride in public water and children’s emotional or behavioural health at the levels studied.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
