Prenatal Water Fluoride Exposure and Children's Behavioral Problems.

Importance: Although fluoride exposure at high levels during the perinatal period has been associated with socioemotional problems among children, there is limited evidence regarding potential associations at lower levels of fluoride exposure, particularly in the US. Objective: To examine the association between prenatal exposure to public drinking water fluoride levels and children's socioemotional problems in a pooled US pediatric consortium. Design, Setting, and Participants: This cohort study used observational pregnancy cohort data from January 1, 2005, to December 31, 2019, on children aged 1.5 to 17 years from the Environmental Influences on Child Health Outcomes (ECHO) Cohort, which took place at 20 prenatal pediatric cohort sites across 34 US states. Statistical analysis was conducted from December 2024 to December 2025. Exposure: Area-level, time-weighted, mean fluoride concentrations in public water were estimated based on residential addresses during pregnancy. Main Outcomes and Measures: Children's socioemotional problems were assessed using caregiver reports of internalizing and externalizing problems via the Child Behavior Checklist. Generalized estimating equation models evaluated the adjusted mean difference in T scores (1) across the range of exposure values in cubic spline models, (2) per 500.0-µg/L higher fluoride level in linear models, (3) across quartiles of exposure, and (4) at the US Public Health Services recommended cutoff (≤700.0 µg/L; 3998 less than the cutoff). Results: The cohort comprised 5520 children (mean [SD] age, 5.8 [3.0] years; 2849 boys [51.6%]). The mean (SD) prenatal time-weighted water fluoride level was 407.9 (361.0) µg/L (range, <1.4-3272.5 µg/L). The adjusted mean difference in emotional and behavioral problem T scores per 500.0-μg/L higher exposure to prenatal public water fluoride was -0.15 (95% CI, -0.85 to 0.56) for internalizing problems and 0.06 (95% CI, -0.44 to 0.55) for externalizing problems, consistently showing no associations at the continuous level. However, some positive associations were observed only when using change point models for externalizing problems (adjusted mean difference, 1.59 [95% CI, 0.72-2.47] per 500.0-µg/L increase above the inflection point), and for some subgroups. Conclusions and Relevance: In this cohort study, prenatal exposure to fluoride levels in regulated public water was not associated with internalizing and externalizing problems among offspring. In change point models, positive associations were found for externalizing problems. The results contribute to growing evidence that could inform future policy decisions regarding fluoride in the US public water systems. Additional studies are needed to further investigate this association, especially examining other sources of fluoride that may have an association with children's emotional and behavioral problems.