Fluoride Exposure and Child Cognitive Development: A Critical Review of the Evidence

Abstract

Background Community water fluoridation (CWF) has long been championed as a cost-effective public health measure for the prevention of dental caries. However, in recent years, growing concern has emerged regarding the potential neurodevelopmental effects of fluoride exposure, especially during prenatal and early childhood periods. An increasing number of epidemiological studies have reported associations between fluoride levels in drinking water and cognitive outcomes in children, raising questions about the safety of current fluoridation guidelines.

Aim This review critically evaluates the scientific evidence on the relationship between fluoride exposure, particularly from drinking water, and cognitive development in children, with a focus on methodological quality, exposure thresholds, and public health implications.

Methods A narrative review was conducted using comprehensive searches of PubMed and Web of Science (2000–2025). Studies were eligible if they assessed fluoride exposure from water or other environmental sources and its association with validated cognitive measures in children ≤18 years. Systematic reviews, meta-analyses, cohort studies, case control studies, and cross-sectional studies were considered. A total of 26 studies met the inclusion criteria. Data were extracted and narratively synthesised.

Results Only three studies evaluated CWF at recommended concentrations, and all reported no association with child cognition. Across syntheses restricted to ≤1.5 mg/L and cohort analyses in fluoridated settings, CWF-range exposure showed no consistent association with lower IQ. In contrast, studies from naturally high-fluoride groundwater contexts more often reported inverse associations particularly when water concentrations exceeded ~2 mg/L; of 12 studies, 10 reported an association and 2 reported no association. Prenatal analyses using maternal urinary fluoride (MUF) indicated small, sometimes sex-specific inverse associations (~2–3 IQ points per +0.5 mg/L), but about half of MUF studies reported null findings.

Conclusion Within guideline CWF levels (~0.5–1.0 mg/L and up to ≤1.5 mg/L), there is no evidence suggesting cognitive harm; potential risks are clearer in high-fluoride groundwater settings and in some prenatal MUF analyses. Future work should prioritise stronger exposure assessment and confounding control at policy-relevant concentrations. On balance, CWF at recommended levels is considered safe, and no immediate policy change is warranted.