- Elevated fluoride concentrations in drinking water may be neurotoxic.
- We carried out a pilot study of 51 first-grade children with stable lifetime fluoride exposures.
- Moderate and severe fluorosis was associated with deficits in digit span total and backward scores.
- The dose-dependence underlying the association needs to be characterized in detail.
Background: A systematic review and meta-analysis of published studies on developmental fluoride neurotoxicity support the hypothesis that exposure to elevated concentrations of fluoride in water is neurotoxic during development.
Methods: We carried out a pilot study of 51 first-grade children in southern Sichuan, China, using the fluoride concentration in morning urine after an exposure-free night; fluoride in well-water source; and dental fluorosis status as indices of past fluoride exposure. We administered a battery of age-appropriate, relatively culture-independent tests that reflect different functional domains: the Wide Range Assessment of Memory and Learning (WRAML), Wechsler Intelligence Scale for Children-Revised (WISC-R) digit span and block design; finger tapping and grooved pegboard. Confounder-adjusted associations between exposure indicators and test scores were assessed using multiple regression models.
Results: Dental fluorosis score was the exposure indicator that had the strongest association with the outcome deficits, and the WISC-R digit span subtest appeared to be the most sensitive outcome, where moderate and severe fluorosis was associated with a digit span total score difference of ? 4.28 (95% CI ? 8.22, ? 0.33) and backward score with ? 2.13 (95% CI ? 4.24, ? 0.02).
Conclusions: This pilot study in a community with stable lifetime fluoride exposures supports the notion that fluoride in drinking water may produce developmental neurotoxicity, and that the dose-dependence underlying this relationship needs to be characterized in detail.
SEE CORRIGENDUM at http://fluoridealert.org/wp-content/uploads/choi-2015.corrigendum.pdf