Background/Aim: Developmental neurotoxicity of fluoride has been demonstrated in animal studies. Additionally, fluoride exposure during prenatal development, infancy, middle-to-late childhood and adolescence has been associated with poorer neurodevelopmental outcomes among children in Mexico and/or Canada. However, potential impacts of chronic low-level fluoride exposure in early childhood on brain structure and neurodevelopment remain relatively unexamined. We conducted the first United States (US) study to examine associations of early childhood urinary fluoride levels with measures of attention and executive function, as well as changes in white matter (WM) microstructure in the brain.
Methods: This community-based sample included 31 children ages 4-6-years recruited from New York City. Executive function was assessed with the Behavior Rating Inventory of Executive Function (BRIEF) and attention and behavior were assessed with the Child Behavior Checklist (CBCL). We assessed whole brain WM microstructure integrity using diffusion tensor imaging (DTI). We applied linear regression to examine associations of urine fluoride with measures of attention, behavior and executive functioning, as well as fractional anisotropy (FA), a common DTI measurement of WM integrity. Urine fluoride concentrations were adjusted for specific gravity to correct for dilution (UFSG). Regression models were adjusted for a priori covariates including age, sex and race. Results: The median (IQR) urine fluoride level was 0.72 (0.49) mg/L. Most children scored within the normal and non-clinical range on measures of attention, behavior and executive function. We did not observe significant associations between UFSG and any of the behavioral outcomes assessed; however, higher UFSG was significantly associated with decreased FA in the dorsolateral prefrontal cortex (p<0.05 fdr adjusted for multiple comparisons, cluster size = 56 voxels).
Conclusions: Early childhood fluoride exposure may contribute to subclinical changes in brain regions implicated in executive functioning. Future prospective studies are needed to examine behavioral consequences of these neurological changes.
*Abstract in the Conference Abstract E-Book at http://fluoridealert.org/wp-content/uploads/isee2020.abstract-e-book..pdf
This abstract was presented in ORAL SESSION 14 at the virtual 32nd Conference of ISEE.
Ashley Malin, E. Rechtman, E. Navarro, J. Nu, M. Lun, C. Tang, and K. Horton
Icahn School of Medicine at Mount Sinai, New York
E. De Water, University of Minnesota, Minneapolis, MN.