Background: There is increasing evidence suggesting that prenatal exposure to fluoride is associated with lower neurocognitive performance in offspring. The objective of this study is defining periods in early life associated with greater sensitivity to fluoride exposures.
METHODS: This study focused on participants from the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) project. Fluoride in archived urine samples taken from mothers across the trimesters of pregnancy were measured and adjusted for urinary creatinine (MUFcr). The main outcome of this analysis was the General Cognitive Index (GCI) of the McCarthy Scales of Children’s Abilities at age 4. Regression models were used to assess the associations between prenatal fluoride at each trimester of pregnancy and GCI adjusted for gestational age, weight at birth, sex, parity , age at outcome measurement, and maternal characteristics including smoking history, marital status, age at delivery, IQ, education, and sub-cohort.
RESULTS: Complete data were available for 256 mother-child pairs for trimester 1, 241 for trimester 2 and 115 for trimester 3. Mean and Standard Deviation (SD) of MUFcr were 0.93 (0.42) mg/L for trimester 1, 0.99 (0.53) for trimester 2 and 0.84 (0.41) for trimester 3. In multivariate models an increase of 1 mg/L MUFcr was associated with declines in GCI scores of -4.9 (95% CI; -8.80, -1.10) in trimester 1 and -3.35 (95%CI; -6.24, -0.47) in trimester 2, respectively. There were no significant associations between MUFcr and GCI score in trimester 3.
CONCLUSION: In this study, trimester-specific analyses suggest that fluoride exposure during the early trimesters of pregnancy may have the strongest negative effect on offspring neurocognitive outcomes.
*Abstract in the Conference Abstract E-Posters at http://fluoridealert.org/wp-content/uploads/isee2020.abstract-e-posters.pdf