In the concluding paragraph, the authors stated.... "This study adds to the growing evidence that even low-level fluoride exposure early in life may adversely impact child cognition." A doubling of urinary exposure above 0.72 mg/L in 5 and 10 year old children resulted in a decrease of full-scale raw scores by 12. Urine fluoride levels were measured in 500 pregnant women at 8 weeks gestation and in their children at 5 & 10 years of age. Researchers stated that all levels of fluoride appeared to have an adverse effect on child cognition. Continue reading for concluding remarks and ABSTRACT from the study authors.
In their concluding remarks, the researchers stated, "This study adds to the growing evidence that even low-level fluoride exposure early in life may adversely impact child cognition. Prenatal exposure was associated with lower cognitive abilities with no indication of a threshold..... Both perceptual reasoning and verbal ability appeared to be affected. Because even minor changes in cognition at a population level can have important implications for public health, the overall results raise concerns about the existing guidelines and standards for fluoride in drinking water."
ABSTRACT
Background:
There are indications that fluoride exposure considered to be beneficial for dental health may not be safe from a neurodevelopmental perspective.
Objective:
We assessed the impact of prenatal and childhood fluoride exposure on cognitive abilities at 5 and 10 years of age.
Methods:
We studied 500 mother–child pairs from the MINIMat (Maternal and Infant Nutrition Interventions in Matlab) birth cohort in rural Bangladesh. Urinary fluoride concentrations were measured in pregnant women at gestational week 8 and in their children at 5 and 10 years of age using an ion-selective electrode and adjusting for specific gravity. Cognitive abilities were assessed using the Wechsler Preschool and Primary Scale for Intelligence, Third Edition, and the Wechsler Intelligence Scale, Fourth Edition, at 5 and 10 years of age, respectively. Associations of urinary fluoride concentrations (log2-transformed) with cognitive abilities (raw scores) were assessed with multivariable-adjusted linear or spline regression models. Water fluoride concentrations at the time of the follow-up of the children at 10 years of age were also measured.
Results:
Maternal urinary fluoride concentrations (median: 0.63mg/L, 5th to 95th percentiles, (0.26 to 1.41mg/L) were inversely associated with full-scale raw scores at 5 and 10 years, B (95% confidence interval), minus 2.8 (minus 5.1 to 0.6) and minus 4.9 (minus 8.0 to 1.8), respectively, by exposure doubling. In cross-sectional analysis at 10 years, child urinary fluoride (overall median, 0.66mg/L, 5th to 95th percentiles, 0.34 to 1.26mg/L) above minus 0.47 on the log2-scale (corresponding to 0.72mg/L) was inversely associated with full-scale raw scores, B (95% confidence interval), minus 12.1 (minus 21.2 to 3.0).
The association at 5 years of age was also negative but nonsignificant. For both prenatal and childhood exposure, associations were most noticeable with perceptual reasoning, but also verbal scores. The estimate for the association between urinary fluoride at 10 years of age and perceptual reasoning became 18% lower after adjustment for prenatal exposure. Inconsistent sex-specific differences were observed.
Conclusion:
Urinary fluoride concentrations measured prenatally and during childhood (child urinary fluoride concentrations above − 0.47 on the log2 scale, corresponding to 0.72mg/L) were associated with lower cognitive abilities, especially perceptual reasoning and verbal abilities, in Bangladeshi children 305-Unexpected worsening of fluorosis from 1986 to 2012
https://pubmed.ncbi.nlm.nih.gov/30931722/
University of Toronto, Canada
Source: JDR Clinical Translational Research, Oct 2019
Fluorosis is a condition where fluoride causes unsightly white and brown stains on teeth and is caused by too high an exposure to fluoride. Looking at data from national US surveys, including the National Health and Nutrition Examination Survey, fluorosis in 12-15 year old children was 22% in 1986-87. It rose to 41% in 1999-2004 and reached 65% in the 2011-2012 survey. In a second study on the topic (reviewed herein), the rate of child fluorosis went up even further to 87.3% in 2013-2014. Interestingly, it was reduced to 68.2% in 2015-2016, which is right after the government reduced fluoride from 1.2 to .07 mg/L. The rate of combined moderate and severe fluorosis increased the most, going from 1.2% in the 1986-87 sample to 3.7% in 1999-2004 and then 30.4% in 2011-12. As fluorosis is associated with increased neurological problems in children, this trend is of concern. Explanations for the increase in fluorosis include exposure from brushing teeth as well as increased fluoride residues in food (coming from fertilizer applications).