Excessive Maternal Fluoride Levels May Lower Child IQ

High prenatal fluoride exposure during pregnancy is associated with poorer scores on tests of cognitive function in offspring, according to a new study.

Researchers at the University of Toronto (Canada), Instituto Nacional de Salud Pública (Cuernavaca, Mexico), and other institutions conducted a study of 299 mother–child pairs to estimate the association of prenatal exposure to fluoride with offspring neurocognitive development. The researchers used an ion-selective electrode technique to measure fluoride in archived urine samples taken from mothers during pregnancy and from their children when 6–12 years old, adjusted for urinary creatinine and specific gravity.

Child intelligence was measured by the general cognitive index (GCI) of the McCarthy Scales of Children’s Abilities at age four, and full-scale intelligence quotient (IQ) from the Wechsler Abbreviated Scale of Intelligence (WASI) was measured at ages 6–12. Mean values for urinary fluoride in all of the mothers and children were 0.90 mg/L and 0.82 mg/L, respectively. Analysis revealed that an increase in maternal urine fluoride of 0.5mg/L predicted a reduction of 3.15 in the children’s GCI and 2.50 in their IQ scores, respectively. The study was published in the September 2017 issue of Environmental Health Perspectives.

“Our study shows that the growing fetal nervous system may be adversely affected by higher levels of fluoride exposure. It also suggests that the prenatal nervous system may be more sensitive to fluoride compared to that of school-aged children,” concluded study co-author Howard Hu, MD, of the University of Toronto, and colleagues. “Our findings, combined with evidence from existing animal and human studies, reinforce the need for additional research on potential adverse effects of fluoride, particularly in pregnant women and children.”

Fluoride is the simplest anion of fluorine. Community water, salt, milk, and dental products have been fluoridated for more than 60 years to prevent dental caries, while fluoride supplementation has been recommended to prevent bone fractures. In addition, people may be exposed to fluoride through the consumption of naturally contaminated drinking water, dietary sources, dental products, and other sources. The maximum safe daily consumption of fluoride is 10 mg/day for an adult (U.S.) or 7 mg/day (European Union).

Related Links:
University of Toronto
Instituto Nacional de Salud Pública