Increased levels of prenatal fluoride exposure have been linked to lower intelligence in children, according to the results of a new study.
In the eye-opening new peer-reviewed study, published on September 19, 2017, in the Journal of Environmental Health Perspectives, researchers found strong evidence of a link between fluoride and lower cognitive function in children.
With an impact factor of 9.78, Environmental Health Perspectives is one of the most highly ranked journals in Toxicology, Public, Environmental and Occupational Health, and Environmental Sciences.
The researchers found that “higher levels of maternal urinary fluoride during pregnancy (a proxy for prenatal fluoride exposure) that are in the range of levels of exposure in other general population samples of pregnant women as well as nonpregnant adults were associated with lower scores on tests of cognitive function in the offspring at 4 and 6–12 y old,” according to the study.
The study involved 1,576 samples taken from over 300 sets of mothers and children in Mexico by a research team from Toronto. The researchers tested the children’s cognitive development twice over the course of 12 years. In Mexico, Fluoride is not added to public water supply, but people are exposed through naturally occurring fluoride in water, toothpaste, fluoridated salt and other supplemental products.
"Childhood exposure to fluoride is safer than prenatal. There is pretty good science now to support the fact that the fetal system tends to be more sensitive to environmental toxicants than once the child is born," said the study's lead author, Howard Hu, founding dean of the Dalla Lana School of Public Health at the University of Toronto, according to CNN.
The authors of the study looked for chemical markers in the urine of mothers and children, as previous studies attempted to measure fluoride exposure by analyzing environmental factors, such as water.
"Since we're using an integrated biological marker, it will give you a fairly standardized measure," Hu explained.
Interestingly, the study found significant effect – with an increase in urine fluoride of 1mg/l being associated with a 5 to 6 point drop in IQ score. For perspective, the average fluoride intake in Mexican mothers was roughly the same as that of women in the United States.
“The range of fluoride levels in Mexico also corresponded closely to the range found in most of the USA. The higher levels were similar to what is found in areas in the USA with fluoridated water, and the lower levels were similar to what is found in most unfluoridated parts of the USA,” according to the Fluoride Action Network (FAN).
According to a report by FAN:
Most of the Mexican women had urine fluoride between 0.5 and 1.5 mg/L. Studies have found that adults in the USA have between about 0.6 and 1.5 mg/L, almost exactly the same range. From the low end of that range to the high end is a difference of 1 mg/L which is what caused the 5 to 6 IQ point difference in the children of the study mothers.
The study found a drop in scores on intelligence tests for every 0.5 milligram-per-liter increase in fluoride exposure beyond 0.8 milligrams per liter found in urine. However, although the researchers found a potential connection to a child's exposure to fluoride in utero, they found no significant influence from fluoride exposure on brain development once a child was born.
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The study reveals the relationship between urine fluoride and IQ in the graph reproduced here:
FAN has recreated the graph in simplified form to more clearly illustrate the relationship between mothers’ urine fluoride and children's IQ.
This simplified version of the graph highlights the range of urine fluoride levels common in women in the USA with the blue text and bracket. When comparing mothers at the low end to those at the high end of this range, the subsequent loss of IQ in their children was 6 points. The light red shaded zone around the relationship line is the 95% Confidence Interval and demonstrates that the relationship is statistically significant across the entire range of fluoride exposures.
This is not the first time fluoride has been shown to act as a neurotoxin.
"There have been similar findings related to exposure to fluoride and IQ from children in China. So this observation or association has been reported before," Linda Birnbaum, director of the National Institute of Environmental Health Sciences, told CNN. Birnbaum was not involved in the study.
In 2012, researchers from the Harvard School of Public Health (HSPH) working in conjunction with China Medical University in Shenyang conducted a meta-analysis of 27 related studies published in Environmental Health Perspectives. The report noted that “fluoride may adversely affect cognitive development in children,” adding “children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas.”
Following up on the original findings, the Harvard cooperative team found“fluoride in drinking water may produce developmental neurotoxicity.”
“Results of our pilot study showed that moderate and severe dental fluorosis was significantly associated with deficits in WISC-IV digit span. Children with moderate or severe dental fluorosis scored significantly lower in total and backward digit span tests than those with normal or questionable fluorosis. These results suggest a deficit in working memory,” according to the Harvard cooperative study.
While some of the Chinese studies were unable to control for other potential neurotoxins such as lead or mercury, giving it less validity, the new Mexican study controlled for those two neurotoxins, along with socioeconomic status, education and numerous other factors.
“This is a very well-conducted study, and it raises serious concerns about fluoride supplementation in water,” Dr. Leonardo Trasande, a pediatrician who studies potential links between environmental exposures and health problems at New York University Langone Health, told Newsweek. (He was not involved in the new study.)
It seems clear that pregnant women should stay away from fluoride, as it appears to clearly and significantly affect the neurological development of their children in utero, and the rest of the population would likely be wise to do the same given the numerous studies critical of fluoride.
Please share this important information -- and especially with anyone you know who is pregnant!