Bottom Line: An observational study of 601 mother-child pairs from six cities in Canada hints at an apparent association between maternal exposure to fluoride during pregnancy and lower IQ scores measured in children ages 3 to 4. Community water has been fluoridated for decades to prevent tooth decay; a majority of U.S. residents are supplied with fluoridated water, as are more than one-third of Canadian residents and about 3% of European residents. This study analyzed two measures of fluoride exposure during pregnancy. Data on maternal urinary fluoride concentrations and children's IQ were available for 512 mother-child pairs, and self-reported consumption of tap water and other water-based drinks (tea and coffee) and IQ scores were available for 400 of the 601 mother-child pairs. After accounting for factors associated with fluoride metabolism and children's intellectual abilities, a 1-mg/L increase in maternal urinary fluoride was associated with a 4.5-point lower IQ score in boys without a statistically significant association with IQ score in girls. A 1-mg higher intake of fluoride was associated with a 3.7 lower IQ score among boys and girls. The study's conclusions are limited by its observational design, which can't account for unmeasured factors that could explain the results, and there was no assessment of children's fluoride exposure during infancy. An accompanying podcast discusses the meaning and implications of the findings.
Author: Christine Till, Ph.D., of York University, Toronto, Canada, is the corresponding author.
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