Association Between Maternal Fluoride Exposure and IQ in Offspring

by | Sep 23, 2019 | 2019, Environmental Health, Infant and Children's Health, Pregnancy and Lactation, Water

Written by Jessica Patella, ND. This study found an association between higher levels of fluoride exposure during pregnancy and lower IQ scores in three to four year old children. 

health hazards - waterA recent research study tried to examine the long-standing question of fluoridation of water and the cost/benefit ratio.  Fluoridation of the water supply has been touted for the prevention of toothy decay, yet there is concern due to the fact that fluoride can cause neurotoxicity 1.  Currently, an estimated 66% of US residents, 38% of Canadian residents and only 3% of European residents consume fluoridated tap water 1,2.  Water fluoridation originally began in the 1950s before dental products were fluoridated to prevent tooth decay and reduce the risk of enamel mottling 1,3.

Research has shown that fluoride crosses the placenta and accumulates in the brain in areas required for learning and memory 1,4.  A past meta-analysis with over 27 epidemiological studies showed higher fluoride exposure from drinking water was associated with lower IQ-scores in children 1,5. The current research wanted to examine effects of fluoride levels in utero.  Participants were included from the Maternal-Infant Research on Environmental Chemicals (MIREC) program across 10 cities in Canada 1.

Concentration of fluoride in the urine of mothers across all 3 trimesters of pregnancy was used as a measure.  This data point was then matched with data from the fluoride levels of water treatment  plants 1.  Lastly, daily fluoride intake in mothers was collected via questionnaire across all 3 trimesters to include tea and coffee intake, because black tea contains high fluoride content. The children’s IQ-score was calculated using the Wechsler Preschool and Primary Scale of Intelligence between ages 3-4 years 1.  Of the 601 children, 42.3% lived in non-fluoridated regions, 30% lived in fluoridated regions and 27.7% fluoridation status was unknown due to missing water data or reported not drinking tap water 1.

The findings were as follows:

  • The average concentration of fluoride in maternal urine was significantly higher in women who lived in communities with fluoridated drinking water (0.69 [0.42]mg/L) compared to women who lived in communities without fluoridated drinking water (0.40 [0.27]mg/L; P<0.001) 1.
  • An increase of 1mg/L of maternal concentration of fluoride in the urine was associated with a 4.49 (95%CI, -8.33 to -0.60; P=0.02) lower IQ score for boys. In contrast, maternal urine fluoride concentration was not associated with IQ scores in girls 1.
  • A 1 mg increase in fluoride intake from water, foods or beverages in the pregnant mother was associated with a 3.66 (95% CI, -7.16 to -0.15; P=0.04) lower IQ score among boys and girls 1.

In conclusion, higher levels of fluoride exposure during pregnancy is associated with lower IQ scores in children from 3-4 years of age 1.  This was the first study to estimate fluoride exposure in a large birth cohort receiving optimally fluoridated water.  These findings support that fluoride exposure in utero may be associated with neurocognitive deficits and therefore the possible need to reduce fluoride intake during pregnancy 1.

Source: Green, Rivka, Bruce Lanphear, Richard Hornung, David Flora, E. Angeles Martinez-Mier, Raichel Neufeld, Pierre Ayotte, Gina Muckle, and Christine Till. “Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada.” JAMA pediatrics (2019).

© 2019 American Medical Association. All rights reserved.

Posted September 23, 2019.

Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health.  She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians.  Visit her website at  www.awarenesswellness.com.

References:

  1. Green R, Lanphear B, Hornung R, et al. Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA pediatrics. 2019.
  2. Canada PHAo. The State of Cummunity Water Fluoridation across Canada. 2017.
  3. Martinez-Mier EA, Shone DB, Buckley CM, Ando M, Lippert F, Soto-Rojas AE. Relationship between enamel fluorosis severity and fluoride content. Journal of dentistry. 2016;46:42-46.
  4. Jiang C, Zhang S, Liu H, et al. Low glucose utilization and neurodegenerative changes caused by sodium fluoride exposure in rat’s developmental brain. Neuromolecular medicine. 2014;16(1):94-105.
  5. Choi AL, Sun G, Zhang Y, Grandjean P. Developmental fluoride neurotoxicity: a systematic review and meta-analysis. Environmental health perspectives. 2012;120(10):1362-1368.