Researchers recently evaluated the impact of prenatal exposure to 26 endocrine disruptors on the IQ scores of seven-year-old children.
Researchers at the Icahn School of Medicine at Mount Sinai and from Sweden and Finland discovered that prenatal exposure to a mixture of suspected endocrine disruptors (EDCs) is associated with a lower IQ in children. This study published in Environment International is unique as it looked at the effect of a mixture of suspected EDCs on neurodevelopment, whereas most prior research has only looked at the effect of a single EDC in isolation.
The Swedish Environmental Longitudinal Mother and Child, Asthma and Allergy (SELMA) study quantified the presence of 26 suspected EDCs in blood and urine samples from 718 mothers during the first trimester of their pregnancies. In particular, phthalates, bisphenols, perfluoroalkyl substances (PFASs), organochlorines and other short-lived pollutants were analyzed. Seven years later, psychologists assessed the IQ (overall cognitive abilities) of the children and the researchers used Weighted Quantile Sum regression and repeated holdout validation as tools to estimate the impact of the EDC mixture on IQ and identify the chemicals of concern in that mixture.
Exposure to endocrine disruptors linked with lower IQ scores
The researchers found that children (particularly boys) whose mothers had higher levels of the EDC mixture during pregnancy, had IQ scores that were lower by two points. Bisphenol F (BPF), which was created to replace bisphenol A (BPA), a harmful substance present in plastic food and drink containers made the largest contribution to lowering children’s IQ suggesting that bisphenol F may not be any safer to adverse neurodevelopmental outcomes than BPA. It is interesting to note that IQ scores obtained were similar when the regression analysis was rerun without BPF indicating that BPF by itself does not fully explain the impact on IQ. Among all children, other chemicals of concern were mostly short-lived pollutants including 3, 5, 6-trichloro-2-pyridinol (TCP) which is present in insecticides, monoethyl phthalate (MEP) which is present in perfume, soap, shampoo, and other personal care products, and perfluorooctanoic acid (PFOS) which is present in non-stick cookware and food packaging.
Since EDCs are in the environment, food, consumer products, and building materials, prenatal exposure to them is practically unavoidable.  Even at low doses, EDCs have the ability to interfere with hormone homeostasis and previous studies have suggested that EDCs, including phthalates and BPA are associated with neurodevelopmental difficulties in children. Although the biological mechanism of how exactly EDCs influence cognitive functioning is not fully known, scientists suspect that multiple EDC’s may interact to elicit unexpected hormone changes. Scientists also fear that prenatal exposure to endocrine disruptors even for a short time may cause permanent health outcomes into adulthood. Therefore, preventing prenatal exposure to endocrine disruptors is of upmost importance for mitigating harmful effects on children.
However, the study did not account for the socioeconomic status of the family when assessing IQ scores and the study did not account for the impact of EDC exposure later in pregnancy and childhood.. Future studies are needed to confirm the negative impacts of BPF and other replacement compounds and much more research is needed to confirm these findings.
Written by Maria-Elena Bernal B.Sc. (Hons)
References:
- Tanner, E. M., Hallerbäck, M. U., Wikström, S., Lindh, C., Kiviranta, H., Gennings, C., & Bornehag, C.-G. (2019, October 24). Early prenatal exposure to suspected endocrine disruptor mixtures is associated with lower IQ at age seven. Retrieved from https://www.sciencedirect.com/science/article/pii/S0160412019314011#f0010.
- (n.d.). Chemicals in consumer products during early pregnancy related to lower IQ. Retrieved from https://www.eurekalert.org/pub_releases/2019-10/tmsh-cic102319.php.
Image by Raman Oza from Pixabay
