Phthalates are chemical substances used in plasticizers and other everyday products (food packaging, cosmetics…), which can be harmful to health. Now, a study provides new evidence that exposure to plasticizers during pregnancy influences brain development in the fetus and is associated with lower volumetric measurements in the brain and lower IQ in childhood.
The research has been published in Molecular Psychiatry and reveals that the sons and daughters of women who had greater exposure to certain phthalates during pregnancy were more likely to show less total gray matter in their brains at age 10. The results also indicate an association between gestational exposure to plasticizers and lower white matter volumes in girls.
The research has been led by the NYU Grossman School of Medicine and the Barcelona Institute for Global Health (ISGlobal) and has also proven that the exposure of pregnant women to plasticizers is associated with a lower IQ of their children when they are 14 years old. , which confirms the results of two previous studies on the subject.
“The impact of phthalate exposure on the brain and childhood cognition continues into adolescence”
Researchers have also observed that this relationship between exposure to certain phthalates and lower childhood IQ is partially influenced by total gray matter volumes. This means that exposure to plasticizers before birth could lead to lower total gray matter volume in childhood which, in turn, could be related to lower IQ.
Prenatal exposure to phthalates and IQ
The authors of the new study used data from 775 mother-child pairs from Generation R, a pediatric neuroimaging cohort based in Rotterdam, the Netherlands. Maternal phthalate exposure was assessed through urine samples collected during pregnancy. Volumetric measurements of the boys’ and girls’ brains were taken using MRI scans at the age of 10, and IQ was assessed using standard tests performed when they were 14 years old.
Statistical analysis revealed an association between higher gestational concentrations of monoethyl phthalate (mEP) and lower total gray matter volumes at 10 years in both sexes. mEP is a metabolite or breakdown product of diethyl phthalate, which is used to make plastics more flexible and in cosmetic products. Higher maternal urinary concentrations during pregnancy of monoisobutylphthalic acid (mIBP), a metabolite of diisobutylphthalate (DIBP), were associated with smaller white matter size only in girls. DIBP is also used as a plasticizer.
Gray matter is the brain tissue that helps us process information and govern our muscles and is essential for learning and retaining information, speaking, moving, or processing sensations and perceptions. White matter is a brain tissue that acts as a communication network between the different areas of gray matter and between our brain and the rest of the body.
In 2020 and 2021, the Generation R study reported that maternal prenatal urinary phthalate concentrations were associated with lower nonverbal IQ at age 6 years. After demonstrating that the association persists at age 14, the scientific team states that “the impact of phthalate exposure on the brain and childhood cognition continues into adolescence.”
The new study estimates that 18% of the total effect of phthalate exposure in pregnancy on childhood IQ could be explained by changes in gray matter volumes in both boys and girls. In girls, it was observed that the association between gestational exposure to mPIBP and a lower IQ was due to a smaller size of the cerebral white matter in a proportion of 76%.
“Although the differences observed in volumetric measures and IQ scores were small at the individual level, it is the overall picture that offers cause for concern due to widespread exposure to phthalates and poor regulation, leading to a high impact in public health,” says Mònica Guxens, ISGlobal researcher and last author of the study.
“In light of scientific evidence on their health effects, countries like the US or regions like the EU have increased regulations on these ubiquitous substances. However, the use of new compounds to replace regulated ones means that the global impact of prenatal exposure to phthalates persists,” says Akhgar Ghassabian, a researcher at the NYU School of Medicine.
Source: Barcelona Institute for Global Health (ISGlobal)
