A recent study, led by the NYU Grossman School of Medicine and the Barcelona Institute for Global Health (ISGlobal), found that children whose mothers had higher exposure to certain phthalates during pregnancy exhibited smaller total gray matter in their brains at age 10 and a lower IQ at age 14. These findings, published in Molecular Psychiatry, corroborate the results of two previous studies on the subject.
Phthalates: Ubiquitous Chemicals of Concern
Phthalates are a group of chemicals widely used as plasticizers and solvents in numerous commercial products, including personal care items, food packaging, and vinyl flooring. Past research has indicated associations between certain phthalates and suboptimal cognitive function, motor skills, social development, and behavioral issues in children.
The researchers analyzed data from 775 mother-child pairs from the Generation R cohort based in Rotterdam, The Netherlands. Mothers' phthalate exposure levels were assessed using urine samples collected during pregnancy, focusing on detecting phthalate metabolites due to the rapid decay of phthalates in the human body. Children underwent MRI scans at age 10 for brain volumetric measures, and their IQ was assessed via standard tests at age 14.
The study found that higher levels of monoethyl phthalate (mEP), which is a byproduct of diethyl phthalate and is used to make plastics flexible, during pregnancy were linked to smaller total gray matter volumes in children at age 10. Higher levels of monoisobutyl phthalic acid (mIBP), a metabolite of diisobutyl phthalate (DIBP), in the mother were also linked to smaller amounts of white matter in girls.
Gray matter contains most of the brain's neuronal cell bodies and is essential for processing information, learning, retaining information, speaking, moving, and processing sensations and perceptions. White matter acts as a communication network between different gray matter areas and between the brain and the rest of the body.
Persistent Impact on Cognition
The Generation R Study had previously reported associations between maternal prenatal urinary concentrations of phthalates and lower non-verbal IQ at age 6. The new study reveals that this association persists into adolescence.
It estimates that changes in gray matter volumes could account for 18% of the overall impact of phthalate exposure during pregnancy on children's IQ. For girls, 76% of the association between gestational exposure to mIBP and lower IQ was due to smaller cerebral white matter.
While the observed differences in volumetric measures and IQ scores were small at the individual level, the widespread exposure to phthalates and lenient regulations raise significant public health concerns. Countries like the US and regions such as the EU have increased regulations on these ubiquitous compounds. However, the use of new compounds to replace the regulated ones results in the persistent global impact of prenatal exposure to phthalates.
Mònica Guxens, an ISGlobal researcher, emphasized the importance of recognizing the wider impact of these findings due to the pervasive exposure to phthalates and the consequent high public health impact. Akhgar Ghassabian, a researcher at the NYU School of Medicine, highlighted the challenges in mitigating the impact of prenatal exposure to phthalates, owing to the introduction of new compounds replacing the regulated ones.
This study underscores the potential long-term effects of prenatal exposure to phthalates on children's brain development and cognitive abilities. It serves as a reminder of the importance of stringent regulations and vigilant monitoring of the use of such chemicals, considering their widespread prevalence and the potential for lasting impact on public health.
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