Synthetic phenols and parabens found in everyday consumer products are under scrutiny for their potential effects on child neurodevelopment. New research suggests that prenatal exposure to methylparaben and bisphenol S during the third trimester of pregnancy may be associated with behavioural difficulties in young children.

Endocrine-disrupting chemicals are known to interfere with hormonal signalling and may adversely affect growth, brain development, reproduction, and metabolism. Against the backdrop of increasing neurodevelopmental disorders in children, their potential role as environmental risk factors has become an increasing focus in public health research.

Although causal links remain difficult to establish and the underlying mechanisms are still unclear, clarification is critical. In Europe, endocrine disruptors are classified on the basis of mechanistic data and evidence of their adverse health effects.

New Data

A recent study was coordinated by an environmental epidemiology research team from the Inserm (National Institute of Health and Medical Research) and the University of Grenoble Alpes, Grenoble, France.

This research project was carried out with numerous partners, including the Grenoble Alpes University Hospital, Grenoble, France, and the Barcelona Institute for Global Health, and provides new insights into the potential effects of these contaminants during pregnancy.

Researchers have assessed prenatal exposure to 12 substances during pregnancy, including phenolic compounds, bisphenols, parabens, and triclosan. Health authorities have classified these substances as endocrine disruptors.

Many common consumer products contain phenolic compounds, particularly bisphenols and parabens such as methylparaben. These sources include plastic packaging, cosmetics, food products, and textiles.

The endocrine-disrupting properties of bisphenol S have been well documented, leading to restrictions in its use. However, substitute compounds, such as bisphenol S, may pose health risks. Methylparaben is suspected to have endocrine-disrupting activity because of its oestrogenic effects and interference with hormonal regulation.

The study drew on data from two complementary mother-child cohorts: the Barcelona Life Study Cohort (BiSC), which enrolled 1080 mother-child pairs in Barcelona, Spain, between 2018 and 2021, and the Assessment of Air Pollution Exposure during Pregnancy and Effect on Health cohort, in which 484 pregnant women were recruited in the area of Grenoble, France, between 2014 and 2017.

Compared with earlier studies, this study differs in its more intensive exposure assessment, with up to 42 urine samples collected during pregnancy than approximately three samples in most previous studies.

When children were 18-24 months of age, one parent completed the Child Behavior Checklist (CBCL), a screening tool used to identify behavioural problems such as attention difficulties, anxiety, depressive symptoms, and aggressive behaviour.

Analyses were performed to examine whether prenatal exposure to confirmed or suspected endocrine disruptors was associated with the CBCL scores.

Third-Trimester Associations

The study highlighted two associations:

• Exposure to methylparaben during the third trimester of pregnancy was associated with significantly higher CBCL scores, suggesting potential behavioural difficulties in children.
• Exposure to bisphenol S during the same period was also associated with higher CBCL scores, but only in boys.

No evidence of a cocktail effect or an amplified biological response due to the combined exposure to multiple phenolic compounds was detected.

Researchers have examined potential biological mechanisms, focusing on the disruption of the hypothalamic-pituitary-adrenal axis, a central regulator of stress responses. Stress-related hormones, including cortisol and cortisone, were measured in maternal hair samples collected at the end of pregnancy. However, the underlying mechanisms remain unclear.

Other biological pathways, including the thyroid and other oestrogenic axes, warrant further investigation.

The authors emphasised the need for further research, particularly because bisphenol S remains relatively understudied despite its increasing use, and methylparaben is currently classified only as a suspected endocrine disruptor. Larger studies are required to better document these potential risks.

This story was translated from Univadis France, part of the Medscape Professional Network.