Study suggests link between plastic chemicals and neurodevelopmental disorders

11 Oct 2023 --- A new study is uncovering potential connections between common plastic chemicals and neurodevelopmental disorders, shedding light on the complex etiology of conditions such as autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD). 

The study’s findings could have implications for understanding the environmental and genetic factors contributing to these disorders.

US researchers from Rutgers University-New Jersey Medical School and Rowan University-School of Osteopathic Medicine focused on two widely used plasticizers — Bisphenol-A (BPA) and Diethylhexyl Phthalate (DEHP) — commonly found in various consumer products. BPA is used in polycarbonate plastics, PVC manufacturing and F&B packaging linings, while DEHP controls plastic rigidity. 

The researchers investigated the potential association between compromised glucuronidation, a key metabolic process for these compounds, and the development of neurodevelopmental disorders.

Glucuronidation is the process that makes substances more water-soluble, facilitating their elimination from the body. The study postulated that individuals with impaired glucuronidation may be more susceptible to the adverse effects of plastic chemicals like BPA and DEHP.

The research team analyzed urine samples from three groups of children aged 3–16. These groups included children diagnosed with ASD, children diagnosed with ADHD and a control group of healthy children. Urine samples were collected and analyzed to determine the efficiency of glucuronidation for various compounds, including BPA, DEHP and other metabolites found in the body.

The study’s findings indicated a potential association between compromised glucuronidation and the risk of developing neurodevelopmental disorders. Specifically, children with ASD and ADHD displayed lower glucuronidation efficiency for specific compounds. However, the associations seemed to vary among different sub-pathways of glucuronidation.

Children with ASD and ADHD displayed lower glucuronidation efficiency for specific compounds. Complex interplay
The researchers believe this study’s results may suggest a genetically determined susceptibility to the adverse effects of plastic chemicals, especially BPA and DEHP. The findings raise important questions about how individual genetic variations may affect a child’s ability to detoxify these chemicals, potentially contributing to the development of neurodevelopmental disorders.

“The principal routes of exposure are believed to be dietary — through ingestion of food products via contaminated packaging although there is some evidence that inhalation and personal products are also important,” state the authors.

The study provides insights into the complex interplay between genetics and environmental factors in developing ASD and ADHD. But further research is needed to explore the mechanisms and implications of compromised glucuronidation and understand the genetic factors that may influence susceptibility to these disorders. 

“There is an extensive body of epidemiological evidence for a relationship between neurodevelopmental disorders and environmental pollutants such as plasticizers,” note the researchers.

“Beyond showing that plasticizers function as wide-acting endocrine disruptors there is little data on the metabolic processes linking plasticizer exposure to neurodevelopmental disease in humans. Ultimately the effects of both genetics and Xenobiotics are expressed through metabolic processes.”

Study approach
The research presents two semi-independent approaches to understanding metabolic pathways. The first primarily focuses on glucuronidation efficiency, while the second approach delves into the interaction between glucuronidation pathways and the body’s metabolome. Genetic factors, likely to influence glucuronidation efficiency, play a substantial role in these processes.The research reveals a strong correlation between reduced glucuronidation efficiency of BPA and both ASD and ADHD.

The research reveals a strong correlation between reduced glucuronidation efficiency of BPA and both ASD and ADHD, confirming previous evidence. Unexpectedly, the ADHD group also displayed a correlation with the BPA pathway, underscoring a common link between compromised detoxification of BPA and these two neurodevelopmental disorders. However, the control group did not exhibit any relationship with any of the glucuronidation pathways.

The second approach adds depth to the metabolic data by exploring the relationship of the 12 glucuronidation pathways to the metabolome and their links to clinical diagnoses. Over 90% of the significant relationships in the ASD and ADHD groups were positive for the BPA and MEHP pathways, further strengthening the connection between compromised plasticizer detoxification and neurodevelopmental disorders.

The study also highlights the potential consequences of this compromised detoxification. Research indicates that BPA and MEHP function as endocrine disruptors, affecting various metabolic processes, from gene expression to oxidative stress. 

In rodent models, these compounds have been associated with fetal growth, development and behavioral impairments. Children with ADHD exhibit distinct metabolic differences compared to control children, including elevated protein turnover, amino acid flux and basal metabolic rate.

The findings indicate that plasticizer-originated neurodevelopmental disorders likely account for a significant proportion of these conditions.Future scope 
It’s important to note that while this study provides insights into the plasticizer-associated pathway to neurodevelopmental disorders, other pathways may also contribute to the development of ASD and ADHD. Nevertheless, the findings indicate that plasticizer-originated neurodevelopmental disorders likely account for a significant proportion of these conditions.

However, the study authors acknowledge certain limitations. The clinical and biological diversity of children with ASD and ADHD, as well as the relatively small sample size, should be considered.

Additionally, the study primarily focuses on a single point in time and lacks data on the impact of neurodevelopmental diseases on the sulfation pathway. BPA and MEHP are markers for other unknown compounds metabolized by the same pathways.

In conclusion, this research sheds light on the connection between compromised plasticizer metabolism and neurodevelopmental disorders, emphasizing the need for further investigation into the relationships between genetics, environmental factors and metabolic processes in developing these conditions. 

By Radhika Sikaria

This feature is provided by Nutrition Insight’s sister website, Packaging Insights.

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