October 25, 2023
The association between Bisphenol-A (BPA) exposure and neurodevelopmental disorders is linked to a compromised metabolic process that powers plasticizer detoxification, according to a study published in PLoS ONE that expands on existing evidence linking BPA to autism spectrum disorder (ASD) and extends this finding to include attention-deficit hyperactivity disorder (ADHD).1
Glucuronidation is a metabolic process that eliminates harmful drugs, toxins, and carcinogens from the body through urine. BPA is typically metabolized quickly; when glucuronidation is impaired, the body is exposed to the adverse effects of BPA for longer. This new research, which studied the urine samples of 149 children aged 3 to 16, found that glucuronidation efficiency for BPA was reduced by 17% for children with ADHD and by 11% for children with ASD, compared to controls.
Humans are exposed to BPA mainly through food packaging, contaminated food or water, or inhalation of plastic airborne particles. Between 2009 and 2010, the U.S. National Health and Nutrition Examination Survey (NHANES) detected BPA in 92% of urine samples in the general population, with slightly higher levels found in women and children.2 A study cited by the researchers showed higher urinary concentrations of BPA in children with neurodivergent conditions.3 However, according to the FDA, the levels of BPA found in food products are not a threat to human health and safety.4
“How important plasticizer-originated neurodevelopmental disorder is in the overall occurrence of these disorders is not known, but it must account for a significant proportion or it would not have been so easy to detect in a metabolic study of moderate size such as this study,” the researchers wrote.
Researchers built on a previous study from 2015, which showed that the efficiency of glucuronidation of BPA metabolites was lower in children with ASD.5 They extended these findings to include ADHD and ruled out other plasticizer sub-pathways in the current study.
“There is nothing new about the efficiency of glucuronidation affecting metabolism and being associated with disease,” they said. “What is new is that we show this is also a plausible mechanism for ASD and ADHD.”
The use of common plasticizers and phthalates has been widespread since the 1950s to make products more flexible and durable. Exposure doesn’t always lead to harmful health effects,6 but recent decades have seen a decline in the use of plasticizers, particularly in products for young children. DEHP, an organic compound found in many plastic products, is prohibited in children’s toys and childcare articles, and BPA is now eliminated from baby bottles and sippy cups. At certain levels, bisphenol and phthalates can lead to reproductive harm, including infertility and early puberty.7
Disruptions to hormone functioning and gene mutations have also linked plasticizers to neurodevelopmental disorders, as cited by the researchers. Genetic susceptibility plays a central role. Many other factors are likely involved, says Charlotte Cecil, Ph.D. “The reality is that no single factor, either genetic or environmental, at the moment, has really emerged to be either necessary or sufficient to explain why a given individual might develop ADHD and particularly any impairment related to that,” she said in a recent webinar on epigenetic research and ADHD.
The study included 12 glucuronidation pathways, none of which showed an association with the control group. The diethylhexyl phthalate (DEHP) sub-pathway showed a similar but non-significant association with ADHD and ASD and was the only other notable sub-pathway besides BPA.
Sources
1 Stein, T.P., Schluter, M.D., Steer, R.A., & Ming, X. (2023) Bisphenol a and phthalate metabolism in children with neurodevelopmental disorders. PLoS ONE 18(9): e0289841.https://doi.org/10.1371/journal.pone.0289841
2 U.S. Environmental Protection Agency. (2013). America’s children and the environment, third edition. https://www.epa.gov/sites/default/files/2015-05/documents/biomonitoring-bpa.pdf
3 Minatoya M, Kishi R. (2021). A review of recent studies on bisphenol a and phthalate exposures and child neurodevelopment. International Journal of Environmental Research & Public Health, 18(7):30. https://doi.org/10.3390/ijerph18073585
4 U.S. Food and Drug Administration. (2023, April 20). Bisphenol a (BPA): use in food contact application. https://www.fda.gov/food/food-packaging-other-substances-come-contact-food-information-consumers/bisphenol-bpa-use-food-contact-application
5 Stein, T.P., Schluter, M.D., Steer, R.A., Guo, L., & Ming, X. (2015) Bisphenol a exposure in children with autism spectrum disorders. Autism Research, 8(3):272–83. https://onlinelibrary.wiley.com/doi/10.1002/aur.1444
6Centers for Disease Control and Prevention. (2021, April 5). Phthalates factsheet. https://www.cdc.gov/biomonitoring/Phthalates_FactSheet.html
7Callaghan, M.A., Alatorre-Hinojosa, S., Connors, L., Singh, R.D., & Thompson, J.A. (2021). Plasticizers and cardiovascular health: role of adipose tissue dysfunction. Frontiers in Pharmacology, 11. https://www.frontiersin.org/articles/10.3389/fphar.2020.626448
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