The incidence of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) has increased considerably in recent decades in many countries. The reasons for this trend are not known in detail, but various scientific investigations have pointed out the most likely relationships with environmental factors such as exposure to pollutants.
A study whose results have been published (September 13, 2023) in the scientific journal PLOS One presents a hitherto unknown relationship between these neurological alterations in children and exposure to bisphenol A (BPA), a plastic additive considered an endocrine disruptor. .
The authors of the research, attached to the Rowan University School of Osteopathic Medicine (United States) and Rutgers University School of Medicine (United States), conclude that children with ASD and ADHD often have a reduced ability to eliminate bisphenol A from their bodies, thus increasing their exposure to this compound and its negative health effects.
The authors also studied the possible effects, in children with these disorders, of exposure to bis phthalate or DEHP (an additive used to give flexibility to plastics) but in this case they did not find statistically significant relationships.
Previous studies found associations between children with autism and BPA exposure. This study, "Bisphenol-A and phthalate metabolism in children with neurodevelopmental disorders," has found that the possible reason for the link is decreased efficiency in a key step involved in BPA detoxification.
After BPA is ingested or inhaled, it is filtered from the blood in the liver through a process called glucuronidation. Glucuronidation is the process of adding a sugar molecule to a toxin. By doing so, the toxin becomes water-soluble, allowing it to quickly leave the body through urine.
Humans show genetic variability in their ability to detoxify BPA. Genetically susceptible people have a harder time detoxifying their blood through this process, meaning their tissues are exposed to BPA at higher concentrations for longer periods of time.
The study showed that for a significant proportion of children with autism, the ability to add the glucose molecule to BPA is approximately 10% lower than that of control children. For a significant proportion of children with ADHD, it is about 17% less.
The compromised ability to remove such environmental pollutants from the body is "the first strong biochemical evidence of the link between BPA and the development of autism or ADHD," said T. Peter Stein, senior author of the study and professor at the University Rowan. "We were surprised to find that ADHD shows the same defect in BPA detoxification."
More research is needed to determine whether autism and ADHD develop in utero through increased exposure of the mother or child at some point after birth, Stein said.
It is likely that there are other factors behind the development of autism and ADHD, Stein said in a briefing note released by his university.
The inability to effectively remove these chemicals from the blood is not present in all children with neurodevelopmental disorders, but compromised removal of BPA is an "important pathway; otherwise it would not have been so easily detectable in a study of moderate size," noted Professor Stein.
The team measured the effectiveness of glucuronidation in three groups of children seen at Rutgers Medical School clinics in New Jersey: 66 with autism, 46 with ADHD and 37 children without any of these disorders.
Co-authors of the study are Margaret D. Schluter and Robert A. Steer of Rowan University School of Osteopathic Medicine and Xue Ming of Rutgers University School of Medicine.
