March 4, 2015
Researchers find that reduced ability to excrete bisphenol-A is more common among children with autism; another possible example of gene-environment interaction affecting autism risk.
In a new study, researchers report an association between autism and a child’s ability to eliminate bisphenol-A (BPA) from the body. Trace amounts of this plasticizer are commonly found in foods and drinks sold or stored in standard plastic containers.
Specifically, the researchers found that a lowered ability to metabolize and eliminate BPA from the body is more common among children who have autism.
Their report appears online in the journal Autism Research.
“This is an example of how environmental factors – in this case, exposure to BPA – might be interacting with a genetic factor – the ability to break down toxins like BPA – to affect autism risk,” comments developmental pediatrician Paul Wang, Autism Speaks head of medical research. “This doesn't prove that BPA causes autism. But it illustrates why some individuals might be more affected by toxic exposures than others.” Dr. Wang was not involved in the study.
The research team included investigators at Rutgers New Jersey Medical School and Rowan University School of Osteopathic Medicine.
“It has been suspected for a lot of years that BPA is involved in autism,” says lead investigator Peter Stein. “We’ve shown there is a link. The metabolism of BPA is different in some children with autism than it is in otherwise healthy children.”
The research team analyzed urine from 46 children with autism and 52 unaffected children. They determined how much of the BPA in each child’s urine had been metabolized in a way that efficiently eliminates it.
As it does with many toxins, the body speeds the elimination of BPA by metabolizing it. It does so by binding the chemical in a process called glucuronidation. This allows the chemical to be efficiently eliminated in urine.
In the study, the children who had autism tended to have significantly more unbound, or unmetabolized, BPA in their urine than did the children unaffected by autism. This difference was particularly large when overall levels of BP were high.
The researchers also saw some evidence that the severity of autism symptoms may increase as the ability to eliminate BPA decreases – at least in some children.
The study involved too few participants to make clear conclusions, the researchers agree. “The key point,” Dr. Stein concludes, “is that the study seems to link BPA to autism and creates an open area for further research. One implication of our study is that there might be a benefit to reducing BPA exposure for pregnant women and for children with autism.”