Researchers at Florey have discovered elevated levels of bisphenol A (BPA), a chemical found in plastics, in the urine of pregnant women who had sons diagnosed with autism.
A study released in Nature Communications, spearheaded by Florey scientists Dr. Wah Chin Boon and Professor Anne-Louise Ponsonby, supports the theory that exposure to plastic chemicals in the womb may correlate with autism.
Professor Ponsonby noted that the team analyzed two major birth cohorts: the Barwon Infant Study (BIS) in Australia and the Columbia Centre for Children’s Health and Environment in the United States.
“Previous studies have linked prenatal plastic chemical exposure to an increased risk of autism in children,” Professor Ponsonby remarked.
“Our research is notable because it highlights one potential biological mechanism at play. BPA can interfere with hormone-regulated brain development in male fetuses by silencing a crucial enzyme, aromatase, which is essential for regulating neurohormones and particularly important for male brain development. This may provide insights into the complexities of autism,” she explained.
The research focused on boys exhibiting lower aromatase enzyme levels, which is involved in converting testosterone to neuroestrogen in the brain, according to Professor Ponsonby.
The association between BPA exposure and autism was especially pronounced among the top fifth of boys who were more susceptible to the endocrine-disrupting effects of this chemical, specifically those who had diminished aromatase levels. The findings indicated that boys in this category, whose mothers had higher urinary BPA levels during late pregnancy, were more likely to:
- Have autism symptoms by age 2 years at a rate 3.5 times higher.
- Receive a confirmed autism diagnosis by age 11 years at a rate 6 times higher than those born to mothers with lower BPA levels in pregnancy.
- Both birth studies provided mechanistic evidence that suggested higher BPA levels were linked to epigenetic suppression of the aromatase enzyme.
In laboratory experiments, Dr. Boon investigated how prenatal BPA exposure affects mice.
“We discovered that BPA inhibits the aromatase enzyme and correlates with physical, neurological, and behavioral changes in male mice that may mirror autism spectrum disorder,” Dr. Boon stated.
“This is the first time we have pinpointed a biological pathway that could clarify the relationship between autism and BPA,” she added.
Professor Ponsonby highlighted that BPA, along with similar bisphenols and other plastic chemicals known to disrupt endocrine functions, is now prevalent and nearly impossible to evade.
“We encounter plastic chemicals in numerous ways—through food and drink packaging, inhaling fumes from home renovations, and applying products like cosmetics on our skin. With so many avenues for these chemicals to enter our bodies, it’s not surprising that a significant number of the women’s urine samples we studied contained BPA. It’s crucial for us to comprehend the implications of these plastics on our health,” said Professor Ponsonby.
These discoveries are now influencing public safety regulators to revise safety guidelines on chemical exposure, particularly plastic chemicals, during pregnancy and early childhood.
The research team is also exploring methods to mitigate the negative effects of BPA on the aromatase system.
Dr. Boon mentioned that a specific type of fatty acid, known as 10-hydroxy-2-decenoic acid, which was examined in mice, shows promise for further research.
“10-hydroxy-2-decenoic acid has shown early potential for activating counteracting biological pathways to enhance autism-like traits in animals exposed to BPA before birth. It deserves further examination to determine if this potential treatment could be applicable to humans,” she concluded.
