Di-(2-ethylhexyl) phthalate (DEHP) is commonly added to plastics to make them more flexible. It may also affect genes that play a critical role in brain development, promoting symptoms of autism and attention-deficit/hyperactivity disorder (ADHD).
Researchers from the Florey Institute of Neuroscience and Mental Health led a study comparing the results of blood and urine screens from pregnant mothers with behavioral assessments on their young children.
Their analysis found concerning links between an elevated exposure to the plasticizer in the mother’s urine, changes to the functioning of hundreds of genes in umbilical cord blood, and a relative increase in signs of autism and ADHD at ages 2 and 4.
It’s difficult to avoid contact with additives like DEHP in today’s world. They are found in everything from hoses to raincoats to medical equipment to plastic food bags. As a compound known as a phthalate, DEHP is added to polyvinyl chloride (PVC) to make it easier to press into soft, malleable sheets.
Phthalates also happen to mimic chemicals in our own bodies that are critical for hormone production. Implicated in declining testosterone levels and reduced sperm quality, phthalates have also been suspected of affecting neurobehavioral outcomes in children, potentially by triggering epigenetic “locks” on their DNA.
To uncover evidence of the phthalate’s epigenetic influence, the researchers assessed cord blood collected through the Barwon Infant Study and compared their resulting profiles with measures of prenatal DEHP exposure.
They found a strong correlation between a network of more than 500 genes with epigenetic changes, DEHP levels, and behaviors associated with autism and ADHD.
“Almost all women in this Australian study showed exposure to the common DEHP chemical,” says senior author Anne-Louise Ponsonby, an epidemiologist from the University of Melbourne.
Further testing on dozens of independently collected blood samples and post-mortem brain tissue samples validated their conclusion that DEHP can change how genes are expressed.
The team also identified differences in changes between the blood tests and the post-mortem analyses, a factor that could complicate interpretation of their findings.
“The authors offer a plausible biological explanation, but this still weakens a simple story about how the mechanism works,” says Senior Principal Research Fellow at The Kids Research Institute, Mirko Uljarevic, who wasn’t involved in the research.
As an observational study, he adds, the research is limited in how it can prove cause and effect.
Nonetheless, links between environmental conditions and the biology responsible for human behavior are notoriously complex and challenging to map. While it is unlikely that phthalates like DEHP cause autism or ADHD, it’s important to understand the role they might play in determining how some brains develop as they do.
“The current study offers important avenues for future research,” says Uljarevic.
“However, autism, ADHD and other neurodevelopmental conditions are multifactorial conditions that arise from many genetic and environmental factors together, so no single exposure like this is likely, on its own, to meaningfully change an individual child's risk."
Not that parents have much of a say in the matter. If a common additive to plastics has even a small chance of affecting neurological development in subtle ways, mothers may be powerless to avoid it.
“Chemical exposure levels are mainly determined at the population level and are not easily a matter of personal choice. Plastic chemicals like DEHP are often ingested, so government safety regulations around food processing and packaging are very important," says Ponsonby.
“Global plastic control efforts should take into consideration recent evidence as it emerges on the need for health protection, particularly for vulnerable populations such as pregnant women and young babies.”
Source: Scimex
This research was published in Med.
