Plasticizer exposure during pregnancy linked to increased autism- and ADHD-related symptoms in children
· Medical Xpressby Sanjukta Mondal, Medical Xpress
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The foundations of brain development are laid during a crucial period of pregnancy, and a common household plasticizer called DEHP may be quietly interfering with this process. Scientists have now found that prenatal exposure to DEHP is linked to higher autism spectrum disorder (ASD)- and attention deficit hyperactivity disorder (ADHD)-related symptoms at ages 2 and 4. The effects could be traced back to changes in gene networks that play a key role in brain development.
Beyond genetics
Both ASD and ADHD are neurodevelopmental conditions that shape how the brain develops and how people experience, process and respond to the world around them. Their diagnoses have been rising, even after accounting for better awareness and changes in diagnostic criteria. Genetics alone cannot explain how fast the numbers are climbing, so scientists are now looking at environmental chemicals as possible contributors.
One chemical that has come under scrutiny is DEHP (di-(2-ethylhexyl) phthalate), which has a notorious tendency to leach out of plastic and eventually find its way into our bodies through ingestion, inhalation or skin contact.
In the recent Med study, researchers from Australia examined whether DEHP affects the developing brain through epigenetic programming, a process in which genes are turned on or off without changing the DNA sequence itself.
After testing DEHP levels in urine samples collected from 847 pregnant women at 36 weeks of pregnancy and umbilical cord blood when the babies were born, the researchers found changes in DNA methylation, chemical tags that act like light switches by turning genes on or off without altering the DNA code itself.
These molecular changes disrupted specific gene networks and hormone-signaling pathways essential for healthy brain development, particularly within the cerebellum and limbic system.
Missing biological evidence
ASD and ADHD affect millions of people worldwide, with estimated rates of 1% to 2% and 2% to 3%, respectively. Globally, these numbers are rising faster than expected, pushing scientists to look beyond genetics for answers.
Phthalates like DEHP have already come under suspicion because of early animal experiments and observational studies linking them to altered brain development. But the biological mechanism and solid evidence of their effects in humans remained murky.
In search of the underlying mechanism behind the link, the researchers measured DEHP levels in mothers' urine during pregnancy, then examined DNA methylation of umbilical cord blood at nearly 800,000 points on the genome using a profiling tool called EPIC microarray.
To evaluate the children's behavior, the team asked parents to complete questionnaires flagging early signs of autism and ADHD, including attention problems, hyperactivity, and social difficulties when the children turned 2 and 4.
Using a statistical method called causal mediation analysis, the researchers traced whether DEHP exposure was linked to changes in DNA methylation and whether those changes, in turn, were linked to behavioral symptoms. Since autism and ADHD involve changes across broad gene networks and neural circuits rather than single genes, they mapped the broader epigenetic signatures left by DEHP exposure.
Following the chemical trail
The analysis revealed that higher DEHP exposure during pregnancy was linked to more hyperactivity, inattention and trouble with peer relationships in children. Children in the top 2% of exposure showed the strongest effects.
The mapping identified two epigenetic signatures behind this link: Methylation Profile Score for DEHP exposure and a network of 531 connected genes called Co-MN1.
This network is influenced by sex hormones like estrogen and androgen and includes genes that shape how the brain develops in regions responsible for emotion, attention and social behavior. Some of these genes also overlapped with those already known to raise the risk of autism and ADHD, such as FOXP1 and SHANK2.
On a positive note, the data hinted that a healthy, whole-food diet during pregnancy affected that same 531-gene network, but in the opposite direction. Its protective nature lowered attention problems in children while boosting prosocial behavior.
The study presents a clear biological link between DEHP and brain development problems, backing up concerns about exposure during pregnancy. What's especially concerning is that these effects showed up at exposure levels far below what is currently considered safe in Europe.
Public health policies should aim to reduce everyday exposure to such hormone-disrupting chemicals and reassess the safety limits for DEHP and similar chemicals during pregnancy.
Written for you by our author Sanjukta Mondal, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.
Publication details
Samuel Tanner et al, Prenatal exposure to the plasticizer DEHP increases the likelihood of early-life autism and ADHD symptoms through epigenetic programming, Med (2026). DOI: 10.1016/j.medj.2026.101291
Journal information: Med
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NeurologyChildren's healthPediatricsWomen's healthObstetrics & gynecologyCommon illnesses & Prevention Who's behind this story?
Sanjukta Mondal
Master's in Chemistry. Freelance science journalist and communicator. Published in Chemistry World, BioSpace, and The Hindu. Full profile →
Sadie Harley
BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →
Robert Egan
Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →
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