Plastic Chemical DEHP Rewires Fetal Brain Anxiety Circuits via GABA, Study Shows
Key Insights
Prenatal exposure to the common plasticizer DEHP produces lasting anxiety (search)-like behavior in adult male rats, persisting long after the chemical is cleared from the body.
The mechanism involves suppression of GABA, the brain's primary inhibitory neurotransmitter, and disruption of the hypothalamic-pituitary-adrenal axis during critical developmental windows.
Both GABA agonists and testosterone treatments reversed the anxiety (search) phenotype in DEHP-exposed animals, pointing to potential therapeutic directions.
A chemical that softens the plastic in hospital IV bags, blood tubing, and premature-infant ventilator equipment permanently reprograms the developing male brain's anxiety (search) circuitry — and exposure after birth is not required to sustain the damage, according to new research presented at ENDO 2026, the Endocrine Society's annual meeting in Chicago.
The Endocrine Society published the findings in an official press release on June 17, 2026. The study has not yet undergone peer review in a scientific journal. What it adds to a body of evidence that has been accumulating for years is significant: di-(2-ethylhexyl) phthalate, or DEHP, the world's most widely used plasticizer, is not merely a reproductive hazard. It appears to be a brain hazard too, and it operates before a child takes a single breath.
"This research demonstrates that one of the most widely used plasticizers worldwide is capable of causing behavioral changes when the subject is exposed during the prenatal and immediate postnatal developmental stages, with this effect lasting over time," said Osvaldo Juan Ponzo, M.D., Ph.D., professor of physiology at the University of Buenos Aires School of Medicine (search) in Buenos Aires, Argentina.
How the Study Was Conducted
Scientists at the University of Buenos Aires School of Medicine (search) gave pregnant female rats daily oral doses of DEHP starting from the first day of gestation through weaning. Once male offspring reached the standard age of rodent adulthood — postnatal day 70 — researchers measured their anxiety (search)-like behavior using the elevated plus maze, a plus-sign-shaped platform with two open, exposed arms and two enclosed arms, designed to exploit rodents' natural wariness of open, elevated spaces.
The DEHP-exposed males spent significantly less time in the open arms and exhibited markedly more freezing behavior than unexposed controls. Critically, no animal had received DEHP since shortly after birth. The chemical was long gone. The brain state it created was not.
The GABA Mechanism: How DEHP Disables the Brain's Anxiety Brakes
The key to the study's findings lies in two overlapping neurological systems that DEHP appears to disrupt during fetal development: the GABAergic system and the hypothalamic-pituitary-adrenal (HPA) axis.
GABA — gamma-aminobutyric acid — is the brain's primary inhibitory neurotransmitter. Roughly 30 percent of all neurons in the central nervous system use GABA as their primary chemical signal, and its function is broadly described as neural "braking": it dampens excitatory signals, prevents anxiety (search)-related messages from reaching the cortex unchecked, and maintains the balance between neural arousal and calm.
The Buenos Aires team found that the anxiety (search) phenotype in DEHP-exposed rats could be reversed. Ninety minutes before elevated plus maze testing, some DEHP-exposed animals received GABA agonists — compounds that directly activate GABA receptors. Others received testosterone injections every 48 hours for two weeks before the test. Both interventions produced the opposite behavioral pattern: treated animals spent more time in the open arms and showed less freezing.
GABA agonists worked, suggesting that prenatal DEHP had left the brain's inhibitory system chronically under-powered — and that pharmacologically boosting it could temporarily restore normal anxiety (search) responses. Testosterone worked too, pointing to a second mechanism: DEHP is a well-established androgen disruptor, and testosterone plays a critical organizational role in male brain development during the perinatal window. Prior animal studies have found that prenatal DEHP exposure suppresses circulating testosterone in male offspring and reduces androgen receptor expression in the brain — both of which impair the testosterone-dependent maturation of GABAergic interneurons.
The HPA axis — the neuroendocrine cascade that governs how animals respond to stress — is separately implicated. Prior research has shown that neonatal DEHP exposure causes corticotropin-releasing hormone neurons to fire more spontaneously, resulting in chronically elevated baseline corticosterone, the rodent equivalent of cortisol. A stress-response system calibrated to a higher set point means normal stimuli produce exaggerated fear responses — which is precisely what the elevated plus maze data showed.
"These neuroendocrine changes can be reversed by treating with GABA agonists or testosterone," Ponzo said, calling the results a potential direction for future therapeutic research.
Why a Developing Brain Cannot Simply Recover
The permanence of these effects reflects a basic principle of developmental neuroscience: critical periods. During fetal and early postnatal development, neural circuits pass through narrow time windows of heightened plasticity, during which environmental inputs — or chemical disruptions — produce structural changes that become locked in when the window closes. After closure, normal environmental experience cannot easily reverse those structural changes.
What makes this particularly relevant for DEHP is that the GABAergic system is not merely one victim of these critical periods — it is one of their gatekeepers. The maturation of GABAergic inhibitory tone is what triggers the opening and closing of critical periods in developing sensory and cortical circuits. A chemical that suppresses GABA development during the fetal window does not simply produce a quieter inhibitory system. It may alter the timing of plasticity windows throughout the brain.
What This Means for Humans — and the Significant Caveat
The study was conducted in rodents, and the research exists only as a conference abstract that has not yet been submitted to a peer-reviewed journal. Both limitations are significant.
Prof. Jean Golding, Emeritus Professor of Paediatric and Perinatal Epidemiology at the University of Bristol, commenting through the Science Media Centre, identified critical missing details: the abstract does not state how many animals were tested, does not describe how controls were selected, and presents no direct human evidence. "These are interesting experimental results which should be tested in humans first to assess whether there is indeed an association between maternal levels of phthalate and anxiety (search) in the offspring," she said. Golding added that existing longitudinal cohort studies with stored maternal blood samples could be used to test this hypothesis.
The human relevance case, however, is not built on this single study. It rests on a converging body of epidemiological research. A 2025 study from the Barwon Infant Study found that prenatal DEHP exposure increases autism and ADHD symptoms in children via specific patterns of DNA methylation. A study published June 8, 2026, from the UNC Gillings School of Global Public Health found that early phthalate exposure was associated with sex-specific changes in the brain networks commonly altered in children with ADHD and anxiety (search), visible on MRI scans.
NICU Infants Face the Highest DEHP Exposure — With No U.S. Regulatory Protection
For most adults, DEHP exposure comes primarily from food packaging, cosmetics, and household plastics. For premature infants in neonatal intensive care units, it comes from something far harder to avoid: the IV tubing, blood bags, and respiratory devices keeping them alive.
DEHP is the only phthalate the U.S. Food and Drug Administration (search) has approved for use in medical devices. Because DEHP is not chemically bonded to PVC plastic — it is simply blended in — it leaches into any liquid or medication passing through DEHP-plasticized tubing. Estimates from published NICU research suggest that a 2-kilogram premature infant may receive DEHP exposure of approximately 16 milligrams per kilogram of body weight per day through intensive care procedures — a figure that exceeds levels associated with adverse effects in animal studies by two to five orders of magnitude.
The European Union restricted DEHP in medical devices under the EU Medical Devices Regulation 2017/745 and has moved toward alternative plasticizers. The United States has not followed. The FDA issued a public health notification in 2002 urging health providers to prefer DEHP-free devices for vulnerable patients — including premature infants — but has issued no ban or binding restriction.
In December 2025, the EPA announced that DEHP presents unreasonable risk to workers and the environment across 30 conditions of use under the Toxic Substances Control Act, initiating a rulemaking process. That process covers industrial and occupational exposures. It does not cover medical devices, food packaging, or most consumer products.
Are Existing Safety Standards Adequate for Neurological Risk?
Many current DEHP safety standards were established based primarily on reproductive harm in adult males — a concern with a decades-long scientific record. The emerging data on developmental neurotoxicity reflects a different kind of risk: one that operates on narrower time windows, at potentially lower doses, and through mechanisms that were not part of the original regulatory calculus.
The EPA's 2025 TSCA evaluation did incorporate developmental endpoints related to the "phthalate syndrome" — disruption of fetal testicular testosterone production — but did not include neurological endpoints such as GABAergic inhibitory development or HPA axis calibration.
Whether a developing brain's anxiety (search) circuitry should now be added to that regulatory conversation is precisely the question the Buenos Aires study places on the table. Researchers who study endocrine-disrupting chemicals have called for updated risk assessments that explicitly account for prenatal windows of neurological vulnerability. The intersection of a growing mechanistic literature in animals and a growing epidemiological record in children makes that call increasingly difficult to defer.