Plastic Chemical DEHP is under renewed scientific review after male rats exposed during early development showed anxiety-like behavior as adults, according to research presented at ENDO 2026, the Endocrine Society’s annual meeting in Chicago.
The research focused on di-(2-ethylhexyl) phthalate, known as DEHP, a plasticizer used to make some plastic products flexible. The findings do not show that DEHP causes anxiety in people. They add animal data to an ongoing scientific review of how early exposure to endocrine-disrupting chemicals may affect behavior later in life.
Researchers from the University of Buenos Aires School of Medicine studied male rats whose mothers received DEHP by mouth every day, starting on the first day of gestation and continuing until the litter was weaned. When the male offspring reached 70 days old, the team placed them in an elevated plus maze, a standard behavioral test that tracks how rodents respond to open and closed spaces.
In that test, the DEHP-only group spent less time exploring the open arms of the maze, spent more time in the closed arms, and showed more freezing time, according to the Endocrine Society release. Those patterns are commonly used in rodent studies as signs of anxiety-like behavior.
What The Plastic Chemical Study Tested
The Plastic Chemical study examined two biological systems that may be connected to the behavior seen in the rats: gamma-aminobutyric acid, or GABA, and testosterone. GABA is an inhibitory neurotransmitter, meaning it helps reduce nerve signaling activity. Testosterone is a hormone that can influence development and behavior in animals.
Ninety minutes before the maze test, some rats received GABA agonists, molecules that bind to and activate GABA receptors. Other rats received testosterone every 48 hours for 14 days before the test.
The treated DEHP-exposed rats showed opposite characteristics from the untreated DEHP-exposed group, according to the researchers. They spent more time in open areas and less time in closed areas than rats exposed to DEHP without those treatments. The study team said the findings suggest GABA signaling and testosterone may be part of the pathway connecting early DEHP exposure with the behavior observed in the maze.
Osvaldo Juan Ponzo, M.D., Ph.D., a professor of physiology at the University of Buenos Aires School of Medicine, said the research showed that contact with DEHP during early life could modify anxiety-related behavior after adult exposure had ended. The finding is based on rats, and animal behavior tests cannot be read as direct proof of the same outcome in humans.
Where DEHP Shows Up In Daily Products
DEHP is part of a broader class of chemicals known as phthalates. U.S. regulators describe phthalates as chemicals used in plastic products, most commonly PVC or vinyl, to make materials soft and less brittle. This function is known as plasticizing.
The Endocrine Society release cited medical devices, toys, shower curtains, and raincoats as examples of products where DEHP may be used. FDA materials state that phthalates have historically been used in food packaging or related food-contact uses, including certain adhesives, lubricants, and sealants. The FDA says phthalates are not authorized to be directly added to food.
That range of uses is one reason the Plastic Chemical finding is drawing public attention. The study does not address everyday consumer exposure levels. It also does not identify any specific consumer product as a cause of anxiety in people. It focuses on a controlled exposure model in animals during a sensitive developmental window.
Why The Rat Findings Are Being Watched
The rats were exposed before birth and shortly after birth, then tested after they reached maturity. That design allowed researchers to examine whether early-life exposure was followed by later behavior changes, even without adult exposure.
Scientists often use the elevated plus maze because rodents tend to avoid exposed spaces and heights. More time in closed arms and less time in open arms can indicate higher anxiety-like behavior in that test. The research team also measured freezing time, which increased in the DEHP-only group.
The treatment arm drew attention because GABA agonists and testosterone appeared to shift the behavior pattern. That does not mean either treatment is being proposed for people exposed to phthalates. It means the researchers saw a biological signal that may help explain the behavior in rats.
A related 2019 paper in Human and Experimental Toxicology reported that chronic postnatal DEHP exposure in male rats affected testosterone, GABA concentration, and anxiety-like behavior in an elevated plus maze. The newer ENDO 2026 research extends that line of inquiry by focusing on exposure during prenatal and immediate postnatal development.
What The Plastic Chemical Study Does Not Say
The Plastic Chemical study does not diagnose anxiety in humans, does not test children, and does not compare household products. It also does not measure real-world U.S. exposure from food, air, dust, cosmetics, medical devices, or vinyl products.
The findings are limited and specific: male rats exposed to DEHP during early development later showed anxiety-like behavior in a maze, and that pattern changed when researchers used GABA agonists or testosterone in the test design.
The study places a familiar plastic additive under closer review while phthalates remain part of food-contact, consumer product, and biomedical discussions in the United States. Its public relevance rests on a narrow research question: whether chemical exposure during early development can be followed by measurable changes in adult animal behavior later.
Disclaimer:
This article is for informational purposes only and should not be taken as medical, scientific, or regulatory advice. The study referenced involved animal research, and its findings should not be interpreted as proof of the same effects in humans. Readers with health-related concerns should consult a qualified medical professional.
