Scientists shared new findings at the ENDO 2026 meeting in Chicago. They discovered that male rats given a common plastic chemical while still in the womb grew up more nervous.
Even though the work was done with animals, it hints that chemicals that disturb hormones could shape human behavior for many years after birth.
"We showed that a widely used plastic softener can change how animals act when they are exposed before birth and shortly after," said Dr. Osvaldo Juan Ponzo, a physiology professor in Buenos Aires.
What Is DEHP?
The study focused on di‑(2‑ethylhexyl) phthalate, called DEHP. This substance makes plastics flexible and is found in items such as medical tubes, toys, shower curtains, and raincoats.
Earlier work linked DEHP and its breakdown products to problems in the reproductive and nervous systems of both animals and people.
Testing Anxiety After Early DEHP Exposure
Pregnant rats received a small dose of DEHP each day, starting on the first day of pregnancy and continuing until their babies were weaned.
When the male pups grew up to about 70 days old, researchers placed them in an elevated plus maze. This maze has two open arms and two closed arms and uses a rat’s natural fear of heights to measure anxiety.
Scientists recorded how often the rats entered each arm, how long they stayed there, and how much time they spent frozen – a sign of fear.
GABA and Testosterone Counter the Effects
Before the maze test, some rats got a GABA‑activating drug, while others received testosterone injections every two days for two weeks.
Rats that only saw DEHP avoided the open arms, lingered in the closed arms, and froze more often, indicating higher anxiety.
In contrast, DEHP‑exposed rats that received either the GABA drug or testosterone behaved like normal rats, suggesting these treatments can reverse the anxiety caused by early DEHP exposure.
"Early contact with DEHP can shape anxiety behavior for life, even if the chemical is absent later," Dr. Ponzo explained. "These changes can be undone with GABA or testosterone therapy."