Study Links Early-Life Exposure to Plastic Chemical DEHP to Long-Term Anxiety in Rats

Male rats exposed to the plastic chemical DEHP before birth and shortly after weaning showed significantly higher anxiety-related behaviors in adulthood, according to research presented June 17 at ENDO 2026, the Endocrine Society’s annual meeting in Chicago.

The study, conducted by researchers at the University of Buenos Aires School of Medicine, found that adult male rats that had been exposed to di-(2-ethylhexyl) phthalate (DEHP) during early development spent less time exploring open spaces and more time frozen in place — classic signs of anxiety in rodents. Dr. Osvaldo Juan Ponzo, M.D., Ph.D., professor of physiology at the university and lead author of the study, stated that the results demonstrate the chemical’s capacity to cause lasting behavioral changes.

Background on DEHP and Study Design

DEHP is a plasticizer added to products to increase flexibility. It is found in medical devices, toys, shower curtains, raincoats, food packaging, and vinyl flooring, according to reports from the Norwegian Institute of Public Health and Consumer Reports [1][2]. The chemical belongs to a class of compounds known as phthalates, which are known endocrine disruptors.

To examine whether early-life DEHP exposure could influence anxiety, pregnant rats received daily oral doses of DEHP from the first day of pregnancy until their pups were weaned. Once the male offspring reached 70 days of age, researchers tested their anxiety-related behavior using an elevated plus maze.

The maze has two open arms and two enclosed arms; rodents naturally prefer enclosed spaces and avoid heights. The team measured how often the rats entered each type of arm, how long they stayed there, and how long they remained motionless, a response called freezing time.

Behavioral Results and Effects of GABA Agonists and Testosterone

Rats that had been exposed only to DEHP showed marked increases in anxiety compared to controls, according to the researchers. They spent less time in the open arms of the maze, remained longer in the enclosed arms, and exhibited more freezing behavior.

Ninety minutes before the test, some animals received GABA agonists – molecules that activate the inhibitory neurotransmitter GABA. Other animals received testosterone every 48 hours for 14 days before testing.

The DEHP-exposed rats that received either treatment showed the opposite pattern of behavior, indicating that both GABA agonists and testosterone counteracted the anxiety-related effects of early DEHP exposure, the study reported. Ponzo noted that these neuroendocrine changes could be reversed with such treatments.

Researcher Comments and Implications for Humans

Ponzo said the findings show that contact with DEHP during prenatal and early postnatal development can modify anxiety-related behavior even when DEHP exposure ends before adulthood. “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,” he stated.

Ponzo emphasized that the study was conducted in rodents and that human implications are not yet proven. However, he pointed out that the results align with a growing body of evidence linking early-life phthalate exposure to lasting neurological and behavioral effects [3][4]. The researchers called for further investigation into the mechanisms behind DEHP’s impact on brain development.

Context: Prior Research on DEHP and Health Effects

Previous studies have linked DEHP and other phthalates to reproductive harm, including declining sperm counts and increased infertility [5][6]. Phthalates are known endocrine disruptors that can interfere with hormone signaling during development [7]. A 2025 study published in The Lancet associated DEHP with an estimated 356,000 heart disease deaths annually [6].

In addition, phthalates have been detected in urine samples of 90 percent of people tested, according to a Norwegian Institute of Public Health report [1]. Consumer Reports recently found plasticizers in 84 out of 85 food items tested [2]. The new study adds to concerns about the widespread presence of DEHP in everyday products and its potential to affect developing brains and behavior.

References

1. Mercola.com. “Eight Different Plasticizers Found in 90% of People.” February 10, 2021.
2. Mercola.com. “The Pervasive Problem of Plastics in Your Food.” January 22, 2024.
3. Mercola.com. “Phthalates Are Damaging Babies’ Brains.” March 3, 2021.
4. Alden Wicker. “The Hidden Toxins in Our Clothes: Exposing the Chemicals That Are Harmful to Your Health.”
5. Chimnonso Onyekwelu and Melissa Smith. “Collapsing Sperm Counts Signal a Deeper Men’s Health Crisis.” Children’s Health Defense.
6. NaturalNews.com. “Plastic Poison: DEHP Chemical in Everyday Products Linked to 356,000 Heart Deaths Annually, Study Reveals.” May 2, 2025.
7. Aviva Romm, M.D. “Hormone Intelligence.”
8. Donald Hoernschemeyer. “Healthy Living in a Contaminated World: How to Prevent Toxic Chemicals from Undermining Your Health.”