Researchers from Rutgers and the University of Rochester detected ZEN or its metabolites in 97 percent of urine samples from pregnant women and 84 percent of placentas.

ZEN is a type of mycoestrogen, an estrogen-like compound produced by certain molds that contaminate grains, meats and processed foods worldwide. It’s most common in crops such as corn, wheat and barley. While well-studied in animals, where it can cause reproductive issues, less is known about its effects in humans.

“We’re just at the beginnings of studying how these compounds affect human bodies in all stages of development,” said Zorimar Rivera-Núñez, an assistant professor at the Rutgers School of Public Health and senior author of the study.

ZEN is so structurally like the hormone 17β-estradiol that it binds with estrogen receptors. Large doses reduce the number and size of offspring in cattle, pigs, mice and rats. Paradoxically, these compounds also promote growth in livestock after birth, so much so that American farmers routinely dose cattle with a synthetic version of ZEN.

To study exposure levels during pregnancy, the researchers collected urine samples from 317 women in Rochester, N.Y. They also gathered 271 placenta samples and asked study participants about lifestyle choices, such as their typical diets.

Women with higher body mass indexes and those who had previously given birth tended to have higher ZEN levels in their urine.

Diet also affected exposure. Women with healthier diets, particularly those eating more protein and vegetables, had lower exposure levels. Diets higher in ultra-processed foods were associated with increased ZEN concentrations.

“For every 1 percent higher ultra-processed food consumption, there was a higher exposure to mycoestrogen,” said lead author Carolyn Kinkade, who studied zearalenone for her PhD thesis in the Rutgers School of Graduate Studies Exposure Science program.

The study appears amid increasing concerns about endocrine-disrupting chemicals in the environment. Unlike many of those other chemicals, ZEN has long been found in our food, but exposure may be increasing because of modern food production and climate change.

“This is climate-change-related exposure,” Rivera-Núñez said. “Current mycotoxin data predict that the levels of these chemicals will increase as we get warmer temperatures and weather.”

Some cell studies suggest ZEN may be more potent than other known endocrine disruptors such as BPA or phthalates. However, its health effects in humans remain unclear. Previous research by the team found associations between ZEN exposure and altered sex hormone levels in pregnant women and umbilical cord blood.

The researchers are continuing to investigate potential health impacts. Upcoming studies will examine associations with pregnancy weight gain, placental development, and child growth and development.

“Moving forward, we would like to expand what we’re doing now to look at children’s health all the way to puberty,” Rivera-Núñez said.

For now, the findings may provide another reason to eat a healthy diet during pregnancy, the researchers said, though they noted that ZEN is so prevalent in food that we would need to create regulations aiming to control the presence of mycoestrogens in the food chain to reduce population exposure.

“People who want to reduce their exposure can do so by reducing their consumption of ultra-processed foods overall,” Kinkade said.