Toxic chemicals bleeding out of plastic don’t just make the user sick, they can affect the metabolic health of an entire family. Researchers from the University of California-Riverside say fathers exposed to chemicals in plastics which affect metabolic health can pass that damage to their children for two generations.

Plastics can be dangerous because they contain hormone-disrupting chemicals that have a connection to several chronic diseases, including diabetes and obesity. So far, scientists have been focusing more on how plastic exposure affects mothers, instead of fathers.

In this new study, the team examined the impact of paternal exposure to a substance called dicyclohexyl phthalate (DCHP), which manufacturers add to plastic to increase its durability. They look at this impact on the metabolic health of the first (F1) and second (F2) generations of mice models. Their experiments reveal that DCHP exposure for four weeks results in high insulin resistance and impaired insulin signaling in both F1 and F2 offspring, though it was weaker in the second generation.

“We found paternal exposure to endocrine disrupting phthalates may have intergenerational and transgenerational adverse effects on the metabolic health of their offspring,” says Changcheng Zhou, a professor of biomedical sciences in the School of Medicine, in a university release. “To the best of our knowledge, our study is the first to demonstrate this.”

Female offspring may be at higher risk

In the context of this study, intergenerational effects refer to changes stemming from direct exposure to stressors, such as DCHP, from fathers and the development of offspring directly. Transgenerational effects refer to changes passed down to second generations. Zhou and the team specifically narrowed their focus on the small RNA molecules within sperm that act as messengers, passing genetic information to future generations. To do this, they used the “PANDORA-seq method,” which is able to show that DCHP exposure can change the RNA of sperm, unlike more traditional methods that can’t detect these changes.

To model their experiment, the team had F1 male mice breed with unexposed females to produce F2 offspring. Interestingly, their work revealed that paternal DCHP exposure induced metabolic disorders in both male and female F1 offspring, but only did so in female F2 offspring.

“This suggests that paternal DCHP exposure can lead to sex-specific transgenerational effects on the metabolic health of their progenies,” Zhou says. “At this time, we do not know why the disorders are not seen in male F2 offspring.”

Studies reveal that DCHP is present in both food and water, as well as human urine and blood samples. Although the direct impact of human exposure to this chemical is still unclear, the U.S. Environmental Protection Agency has added DCHP to a list of the 20 high-priority substances for risk evaluation.

“It’s best to minimize our use of plastic products,” Zhou concludes. “This can also help reduce plastic pollution, one of our most pressing environmental issues.”

The findings are published in the journal Environmental International.