Everyday products contain unregulated toxic chemicals.

For years, the scientific community has assumed that polymers—large molecules—are too big to migrate from products into the human body and therefore pose no health risks. As a result, polymers have largely remained unregulated and are exempt from major toxic substance laws, such as the U.S. Toxic Substances Control Act and the E.U.’s REACH regulation. However, a groundbreaking peer-reviewed study published in Nature Sustainability reveals that certain polymers used as flame retardants can degrade into smaller, harmful chemicals.

“Our study suggests polymers can act as a trojan horse for toxic chemicals,” said Da Chen, senior author and scientist at Jinan University in China. “They are added to products as inert large molecules, but over time they can degrade, exposing us to their harmful breakdown products.”

The researchers tested two polymeric brominated flame retardants (polyBFRs) that were developed as “non-toxic” alternatives to banned flame retardants. They found that both polyBFRs broke down into dozens of types of smaller molecules. Toxicity testing of these smaller molecules in zebrafish showed significant potential for causing mitochondrial dysfunction and developmental and cardiovascular harm.

Environmental Contamination and Human Exposure

The scientists went on to search for these polymer break-down products in the environment and, further raising alarm, detected them in soil, air, and dust. The levels were highest near electronic waste recycling facilities and lessened moving away from the facilities. These results confirm that the use of polyBFRs in electronics leads to the release of toxic breakdown products into the environment with potential for human and wildlife exposure and harm.

“Widespread use of these polyBFRs in electronics may result in exposures when these products are manufactured, when they’re in our homes, and when they’re discarded or recycled,” said Miriam Diamond, co-author and professor at the University of Toronto. “Since it is suspected that production volumes are very high (the chemical industry does not disclose the volumes), the potential for pollution—and resulting serious harm to people and wildlife— greatly concerns me.”

Industry Claims vs. Scientific Evidence

The chemical producers and their trade groups promote polyBFRs as environmentally friendly and non-hazardous substitutes for banned monomeric flame retardants (e.g., hexabromocyclododecane and decabromodiphenyl ether) to meet flammability standards for electronics, building materials, and vehicles. However, real-world fire safety benefits for many of these standards have not been demonstrated.

The study also has implications for other types of polymers used in consumer products such as per- and polyfluoroalkyl substances (PFAS). PFAS polymers have been put into textiles including children’s uniforms, food packaging, and cosmetics to name a few uses. Similar to this study, previous research has shown that fluorinated polymers contain numerous impurities and release smaller toxic molecules. Although the producers of PFAS argue that fluorinated polymers should be exempt from regulation, scientists maintain that fluorinated polymers are members of the class of PFAS and that the use of the whole class of PFAS should be avoided.

“To escape regulation, flame retardant, and PFAS producers are increasingly pivoting to polymers for use in everyday products,” said Arlene Blum, co-author and Executive Director of the Green Science Policy Institute. “As a result, problematic polymers emit toxic small molecules from products we touch, sit on, wear, and keep in our homes. Regulators need to close this loophole to protect consumers—especially children—from the possibility of serious chemical harm.”

Reference: “Environmental impacts of polymeric flame retardant breakdown” by Xiaotu Liu, Yinran Xiong, Xiao Gou, Lei Zhao, Shanquan Wang, Yanhong Wei, Xiaoyun Fan, Yang Yu, Arlene Blum, Lydia Jahl, Miriam L. Diamond, Yiping Du, Zhuyi Zhang, Shuxin Jiang, Xiaowei Zhang, Ting Wu and Da Chen, 3 March 2025, Nature Sustainability.
DOI: 10.1038/s41893-025-01513-z