Study Shows Flame Retardants in Cars Could Boost Exposure to Cancer-Causing Chemicals

According to a study published on May 7 in Environmental Science & Technology, chemicals that are linked to cancer could be released into the car's cabin air by flame retardants applied to interior surfaces. The team of researchers observed the existence of flame retardants that are known and potential carcinogens in the seat foam of almost all the tested cars - a total of 101 personal vehicles manufactured between 2015 and 2022. They also detected the same chemicals in the car's indoor air.

Vehicle manufacturers have been incorporating flame retardants into car designs since 1971. This was a requirement from the National Highway Traffic Safety Administration to reduce the spread of fires. However, some specialists have raised concerns about their effectiveness. The latest study indicates a severe unintended consequence - exposure to harmful chemicals through inhalation for numerous car occupants.

Lydia Jahl, PhD, a senior scientist at the Green Science Policy Institute in Berkeley, California, highlighted that supposedly protective safety measures are increasingly causing harmful chemical exposure. Jahl also co-authored the study.

Jahl and her associates conducted the latest research inspired by a 2020 study. It revealed that college students commuting longer distances were exposed to elevated amounts of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP)—a recognized carcinogen as per California’s Proposition 65.

For their study, Jahl's team analysed the seat foam and cabin air in over 100 vehicles that featured electric, hybrid, and gas versions, spread across 30 states. They found that both the foam and air in 99% of the cars contained tris(1-chloro-isopropyl) phosphate (TCIPP), a chemical flame retardant. This substance is currently being examined by the U.S. National Toxicology Program as a possible carcinogen.

Additionally, several research studies have linked TCIPP with reproductive issues in rodents, as well as gastrointestinal cancers in humans.

Most vehicles contained multiple flame retardants. Alongside TDCIPP, the scientists identified another substance recognized as a carcinogen by California - tris(2-chloroethyl) phosphate (TCEP). Both chemicals have also been associated with neurological and reproductive health risks.

Generally, the concentration of airborne particles from fire retardants was two to five times greater in summer than in winter. TCIPP levels were on average four times higher than other chemicals in winter and nine times higher in summer.

Michael Levine, MD, from the University of California, Los Angeles, expressed that inadequate information existed regarding the health impact of inhaling these chemicals in vehicles. He highlighted that merely because a substance is carcinogenic, it doesn't necessarily mean it will lead to cancer, nor is it surely carcinogenic at the level of exposure in cars.

Jahl suggested several steps to reduce potential exposure to carcinogenic particles in cars. This includes rolling down the windows when first entering the car and occasionally opening the windows during extended trips to replenish cabin air.

Consumer Reports have initiated a petition in response to the study, asking for the revocation of the 1971 NHTSA regulation, calling it "outdated". Sean DeCrane, from the International Association of Fire Fighters in Washington D.C., argued that the risk of carcinogen exposure surpasses the benefits of flame retardants during a fire.

The researchers recommended that NHTSA update their flammability standard for vehicles. Jahl pointed out the high frequency of vehicle usage and the significantly increased exposure for those involved in car production or ride-sharing services.