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In the United States, the majority of cars use flame retardants in their seat foams, coverings, and other parts of the vehicle cabins. This complies with the Federal Motor Vehicle Safety Standard (FMVSS 302) and helps make sure we don’t burst into flame… At least, that’s the theory.

Unfortunately, some studies have shown that exposure to certain flame retardants can lead to a host of health concerns like neurological issues, hormone disruption, and cancer-related death.

According to a recent study published in the journal Environmental Science & Technology, researchers from Duke University and the Green Science Policy Institute found that the air inside the cabins of certain cars manufactured in 2015 or later contains flame retardants, which could be harmful to human health. Furthermore, the study found that these harmful flame retardants in the air were two to five times higher during summer than in winter.

In this study, 101 American car owners with a model year of 2015 or newer were asked to participate. They were asked to hang a silicone passive sampler on their rearview mirror for seven days. A silicone passive sampler is a tool that can be used to measure various types of pollutants present in the air, including flame retardants such as brominated and organophosphate (OPEs).

According to researchers, OPEs were the most commonly found fire retardant in the silicone passive samplers.

“OPEs are increasingly used as both flame retardants and plasticizers — i.e., chemicals that change the properties of plastics — in various materials,” said Heather M. Stapleton, PhD, Ronie-Richele Garcia-Johnson Distinguished Professor in the Nicholas School of the Environment at Duke University and corresponding author of this study.

Car interiors often contain large amounts of plastic components that are sources of OPEs, including foam in the roof lining, seats, and dashboard electronics. A probable carcinogen, TCIPP, was detected in car cabins in 99% of cases, with levels ranging from 0.2 to 11,600 ng/g. TCIPP was also found to be the dominant fire retardant in car seat foam.

“TCIPP is a chlorinated organophosphate flame retardant that has been used extensively in some textiles, building insulation, and furniture,” Stapleton said. “It has been increasingly used following the phase-out of its close chemical cousin, which is considered a probable human carcinogen.”

“New data suggest that TCIPP may also be carcinogenic. Some recent epidemiology and toxicology studies also suggest TCIPP may be neurotoxic at high exposures and impact thyroid hormone regulation.”

They also found that the presence of TCIPP in foam resulted in almost nine times higher concentrations during the summer months.

Chemicals are released from plastics at higher rates in warmer areas, which means that the concentration of these chemicals in the cabin air of a vehicle parked in such areas will be higher.

What’s more, using flame retardant chemicals in car seats has not been proven to save lives. In fact, data shows that such chemicals in seat foam lead to the generation of more smoke and toxic chemicals during a fire.

“It’s also important to note that these chemicals do not stop materials from burning; they only slow the rate at which they burn, and while they burn, they are creating dangerous conditions — i.e., more smoke and toxic chemicals,” Stapleton explained. “We need to address fire safety with different technologies and approaches, such as using inherently non-flammable materials or redesigning flame retardants so they do not escape from materials over time.”

Ventilating your car during the hot summer months can help reduce the risk of exposure to flame retardants and other possible carcinogens.

“And if possible, park your car in the shade or use a sun visor to minimize the car interior temperature during the day,” she continued. “I also recommend that people open the car windows and ventilate the air before getting into the car to drive. If you have an automatic starter, it would be best to start the car for a few minutes before driving and put the air conditioner on to cool the interior temperature.”

Many vehicles also allow the ability to recirculate air within or utilize outside air when heating/cooling. Consider avoiding using the recirculating air feature.

The research raises awareness about potential environmental exposures to harmful compounds. Identifying these exposures is an important first step in clinical practice, as defining absolute risks for cancer development remains challenging. Millions of people drive or travel daily, and this exposure is obviously toxic. Research is needed to modernize regulations for material requirements in vehicles and develop alternative materials that do not contain harmful compounds.