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Are we breathing cancer-causing chemicals in our cars?

A recent study led by Duke University has identified significant levels of toxic flame retardants in the air inside personal vehicles, raising serious public health concerns. The findings highlight the pervasive presence of these chemicals in cars, which are added to materials like seat foam to adhere to federal flammability standards.

Harmful chemicals in our cars

“Our research found that interior materials release harmful chemicals into the cabin air of our cars,” said lead author Rebecca Hoehn, an expert in integrated toxicology and environmental health at Duke. 

“Considering the average driver spends about an hour in the car every day, this is a significant public health issue. It’s particularly concerning for drivers with longer commutes as well as child passengers, who breathe more air pound for pound than adults.”

The experts analyzed the interior air of 101 cars from the U.S., model year 2015 or newer, and found that 99% contained tris (1-chloro-isopropyl) phosphate (TCIPP), a flame retardant currently under scrutiny by the U.S. National Toxicology Program for its potential carcinogenic properties. 

Additionally, the presence of other harmful chemicals, such as tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) and tris (2-chloroethyl) phosphate (TCEP) – both recognized as carcinogens under California Proposition 65 – was noted. These chemicals have also been associated with neurological and reproductive damage.

Source of the flame retardants 

Seasonal variations affect the concentration of these flame retardants, with higher levels detected during warmer months. This is attributed to increased off-gassing from car interiors, which can reach temperatures up to 150 degrees Fahrenheit. 

The experts established a correlation between the presence of TCIPP in seat foam and higher airborne, suggesting that seat foam is a significant source of this chemical in the cabin air.

Flame retardant safety standards 

Flame retardants are mandated by the U.S. National Highway Traffic Safety Administration (NHTSA) under the Federal Motor Vehicle Safety Standard (FMVSS) 302. This standard, which dates back to the 1970s, necessitates that interior materials in vehicles withstand exposure to open flames.

“Firefighters are concerned that flame retardants contribute to their very high cancer rates,” noted Patrick Morrison, a health and safety official responsible for 350,000 U.S. and Canadian firefighters at the International Association of Fire Fighters

“Filling products with these harmful chemicals does little to prevent fires for most uses and instead makes the blazes smokier and more toxic for victims, and especially for first responders. I urge NHTSA to update their flammability standard to be met without flame retardant chemicals inside vehicles.”

The call for updated regulations mirrors changes made to California’s flammability standards for furniture and baby products a decade ago, which now allow for safety compliance without the use of flame retardants. This shift has resulted in enhanced or maintained fire safety, as well as reduced levels of flame retardants in U.S. homes.

Reducing exposure to chemicals in cars

Additionally, the researchers documented the detrimental impact of flame retardants on intellectual development and cancer risks. “You may be able to reduce your exposure to flame retardants in your car by opening your windows and parking in the shade,” suggested Lydia Jahl, a senior scientist at the Green Science Policy Institute

“But what’s really needed is reducing the amount of flame retardants being added to cars in the first place. Commuting to work shouldn’t come with a cancer risk, and children shouldn’t breathe in chemicals that can harm their brains on their way to school.”

These findings call for a reevaluation of safety standards and advocate for significant reductions in the use of hazardous chemicals in automotive manufacturing.

Health concerns associated with flame retardants 

Flame retardants can accumulate in the human body over time, and they are linked to a range of health problems. Some of the most concerning risks include hormonal disruption, which can affect reproductive health and development. Flame retardants can also impair thyroid function, which is crucial for metabolism and brain development.

Additionally, these chemicals have been associated with negative impacts on the immune system, making it harder for the body to fight off infections and may also increase the risk of autoimmune disorders. There is evidence suggesting that exposure to flame retardants can lead to neurodevelopmental issues in children, such as learning disabilities and behavioral problems.

Cancer is another significant concern, as some flame retardants are considered potential carcinogens. The risk of cancer, particularly for those frequently exposed to these chemicals, underscores the importance of managing and limiting exposure to flame retardants in environments like homes and workplaces. 

The study is published in the journal Environmental Science & Technology.


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