In a new study, researchers found that the longer your commute, the more you’re exposed to a chemical flame retardant that is a known carcinogen.
The chemical was phased out of furniture use because it required a Proposition 65 warning label in California.
While much research on automobile pollution focuses on external air pollutants entering vehicle interiors, this study shows that chemicals emanating from inside your car could also be cause for concern.
The research was conducted by a team at UC Riverside and elsewhere.
Though there are other Proposition 65-list chemicals that are typically used in the manufacture of automobiles, this flame retardant is a new addition to the list.
Known as the Safe Drinking Water and Toxic Enforcement Act, Proposition 65 requires the state to maintain and update a list of chemicals known to cause cancer or reproductive harm.
Some scientists assumed that humans stopped being exposed to the chemical, called TDCIPP or chlorinated tris, after it was placed on California’s Proposition 65 list in 2013.
However, it is still widely used in automobile seat foam. The study shows that not only is your car a source of TDCIPP exposure but that less than a week of commuting results in elevated exposure to it.
Using zebrafish and human cells as models, the team has been studying the toxicity of a newer class of flame retardants called organophosphate esters since 2011.
Little is known about the toxicity of these organophosphate esters—TDCIPP is one of them—but they’ve replaced older flame-retardant chemicals that lasted longer in the environment and took longer to metabolize.
The team found TDCIPP prevents an embryo from developing normally.
Other studies have reported a strong association between TDCIPP and infertility among women undergoing fertility treatments.
Knowing its use is still widespread in cars, the team wondered whether a person’s exposure is elevated based on their commute.
Participants in the study included around 90 students, each of whom had commute times that varied from less than 15 minutes to more than two hours round trip.
All of them were given silicone wristbands to wear continuously for five days.
The molecular structure of silicone makes it ideal for capturing airborne contaminants.
Since TDCIPP isn’t chemically bound to the foam, it gets forced out over time and ends up in dust that gets inhaled.
Multiple organophosphate esters were tested, but TDCIPP was the only one that showed a strong positive association with commute time.
This means the exposure to TDCIPP is higher the longer people spend in their vehicles.
The research team would like to repeat the study with a larger group of people whose ages are more varied. They would also like to study ways to protect commuters from this and other toxic compounds.
Until more specific reduction methods can be identified, the team encourages frequently dusting the inside of vehicles, and following U.S. Environmental Protection Agency guidelines for reducing exposure to contaminants.
The lead author of the study is David Volz, an associate professor of environmental toxicology at UCR.
The study is published in the journal Environment International.
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