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Flame Retardants in Car Seats Prompt Cancer Concern
A U.S.-focused study notes organophosphate ester flame retardants were detected in cabin air within 101 vehicles tested, “indicating a route for human exposure to chemicals of concern from passenger vehicles.”
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Invisible dangers lurk within car seat foam, scientists claim.
The integration of flame retardants into car seat foam may increase auto passengers’ exposure to chemicals that can cause cancer, especially during the summer, according to a new study in the American Chemical Society journal Environmental Science & Technology.
Researchers are urging federal U.S. government officials to review the U.S. Federal Motor Vehicle Safety Standard FMVSS 302, noting: “This study concludes that vehicles are likely important sources of human exposure to potentially harmful FRs (flame retardants). Coupled with the uncertain fire safety benefits of adding FRs to personal vehicle interiors, these results suggest that FMVSS 302 should be reevaluated.”
These mandatory standards are issued by NHTSA and designed to boost safety in U.S.-made vehicles.
The U.S.-focused study notes organophosphate ester (OPE) flame retardants were detected in cabin air within 101 vehicles tested, “indicating a route for human exposure to chemicals of concern from passenger vehicles.” The study assessed mostly autos made between 2015 and 2022 across 30 different U.S. states, with the largest number in California.
Countries of manufacture included the U.S., Japan, Mexico, Germany, South Korea and Canada.
The researchers found summer concentrations of OPE compounds triethyl phosphate (TEP), triisobutyl phosphate (TIBP), tri-n-butyl phosphate (TNBP), and tris(1-chloro-2-propyl) phosphate (TCIPP) were “significantly higher than winter concentrations.” They say the “frequent detection of TCIPP in vehicles is particularly concerning,” given the United States National Toxicology Report 2023 linked the chemical to cancer in male and female rats in experiments.
“Carcinogenic potential of other OPEs has led to restrictions on their use,” adds the study, written by academics from Duke University in North Carolina; the Green Science Policy Institute, Berkeley, CA; and Canada’s University of Toronto.
They argue there are “uncertain fire safety benefits of adding FRs to personal vehicle interiors,” and hence reviewing standards makes sense, with California’s TB 117 2013 flammability standard for upholstered furniture as an example of an updated standard that led to reduced flame-retardant usage.
The health risks posed by these organophosphate esters have been highlighted by other studies. For example, researchers at Simon Fraser University, Vancouver, Canada, found TCIPP was cytotoxic (kills cells) above certain limits. An assessment by U.S. chemical company Bisley International said of TIBP: “There has been concern that this material can cause cancer or mutations...”
A 2021 paper in the Journal of Hazardous Materials concluded TPHP exposure was “associated with cervical cancer risk.” https://www.sciencedirect.com/science/article/abs/pii/S0304389420320100
That said, many studies have concluded TEP is safe – for example, a 2024 study in Green Chemistry Letters and Reviews concluded “TEP shows almost no toxicity and no carcinogenic or mutagenic properties.”
There are examples of substitutes, especially natural materials, that do not pose the same risks.One market segment that is responding is fitted car seats for young children, with U.S.-based blog “Safe in the Seat” highlighting the benefits of using wool, whose “inherent properties offer an effective, environmentally friendly alternative that eliminates the need for added chemicals,” which is “important for parents who have health concerns about chemical flame retardants.”
Examples of child auto seat manufacturers who have responded include Netherlands-based Nuna, which the blog hailed as a “manufacturer with 100% of their seats being free of flame-retardant chemicals.” https://nunababy.com/en/stories
Meanwhile, South Carolina-based car seat manufacturer Britax Child Safety has also been developing flame retardant-free products. A company statement says it “uses a unique knit fabric construction (non-wool) and incorporates selective foam, harness straps, plastic, and metal parts – all of which are free of added flame-retardant chemicals...to reduce the child’s exposure to certain chemicals.”
One of the Environmental Science & Technology researchers, Lydia Jahl, senior scientist with the U.S.-based Green Science Policy Institute, tells WardsAuto there are workarounds, even if the current standards remain unchanged. FMVSS 302 requires that seats and other vehicle interior materials can withstand a small open flame, like a match.
One would be adhering car seat foam to the upholstery cover, which – under the rules – she says, would enable auto manufacturers to only test the fabric/foam together – applying the flame to the foam - rather than also assessing the underlying foam separately, which could then be flame-retardant free. “If that’s a thick woven polyester, then it might be able to pass the standard,” Jahl says.
Another option might be chemically bonding foam with flame retardant, rather than the current additive application. But the problem here is that such a manufacturing process is “more expensive,” she says: “It is really hard to make, so the foam manufacturers don’t want to have to do it, and if they did, the auto manufacturers would have to pay a lot more money…”
Besides higher costs, automakers face an often arduous task with their own purchasing departments to qualify new suppliers. If the federal government requires changes for health and safety reasons, automakers and suppliers are under pressure to fast-track changes in materials.
Indeed, a a simpler solution could be simply to change the current standard. Jahl notes the influential California standard for home furniture was changed in 2013 to maintain fire safety without using retardants, and while auto seats have additional risks such as integrated electronics, she says a federal standard review would be justified: “It was first propagated 50 years ago with a lot more people who smoked. And vehicles have become a lot safer in general so there’s a lot less fires.”
She adds: “There’s also data showing that a very small percentage of vehicle fires start in vehicle interiors. Most fires, especially with fatalities, are after a full collision, when a person might not be able to escape and the engine catches fire or gas is pooling under the car and then that catches fire.”
William Wallace, associate director of safety policy for U.S. consumer advocate organization Consumer Reports, says: “It’s long overdue for NHTSA to consider a better flammability standard for the inside of our cars.” He calls on the auto sector to develop alternatives to flame retardants “that can similarly protect consumers from fires while sparing them the long-term health harms of toxic chemical exposure.”
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