Hundreds of chemicals, such as polyvinyl chloride (PVC) and brominated flame retardants (BFR), are used in automotive interiors. These chemicals are used to make plastics flexible, make fabrics fire-resistant, and contribute to that "new car smell." But they're also associated with birth defects, impaired learning, liver toxicity, and cancer.
To find out what chemicals and their amounts are used in cars, researchers at Ecology Center, which publishes the consumer awareness site Healthystuff.org, tested 11 components in more than 200 vehicles from the 2011 and 2012 model years using an x-ray fluorescence analyzer. The test scans a component, such as seats, dashboard, carpets, headliner, and door trim, and identifies the elements in a material.
Researchers weighted the samples by the size of the component and how much contact a person would have with the component, and rated the vehicle on a scale of 0-5. Off-gassing from seats would have a higher weight than the off-gassing from floor mats because occupants come into physical contact with the seats for long periods of time.
A score of 1 would mean the researchers didn't detect the chemicals they were testing for, and a 5 would mean they found high levels of the chemicals they were testing for in materials with which people come into frequent contact.
The biggest offender, Ecology Center found, was the 2011 Mitsubishi Outlander Sport, with a score of 3.17. On the other end of the scale, the cleanest vehicle was the 2012 Honda Civic with a score of 0.46.
Honda earned a low toxicity score by not using bromine-based flame retardants in all interior components, using PVC-free interior fabrics and trim, and low levels of heavy metals and other metal allergens. However, Ecology Center researchers found bromine and antimony-based flame retardants in seat materials, the center console, and seat base of the Mitsubishi Outlander Sport. Mitsubishi also uses chromium-treated leather on several components and over 400 parts per million (ppm) lead in seating materials in the Outlander Sport, according to Ecology Center.
Unfortunately, Mitsubishi is in good company. Researchers found that 40 percent of vehicles tested contained BFRs in the vehicle interiors. Other high offenders on the list included the 2012 Chrysler 200 SC with a score of 3.17 and the 2011 Kia Soul with a 3.11.
The full list of vehicles can be found on the organization's Web site, Healthystuff.org. Car shoppers can look up a prospective model to see how each vehicle ranked and the levels of chemicals detected in each component.
But if the vehicle you want scores high in toxicity, don't be so sure that buying used is a way to avoid chemical off-gassing, said Jeff Gearhart, research director at the Ecology Center.
"It just depends; if what you're reacting to is the VOCs, then the answer is probably yes," said Gearhart. "But there are other chemicals that break down over time, such as polyurethane foam."
On the upside, PVC use in vehicles is declining. The organization reports that when they they started testing cars in 2006, none of the vehicles were PVC-free. Today, 17 percent of the 2011 and 2012 vehicle models don't use PVC in their interiors.