Unintended consequences are a pain. California has long had some of the strictest flammability regulations in the country for furniture and other household items. As a result, in the 1970s flame retardant chemicals called polybrominated diphenyl ethers (PBDEs) were added to consumer products, including electronics and foam in furniture.
No doubt those PBDEs, which slow the ignition rate for fires, saved some lives by preventing household fires. But it turned out that slowing fires wasn’t the only thing PBDEs did. Later, the Environmental Protection Agency would link the chemicals to liver, thyroid and neurodevelopmental toxicity — enough that California decided to ban the use of pentaBDE and octaBDE, two of the main commercial mixtures of PBDE flame retardants, in 2003.
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But those unintended consequences are still being felt in California. A new study published in the journal Environmental Science and Technology found that women in California had the highest levels of PBDEs ever reported among pregnant women — a result, the researchers believe, of the state’s earlier fire-prevention regulations.
Here’s what Ami Zota, lead author on the paper and a researcher at the University of California, San Francisco, had to say:
While our study group was small, the higher chemical exposure in pregnant women is particularly concerning and warrants further research. PBDEs can disrupt the thyroid system and have been linked to neurodevelopmental problems in children following prenatal exposure.
Despite the ban, blood levels of flame retardant chemicals are two times higher for California residents than for people in the rest of the country, likely because our state has the most restrictive flammability requirements nationally.
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Although California has moved to phase out PBDEs, the chemicals are still present in older furniture. As the products break down, PBDEs are released into the air. The price may be unintended, but Californians are still paying it.
Bryan Walsh is a senior writer at TIME. Find him on Twitter at @bryanrwalsh. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME