Since 2011, when I started writing about flame retardants, I’ve been struck by how the researchers studying these chemicals talk about their findings. Scientists tend to talk about their results in terms of what they don’t know and what new questions their studies raise. (All exceptions duly noted.) And those studying flame retardants do discuss their findings with all the usual caveats. But they also do something else. They tell me, "We don’t like what we’re seeing."
A few weeks ago, I spoke with Heather Stapleton, a flame retardant expert at Duke University who’s pioneered methods to correlate levels of dust on people’s hands with levels found in their blood or urine. With two small children, a four-year-old son and a daughter who will be two next month, Stapleton said she thinks very carefully “as a mother and scientist” about the products she buys and washes her children’s hands frequently to reduce exposure.
She’s particularly worried about people using hand-me-down nursing pillows and other baby products that likely exude more flame retardants as they age. “No one to my knowledge is examining infants’ exposure to flame retardants from these small items,” she said. “They’re small but an infant spends a lot of contact time with them.” What’s more, babies are likely to go from sleep positioner to a car seat to a changing table, spending the better part of a day in contact with products that could be leaching the chemicals.
Last week at the flame retardant conference, researchers talked about the global reach of these chemicals, now detected in trees, sludge, wildlife and people around the world. They listed the wide range of health effects associated with the well-studied brominated flame retardants—including endocrine disruption and developmental, neurological and reproductive defects—and emphasized that the effects have been found in both animals and humans. They also reported worrying early results on new formulations like tetrabromobisphenol A (TBBPA), which is showing up in human breast milk and maternal cord blood samples.
Historically, TBBPA was added mostly to electronics and circuit boards in a “reactive mode,” which means it’s unlikely to leach from the product. But as Linda Birnbaum pointed out at the meeting, it’s now being used as a replacement for banned or discontinued brominated flame retardants in an “additive mode”—so it can offgas, migrate from the product into the air. “Which means more is going to get into the environment,” Birnbaum said, “which means more is going to get into people and wildlife.”
Birnbaum, director of the National Institute of Environmental Health Sciences and the National Toxicology Program, reported that a two-year study of TBBPA in rats and mice found a dose-related increase in aggressive uterine tumors in the female rats—“these are highly malignant tumors that metastasize to many different sites,” she told the crowd—as well as liver tumors in male and female mice. These results suggest, she said, that TBBPA is a “two species carcinogen” that warrants closer study.
A few months ago, Birnbaum told me that she used to think flame retardants were providing fire safety but now isn't so sure. She allows there may be applications that warrant them, like airplanes, but even then, she said, “If we think flame retardants are going to be helpful, why not use them in a reactive mode, so they don’t easily escape into the environment?”
A decade ago, after seeing data showing rising levels of flame retardants in people along with animal evidence linking neurological effects to exposure early in life, Birnbaum called attention to the issue with a paper called "Brominated Flame Retardants: Cause for Concern?"
Now, she said, “everything that is being seen in people when you look—and until recently, no one looked—is consistent with things that we’ve seen in animal models.”
The weight of the evidence inspired Birnbaum to write another paper. “I changed the question mark,” she said, “to an exclamation point.”