Durham, N.C. – Heather Stapleton, assistant professor of environmental chemistry at 91’s Nicholas School of the Environment, has received a $2.2 million, five-year research grant from the National Institutes of Health to examine children’s exposure to flame retardants.
The study, “Children’s Exposure to Flame Retardants: Effects on Thyroid Hormone Regulation,” will focus on determining the extent to which children are exposed to polybrominated diphenyl ethers (PBDEs), flame-retardant chemicals that are present in indoor air and dust.
“Children get exposed to these compounds on a daily basis, and we know very little about what effects this might have,” says Stapleton.
In addition to investigating the extent of exposure, Stapleton and her team will investigate what effects exposure to PBDEs may have on children’s thyroid hormone regulation, which can potentially affect their development.
PBDEs have been used for decades to reduce flammability in many common household items, including furniture, mattresses, televisions, cell phones and other electronic products. They are long-lasting compounds that can persist in the environment for decades. When people throw items with flame-retardants into landfills, the PBDEs leach into the soil and make their way into surrounding ecosystems. They can then accumulate in the tissues of fish and other animals. Through the process of biomagnification, these levels can become quite high.
Traces of PBDEs have even been found in human blood and breast milk, but it is unknown what effects these contaminants might have on human health.
As of yet there is no federal ban on the commercial use of PBDEs in North America. U.S. manufacturers have voluntarily phased out use of two of the three commercial PBDE mixtures, but the use of the remaining mixture, DecaBDE, along with the increasing use of alternative brominated flame retardant chemicals, continues to cause concern about human health.
Children are especially susceptible to high PBDE levels because of their crawling and mouthing behaviors, which exposes them to indoor dust that contains elevated levels of these contaminants.
Stapleton previously has studied how PBDEs distribute themselves in the tissues of fish, and how certain fish metabolize them. More recently, she has begun to examine human exposures to these contaminants.
“Kids likely have the highest exposure to these contaminants,” says Stapleton. “During our study we expect to find PBDEs in house dust and on the children’s hands. What we’re trying to determine is whether or not the body burdens of PBDEs are higher in children or adults.”
Stapleton’s study will be conducted in two phases. In the first phase, researchers will study exposure in approximately 100 homes in the Raleigh-Durham area, focusing on households with children between the ages of two and four. Researchers will collect samples of house dust, and dust and dirt from children’s hands, to determine what contaminants are present, and to what extend the children are exposed to when they put their hands in their mouths. In the second phase, Stapleton and her team will conduct in vitro tests to examine what effects these contaminants might have on thyroid hormone production and regulation.
“This will hopefully allow us to gain a better understanding of what effect these contaminants may actually have on children,” she says.
Stapleton hopes her research will lead to more extensive studies about how exposure to different contaminants and mixtures of pollutants may affect the human body.
“One of the most troublesome thoughts is that not only are there flame retardant contaminants in dust, but children are also exposed to numerous other contaminants both indoors and outdoors, and we really don’t know how they interact,” she says.
“We typically think that children are being exposed to contaminants and chemicals outdoors, but in reality, they’re being exposed to a combination of pollutants in their own homes. We need to understand what effects this might have on their development.”
