Research published in ES&T (DOI 10.1021/es9003679) shows for the first time that compounds produced when PBDE flame retardants are exposed to wastewater treatment can generate dioxins. Kris McNeill, Bill Arnold, and their University of Minnesota colleagues say they believe that the photochemically created brominated and mixed halogenated dibenzo-p-dioxins they discovered are likely to be “ubiquitous in aquatic environments.” Experts agree that both the dioxins and the compounds that produce them, hydroxylated PBDEs (OH-PBDEs), could be impacting aquatic wildlife, and humans as well.
Buttressing the finding’s significance is a report by the U.S. National Atmospheric and Oceanic Administration (NOAA) released on April 1, which documents “that PBDEs are clearly ubiquitous” in U.S. coastal waters. When the report was issued, John H. Dunnigan, assistant administrator of NOAA’s National Ocean Service, said: “Scientific evidence strongly documents that these contaminants impact the food web and action is needed to reduce the threats posed to aquatic resources and human health.” The report points out that laboratory toxicity studies have connected PBDEs to liver, thyroid, and neurobehavioral development impairments. It also says PBDEs “show the potential for adverse human health effects.”
The NOAA report is the most comprehensive assessment of the presence of PBDEs in the U.S. coastal environment, says Susan Shaw, director of the Marine Environmental Research Institute, a nonprofit organization. Shaw is the lead author of a 2009 paper documenting the biomagnification of PBDEs in northwest Atlantic marine food chains, including predatory fish and seals.
Although the NOAA scientists measured neither OH-PBDEs nor the dioxins that they can spawn, McNeill and Arnold predict that scientists are likely to find these byproducts wherever PBDEs are present in the water environment. “It’s logical to assume if you have PBDEs [in wastewater], you’ll have OH-PBDEs. . .and if the OH-PBDEs are exposed to sunlight, you’re going to get brominated dioxins formed in the water,” Arnold says.
When considered together, the new research and report suggest that additional research is needed to investigate whether the mechanism discussed in the paper could produce more toxic dioxins from other PBDE compounds, says Linda Birnbaum, director of the National Institute of Environmental Health Sciences and one of the world’s foremost authorities on dioxin toxicity. She says that the dioxins produced in the new experiment seem unlikely to be very toxic, however.
Birnbaum says she is also concerned about the potential health effects from OH-PBDEs. “They appear to be relatively persistent and do appear to have endocrine properties,” she says. According to the new paper, a growing body of research suggests that they, too, are ubiquitous in the water environment.