Researchers at the Virginia Institute of Marine Sciences report finding edible fish with the highest levels of polybrominated diphenyl ether (PBDE) flame retardants recorded to date in a research article recently posted to ES&T’s Research ASAP Web site. The team, led by Rob Hale, one of the nation’s leading PBDE researchers, found a carp with 47.9 milligrams of PBDEs per kilogram (mg/kg) of body fat, a level 30% greater than the highest level reported for Swedish perch.

The research “is important because it shows PBDEs are as much (or more) of a problem in the United States as Sweden,” says Hale, who calls PBDEs “a major, albeit generally unmonitored, class of pollutants with persistent, bioaccumulative, and toxic (PBT) like qualities” in the United States.

Hale’s team studied 33 species of edible fish, including varieties of catfish, bass, and carp, and focused on six bioaccumulative and toxic PBDE compounds. PBDEs were found in 89% of the 332 fish that the researchers collected from the watersheds around two Virginia rivers, the Roanoke and the Dan, making the presence of PBDEs in that population nearly as common as polychlorinated biphenyls (PCBs) and a breakdown product of DDT. Hale had previously collected fish from these rivers that had PBDE levels of more than 1 mg/kg in their body fat, but this latest research reflects a larger sample population.

The researchers found that the most abundant PBDE was BDE-47, one of the compounds associated with the “Penta” PBDE flame retardant formulation, which is slated to be banned in Europe. Over half of the fish they collected contained more than 100 µg/kg of BDE-47, and fish from 16 of the 133 collection sites contained more than 1000 µg/kg of BDE-47.

BDE-47 is one of the most bioaccumulative, toxic, and widely distributed PBDEs, according to Jacques de Boer, an expert on worldwide PBDE distribution at the Netherlands Institute for Fisheries Research. Although the levels of BDE-47 in human tissue have been declining in Europe in tandem with decreasing usage there, recent U.S. studies show high levels in breast milk and body fat. Toxicology studies suggest that PBDE compounds like BDE-47 may be endocrine disrupters that also affect neurodevelopment and liver function, and Hale’s team notes that Virginians eating locally caught fish may be exposed to PBDEs.

Although many of the fish in the study appear to have high PBDE levels due to their proximity to local industrial sites, Hale believes that most of the fish were exposed by nonpoint sources. In fact, the fish with the highest level of total PBDEs was a carp found in Virginia’s Hyco River at a site with no known manufacturing facilities. The source of the PBDEs in fish from that river remains under investigation.

Hale’s team hypothesizes that potential PBDE sources include airborne emissions from the manufacture of polyurethane foam with which the Penta BDE formation is used and sludge containing high levels of PBDEs. The researchers are also investigating the possibility that Penta-laced polyurethane foam from discarded automotive upholstery or furniture was the source.

The U.S.’s EPA’s National Health and Environmental Effects Research Laboratory is “very interested in the PBDEs,” says Linda Birnbaum, director of the lab’s Human Studies Division. The agency has commissioned several studies on PBDEs and started a number of research projects, adds a laboratory spokesperson. —KELLYN S. BETTS