Studies: PBDE Rules Lower Level in Fish, Bird Eggs
Regulations on flame-retardant compounds and elimination of their use may be reducing the levels of these chemicals in fish eggs and seabird eggs in northern areas of the Earth, according to results from two studies published in the April 2009 issue of Environmental Toxicology and Chemistry.
The studies examine tissue levels of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) during at least 20-year periods in Canada and Norway. The issue of global distillation—the transport of certain chemicals from warmer to colder areas of the Earth—is a concern in these areas, where the chemicals have not been used in large amounts but have been found in the environment and bodies of people and animals that live there.
PBDEs are flame-retardant chemicals used to make electrical equipment, textiles, and other fireproof products. These chemicals leak from products and have been found in animal cells. Research and health concerns have led to the banning of two types of PBDEs—penta- and octa-mixtures—by the European Union and reductions of their use in the United States and Canada since 2004. More recently, use of deca-PBDE also has been banned in parts of the United States as well as the European Union.
The first study examined trout in Lake Ontario, Canada, from 1979 to 2004, and how flame-retardant levels might affect the food web in that area. Researchers found that PBDE concentrations increased from 1979 to the mid-1990s but then leveled off or decreased through 2004, and that HBCD levels also decreased through that period, although at a slower rate.
"Our observations are consistent with the trend patterns previously observed in both Lake Ontario lake trout and herring gull eggs, and these findings have been attributed to the phasing out of the penta- and octa-BDE mixtures," the researchers write.
They also examined the Lake Ontario food web and its influence on chemical levels, and found that "food-web changes may be at least partially responsible for the observed decrease in PDBE concentrations between 1998 and 2004," although they say more research on this factor is needed.
For the second study, a different group of researchers looked at PBDE and HBCD levels in seabird eggs in northern Norway from 1983 to 2003. They also found that PBDE concentrations increased from 1983 to 1993 but then decreased.
"A reduction in emissions from European production could explain the decreasing concentrations of PBDEs in the present study," the authors write, adding that local use and emissions of PBDEs also could have an effect. HBCD levels in seabird eggs increased, possibly because of the compound’s enhanced emissions.