Web Date: October 11, 2011
New Brominated Chemicals Detected In Gull Eggs
Although designed to be more environmentally friendly, new polybrominated flame retardants may accumulate in living tissues just like older ones, according to a study in Environmental Science & Technology (DOI: 10.1021/es201325g). Researchers have detected chemical signatures consistent with these products in herring gull eggs collected around the Great Lakes.
In 2004, U.S. manufacturers voluntarily ceased production of some polybrominated flame retardants, such as penta- and octa-polybrominated diphenyl ethers (PBDEs). The move came after scientists detected the retardants in humans and, in animal experiments, linked the chemicals with thyroid and neurological problems. Some manufactures replaced PBDEs with new compounds such as tetradecabromodiphenoxybenzene, marketed as Saytex 120. Saytex 120 contains 14 bromine atoms, making it heavy and involatile, and therefore less likely to accumulate in the food web, according to scientists.
Robert Letcher and Da Chen of the National Wildlife Research Center at Carleton University, in Ottawa, Ontario, study how flame retardants move through the Great Lakes food web and accumulate in the eggs of herring gulls (Larus argentatus smithsonianus). Using high-resolution mass spectrometry, they detected a previously unidentified class of compounds¬¬ in eggs collected from 14 sites around the Great Lakes. These six compounds, called methoxylated polybrominated diphenoxybenzenes, each contained between four and six bromine atoms. The team detected the highest levels in eggs from Channel-Shelter Island in Saginaw Bay, an area of Lake Huron in Michigan near several manufacturing plants.
The researchers hypothesize that the new class of chemicals form when flame retardants such as Saytex 120 enter wastewater streams. In the water, the retardants lose bromine atoms, either through a sun-catalyzed reaction or by microbial degradation. Then, metabolic processes in the gulls or their prey add methoxyl groups to the aromatic backbones. The team is studying other organisms in the food web to test this hypothesis.
If it proves correct, Letcher says, the findings suggest that environmental scientists should “continually question the stability of replacement flame retardants.”
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society