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For the first time, researchers report concentrations of environmentally unfriendly PCNs ' polychlorinated naphthalenes ' in the air over the arctic region of the globe. PCNs, predecessors to the infamous PCBs (polychlorinated biphenyls), previously have been found in humans, birds, fish, water, air and sediment in non-polar regions in North America and Europe. They also have been found in fish from the Arctic.
"The ubiquitous nature of PCNs is of concern because of their dioxin-like toxicity," claims a group of Canadian and Swedish researchers writing in the Nov. 1 issue of the journal Environmental Science & Technology, published by the American Chemical Society, the world's largest scientific society. PCN use has declined in recent years, but, unlike PCBs, they are not banned in most countries and can still be found in capacitor fluids, engine oil additives and electrical insulators, according to the report. The results of the study are based on air samples taken over the Eastern Arctic Ocean, the Barents Sea, the Norwegian Sea, and at two land-based sites in Canada and eastern Siberia in Russia.
PCB Levels In Lake Michigan Salmon Within FDA Guidelines
Findings from a newly reported study, described as the most comprehensive ever of its type, confirm that Lake Michigan coho salmon retain about 50 percent of the PCBs (polychlorinated biphenyls) they consume in their natural diet of smaller fish. However, the study also shows the PCB levels in the salmon are well within acceptable guidelines for human consumption, established by the U.S. Food and Drug Administration.
The joint study by the U.S. Geological Survey and the U.S. Fish and Wildlife Service appears in the Oct. 15 issue of Environmental Science & Technology, published by the American Chemical Society, the world's largest scientific society. Considerably smaller than Chinook (king) salmon, the silver coho salmon were introduced to the Great Lakes from North Pacific waters in the 1960s to control the lake's population of alewife, a member of the herring family, that had become a public health nuisance.
The two-year study measured the concentrations of PCBs in the salmon and estimated the efficiency with which the fish retain PCBs as a result of their natural diet of smaller fish such as alewife, bloater and smelt. The study also measured the level of PCBs in the smaller prey fish. The findings are consistent with a smaller, less extensive study of Lake Michigan coho salmon from about 15 years ago.
Iron Sulfate Speeds PCB Biodegradation, Reduces Toxicity
Iron sulfate offers a new approach to removing the chlorine molecules found in PCBs (polychlorinated biphenyls). Chlorine is the primary component involved in the toxic effects of this industrial compound. Partial PCB dechlorination takes place routinely in nature, thanks to certain bacteria. Unfortunately, in many instances only about 10 percent of the chlorine is removed this way, and researchers worldwide are looking for ways of increasing the effectiveness of this biodegradation.
Writing in the Nov. 1 issue of Environmental Science & Technology, Michigan State University scientists report the results of a study involving the addition of iron sulfate to PCB contaminated sediments. The journal is published by the American Chemical Society, the world's largest scientific society.
"Iron sulfate appears to both stimulate the growth of PCB dechlorinating bacteria so that there are more of them and hence more activity, and also to reduce toxicity of byproducts of dechlorination that inhibit further dechlorination," said Stephen Boyd, Ph.D., lead scientist for the study and a professor in MSU's Institute for Environmental Toxicology. "No one else has ever tried this approach," according to Boyd. Prior to this, he said, "there were no reliable and practical methods to stimulate the most important dechlorination processes."
The study involved sediments from the upper Hudson River near Hudson Falls, N.Y.