DDT - Global Problem


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DDT in pristine environments points to a "global problem"

May 1996

U.S. Water News Online

MIDWAY ATOLL -- Isolation has not protected oceanic birds nesting on a remote Pacific atoll from environmental contaminants that originate in distant places, new research shows.

Researchers have found high levels of DDT compounds, PCBs and dioxin-like compounds, in blackfooted albatross adults, chicks, and eggs on Midway Atoll in the North Pacific. This atoll is "a long way from anywhere," say researchers who conducted the study here -- 3,100 miles from Los Angeles, 2,400 miles from Tokyo, and 1,150 miles from Honolulu.

These chemicals remain in the environment for a long time, and long-term exposure has had a serious impact on these birds, researchers found. Deformed embryos and eggshell thinning, among other things they say, have led to a 3 percent drop in nest productivity.

This is a serious cause of concern, said scientists, because of the potential for even greater harm to albatrosses, as well as other bird species. Dr. Paul Jones was one of the researchers at Midway Atoll. Jones, an environmental chemist from New Zealand, recently published his findings on the Midway albatrosses in []Environmental Toxicology and Chemistry.[] And Dr. James Ludwig, the head of the research team, presented an abstract of his findings at a recent meeting of the American Chemical Society of Honolulu.

"Concentrations of persistent chemicals in black-footed albatrosses on Midway are nearly as great as current levels in bald eagles from the highly contaminated Great Lakes," said Ludwig, a bird population ecologist. Ludwig, who led an international research team to the atoll, said the pollutants in the birds' diet were probably coming from India, Southeast Asia, and Japan.

Laysan albatrosses, which also breed on Midway, have a significantly lower toxic burden in their blood and eggs, and scientists attribute this to the two species' different feeding habits.

Dr. John Giesy, a toxicologist at Michigan State University, and member of the Midway team stressed the need for global controls on contaminants like DDT. "While albatrosses feed near the top of the food chain, they forage on the open ocean far from continental pollution sources," Giesy said.

Researchers, Giesy explained, expected to find very low contaminant levels in these birds. But this research, he said, "demonstrates that global controls on the distribution of persistent, bioaccumulative toxic compounds need to be considered. The problem can't be approached on a country-by-country basis."

Ludwig said amounts of DDT compounds in black-footed albatross eggs were running just under two parts per million. "These are not trivial amounts when you consider that eggshell thinning in a number of birds has been shown to occur at levels of between two and three parts per million," he said.

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