Contact:
James Tiedje, Center for Microbial Ecology, (517) 353-9021 or
Tom Oswald, Media Communications, (517) 355-2281
MSU RESEARCH FINDS DDT BY-PRODUCTS DEGRADE NATURALLY IN MARINE SEDIMENTS
EAST LANSING, Mich. - Researchers have found that DDE, a by-product of DDT, the now-banned pesticide that continues to have a presence within the Earth's soils and sediments, is degrading naturally in the environment.
A study by researchers at Michigan State University and MBI International found that DDE, like some of the other by-products of DDT, is being naturally degraded in oxygen-free ocean sediments off the coast of California.
The research is published in the May 1 issue of the journal Science.
"These finding are important because it suggests that the problem products from DDT use may not persist forever," said James Tiedje, director of the MSU Center for Microbial Ecology. "These results also indicate the need to re-evaluate environmental risk assessment and remediation decisions which assume natural decay of DDT-related compounds does not occur."
"Earlier studies found that DDT degrades to DDE and DDD," said John Quensen, of MSU's Center for Microbial Ecology and a senior scientist at MBI. "And while it was known that DDD can degrade even further, it wasn't known until now that DDE can further degrade as well."
Working with DDE-contaminated sediments collected from the ocean floor near southern California, Tiedje, Quensen and colleagues carefully simulated the marine conditions in the laboratory. They found that over a 32-week period, bacteria living in the sediments' anaerobic, or oxygen-free, environment, destroyed the DDE by transforming it to a less-chlorinated product - DDMU.
DDT was one of the first synthetic pesticides to gain widespread acceptance. Initially, its use greatly increased crop yields and controlled insect-borne human diseases, but its use declined when resistance began to develop. Due to environmental concerns, the use of DDT was banned in the United States in the early 1970s.
Today, the U.S. Environmental Protection Agency reports that DDT and its DDE by-product have been reported at 3,422 sites that are identified as posing danger to human and animal life.
Other members of the research team included Sherry Mueller, a research technician at MBI International, and Mahendra Jain, director of MBI's Applied Biocatalysis Program.
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