"MOREAU, N.Y. — Twenty-five years after the federal government declared a long stretch of the Hudson River to be a contaminated Superfund site, the cleanup of its chief remaining source of pollution began here Friday with a single scoop of mud extracted by a computer-guided dredge.

Twelve dredges are to work round the clock, six days a week, into October, removing sediment laced with the chemicals known as PCBs. Mile-long freight trains running every several days will carry the dried mud to a hazardous-waste landfill in Texas.

An estimated 1.3 million pounds of PCBs, or polychlorinated biphenyls, flowed into the upper Hudson from two General Electric factories for three decades before they were banned, in 1977, as a health threat to people and wildlife. In high doses, they have been shown to cause cancer in animals and are listed by federal agencies as a probable human carcinogen."

Andrew C. Revkin reports for the New York Times May 15, 2009. [2]