10/31/10
The government has spent many millions of dollars in recent decades cleaning up sites contaminated with dioxin and, in extreme cases, relocating residents of entire neighborhoods tainted by the toxin.
But tough new pollution standards proposed by the Obama administration could require additional dioxin cleanups at scores of abandoned factories, military bases, landfills and other locations declared safe years ago, officials say.
If the guidelines receive final approval, federal and state officials will examine sites with known dioxin contamination to identify those needing work and what the work will cost. Among those expected to be reviewed are notorious places such as the former village of Times Beach, Mo., where about 2,000 people were relocated in the 1980s after dioxin-laced waste oil was sprayed on roads to control dust.
The Environmental Protection Agency plan has escalated a decades-long debate over the danger of dioxin, a family of chemical byproducts from industries such as pesticide and herbicide production, waste incineration and smelting. One form of dioxin was in Agent Orange, the defoliant used by U.S. forces during the Vietnam War.
The EPA is expected to make a final decision this fall on the new standards. But congressional critics and chemical companies say the agency is acting hastily and should wait until it completes a reassessment of dioxin's health effects in the coming months.
"They're proposing these sweeping changes to regulations without giving us an idea of how many sites will be affected, how many homes will be affected, what the economic impact would be," said Rep. Dave Camp, a Republican whose Michigan district includes a 50-mile-long watershed polluted with dioxin from a Dow Chemical Co. plant.
EPA officials say they want to move ahead because they are convinced dioxin is hazardous at lower concentrations than previously thought. If necessary, they say, the standards can be adjusted later.
"We're driven by the need to protect against excessive risk of both cancer and non-cancer health concerns," said Mathy Stanislaus, EPA assistant administrator for solid waste and emergency response. "We believe (the current standards) are not sufficiently protective and more stringent numbers are needed."
Since 1998, the agency has regarded dioxin soil concentrations of less than 1,000 parts per trillion (ppt) as safe for residential areas. For commercial and industrial zones, 5,000 ppt to 20,000 ppt has been considered safe.
The proposed revisions would drop the safe levels to a fraction as much - 72 ppt for residential areas and 950 ppt for commercial and industrial sites.
Cleanups could be ordered anywhere dioxin readings exceed those thresholds, including sites where previous cleanups used less stringent standards.
