Still more pieces to dioxin puzzle

Officials at the National Academy of Sciences and the World Health Association last week added new pieces to the Tittabawassee River toxin puzzle.
One of the new pieces: The level of the most potent form of dioxins — while still potentially hazardous — was lower than previously thought. The World Health Organization downgraded the toxicity assessment of some types of dioxins, which means the Tittabawassee is less polluted downstream from Dow Chemical Co.
Less toxic, however, is not safe. Fish and game consumption advisories remain in effect in the flood plain. The state Department of Health has advised residents to limit exposure to soil in the flood plain.
There remain plenty of questions about the health effects of dioxin exposure to humans. University of Michigan researchers don’t intend to release the results of a two-year study on human exposure to dioxin until later this summer.
The National Academy of Sciences last week also asked the U.S. Environmental Protection Agency to provide more justification for linking dioxin to cancer and other ailments. The academy, as part of its peer review process, didn’t question the contention that dioxin is a health risk, it simply demanded better evidence from the EPA. Some observers said the academy’s report provided little new information — and there’s a chance its questions will further delay the development of a cleanup plan.
Meanwhile, residents shouldn’t shrug off the potential health effects of exposure to dioxin downriver from Dow. We still don’t know if exposure levels are high enough to affect residents’ health. The U-M study is designed only to report the extent of human exposure. There’s no dispute that exposure to dioxin at some level is toxic and harmful to humans. The science behind those levels, the toxicity of types of dioxin and other factors that relate directly to the health effects remain a moving target, however.
Dow, the EPA and the state Department of Environmental Quality are developing a cleanup plan. Everyone agrees that the Midland-based chemical giant needs to conduct a cleanup in the flood plain — including Dow. The greatest point of contention teeters on threshold for cleanup.
Reliable information from sources such as the National Academy of Sciences and the World Health Organization are worthwhile considerations. The U-M study also promises to bring valuable information to the cleanup discussion.
Yet those discussions shouldn’t last forever. The goal is to minimize the health risks of dioxin contamination in the flood plain and the cleanup’s impact on the region.

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