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Saginaw News Editorial 8/17/06
Study moderates the dioxin alarm
Thursday, August 17, 2006
The results of a two-year study into dioxin exposure near Dow Chemical Co.'s Midland plant isn't likely to put to rest the debate over a cleanup of the Tittabawassee River flood plain.
It should, however, provide the state Department of Environmental Quality a barometer to judge the scope and scale of any cleanup plan downstream from the chemical giant.
The University of Michigan study indicates a small -- perhaps insignificant -- increase in blood-dioxin exposure in Saginaw and Midland counties. Researchers attributed much of the area's higher dioxin exposure level to the older population in the floodplain.
The question now is whether the elevated human exposure to dioxin compared to the rest of the state is great enough to justify a wide-scale cleanup in mid-Michigan.
There's no debate over dioxin's presence. Soil in the floodplain contains far higher levels of dioxin -- up to 15,300 parts per trillion, far exceeding the federal government's 1,000 parts per trillion standard and the state's 90 parts per trillion threshold for cleanup. And it's the debate over the safe standard that could further delay a cleanup.
On the whole, the study did offer some encouraging news. Dr. David H. Garabrant, the U-M research team's leader, said the high levels of dioxin in the soil had a small effect on the increase in the level of dioxin in blood -- an 0.7 parts per trillion increase in dioxin blood levels for every increase of 1,000 parts per trillion increase of soil contamination. On average, people living in the floodplain near Dow had 32 parts of dioxin for every trillion parts of blood. The national average is about 25 parts per trillion.
Other findings were more predictable. Participants who ate fish, game and other animal products such as eggs and milk had higher exposure levels -- dioxin amasses in fatty tissue -- while people who consume more fruits and vegetables had lower exposure. Nor is it a great surprise that older people had higher blood dioxin levels. Longevity increases dioxin exposure in everyone.
Less predictable and more perplexing: Smokers in the floodplain had lower exposure levels.
The report, funded by Dow and reviewed by an independent advisory panel, should help the state and region develop a plan for dealing with the dioxin contamination. The U-M study places dioxin exposure in the floodplain in a context that previously was unavailable.
Dioxin levels are 100 times higher than the state standard in some Tittabawassee River sediment. Those levels have prompted the state to issue fish and game consumption warnings in the flood plain. Those risks increase for children and pregnant women. Residents should continue to limit consumption of fish and game as well as exposure to soil in the flood plain. Make no mistake: Residents with higher soil exposure or consumption of fish and game have higher levels of dioxin-like compounds in their blood. The National Academies of Sciences labels the most dangerous group of dioxins a "likely human carcinogen."
Yet if the bottom line is that dioxin soil levels are high and human exposure levels are not significantly greater than elsewhere in Michigan, the state Department of Environmental Quality must balance the exposure and potential health risks against the cost and benefits of an environmental cleanup.
The University of Michigan study should speed up that process -- provided the debate over a safe cleanup level doesn't get in the way.
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