Kathie Marchlewski, Midland Daily News 06/10/2005
Some people in Midland and Saginaw counties know, or soon will know the level of dioxin in their yards and homes.
Results from soil and dust samples are being mailed to residents participating in the University of Michigan dioxin exposure study, but the ranges found won’t be available to the public until the study is complete in 2006. About two-thirds of participants requested their personal property information, though they had the option not to. All were warned that if they have knowledge of contamination, they are subject to disclosure requirements and that the levels could affect the value of their property. They were told that if the levels are higher than the state’s standard of 90 parts per trillion, they must notify potential buyers. They also must take care not to move soil in a way that could spread contamination.
If they chose not to be notified of levels, they might not be subject to disclosure. Since the data is confidential, it can’t be accessed by governmental agencies or courts.
That confidentiality is an important part of the study, said Professor Al Franzblau, who is working alongside project leader Dr. David Garabrant. So is the decision not to go public with partial results.
"I don’t think it makes sense to give out a message that we’re quite sure is going to be the wrong message," Franzblau said.
The team of researchers also is working in Jackson and Calhoun counties, places similar demographically to the Saginaw Valley, on the $15 million study that is expected to show whether living in the contaminated Tittabawassee River flood plain, or in industrial Bay, Saginaw and Midland counties, increases levels of dioxin in the body.
To find out, U-M has collected and still is collecting soil from yards, dust from homes and blood from residents to determine whether a relationship exists between levels in bodies and their environment.
All components of the research must be complete before any meaningful conclusions are reached, Franzblau said. "Quite obviously the (results) going to change (when the data is complete)."
Participants who are receiving results also will get a comparison to background levels found by the DEQ in a 52-sample 1990s survey of non-industrialized areas of the state. "Almost all soil in Michigan is believed to have measurable levels of dioxin, even in areas not known to have industrial contamination," Franzblau said. The DEQ samples found levels ranging from 0.4 parts per trillion to 34.7 parts per trillion.
While participants will know how their soil compares to the rest of the state, there is no comparison available for inside dust samples because residential dust studies never have been analyzed for dioxin concentrations in Michigan or elsewhere. At the end of the study, Franzblau said, that will change. "Those data will provide a benchmark."
For dust sampling, researchers vacuumed 1-square-meter areas until they had 10 grams of dust to analyze.
To take soil samples, they used a push-core sampler and marked areas around each side of each home with a hula hoop. They took three samples, each 2 inches in diameter and 6 inches deep, from each of those four circles. From homes located in the flood plain, additional samples were taken from that portion of the yards, and if there were gardens, samples were taken from their soils. Depending on those variables, as many as 21 samples were taken in all.
Samples were separated into two groups, one from the top inch and one from the bottom 5 inches. The top inch was analyzed for dioxin levels first. If it turned up a level higher than 8 parts per trillion, the 75th percentile of the state background level, the other 5 inches also were analyzed. While contamination might have settled further below the surface 6 inches, the depth U-M is using is adequate for purposes of the study, Franzblau said. "We looked at all of the DEQ data, and in not one was there a clear top 6 inches with contamination under it."
For more information about state regulations, visit www.michigan.gov/deq. For more information about the U-M study, visit www.umdioxin.org.
©Midland Daily News 2005
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Paul Hanly Jun, 10 2005
Although it might be rare for undisturbed residential land to have dioxin contaminated soil under a clean top 6", it has been shown that where land has been reclaimed from bays, rivers or swamps and chemical wastes were used in fill (even in municipal tips) the top layer can be clean and the soil contaminated at depth, with possible/likely impacts on groundwater, and risks if the soil is disturbed during gardening or lnadscaping.
Near the former Union Carbide plant at Rhodes, on Homebush Bay, Sydney, Australia some soil in a local school was contaminated to 300 ppt because Union Carbide had provided plantings and the soil that was used came from the land the factory was on. Residential blocks that have been leveled by importing soil from off site could be at risk if the soil was imported from a contaminated site.
In Rivers and Bays, the contamination to a depth of 20" or 0.5 m is critical as that is the likley range of the benthic organism eaten by fish which then flows up the food chain to humans. At Homebush Bay the top 20" (0.5 Metre)of the most dioxin contaminated sediments will be removed, treated and replaced with clean material (VENM - virgin excavated natural material). Sedimentation and scouring from water flows and wave action can conver and uncover dioxin contaminated sediments, hence the need to sample through the full range of the benthos ( eg worms.)
For more imformation see httm://www.rhodesnsw.org
For additional articles like this one, go to the Tittabawassee River Watch web site www.trwnews.net for complete coverage of the Tittabawassee River Dow Chemical dioxin contamination saga. . The Newspaper / Media page of our site contains an extensive archive of media articles dating back to January 2002. The source organization's web site link is listed to the right of the article, visit often for other news in our area. The Newspaper / Media page may be accessed by scrolling down to the bottom of the CONTENTS section and clicking on the Newspaper/Media link.