Dioxin study near Mich. Dow plant draws scrutiny
Monday May 4, 2009, 8:22 am EDT
State regulators question Dow-funded study of dioxin exposures near company plant in Michigan
DETROIT (AP) -- A study that measures human exposure to dioxins in a Lake Huron watershed polluted by a Dow Chemical Co. plant is drawing criticism from Michigan regulators negotiating with the company over a long-delayed cleanup.
A statistician hired by the Department of Environmental Quality recently advised regulators not to use the Dow-funded study as a basis for decisions about dealing with the dioxin contamination -- at least until problems he identified were fixed.
The lead researcher for the project, Dr. David Garabrant of the University of Michigan's School of Public Health, said his team had done additional data analysis sought by the DEQ and the statistician, John W. Kern. But Garabrant insisted the methodology and conclusions were sound and said the study should play a role as the cleanup is designed.
"Our study tells us more about the relationship between dioxins in the environment and dioxins in people's (blood) serum than any other study that's ever been done," Garabrant said in an interview last week.
DEQ spokesman Robert McCann said the department still had concerns about the project and how company supporters in communities near the Dow plant in Midland had interpreted the results.
"At public meetings, people will say that the U-M study showed there's no problem with the dioxin," McCann said. "There's a common misperception out there about what this report says."
Dow has acknowledged polluting parts of the Saginaw Bay watershed, including the Tittabawassee and Saginaw rivers and their floodplains, with dioxins from its Midland plant for decades in the last century.
The company has negotiated with state and federal regulators for years and has cleaned up a few heavily tainted sites, but no agreement has been reached on a comprehensive plan.
Some residents in the community say the pollution endangers their health, while the company and its supporters disagree.
"We continue to believe that, based on this (University of Michigan) study and decades of studies we've conducted of our workers, there is no imminent threat to people living in the area on contaminated soil," Dow spokeswoman Mary Draves said.
Garabrant said he, Kern and state regulators resolved many of their differences during meetings last week.
"There are a small number of questions that remained unanswered and a plan has been laid out to address them," Garabrant said. "We will implement that plan over the next few weeks."
One of the issues is that Garabrant's team did not assess the health of the people it examined.
Its report, initially released in 2006 and updated since, concluded that people living in parts of Midland and Saginaw counties had higher levels of dioxins in their blood than residents of comparable areas in Jackson and Calhoun counties, about 100 miles away from the plant.
But it found that where people lived played only a minor role in determining dioxin content in their blood. The biggest factor was age, with older people tending to have higher levels than the young.
Kern, whose statistical consulting firm is based in Sauk Rapids, Minn., submitted a critical review of the study in March.
He found fault with some of the methodology and with confidentiality requirements that limited public access to the data.
"If we don't have access to the data itself, it makes it more difficult to determine whether the analysis was done appropriately," McCann said.
Garabrant said he had offered to let Kern examine raw data if he would sign a confidentiality pledge to protect the privacy of study participants -- a requirement he said was common practice for clinical researchers.
Kern also contended the study may have included too few subjects representing groups with the highest exposures to dioxin contamination from the Dow plant, a complaint echoed by the DEQ and the Michigan Department of Community Health.
Only about 14 of the roughly 900 people who provided blood samples lived in areas with the most highly contaminated soil, said Linda Dykema, manager of the community health department's toxicology section.
Also lacking were statistics on dioxin levels for people who regularly eat bottom-feeding fish such as catfish and white bass, which are known to carry particularly high concentrations of toxins, Dykema said.
"There's some good information in the study but it's limited," she said. "We'd like to see a more focused study of fish consumers."
Garabrant said the design had been modified to include more information about particular groups -- such as people living downwind from the Dow plant.
The study included "substantial numbers" of people who ate fish caught by sport anglers in the Tittabawassee and Saginaw rivers and in Lake Huron's Saginaw Bay, he said. He acknowledged that few participants regularly ate bottom-feeding species.
Environmentalists have been suspicious of the study because Dow paid for it, despite Garabrant's insistence that the research team had complete independence. Tracey Easthope, director of The Ecology Center's environmental health project, said Kern's analysis had echoed many of the complaints her group had raised.
"I think the U-M study has been used to suggest that dioxin shouldn't be much of a concern for people in the community," Easthope said.
Source: Associated Press
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