Dioxin is a highly toxic and carcinogenic compound that is a byproduct of the chemical manufacturing process. Emissions from Dow Chemical’s Midland complex have contaminated a 52 mile long swath that stretches from the Tittabawassee River, into the Saginaw River and Lake Huron’s Saginaw Bay. Periodic flooding of the river system has deposited the chemical contamination on the surrounding floodplain.
Since 2003 the University of Michigan Dioxin Exposure Study, funded by Dow, has been involved in studying the relationship between dioxin in area soils and the level of dioxin in the blood of residents. The group has sampled soil, blood and household dust at hundreds of locations in and around the floodplain and compared them to samples from another region.
In the latest segment of the U-M study, published in the April 23 edition of the journal Environmental Health Perspectives the research group states that of the 946 people sampled in their original study the person with the highest blood dioxin levels was a man who reported a history of raising and eating cattle and vegetables in the floodplain between 1984-1997.
In a follow-up investigation the researchers interviewed and took blood samples from this farmer and from 15 other people who had eaten the foods he had raised. These people all showed blood dioxin levels significantly higher than those recorded in the control population, despite the fact that the farmer had stopped raising and sharing both beef and vegetables by 1997.
“The results suggest that prolonged regular consumption of beef and/or vegetables raised in the flood plain of the Tittabawassee River, a region documented to have widespread and high levels of dioxin contamination of flood plain sediments, can be a completed pathway of human exposure,” the study says.
It concludes that for public health reasons, “Animals and crops should not be raised for human consumption in areas contaminated with dioxins.”
The group’s strongly-worded recommendation against farming in the floodplain seems to contradict their earlier statements that food from home gardens does not pose a dioxin exposure risk and stands in stark contrast to the public relations message Dow has long sent out regarding the results of this study.
In numerous community presentations the researchers have claimed that dioxin levels in soil have very little relationship to the levels in people’s blood. Dow Chemical has touted these findings as evidence that residents of the floodplain are not endangered by the pollution caused by the company.
State and federal environmental officials have criticized the U-M research for failing to closely examine populations — such as those who eat local foods — that may face elevated exposure risks. And state officials have long cautioned residents of the floodplain to take steps to reduce their dioxin exposure when gardening or farming, and have warned of possible dioxin exposure through food.
According to Deborah Mackenzie-Taylor, toxicology specialist with the Michigan Dept. of Natural Resources and Environment, the U-M team’s latest conclusions are not surprising.
“This is part of the food chain exposure pathway that you would expect to see,” she said.
Though previous findings by the U-M team have been aggressively communicated through the regional media and at community meetings, the latest information about the dangers of locally raised food has received little media coverage.
“This supports what we have been saying all along, and it seems to run counter to the message they have been giving to local residents,” said Tracey Easthope, Environmental Health Director for the Ecology Center in Ann Arbor. “Of course this inevitably means you have to clean up the contamination in order to be able to protect the food web.”
“The report does not surprise me at all,” said former floodplain resident Kathy Henry. “You won’t see this information in any of our local news outlets, however. They continue to spout off that there is no relationship between the dioxin in the soil and human contamination.”
Lead author of the study, Dr. Alfred Franzblau, did not respond to questions for this story.
Dow spokeswoman Mary Draves said that the company had not yet had a chance to review the study and could not comment on its implications.