Dow Chemical’s Midland plant has contaminated the Tittabawassee River floodplain with dioxin — one of the most toxic chemicals known — and property owners in the contaminated zone are seeking damages in a class action suit against the company. 

A Court of Appeals panel upheld the property owners certification as a class in January 2008. Today the recently reformulated Michigan Supreme Court will hear Dow’s appeal of the cases class action status. Dow is arguing that the group should not be designated as a class because the individual properties have different levels of dioxin contamination.

The Michigan Department of Environmental Quality and the U.S. Environmental Protection Agency have stated that Dow is responsible for the dioxin contamination along the Tittabawassee. A study by Illinois researchers last year found that women who live in the rivers contaminated floodplain have elevated levels of breast cancer.

“The ability to certify an environmental class as a remedy in the State of Michigan may be decided by this case,“ Michelle Hurd Riddick of the environmental group Lone Tree Council said in a statement.

The case was originally filed six years ago in Saginaw Circuit Court.

A map of the documented dioxin contamination along the Tittabawassee is viewable here.