Sludge Watch ==> Michigan Dioxin Study may add to NAS Criticism of EPA Standard

[Maureen Reilly]

 Inside Washington

Water Policy Report

July 10, 2006

 MICHIGAN DIOXIN STUDY MAY ADD TO NAS CRITICISM OF EPA STANDARD

 


An upcoming study evaluating dioxin exposures at a highly contaminated Dow Chemical Co. site in Midland, MI, may add to growing questions about the stringency of state and EPA cleanup standards, with the National Academy of Sciences (NAS) preparing to unveil its report early this week that reportedly questions EPA's risk assessment.

While the NAS conducted a full risk assessment, the University of Michigan study is a wide-ranging exposure evaluation at a specific site that may be one of the most significant in the history of dioxin exposure research because of its large size and the amount of environmental sampling involved, according to a scientist involved in the study. 

It could show how dioxin in contaminated environments gets into human blood and in particular demonstrate whether living in a highly contaminated area creates a significantly higher exposure risk than normal exposures through the food chain and other common pathways, according to a Dow source.

Although results from the studies are not yet public, they are set to be issued within the next six weeks and may significantly influence EPA's plan to dramatically tighten its dioxin cleanup standard as well as what constitutes an appropriate state standard. The NAS study -- due for release July 11 -- reportedly questions EPA's plans to significantly tighten its estimated cancer risk by a factor of six. That could result in cleanup standards significantly tighter than the current interim action level of 1,000 parts per trillion (ppt).

A Michigan legislator is also suggesting that the state exposure study -- prompted by the contaminated Dow site -- may significantly influence the debate over whether the state standard of 90 ppt is too strict.

Activists groups have long raised concerns about the levels of dioxin in biosolids, or sewage sludge, that is used as fertilizer. However, in 20003, EPA decided against regulating dioxins in biosolids, saying no public health benefit would result from establishing a regulatory limit because the levels of dioxins in sewage sludge are extremely low. EPA officials have said in the past that dioxin levels in biosolids are so low that even if the agency revises its dioxin risk assessment to make it more conservative, the original conclusions about the chemicals in biosolids remain valid.

Even before the NAS and Michigan studies are released, industry officials are claiming victory, warning EPA that it should implement the NAS recommendations. "We're placing a premium on the NAS' views on dioxin and fully expect EPA to be responsive to the report's conclusions," one industry source says.

An environmentalist who has tracked the issue agrees that EPA should quickly implement the recommendations and not get caught up in an endless review cycle. "EPA has let industry walk all over them for 10 years" and should not get caught up in another round of delays, the source says.

The pending NAS study and the ongoing fight over cleaning up the Dow site sparked legislation that passed the Michigan House last month requiring the Michigan Department of Environmental Quality (DEQ) to consider the NAS report's conclusions when setting dioxin cleanup levels.

A DEQ spokesman says Gov. Jennifer Granholm (D) will not oppose the legislation, despite vetoing a bill last year that also affected the cleanup plan. The spokesman says the earlier bill sought to allow Dow to control how the cleanup was conducted, while the new bill, sponsored by state Rep. John Moolenaar (R), simply requires DEQ to consider the most recent science, something the source says the department would do anyway.

The Michigan contamination came from a Dow chemical plant that released dioxin through chemical manufacturing processes, which then got into soil and the nearby Tittabawassee River, contaminating the river's fish.

The state study, which was conducted as part of an agreement between Dow and DEQ, evaluates people living in the Tittabawassee River flood plain downriver from Midland, those living in Saginaw, Midland and parts of Bay County, but who do not live in a flood plain, and others living in different parts of Michigan. It involved taking soil samples, dust samples in homes and other factors that could contribute to dioxin exposure, such as food sources and occupations.

The researcher says the study "is going to be relatively important in [the dioxin] literature" because of the cross-sectional sampling conducted across different geographic areas, the number of participants involved, and the broader measurements the researchers are taking from a variety of possible exposures sources.

And Moolenaar told Water Policy Report the Michigan study is crucial because dioxin exposure has not been adequately considered. Moolenaar said a key question to consider when developing a dioxin cleanup plan is "how available is [dioxin] to human uptake." Moolenaar suggested that if the study shows lower exposure levels than expected, it may encourage Michigan to soften its cleanup level of 90 ppt, which is dramatically lower than both EPA's interim level and a 1,000 ppt cleanup guideline set by the Agency for Toxic Substances & Disease Registry.

The Dow source adds that the study will answer the critical question of whether living near the Midland site increased dioxin levels in residents' blood and therefore whether the cleanup plan will have to take such heightened exposures into account. The study will represent the first step in determining the direction of the eventual cleanup plan for the site, over which EPA and Dow have long fought. EPA earlier this year rejected a Dow sampling proposal as "severely inadequate," calling the company's plan to take approximately one sample per mile of river "unacceptable."

EPA did not return calls seeking comment.

The state study's results are set to be announced Aug. 15.
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