“An MDEQ official says Michigan opted for the 1-ppb cleanup level -- instead of its own more stringent 0.9-ppb cleanup level -- because the amount of land in the Midland area that would have been considered contaminated at that level is too great to possibly remediate in the interim…”

 Risk Policy Report
July 29, 2008

EPA Requires Limited Dioxin Cleanup At Dow Site Absent Final Risk Levels
EPA is requiring Dow Chemical Co.  to conduct a limited dioxin removal action in a residential neighborhood near the company's Michigan site, but regulators will not be able to impose stricter remediation levels until the agency finalizes a long-awaited risk assessment for the chemical, a state official says.

At the same time, environmentalists are criticizing EPA's decision to set a 1 part-per-billion (ppb) cleanup level for the removal action, saying the agency has adopted levels significantly weaker than requirements at other dioxin-contaminated sites, which could undermine state efforts to impose their own, stricter requirements.

EPA entered into an Administrative Order of Consent (AOC) with Dow July 11 to remove dioxin contamination from soil at 11 homes near the company's Midland, MI, facility. The residential neighborhood is part of a massive dioxin-contaminated area in the Tittabawassee and Saginaw River areas, which has gained notoriety after former EPA Region V Administrator Mary Gade claimed she was ousted for requiring strict cleanup levels there.

The site has also highlighted the difficulty EPA is facing setting dioxin cleanup levels as it struggles to complete a decades-in-the-making risk assessment for the chemical. As a result, many observers are also closely watching developments at the site because they believe it could set a precedent for the stringency of other dioxin cleanups in the absence of EPA completing its risk assessment.

EPA has been struggling to revise the assessment and has not yet set regulatory levels for dioxin while its final risk assessment is unfinished. Agency sources said recently that EPA is restarting its stalled review of its draft risk assessment of dioxin, and in coming weeks the agency's Science Advisory Board will begin forming a panel to conduct a review and provide advice in finalizing the assessment, which will eventually be used to set regulatory levels.

In this case, the AOC, which was released July 15, said EPA's general cleanup level for direct contact in residential soils was 1 ppb, but noted the Michigan Department of Environmental Quality (MDEQ) requires a more restrictive cleanup level of 0.09 ppb. Michigan waived its standard and consented to the 1-ppb cleanup level, however, because state regulations allow for a different cleanup number to be developed and used based on site-specific and other information, the AOC says.

Joel Hirschorn, a Superfund consultant to some communities, said in a 2006 article for Remediation Journal that the 1-ppb cleanup level that EPA uses for residential areas is based on the 1984 risk assessment EPA is now struggling to revise. Hirschorn says EPA has called the 1-ppb level a policy-based level, which correctly distinguishes it from a risk- or health-based cleanup standard.

An MDEQ official says Michigan opted for the 1-ppb cleanup level -- instead of its own more stringent 0.9-ppb cleanup level -- because the amount of land in the Midland area that would have been considered contaminated at that level is too great to possibly remediate in the interim, so as a matter of practicality the level had to be set to 1 ppb. "Part of it is that there's so much area that's above 0.9 [ppb], it would be too [large]," the source said. "We tried to find places that, in the interim, could be addressed, and it was decided and agreed between the state and Dow that 1 ppb [was acceptable]. We have to move forward and the people with the highest concentrations get addressed first."

EPA said in a statement that the remediation effort at the Riverside Boulevard site was designed to remove contaminated soil to a specific depth and replace it with clean soil to eliminate a direct contact threat to the residents of the neighborhood, and thus was "not keyed to a specific dioxin risk level" and that MDEQ had taken part in the negotiations as well. The statement adds that the site was one of a series of ongoing remediation projects related to the Midland plant and "was not envisioned as establishing a national dioxin policy precedent."

EPA and state officials say the agreement does not foreclose the possibility that regulators could come back in the future and require stricter cleanup levels. Superfund law generally allows removal actions such as this to meet less-restrictive cleanups as remedial actions.

The MDEQ official, however, says regulators will not be able to do that until after EPA finalizes its risk assessment. A future cleanup requirement could be stricter than 1 ppb, the source says, "but it depends on the contamination pathways and what [EPA's] dioxin toxicity value ends up being. Everybody's waiting for the [risk] assessment to be finalized, so without having that, we have to wait for Dow to propose something."

The state official's comments highlight long-standing concerns from environmentalists and others, who say that in the absence of EPA finalizing its risk assessment industry will be able to delay strict cleanup levels. Industry "wants to get final cleanup plans in place so that [regulators] won't be able to backtrack" when EPA releases the final risk data, one environmental scientist has said.

Meanwhile, other sources say EPA's selection of a 1-ppb cleanup level is inadequate, even as an interim measure. The 1-ppb cleanup level is "still an old standard, and not protective of human health," one environmentalist says, pointing out that other regulators have adopted a dioxin cleanup level for residential soils that is an order of magnitude lower than 1 ppb.

In his 2006 article, Hirschorn noted, for example, that EPA Region IV has set a residential cleanup level for dioxin at 200 parts per trillion (ppt) for two Superfund sites, while Montana's Department of Environmental Quality has also adopted the 200-ppt cleanup level. "This suggests a shift in EPA policy" away from the 1-ppb level, he says.

The environmentalist adds that the argument for adopting a weak cleanup standard as a means of creating a manageable solution is not a novel one, and has been employed almost as long as Superfund has been around. "They're making management decisions based on what they can do rather than what's protective" of the residents, the source says.

The source welcomes EPA's disclaimer that the removal action was not a precedent. "I'm glad they went to the trouble of acknowledging that it's not something worth copying," the source says. "They're just trying to justify their approval" of the 1-ppb level.

A source with Dow says the company's negotiations with EPA have been "reasonable" but added that the company maintains the work is unnecessary because soil contamination is not a source of exposure to the residents in the area. The source says Dow conducted a study on its own of the residents in the area and concluded the dioxin in the soil was not reaching the residents, therefore making the remediation superfluous to ensuring their health. "But we're a regulated party, and we're going to do what we said we would do," the source says.

The site is the fourth of five projects EPA is requiring Dow to complete in order to remove the dioxin and furan contamination along the Tittabawassee and Saginaw Rivers caused by the Midland plant, which has been in operation since the late 19th century. Two of the other remediation projects were completed in 2007, and an environmental dredging project in the Tittabawassee is ongoing. -- John Heltman