WASHINGTON -- The U.S. Environmental Protection Agency's scientific and technical decisions in assessing risks to human health from pollution at a Superfund site in the Coeur d'Alene River Basin have been generally sound, says a new report from the National Academies' National Research Council. And the agency's remediation plans for residential areas should adequately protect residents against the most serious health threats, provided floods do not recontaminate cleaned-up areas. However, the committee that wrote the report expressed "substantial concerns" about EPA's proposed strategies for cleaning up and protecting the environment, including fish and wildlife.
Congress asked the Research Council to assess EPA's decisions concerning a 1,500-square-mile area in the Coeur d'Alene River Basin of northern Idaho and eastern Washington that is designated for cleanup under Superfund legislation because of contamination from years of mining for silver, zinc, and lead. A 21-square-mile "box" around Idaho's Bunker Hill Mining and Metallurgical Complex was declared a Superfund site in 1983 after high blood levels of lead were detected in local children, and high levels of metals were measured in the environment.
EPA expanded its Superfund cleanup in 1998 to include contaminated areas throughout the Coeur d'Alene River Basin, and in 2002 outlined a plan to clean up parts of this pollution and lessen risks to human health and the environment. Three-quarters of the proposed $359 million expenditures are to finance the first steps toward protecting the environment, including fish and wildlife, over an approximate 30-year period. The committee's concerns pertain primarily to these remedies. The other quarter of the funds is intended to address human health risks, which EPA expects to accomplish well before the 30-year mark.
EPA correctly concludes that environmental lead poses health risks to some basin residents, the report says. The agency's finding that lead in the environment -- as opposed to lead in house paint -- is the main source of children's health risk from lead also was warranted, and EPA's emphasis on cleaning up residential yards by replacing polluted soil with clean soil is appropriate. But the committee called the current rate of blood testing in children suboptimal, given the high concentration of lead in the soils of many communities. All children ages 1-4 years throughout the basin should be screened annually for blood lead in conjunction with other routine health care screening tests, the report says.
Wider blood testing would also complement EPA's use of the so-called IEUBK model, which estimates residents' future levels of blood lead. The agency's choice to base its cleanup decisions on these estimates rather than on actual blood-lead levels created controversy at the site, but the committee concluded that use of this model was in accord with EPA's policy and was reasonable given the need to predict and lessen future risks to residents as well as current ones. Information on the bioavailability of lead from the site's soil that is, the amount of lead in soil that is actually absorbed by the body would improve the reliability of the model's predictions.
EPA's assessment of risks to the environment, including fish and wildlife, was generally in line with best scientific practices and was based on quality monitoring studies of metals in the environment, the committee said, but it expressed serious concern about the likely effectiveness of the agency's interim plan to mitigate those risks. For example, EPA has not targeted groundwater for cleanup even though the main source of dissolved metals in rivers and lakes and the greatest threat to aquatic life in the basin is zinc that seeps into surface water from groundwater. The agency should more thoroughly identify specific places where zinc is leaching into groundwater and set priorities for removing or stabilizing these materials, the committee said. Locating and removing the largest sources of lead-contaminated sediments in riverbeds especially those likely to be carried downstream should be a priority as well.
The agency's plan also does not adequately take into account the basin's frequent floods, which could recontaminate cleaned-up land with metal-polluted sediments, the report says. EPA should select strategies that are likely to withstand this danger and lessen the impact of these floods.
In addition, the committee pointed out that although the EPA's plan relies heavily on removing hazardous metals from the ground, there are no repositories in the area to hold these materials. Constructing new ones will be difficult and time-consuming given the basin's complex terrain and the controversy surrounding Superfund issues. Still, the report acknowledges, the only ultimate solution to the basin's pollution problems is to remove or stabilize contaminated materials.
The committee was asked to extract lessons from the Coeur d'Alene site that could be applied at other large, mining-related Superfund sites. Laying out detailed, long-range plans for cleaning up these complex "megasites" is unrealistic, the committee said. Instead, programs should emphasize adaptive management a flexible approach that allows plans to be revised based on evaluations of each phase in the cleanup. EPA is currently using some of these principles at the Coeur d'Alene site, the report notes, but the agency's approach lacks some needed elements, such as specific benchmarks to indicate whether remedies are working.
The committee's findings and recommendations reflect a unanimous consensus, and the report was subjected to a rigorous peer-review process overseen by the National Academies. The study was sponsored by the U.S. Environmental Protection Agency. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provides science and technology advice under a congressional charter. A committee roster follows.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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