This report is the product of a 17-person Task Force chartered by the Washington State Departments of Agriculture, Ecology, Health, and Community, Trade and Economic Development (the Agencies). The Area-Wide Soil Contamination Task Force (Task Force) was charged with developing findings and recommendations related to large areas of low- to moderate-level arsenic and lead soil contamination (so called "area-wide soil contamination") in Washington State. The Task Force process was carried out over 18 months, from January 2002 to June 2003.

As used in this report, "area-wide soil contamination" means low- to moderate-level soil contamination that is dispersed over a large geographic area, ranging in size from several hundred acres to many square miles. Area-wide soil contamination is different from most cleanup sites, which are typically smaller and have higher levels of contamination.

Concentrations of arsenic and lead within areas affected by area-wide soil contamination are highly variable. The Task Force relied on the current views of the Department of Ecology (Ecology) about what constitutes "low-to-moderate" levels of arsenic and lead in soil. For schools, childcare centers, and residential land uses, in general, Ecology considers total arsenic concentrations of up to 100 milligrams per kilogram (mg/kg)² and total lead concentrations of up to 500-700 mg/kg to be within the low-to-moderate range. For properties where exposure of children is less likely or less frequent, such as commercial properties, parks, and camps, Ecology considers total arsenic concentrations of up to 200 mg/kg and total lead concentrations of up to 700-1,000 mg/kg to be within the low-to-moderate range. Ecology plans to ask the Science Advisory Board to review these values and their use in implementing the Task Force recommendations. For comparison, the State cleanup levels for total arsenic and lead in soil are 20 mg/kg and 250 mg/kg, respectively. Arsenic occurs naturally in Washington State soils at approximately 5-9 mg/kg; lead at 11-24 mg/kg.

Task Force deliberations focused on understanding and mapping the nature and extent of low- to moderate-level arsenic and lead soil contamination from two historical sources: emissions from metal smelters, and use of pesticides containing lead arsenate. The Task Force also offers recommendations about considering the potential for area-wide soil contamination from combustion of leaded gasoline. Task Force recommendations are focused on effective, practical, and affordable steps that organizations and individuals can take to reduce the potential for exposure to low-to-moderate levels of arsenic and lead soil contamination.

The foundation of the Task Force recommendations calls for the Agencies to initiate a broad-based education and awareness-building campaign about low- to moderate-level arsenic and lead soil contamination, and to support and encourage actions individuals can take to reduce the likelihood that they will be exposed to arsenic and lead in soil. To complement broad-based education and awareness-building, the Task Force also recommends specific activities for a number of land-use situations, with an emphasis on child-use areas. Finally, the Task Force recommends creation of a special process under the Model Toxics Control Act (MTCA) tailored for properties affected by area-wide soil contamination.

In making these recommendations, the Task Force was guided by six principles which are listed here and described more fully later in the report:

• A balanced approach is needed, centered on effective, practical, and affordable solutions.
• Risks from area-wide soil contamination appear to be relatively low when compared to risks at sites with higher concentrations of contaminants.
• It is prudent to take effective, practical, and affordable steps to minimize the potential for exposure to area-wide soil contamination.
• Efforts should focus on children, because they are believed to the human population most sensitive to elevated levels of lead and arsenic in the environment.
• Responses to area-wide soil contamination should be commensurate with the level of risk associated with potential exposures and should increase as potential exposure increases.
• Decisions about area-wide soil contamination should be made locally.

² Milligrams per kilogram (mg/kg) is numerically equivalent to parts per million.

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