Monitoring of Arsenic and Lead Exposure

To develop recommendations for responding to area-wide soil contamination, the Task Force had repeated discussions about the implications that elevated levels of arsenic and lead in soil may have for the health of Washington State residents. Based on these discussions, the Task Force understands there is only limited information available on the actual health of Washington residents who, because of where they live, work, or go to school, may be exposed to elevated levels of arsenic and lead in soil. The Task Force is concerned about this lack of health data for Washington residents, particularly with respect to children, who may be at greatest risk.

The Task Force encourages the Washington Department of Health, in partnership with other agencies as appropriate, to expand its use of blood-lead testing, fluoroscopy, or any other appropriate techniques to gather additional information on the health of Washington residents, particularly children, who may be exposed to arsenic and lead. The Task Force believes it is important for the Department of Health to look at both arsenic and lead, even though the test methods for arsenic have limitations. Furthermore, any studies should not be directed only at voluntary subpopulations, but should be representative of all Washington residents who might be exposed to lead or arsenic in the soil. Appropriate use of random testing and finding ways to eliminate or minimize the effects of confounding factors, such as smoking and home remedies, are also needed to give a better picture of how the health of Washington residents might be affected by lead and arsenic in the soil.

The Task Force felt so strongly that additional information on the health of Washington residents who may be exposed to elevated levels of arsenic and lead in soil is needed that it offered this recommendation to the Department of Health approximately mid-way through the Task Force process. The Task Force acknowledges and appreciates the Department of Health's concern about the practicality of implementing this recommendation and about the need to apply the precautionary principle to potentially exposed populations. Nonetheless, the Task Force continues to feel strongly that gathering additional information on the health of Washington residents is important to better understand the effects of area-wide soil contamination and thereby focus response actions over time.

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Research on Roadside Lead Contamination

According to the study prepared by the contractor project team to support Task Force deliberations, little is known about the distribution of contamination from combustion of leaded gasoline in Washington or the concentrations of lead that are likely to be present in roadside soils. Analogous circumstances in other states and countries suggest that roadside lead contamination may be extensive and may occur in many areas routinely used by people, such as adjacent to driveways and residential streets. The Task Force recommends that the Agencies conduct further research to characterize the location and extent of elevated levels of lead in soil from past use of leaded gasoline in Washington. Research should be focused in areas where there is the greatest potential for exposure of children and where concentrations are likely to be the greatest, such as areas adjacent to older, more heavily used roads. If the results of this research warrant such action, the Agencies should extend implementation of the Task Force's recommendations to areas that are most likely to be affected by combustion of leaded gasoline.

Research on Ecological Risks

There is a significant body of scientific information demonstrating that high levels of arsenic and lead in soils can adversely affect plants and animals. However, the ecological risks associated with the range of concentrations associated with area-wide soil contamination are less well understood. In general, low-to-moderate arsenic and lead soil contamination has been found to adversely impact several plant species in laboratory and field studies. At the same time, other field studies have documented healthy and thriving plant communities in areas with soil arsenic and lead concentrations of similar magnitudes. Ecological receptors such as plants and animals exhibit differing sensitivities and tolerances to soil arsenic and lead, which may over long periods of time effect some changes in the distribution and thriftiness of the ecological community relative to an uncontaminated site.

Assessments of and responses to ecological risks are further complicated by site-specific circumstances. In general, ecological concerns at developed commercial and residential properties do not trigger response actions beyond those actions that would be necessary to protect human health. Cleanups of larger properties, such as open land, however, raise more complicated concerns. The Task Force recommendations for response actions for open land not proposed for development focus on reducing the potential for human exposure to arsenic and lead in soil through education and awareness-building, but do not address protection of ecological receptors. Given the lack of definitive evidence of substantive impacts on ecological systems and the complexity of these issues, the Task Force recommends that Ecology conduct or support studies that evaluate the potential ecological impacts associated with low- to moderate-level arsenic and lead soil contamination. The results of these studies might suggest circumstances where measures beyond those recommended by the Task Force to limit human exposure are needed to protect plants and animals.

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