Toxic hazards
Soil sampling: 1999-2000 Vashon-Maury Island Soil Study
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Findings from Soil Sampling of Vashon-Maury Island and the Southern Mainland Coastline of King County |
Soil Study Summary and Support Information (7/00)
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Introduction, History and Summary
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Introduction
This report describes data concerning the presence of arsenic and lead contamination of Vashon-Maury Island as well as along the mainland shoreline of King County between West Seattle and the southern King County line.
Studies over the past 30 years have shown that the soils on portions of Vashon-Maury Island have elevated concentrations of arsenic, lead, and cadmium, probably due to decades of copper smelter operations in Ruston, Washington, located just south of the southern tip of Vashon Island. Unfortunately, the methodology differed between studies and no one study measured soil contamination on the entire island.
At a public meeting in February, 1999, following the public disclosure of elevated levels on the Lone Star Northwest Gravel Mine site, the community raised new questions about the level of arsenic contamination for Vashon-Maury Island as a whole.
Public Health -- Seattle & King County, the Washington State Department of Ecology (Ecology), the Washington State Department of Health (DOH) and community members responded to the concerns raised by the Lone Star report by forming a work group to design a study of arsenic, lead and cadmium soil contamination in Vashon-Maury Island and mainland coastline areas of southern King County. The study was coordinated by Public Health with funds from a Ecology grant.
The study was designed to find out the extent and seriousness of arsenic, lead, and cadmium soil contamination in Vashon-Maury Island and mainland coastline areas of southern King County. An environmental scientist familiar with arsenic contamination issues in this area led the data collection and analysis work group, with help from Public Health.
Arsenic and Lead Contamination in the Tacoma-Ruston Area
The arsenic and lead contamination described in this preliminary report is believed to have originated with copper smelting operations in Ruston. The smelter began operations in 1890 and was closed in 1986.
According to one historical review, the Ruston plant's emissions were substantial, accounting for nearly 25% of the total annual inorganic arsenic emissions in the United States. The arsenic emissions were a by-product of the processing of copper contaminated with arsenical (arsenic-based) compounds. The plant also turned out arsenic as a commercial product. Emissions from the plant heavily contaminated the soils in the surrounding Ruston community.
Cleanup of soil arsenic and lead fallout in this area, named by the U.S. Environmental Protection Agency (EPA) as the Tacoma-Ruston Federal Cleanup Site, is being carried out according to the site consent decree established in May 1995. The decree did not include Vashon-Maury Island or the mainland coastline of southern King County.
Findings of Current Study
This study targeted areas where the soil was identified as being the least disturbed in recent years (such as in off-trail forested areas) to look at the worst case scenario of contamination. Soils that have been moved or have been involved in new construction over time may have lower levels of the contaminants. The worst case scenario method is standard public health practice and was chosen to provide the most protection for health.
Findings include:
- Arsenic and lead concentrations were elevated more often than cadmium concentrations. Because cadmium is probably not a problem in the area sampled, the remainder of the report deals with arsenic and lead contamination.
- Arsenic and lead tend to be found together. This is consistent with the expected pattern of fallout occurring from the Ruston smelter operations.
- Arsenic concentrations ranged from "Not Detectable" to 460 ppm. Lead concentrations ranged from "Not Detectable" to 1300 ppm.
- Arsenic and lead concentrations can vary by several hundred percent, even over distances of as little as 50 feet. This means that levels of arsenic and lead found in soil in nearby areas may not be a reliable measure of arsenic and lead on specific residential properties in Vashon-Maury Island or on the mainland coastline of southern King County.
- Sometimes concentrations of arsenic and lead in deeper soil, 2 to 6 inches, is higher than concentrations in shallower soil, 0 to 2 inches. This occurs more frequently with arsenic than with lead. This means that residents wanting to know their soil arsenic and lead levels may have to sample at both shallower and deeper levels to determine accurate levels of arsenic and lead.
- The highest concentration of arsenic and lead are found in Maury Island and South Vashon Island, followed by the mainland, followed by North Vashon Island. This is consistent with previous studies of fallout from the Ruston smelter plant.
Risk to the Public
State and federal regulatory agencies agree that a person's health risk increases with increasing exposure to arsenic and lead. There are a range of opinions among communities, businesses, and regulatory agencies on what constitutes an acceptable increased risk of adverse health outcomes, and, therefore, what is a reasonable threshold for low-level, long-term exposure, especially for arsenic.
For instance, in the Ruston study area, the residential cleanup level for arsenic contamination is set at 230 ppm in soil by the EPA; however, Ecology set the residential cleanup level at a site of arsenic contamination in Everett at 20 ppm. For lead, the EPA set the residential cleanup level at 500 ppm in Ruston, while Ecology set the residential cleanup level at 353 ppm in Everett.
Because of the lack of agreement and the nature of our study, we are not now able to say exactly how much risk residents of affected areas in King County have. Public Health will be working with our agency and community partners to further assess risk through a follow-up soil sampling study.
Arsenic: When examined by area, the data clearly indicates the most serious arsenic contamination occurred in South Vashon-Maury Island. Arsenic contamination ranged from 8 ppm to 460 ppm in this area, while it ranged from 3 ppm to 140 ppm in North Vashon Island.
Lead: On average, lead contamination is also more serious in South Maury/Vashon Island. In that area, soil lead levels ranged from "Not Detectable" to 1,300 ppm, while on North Vashon, the levels ranged from "Not Detectable" to 440 ppm.
Ecology estimates that children 6 and under exposed to soil lead levels of greater than 353 ppm have a significant chance of having elevated blood lead levels, with higher soil contamination levels increasing the chance of elevated blood lead levels. Public Health recommends that concerned parents with children in this age group consult their health care provider at their next regularly-scheduled visit on whether a blood test for lead is advisable. These recommendations are consistent with recommended guidelines from the federal Centers for Disease Control and Prevention.
Public Health has contacted, and will continue to be in communication with area physicians with guidance on monitoring for arsenic and lead. More information on biological tests for lead and arsenic can be found in "Frequently Asked Questions" section of this preliminary report.
The samples taken for this report are meant to represent a worst-case scenario. If you live in an area with high levels of contaminants, it does not necessarily mean your property also has elevated levels. Only sampling and testing soil from your own property can answer this question. The section on "Resident Self-Testing Protocol" will provide information on how to do your own soil sampling, and where you can take the soil to be tested.
Health Effects
Exposure to arsenic and lead can cause health effects in the short term (acute effects from high-level exposures) and the long-term (chronic effects from low-level exposures). For instance, the short-term effects of arsenic include gastrointestinal disturbances, abnormal heart rhythm, and blood vessel damage. Lead also can cause short-term problems such as anemia, abortion and damage to the male reproductive system.
We believe that exposure at the levels of arsenic and lead found in this study are very unlikely to cause short-term, acute effects.
Some of the higher contamination levels for arsenic and lead measured in this study, however, may be capable of causing serious health effects in people who have been exposed over many years. The long-term health effects for arsenic include cancer of the skin, bladder, kidney, liver and lung. Problems from long-term exposure to lead for children include learning difficulties, reduced growth, and decreased mental abilities.
Maps to Vashon/Maury Island sample sites
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PROCESS OF RESIDENT SAMPLE OF SOILS
Laboratory Directions:
The analysis of soil samples should include the following steps:
Analytes
Several metals are knows to occur at elevated levels in Vashon-Maury Island and mainland soils. Their concentrations in soils are reasonably (but not perfectly) correlated. From the basic protocol, lab analysis for only one analyte - total arsenic - is recommended. Concerns over possible human exposures and health risk have focused primarily on arsenic in soils, and arsenic can serve as an initial indicator for the inter-correlated set of metals in soils. Limiting analyses to arsenic allows a greater number of soil samples to be collected and tested for a fixed price. This provides more information on soil contamination levels across a property.
Sample Preparation
The concentration of arsenic in soils typically varies with the size of the soil particles; smaller particles have much greater surface area in proportion to their mass, providing more locations for arsenic attachment. The lab should screen or sieve the bulk soil samples it receives to retain those particles less than 2 mm in size for testing. These smaller particles better represent potential human exposures. The less-than-2 mm size fraction is also the basis for state regulations and cleanup standards. The lab should homogenize (thoroughly mix) each soil sample before testing.
Results on Dry Weight Basis
Bulk soil samples always contain some water. The lab should report all results on a dry weight basis. Therefore, a percent moisture analysis needs to be performed to adjust measured results to dry weight.
Analytical Methods and Detection Limits
The detection limit for total arsenic should be no greater than 10 parts per million (ppm), and is commonly 5 ppm or less. Any of several methods of analysis can be used, depending on available instruments at the selected lab. Those methods include ICP (inductively couples plasma), graphite furnace atomic absorption (GFAA), or flame atomic absorption (flame AA). All of these methods involve first digesting a small amount of soil and then using an analysis instrument and detector to measure arsenic concentrations in the liquid digest.
Quality Assurance/Quality Control Analyses
In addition to reporting the arsenic concentration in each soil sample, the lab should also run and report the results of basic quality control analyses. These should include a blank analysis (results should be not detected), a duplicate analysis (to assess the precision, or replicability, of the results), and a spike analysis (to assess accuracy in results by measuring a known quantity added to a sample).
- Public Health's Hazard Hotline:
(206) 296-4692
- White Center Public Health Center
10821 8th Avenue SW
Seattle, WA 98146
(206) 296-4646
- Federal Way Public Health Center
33431 13th Place South
Federal Way, WA 98003
(206) 296-8410 (Seattle), (253) 838-4557 (Local)
- Downtown Public Health Center
2124 Fourth Avenue
Seattle, WA 98121
(206) 296-4755
- Laboratories Certified by the Washington State Department of Ecology:
If you are doing soil self-testing, you will need to select an analytical laboratory to perform the chemical analyses. The Washington State Department of Ecology maintains a list of accredited laboratories. Information is available on these laboratories by calling (360) 895-4649.
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