BUNKER HILL MINING AND METALLURGICAL
KELLOGG, SHOSHONE COUNTY, IDAHO
ATSDR's review of available sampling data indicate that the EPA's site cleanup actions to date in the city of Smelterville, including the installation of clean soil "barriers" in residential yards, commercial properties, and ROWs, have reduced the levels of lead in community soils and housedust. As a result, the potential for human exposure to lead has been reduced, as evidenced by declining blood lead levels in Smelterville children. However, although residential soil lead levels in Smelterville are generally below site cleanup goals, household dust levels, especially in samples collect by the dust mat method, remain above cleanup goals in some homes. This indicates that lead is continuing to enter homes from exterior sources, such as contaminated hillsides, recontaminated ROWs, unremediated yards, or exterior lead-based paint; interior sources, such as interior lead-based paint; or both. In some cases, soil barrier disturbances, due to homeowner projects or utility work, may also contribute to increased indoor dust loadings. In addition, carpeting and upholstered furniture may be acting as long-term reservoirs of lead contaminated house dust in some homes.
ATSDR believes that the current community-wide household dust lead levels do not represent a public health concern for the general population of children in Smelterville. However, the high (>1000 mg/kg) lead housedust levels found in some homes may be a public health threat to individual children living in such homes, especially younger (1 and 2 year old) children. One and 2 year olds generally spend much of their time playing on and/or crawling along floors and, therefore, tend to ingest the most contaminated dust. These children, and young children who live in homes with unremediated yards (which may have lead soil levels up to 1000 mg/kg), will likely have a greater than 5% probability of experiencing elevated (>10 ug/dL) blood lead levels.
Although overall blood lead levels have generally been declining over time in Smelterville, some children continue to have blood lead levels in excess of 10 ug/dL. This finding, along with continuing house dust concentrations in excess of site cleanup goals, suggest that additional remedial actions, such as cleanup of home interiors, may be necessary to lower the blood lead levels of all Smelterville children to acceptable levels. This is especially true for one and two year olds who generally exhibit the highest blood lead levels and receive the greatest household lead dust exposures among all age groups of children.
Exposure of Smelterville children to lead in soil, dust, air, or paint at areas outside the home, such as schools and day care centers, may also lead to elevated blood lead levels. In addition, consumption of lead in drinking water, fish, and homegrown produce, and ingestion of residential lead-based paint may also contribute to increased blood lead levels.
In light of continuing elevated lead levels in house dusts and elevated blood lead levels in some Smelterville children, ATSDR believes that review of the Institutional Control Program (ICP) is warranted. Review of the ICP should include an evaluation of the program's overall effectiveness in preventing human exposure to lead and other site contaminants.
Ambient air concentrations of lead and particulates in Kellogg are generally below national standards for protection of the general public. Ambient levels of lead and particulates in Smelterville and other site communities are not as well characterized but are likely similar to the levels in Kellogg. Exceedence of air quality standards for lead and/or particulates are infrequent and are limited to certain work areas where trucks and heavy equipment operate, such as the Smelterville haul routes and the Central Impoundment Area (CIA), and, to a lesser extent, to areas where contaminated yards are being excavated. However, based on the levels of lead and particulates reported, adverse health effects are not likely as a result of these site activities. Nevertheless, air monitoring in such areas should continue to be conducted regularly to ensure that existing dust control actions are adequate to protect site workers and area residents. In addition, exposure of sensitive people, such as those with pre-existing medical conditions (e.g., asthma, emphysema, chronic obstructive pulmonary disease), to fugitive dust should be minimized.
ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of environmental media. As part of the ATSDR initiative, ATSDR health consultations must indicate whether any site-related exposures are of particular concern for children. At this site, sampling has identified lead as a contaminant of concern in surface soil, indoor dust, and ambient air. Children are uniquely susceptible to the deleterious effects of lead because they absorb lead more easily than adults do. Blood lead levels equal to or greater than 10 micrograms per deciliter have been associated with adverse health effects in children, particularly harm to the nervous system, hearing impairment, reductions in scores on standardized intelligence tests, and impaired or delayed growth development.
- continue remediation of residential yards, commercial properties, and ROWs with soil lead levels above site cleanup goals to reduce human exposures to lead and other metals in community soils and dusts;
- conduct periodic soil sampling of previously remediated properties to determine whether recontamination is occurring and, if so, whether followup remediation is needed;
- continue personal air sampling and ambient air monitoring around soil remediation and other work areas to ensure that workers and nearby residents are not exposed to contaminants (including lead and particulates) at levels of public health concern; where necessary, use additional dust control measures to minimize fugitive dust emissions;
- conduct additional evaluations to determine which house dust sampling method, vacuum bag or dust mat, best correlates with lead exposures and blood lead levels in site residents.
- monitor lead levels in house dust following soil remediation to measure remediation effectiveness, evaluate the potential for recontamination, and determine if additional remediation actions, such as cleaning of home interiors, is necessary;
- consider interior cleaning of homes where indoor dust levels exceed site cleanup goals or where children have elevated blood lead levels.
- investigate other pathways by which area children may be exposed to lead, such as consumption of drinking water, fish, and home-grown produce; ingestion of lead-based paint; and other places where exposure may occur such as schools and day care centers.
The Panhandle Health District should:
- continue annual blood lead surveys of area children to determine if exposure to lead is occurring at levels of public health concern.
- evaluate the public health significance of other metals, such as arsenic and cadmium, in community soils and household dusts.
- evaluate the effectiveness of the site Institutional Controls Program (ICP) in preventing human exposure to lead and other site contaminants, including (1) the adequacy of the institutional control ordinance(s), (2) the application and management of the program, and (3) the adequacy of program funding/staffing, and determine the need for revisions or additions to strengthen the program.
Environmental Health Scientist
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Lisa Hayes, P.E.
Chief, Section B
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Richard Kauffman, M.S.
Senior Regional Representative
ATSDR Region 10
Agency for Toxic Substances and Disease Registry. Health Consultation Request from Richard Kauffman, ATSDR Region X, regarding: Public health significance of contaminants in surface soil, housedusts, and fugitive dusts at Bunker Hill NPL site. February 10, 2000.
Environmental Protection Agency. Draft Bunker Hill Populated Areas Operable Unit First Five Year Review Report. Seattle: EPA, Region 10. Available from URL: http://joshua.epa.gov/r10/cleanup.nsf/9f3c21896330b4898825687b007a0f33/1a829ac00e6d429e882566290004a644?OpenDocument.
Environmental Protection Agency. 1990-1998 ambient air monitoring data for lead and total suspended particulate from the Kellogg Medical Center monitoring station, downloaded from EPA's Aerometric Information Retrieval System (AIRS).
McCulley, Frick & Gilman, Inc. (MFG). Draft Bunker Hill Superfund Site 5-Year Review Report. Wallace, Idaho: MFG, Inc. July 1999.
TerraGraphics Environmental Engineering, Inc. (TerraGraphics). Draft 1999 Annual Summary - Blood Lead Absorption and Exposure Survey. Moscow, Idaho: TerraGraphics. April 2000.
TerraGraphics Environmental Engineering, Inc. 1997 Interior House Dust and Smelterville Rights of Way Data Summary Report. Moscow, Idaho: TerraGraphics. April 1999.
TerraGraphics Environmental Engineering, Inc. 1998 Interior House Dust Data Summary Report. Moscow, Idaho: TerraGraphics. May 1999.
TerraGraphics Environmental Engineering, Inc. Field Work Plan for Interior Dust Sampling, Bunker Hill Superfund Site. Moscow, Idaho: TerraGraphics. July 1998.
TerraGraphics Environmental Engineering, Inc. Bunker Hill NPL Site, Summary of Lead Health Intervention and Source Removal Efforts 1985-1996. Moscow, Idaho: TerraGraphics. October 1997.