COEUR D'ALENE RIVER BASIN
PANHANDLE REGION OF IDAHO
INCLUDING BENEWAH, KOOTENAI, & SHOSHONE COUNTIES
The Agency for Toxic Substances and Disease Registry (ATSDR) was requested by the Environmental Protection Agency (EPA) to review environmental sampling data from 80 residential properties sampled in the Coeur d'Alene River Basin. These homes are outside of the Bunker Hill Superfund Site. Because of prevalent mining and smelting activities, increased levels of lead have been seen throughout the basin. The health threat posed by lead contamination in soil, indoor dust, and water to children was evaluated through 1) calculation of an estimated daily intake (dose) and comparison to an Intake Of Concern for the population (IOC), 2) estimation of expected blood lead levels through use of the EPA's Integrated Exposure Uptake Biokinetic Model for Lead ( IEUBK), and 3) estimation of blood lead levels through an ATSDR integrated exposure regression analysis model for use at lead sites. Results of these methods were then compared to blood lead levels associated with adverse health effects.
NOTE: The methods used in this health consultation are not meant to predict actual conditions within the Basin. The intent of this screening is to identify those residences which should be considered further, particularly for blood lead screening and possible remedial activities.
Based on the three methodologies utilized in this health consultation and currently available data, a public heath hazard may exist for children living at more than half of the residences sampled through FSPA06. Of particular concern are residences 12, 13, 15, 32, 39, 40, 43, 44, 46, 50, 51, 58, 62, 64, 67, 74, 76, & 77. Children in approximately 50 homes had estimated lead exposures twice the IOC and/or estimated blood lead levels in excess of the Centers for Disease Control and Prevention (CDC) action level of 10 µg/dl . Results of this evaluation suggest that children one to two years old may be the population of concern for elevated blood lead levels.
Overt health effects from lead exposure may not be apparent in individuals at these blood lead levels, but concern is based upon findings of population based studies. Data suggest that children in some of these residences may be at risk for subtle neurobehavioral and developmental effects. Increased hazard may also be likely if other routes of exposure unaccounted for in these calculations, such as lead based paint, consumption of biota, and recreational activities in the basin, are a significant route of exposure to lead.
Recommendations include intervention strategies that differ based on the level of risk. Medical surveillance strategies such as blood lead monitoring and the current intervention program should be continued or initiated. Blood lead levels for children in these homes should be obtained to identify which children need follow-up and to evaluate the predictive models.
The Agency for Toxic Substances and Disease Registry (ATSDR) was requested by the Environmental Protection Agency (EPA) to review environmental data on the Coeur d'Alene River Basin residential properties sampled under field sampling plan addendum 06 (FSPA06) as part of the basin-wide remedial investigation/feasibility study (RI/FS). Residential samples were collected and analyzed for heavy metals. The EPA specifically requested ATSDR to:
- Evaluate the health threat posed by lead in soil, dust, paint, drinking water, and vegetables to the residents of the Coeur d'Alene River Basin.
- Determine the need for emergency or time-critical removal of contaminated media.
- Make recommendations for long-term remediation strategies including how to deal with lead-based paint or lead plumbing.
- Where should intervention be considered? What should an intervention program include? Which yards should be addressed as part of a clean-up action?
Heavy metals, including lead, arsenic, and cadmium, have been found throughout the Coeur d'Alene River Basin as a result of extensive mining in the Silver Valley for the past century. The Coeur d'Alene River Basin covers approximately 3, 700 square miles with 11, 000 people living in the river basin. The Bunker Hill Superfund Site is a 21 square mile area around the former smelter, inside the river basin. Silver was discovered in the South Fork of the Coeur d'Alene River Basin (Basin) in the late 1880s. Silver, lead, zinc, cadmium, copper, and gold were actively mined. Mining and smelting activities lead to high concentrations of metals in mine waste and tailings, which continue to erode (URS, 1998). Metals may also leach from mine waste and tailings. This health consultation focuses on the review of environmental data from residences in the river basin but outside of the Superfund site.
Soil, indoor dust, and tap water samples were collected from 80 residential properties throughout the river basin. Residences were sampled only if the homeowner requested the sampling and the residence met EPA's criteria of having a child under the age of seven or a pregnant woman living in the household (URS, 1999). Other possible situations such as a family that moves into the area or a pregnant woman that is not aware she is pregnant were not included in the sampling conducted here, but should be evaluated in the future. Samples were analyzed for heavy metals but only results for lead are presented and analyzed in this health consultation. Lead has been the primary driver of health risk, particularly to children, at the Bunker Hill Superfund Site (ABox"), and is the primary contaminant of concern for the Basin. However, the other metals need to be evaluated further. All results are quality assured. Specific results for each of the residential properties sampled are seen in Appendix A. Yard surface soil lead levels ranged from 26.9 to 16,000 milligram per kilogram (mg/kg). Additionally, indoor house dust, tap water, and surface soils in play areas and gardens were sampled. Surface soils were a composite mix of four subsamples for each area, from the top 0-1 inches of soil below the ground surface. Indoor dust was sampled from the household's vacuum cleaner bag. Both first-run and flushed water samples were taken from the residences sampled. Both municipal and private water sources were sampled in the study, depending on the residential water source. For the complete field sampling plan, see URS, 1998.