COEUR D'ALENE RIVER BASIN
PANHANDLE REGION OF IDAHO COMMON USE AREAS
The U.S. Environmental Protection Agency (EPA) asked the Agency for Toxic Substances and Disease Registry (ATSDR) to review and comment on the Candidates for Early Removal and/or Intervention Strategies Among the 47 Common Use Areas (CUAs) in the Coeur d'Alene Basin East of Harrison Memo (Quiring, 1999).
Past studies and ongoing data gathering in the Coeur d'Alene River and Coeur d'Alene River Basin indicate that large quantities of Silver Valley mine tailings and mine related wastes have been deposited in the Coeur d'Alene River Basin over the past 100 years (EPA, 1998a). Exposure and adverse health effects have been reported, primarily for lead, in the population residing in Coeur d'Alene River Basin (ATSDR, 1999a). Biological monitoring revealed elevated arsenic, cadmium, and lead levels in smelter workers (non-occupational exposures of these workers were also occurring) (ATSDR, 1999a). Exposure interventions were instituted in 1974; the Bunker Hill facility was closed in 1981, partially reopened in 1982, fully reopened in 1988, and closed in 1991 (ATSDR, 1999a).
Recently, sediment, water, and soil samples were collected at CUAs on the Coeur d'Alene River Basin. The samples were evaluated for antimony, arsenic, cadmium, copper, lead, manganese, mercury, and zinc. Sediments were defined as sandy areas immediately adjacent to, and under, the water (above and below the water line). Sediments samples collected above the water line were composite of 0-12 inches in depth. Samples collected below the water line were composite of 0-6 inches in depth. Samples deeper than the top inch were collected because exposures were believed to be occurring at greater depths (children digging on the beaches) (EPA, 1998a).
At the beaches, soils were defined as areas up gradient of the beach sediments. Soil samples were collected from 0-1, 1-6, 6-12, and 12-18 inches depths (EPA, 1998b).
EPA has proposed Early Action Levels (EALs) for metals reported at the CUAs to determine the areas that need immediate intervention (see Table 1) (Quiring, 1999). There was a difference in the levels of metals in soil and sediment between Coeur d'Alene Lake and Coeur d'Alene River CUAs. Lower levels of metals were reported at sampling locations at Coeur d'Alene Lake beaches (EPA, 1998a).
Beach soil lead levels ranged from 9 milligrams of lead per kilogram soil (mg Pb/kg soil) at Harrison Beach to 722 mg Pb/kg soil at Blackwell Island Beach (See Table 2). Arsenic levels ranged from 2 mg As/kg soil at Harrison Beach to 107 mg As/kg soil at Loffs Bay Beach (See Table 2) (EPA, 1998a).
Sediment levels for lead ranged from 16 mg Pb/kg sediment at Tubbs Hill Beach to 12,100 mg Pb/kg sediment at Harrison Beach (See Table 2). Arsenic sediment levels ranged from 2 mg As/kg sediment at Tubbs Hill Beach to 158 mg As/kg sediment at Harrison Beach (See Table 2) (EPA, 1998a).
Elevated metal levels were detected at CUAs sampling locations along the Coeur d'Alene River upstream from Coeur d'Alene Lake (Quiring, 1999). Beach soil lead levels ranged from 15.3 mg Pb/kg soil at Killarney Lake Boat Launch to 15,400 mg Pb/kg soil at Elk Creek Frontage Road. Soil arsenic levels ranged from 5.4 mg As/kg soil at Thompson Lake to 1,060 mg As/kg soil at Silverton T-ball-Wellman & HS parking lot (See Table 3).
Sediment levels for lead ranged 18.3 mg Pb/kg sediment at Thompson Lake to 29,200 mg Pb/kg sediment at Bull Run Peak Beach. Arsenic sediment levels ranged 1.5 mg As/kg sediment at Thompson Lake to 375 mg As/kg sediment at West of Rose Lake (See Table 3) (Quiring, 1999).
The mean concentrations among the beaches were variable. Eleven CUAs had mean lead levels below 1,000 mg Pb/kg soil (the range among means was 73 - 927 mg Pb/kg soil). One sediment sample level (1/11 CUAs) was reported in this group (56 mg Pb/kg sediment) (Quiring, 1999).
Four CUAs had mean lead levels between 1,000 and 2,000 mg Pb/kg soil/sediment (the range among means was 1,070 - 1,570 mg Pb/kg soil). Beach soil lead levels ranged from approximately 9 - 11,600 mg Pb/kg soil. The mean sediment lead level (1/4 CUAs) was 980 mg Pb/kg sediment (Quiring, 1999).
Six CUAs had mean lead levels between 2,000 and 3,000 mg Pb/kg soil (the range among means was 1,930 - 2,910 mg Pb/kg soil). The range among mean sediment lead levels (4/6 CUAs) in this category was 2,210 - 2,890 mg Pb/kg sediment (Quiring, 1999).
Twenty-one CUAs had mean lead levels between 3,000 and 5,000 mg Pb/kg soil (the range among means [20/21 CUAs] was 3,130 - 4,900 mg Pb/kg soil). The range among mean sediment lead levels (16/21 CUAs) in this category was 2,720 - 4,840 mg Pb/kg sediment (Quiring, 1999).
Five CUAs had mean lead levels 5,000 mg Pb/kg soil (the range among means was 4,350 - 12,100 mg Pb/kg soil). The range among mean sediment lead levels (4/5 CUAs) in this category ranged from 5,000 - 12,100 mg Pb/kg soil (Quiring, 1999).
Lead and arsenic were detected in surface water at CUA sampling locations along the Coeur d'Alene Lake and River (Quiring, 1999). Water samples were collected near the shore (water depth not exceeding 3 feet) immediately after vigorously disturbing the sediments (EPA, 1998b).
In the Coeur d'Alene Lake, water lead levels ranged from 0.42 -917 micrograms of lead per liter of water (µg Pb/L) (See Table 4). Surface water arsenic levels ranged from 0.3 - 20 µg As/L (See Table 4) (EPA, 1998a). Water lead levels in the Coeur d'Alene River ranged from 2.9 - 81,500 µg Pb/L (See Table 5). Surface water arsenic levels ranged from 4.3 - 600 µg As/L (See Table 5) (Quiring, 1999).
Exposures to metals at the CUAs are most likely to occur from incidental ingestion of soil at the CUAs. Ingestion of turbid water may occur; however, the water will contain sediment particles giving the water an unpleasant texture and, possibly, an unpleasant taste. Since water samples were collected in shallow water close to the shore immediately after vigorously disturbing the sediments, the levels of metals reported in surface water near the shore were probably particulate bound, particularly since deeper water did not contain appreciable levels of metals.
Sampling river sediments and water present substantial problems. Sediments move downstream; the rate and volume of flow are important variables. Slow-moving water will deposit sediments, whereas an increase in the rate of flow will move sediments. The water is constantly moving; consequently, the metal levels in the sediments and water is constantly changing; the rate of change is determined by the rate and volume of flow, and upstream sources.
Interpreting data from soil samples collected at the CUAs where flooding occurs is also difficult. The volume and flow rate can be substantially increased during flooding; consequently, the levels of lead and other metals are likely to be variable because of removal and deposition of soil and sediments during flooding.
Assessing health threats at CUAs requires that the environmental levels of metals be relatively constant. The levels of metals reported at CUAs at Coeur d'Alene Lake are similar among CUAs. The levels reported at the lake are much lower and less variable than the levels reported among the upstream CUAs along the Coeur d'Alene River.
The levels of metals in soil may be relative constant at the river CUAs during periods between floods; however, the levels may dramatically change following a flood. Since the levels of metals will change over time, the likelihood that adverse health effects will occur will also change necessitating additional sampling and data evaluation following changes in the rate and volume of flow of the river.
The allowable levels of metals in environmental media depend on previous exposure histories. The EAL proposed for lead may not provide an adequate margin of safety for local residents. Biologic monitoring data for lead indicate that the mean blood lead level for area children is 5.4 micrograms of lead per deciliter of blood (µg/dL) (arithmetic mean range: 4.1 µg/dL - 6.4 µg/dL; geometric mean range: 3.5 µg/dL - 5.8 µg/dL) (von Lindern, 1999). Approximately 8% of the children have blood lead levels greater than 10 µg/dL (Range: 0-14%) (von Lindern, 1999). NHANES III data indicate that the mean blood level for children in the U.S. is approximately 2.5 µg/dL (Pirkle et al, 1994). Since blood lead levels are already elevated with an appreciable number of children with blood lead levels greater than 10 µg/dL, exposure to lead should be minimized.
Several of the levels of metals at the CUAs along the Coeur d'Alene River are at levels of health concern. Cleaning the CUAs along the river to the proposed EAL levels would reduce health threats. Estimated external doses for the levels of metals remaining after cleanup activities at the CUAs exceed available chronic health guidelines for the levels of antimony, arsenic, cadmium, and lead reported at the CUAs (assumptions: 200 mg soil/sediment ingested, 10 kg BW, absorption 60%, and two days per week for four months for area residents). The estimated external doses, however, are not likely to result in acute toxicity for vacationers (the exposure assumption for vacationers was two weeks per year); consequently, the EALs proposed by EPA are likely to be adequate for protecting the health of vacationers.
Chronic exposures to lead have been shown to adversely effect blood lead levels of local residents. No information concerning biologic levels of the other CUA contaminants was located. Since elevated levels of the other metals were usually detected when elevated levels of lead were detected, exposures to the other metals are likely to be concurrently occurring with lead exposures. Minimizing exposure of area residents to these substances is appropriate since chronic exposures may be ongoing.
Based on the information available, ATSDR concludes the following:
- The proposed EALs for antimony, arsenic, cadmium, and lead may not provide
an adequate margin of safety for area residents.
- People vacationing the CUAs are not likely to experience adverse health effects from metals below the EALs.
- Notify area residents of the hazards posed by recreational activities at the CUAs along Coeur d'Alene River.
If additional information becomes available or if further clarification is required, please contact this office at (404) 639-0616.