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PUBLIC HEALTH ASSESSMENT
Elizabeth Copper Mine
(a/k/a Elizabeth Mine)
Strafford, Orange County, Vermont
CERCLIS NO. VTD988366621
August 23, 2004




Appendix C: Summary of ATSDR Health Consultations for Soil (2000) and Soil, Dust, and Air (2001)

In 2000, the Agency for Toxic Substances and Disease Registry (ATSDR) received petition letters from community members concerned about possible health effects associated with exposures to site-related contaminants. In 2000, the U.S. Environmental Protection Agency (EPA) also requested that ATSDR review soil sampling data collected near the site. To address the community concerns and the EPA request, ATSDR produced three health consultations examining exposure to drinking water from private wells, contacting on-site and residential soil, and inhaling airborne contaminants. Exposures to drinking water from private wells was addressed in the Discussion section of this Public Health Assessment (PHA) because new data were available. Appendix C summarizes the evaluations and results from the health consultations addressing soil and air exposures (Table C-1).

  1. Surface Soil

    No adverse health effects from exposure to surface soil or dust are expected on the basis of the levels of metals found in mine tailing piles, residential soil samples, and residential dust (bulk and wipe) samples. Soil samples from mine tailings piles and from residential yards near the site contain elevated levels of certain metals, but ATSDR evaluated possible exposure scenarios and determined that people are unlikely to come in contact with these metals at a level that would cause any harm. One dust sample contained lead at a level of potential exposure concern for small children. This concentration was not considered representative of exposure concentrations. On the basis of best public health practices to prevent possible future health effects. ATSDR recommends testing blood lead levels of young children.

    Three homes along Old Mine Road are located within 0.5 miles of the three tailings piles on the Elizabeth Mine site. The closest of these residences is located within 150 feet of TP3. The soil in the yards of these homes, and the dirt and dust inside the homes, may contain windblown dust from tailings piles and other contamination sources on the Elizabeth Mine site. TP1 and TP2 consist of fine-grained tailings from a flotation mill that operated onsite from 1943 to 1958 (USGS 2000). A local landowner previously covered parts of TP1 with 6 inches of topsoil, to grow vegetation and reduce wind-blown dust. Some trees and sparse vegetation grew in those areas. TP3 consists of coarser mine spoils from earlier mining operations (USGS 2000); it has little vegetation except for a few small birch and white pine trees.

    The primary exposure routes to contaminants in soil at residential homes and to indoor dust are inhalation of dust, dermal contact with soil and dust, and ingestion of soil or dust on contaminated foods (or mouthing of contaminated objects by toddlers and infants), or accidental ingestion of soil during outdoor activities.

    The mine site contains open pit mines, extensive underground workings, three tailings areas, and several buildings; there are no fences restricting access to the site. Children living nearby could play on the site and be exposed to on-site soil through incidental ingestion, dermal contact, or inhalation. During ATSDR's site visit, there was no evidence of on-site recreational activities or trespassing on the site by children; however, all-terrain vehicle riders use the unpaved road that cuts across TP3, and local students have been known to swim in the mine cuts (EPA 2003a).

    Evaluation of Soil Data

    Off-Site Soil (Residential Soil)

    In July and November 2000, EPA conducted two rounds of surface soil sampling at three residential yards and two background locations (Weston RF ND). EPA analyzed the samples for metals. The highest level of arsenic found in a residential yard was estimated at 18.3 parts per million (ppm) . The next highest level was 15.8 ppm. Iron and copper were detected in residential soil at concentrations of 198,000 ppm and 4,690 ppm, respectively. The residential and non-residential sampling locations are shown in Figures C-1 and C-2. The maximum levels of contaminants detected above CVs in residential soil samples are shown in Table C-2. No elevated contaminant levels were detected in the background samples.

    Off-Site Dust/Wipe (Indoor Dust/Wipe)

    In November 2000, EPA collected indoor dust samples (as bulk samples and wipe samples) from three residences located on Old Mine Road (Lockheed Martin 2001). Indoor dust samples were obtained using two methods. The first method ("bulk samples") used a vacuum sampler to collect dust from a measured area on the floor in three different living spaces within each residence. In the second method ("wipe samples"), cloth wipes were used to collect dust samples at locations adjacent to the vacuum sample locations. All samples were analyzed for metals. Aluminum, copper, iron, lead, magnesium, manganese, phosphorus, selenium, sodium, thallium, titanium, and zinc were found in residential house wipe samples. Iron, lead, magnesium, phosphorus, sodium, and thallium were found in bulk dust samples at levels above surface soil CVs. The highest metal levels were primarily found in one sample location (Lockheed Martin 2001). Tables C-3 and C-4 show the maximum levels of contaminants detected above CVs, the number of samples collected, and the location of the maximum detected concentration.

    On-Site Soil (Mine Tailings)

    USGS collected 11 composite waste dump and tailings samples from the site (each sample was a 30-point composite of soil collected from the tailings surfaces) and analyzed these for metals (USGS 2000). Arsenic levels at the tailings ranged from 4 ppm to 25 ppm. Copper levels ranged from 96 ppm to 6,600 ppm. Iron levels in the tailings ranged from 79,000 ppm to 360,000 ppm. Table C-5 presents these sampling results.

    Public Health Implications

    ATSDR assessed the public health implications associated with contacting soil and dust in two public health consultations: Residential Soil and Mine Tailings, Elizabeth Copper Mine Site, Elizabeth Mine, Strafford, Orange County, Vermont, and Residential Soil, Indoor Dust and Ambient Air, Elizabeth Copper Mine Site, Elizabeth Mine, Strafford, Orange County, Vermont. In these health consultations, ATSDR concluded that contact with residential surface soil posed no public health hazards. Contact with lead in indoor dust, however, was identified as a possible concern by ATSDR. Conclusions and analyses from these health consultations are summarized in this Appendix.

    Off-Site Soil (Residential Soil)

    Arsenic (18.3 ppm), copper (4,690 ppm), iron (198,000 ppm), and thallium (20.5 ppm) were detected in residential soil at concentrations that exceed their respective CVs. ATSDR conducted an evaluation of potential exposures to each of these metals. For these evaluations, ATSDR examined plausible exposure scenarios and reviewed relevant toxicological information for each metal. ATSDR calculated exposure doses using the maximum detected level and conservative assumptions about exposures. The resulting doses were below levels shown to cause health effects in a review of the toxicological literature. ATSDR concluded that no past, current, or future adverse health effects are expected to result from potential exposures to metals in surface soil in residential yards (ATSDR 2001a).

    Off-Site Dust/Wipe (Indoor Dust/Wipe)

    A number of metals were detected in indoor dust samples (bulk samples and wipe samples), as shown in Appendix B, Tables 4 and 5. ATSDR assessed possible exposures to lead as a contaminant of possible concern. For the health consultation, ATSDR converted raw bulk sampling results to parts per million (ppm) and compared results to the surface soil CVs. No CVs are available for wipe sample results; therefore, ATSDR assessed each of the detected metals. The health consultation concluded that indoor dust contained elevated levels of metals. All but two detections of lead are not associated with adverse health effects in children or adults. Two bulk dust samples, found at the house identified as Residence 2, contained lead at a level that is of potential concern for young children.

    Two indoor bulk samples from a single home contained lead at 430 ppm and 1,600 ppm, which exceed EPA's Office of Solid Waste and Emergency Response recommendation of a 400 ppm screening level for lead in residential soil and Superfund sites. The other two bulk samples collected from this home contained lead at 220 ppm and 360 ppm. Of the five wipe samples collected from this home, one contained lead to 550 micrograms per square meter ( g/m2). The remaining four samples reported lead concentrations ranging from non-detect to 290 g/m2. The U.S. Agency for Housing and Urban Development (HUD) defines a lead dust hazard as a lead level greater than 1,080 g/m2 on surface floors (hard floors or carpeting) for public housing (HUD 1995). EPA has proposed 540 g/m2 of lead on uncarpeted floors as a lead dust hazard for child-occupied facilities (Federal Register 1998). Based on these results and best public health practices, ATSDR recommended periodic blood lead testing of young children living in the residence with the highest lead findings (Residence 2).

    Of the six bulk samples collected from two other homes, three contained lead from 30 ppm to 60 ppm, and three detected no lead. These levels are below EPA's Office of Solid Waste and Emergency Response recommendation of a 400 ppm screening level for lead in residential soil at Superfund sites. The wipe samples from these two homes contained lead in dust ranging from 120 g/m2 to 240 g/m2 in six samples and non-detect in two samples. The detected lead levels are below the HUD lead dust hazard level of 1,080 g/m2 and proposed EPA lead hazard level of 540 g/m2 (HUD 1995, Federal Register 1998). As such, no adverse health effects are expected.

    ATSDR's detailed evaluation of exposures to other metals identified no public health hazards to adults and children who come in contact with other metals found in indoor bulk and wipe dust samples. ATSDR examined plausible exposure scenarios and reviewed relevant toxicological information for each metal. ATSDR calculated exposure doses using the maximum detected level and conservative assumptions about exposures. The resulting doses were below levels shown to cause adverse health effects in a review of the toxicological literature. ATSDR concluded that no past, current, or future health effects are expected to result from potential exposures to metals in surface soil in dust (ATSDR 2001).

    On-Site Soil (Mine Tailings)

    Arsenic (25 ppm), copper (6,600 ppm), and iron (360,000) were detected in mine tailings piles at levels exceeding the soil CVs. ATSDR considered possible exposure scenarios, calculated exposure doses, and reviewed the chemical-specific toxicology data to assess possible adverse health effects.

    On-site soil samples were collected from tailings piles at the Elizabeth Mine site. Trespassers may ignore warning signs and access these areas for recreation. The maximum arsenic, copper, and iron concentrations exceeded their surface soil CVs. The surface soil CVs are derived by assuming daily contact with contaminants. However, trespassers, including children, are unlikely to have daily contact with on-site soil. Recreational use of the area would likely be limited by Vermont's winter climate, and contact with on-site soil would be limited by snow cover. Nonetheless, exposure doses calculated assuming daily exposure to the maximum detected arsenic levels are below doses reported in the literature to result in adverse health effects (ATSDR 1998). Copper and iron are considered essential nutrients in humans. Infrequent exposure to them is not expected to result in adverse health effects. ATSDR concluded that infrequent contact with on-site soils during recreational use poses no public health hazards.

  2. Air

    Chromium was detected above its CV in air samples collected outside of homes on Old Mine Road. Lead and phosphorus were also detected, but these do not have established CVs. On the basis of an evaluation of exposures and chemical-specific toxicity information, ATSDR concluded that breathing air containing these contaminants poses no public health hazard.

    From the mine's opening in 1793 to the present, contaminants may have been released to the air through site activities, such as volatilization of stored material or windblown dust. Homes are located along Old Mine Road within 0.5 mile of the Elizabeth Mine site. ATSDR could not ascertain the length of time that current residents (of the houses on Old Mine Road) have lived in those locations. No remediation activities have occurred at the site, so potential sources of air contamination (bare surface soil transported as windblown dust) still exist at Elizabeth Mine.

    Evaluation of Air Data

    In November 2000, EPA collected five ambient air samples near two homes on Old Mine Road and located downwind of the tailings piles (see Appendix A, Figure 3). Three samples were collected from one yard and two samples were collected from another yard. Aluminum and lead were detected above CVs near both homes. Chromium (total chromium) was detected above CVs in ambient air near one residence and in the sampling background. Iron and phosphorus were detected above CVs in three air samples. The highest detection of aluminum was at the home at 194 Old Mine Road, and the highest detections of chromium, iron, lead and phosphorus were all at the home at 190 Old Mine Road. Table C-6 provides the maximum detected levels of each of these contaminants.

    Public Health Implications

    ATSDR evaluated possible health hazards from contamination in air in the 2001 health consultation Residential Soil, Indoor Dust, and Ambient Air, Elizabeth Copper Mine, Strafford, Orange County, Vermont. ATSDR concluded in this health consultation that no past, current, or future adverse health effects were expected from exposure to contaminants detected in air.

    Chromium (0.56 g/m3 and 0.27 g/m3) was detected above the CV (0.00008 g/m3) in two air samples taken at homes on Old Mine Road. Chromium was also found in the blank sample (1.4 g), which indicates that chromium may have been introduced to the samples from a source other than ambient air. In the environment, chromium occurs as a mixture of primarily trivalent (III) chromium and hexavalent (VI) chromium. Trivalent chromium, which is found at greater concentrations in a chromium mixture, is less toxic than hexavalent chromium (ATSDR 2000c). In the 2001 health consultation, ATSDR conducted a detailed review of possible health effects associated with detected chromium concentrations. A review of the toxicology literature found that lowest concentration of total chromium (a mixture of both trivalent and hexavalent chromium) to cause adverse health effects (lung cancer in humans) was 40 g/m3. This is a concentration 70 times greater than the concentration detected at the Elizabeth Mine site. In addition, the chromium CV is developed assuming there is no threshold to cancer effects, that is any concentration of chromium can cause cancer. However, evidence indicates that a threshold for lung cancers associated with chromium does exist. Inflamation or damage to the lungs is a necessary precursor to cancer effects. Chromium levels found at the site are lower than the lowest concentration observed to cause non-cancerous damage to the lungs (2 g/m3) (ATSDR 2001a).

    Lead (0.18 g/m3) was detected in two of four air samples taken at homes on Old Mine Road. Although lead has no CV, the 2001 health consultation notes that the lowest level at which health effects have been found from lead exposure via inhalation is 11 g/m3. Phosphorus was detected in one, at a level of 2,300 g/m3 at one home on Old Mine Road, of four samples. Phosphorus has no CV; however, it is a major mineral nutrient, and children need about 800 mg in their daily diet (ATSDR 2001).

Figure C-1. Soil Sampling Locations (Residences 1, 2 and 3) [PDF, 214KB]

Figure C-2. Soil Sampling Locations (Non-Residential Samples) [PDF, 447KB]

Table C-1.

Exposure Pathways, Elizabeth Copper Mine Site
Pathway Name Source Media Point of Exposure Route of Exposure Exposed Population Time-frame Comments
Surface Soil Elizabeth Mine Surface soil Tailings piles at site

Residential surface soil
Incidental ingestion, Dermal contact Past workers, nearby residents, trespassers Past Current Future Exposure to on-site soil is thought to be limited to past workers and possibly occasional site trespassers. Wind may have blown soil from the site to nearby residences. Metals were detected at slightly elevated levels in tailings piles and in residential yards.
Indoor dust Elizabeth Mine Indoor dust Residential homes near the site Incidental ingestion, Dermal contact Residents living near the site Past Current Future Winds may have blown soil from the site to homes nearby, where residents come in contact with dust that settles in their homes. Indoor dust samples contained slightly elevated levels of certain metals.
Ambient Air Elizabeth Mine Air Site vicinity Inhalation Residents near the site Past Current Future Residences are located within a few hundred feet of the mine site boundary. The closest residence is 150 feet from one mine tailings pile. Slightly elevated levels of some metals were detected in air sampled outside three nearby homes.


Table C-2.

Off-site surface soil contaminants detected above comparison values, Elizabeth Copper Mine Site
Chemical Maximum Level (ppm) Date of Maximum Comparison Value (CV) (ppm) Type Exceedences / Detections / Samples Location of Maximum
First Sampling Round
Arsenic 8.5 7/20/00 0.5 CREG 8/8/9 Residence #3
Iron 198,000 7/20/00 23,000 RBC-N 5/9/9 Residence #3
Thallium 20.5 7/27/00 5.5 RBC-N 1/4/9 Residence #3
Second Sampling Round
Arsenic 18.3 11/02/00 0.5 CREG 25/25/54 Residence #2
Copper 4,690 11/01/00 3,100 RBC-N 1/54/54 Residence #3
Iron 144,000 11/01/00 23,000 RBC-N 39/54/54 Residence #3
Source: Weston RF 2000b; Arthur D. Little 2000b.

Key:
CREG = Cancer Risk Evaluation Guide (ATSDR)
ppm = parts per million
RBC-N = Risk-Based Concentration for Non-Cancer effects (EPA)


Table C-3.

esidential house dust (bulk sample) contaminants detected above comparison values for the Elizabeth Copper Mine Site
Chemical Maximum Level (ppm) Date Comparison Value (CV) (ppm) Type Detections / Samples Location of Maximum
Iron 34,000 11/2/2000 23,000 RBC-N 10/10 House 3 (Living room)
Lead 600 11/2/2000 400 EPA
Soil Screening Level
7/10 House 2 (3rd Floor Girl bedroom)
Magnesium 8,000 11/2/2000 N/A None 10/10 House 2 (3rd Floor Girl bedroom)
Phosphorus 1,700 11/2/2000 10 I-EMEG-child 10/10 House 2 (3rd Floor Boy bedroom)
Sodium 5,000 11/2/2000 N/A None 10/10 House 2 (Parent bedroom/North)
Thallium 510 11/2/2000 140 RBC-N 7/10 House 2 (3rd Floor Girl bedroom)
Source: Lockheed Martin 2001

Note: Comparison values are soil-based; the chromium comparison value is for hexavalent chromium
Key:
EPA = U.S. Environmental Protection Agency
I-EMEG-child = Environmental Media Evaluation Guide for Intermediate exposure to a child (ATSDR)
N/A = not applicable (no CV exists)
ppm = parts per million
RBC-N = Risk-Based Concentration for Non-cancer effects (EPA)


Table C-4.

Residential house wipe contaminants for the Elizabeth Copper Mine Site
Chemical Maximum Level (µg/m2) Date Comparison Value (CV) (µg/m2) Type Detections / Samples Location of Maximum
Aluminum 1,500 11/2/2000 None 13/13 House 1 (Child bedroom)
Copper 56 11/2/2000 None 2/13 House 1 (Child bedroom)
Iron 3,500 11/2/2000 None 13/13 House 3 (Living room)
Lead 550 11/2/2000 540 EPA (proposed) 12/13 House 2 (Child bedroom)
Magnesium 920 11/2/2000 None 12/13 House 1 (Child bedroom)
Manganese 72 11/2/2000 None 9/13 House 1 (Child bedroom)
Phosphorus 1,100 11/2/2000 None 13/13 House 1 (Kitchen)
Selenium 12 11/2/2000 None 2/13 House 1 (Child bedroom)
Sodium 1,800 11/2/2000 None 12/13 House 1 (Kitchen)
Thallium 250 11/2/2000 None 7/13 House 3 (Kitchen)
Titanium 110 11/2/2000 None 12/13 House 3 (Living room)
Zinc 86 11/2/2000 None 13/13 House 3 (Living room)
Source: Lockheed Martin 2001

Key:
EPA = U.S. Environmental Protection Agency
µg/m2 = micrograms per square meter


Table C-5.

On-site surface soil contaminants detected above comparison values, Elizabeth Copper Mine Site
Chemical Maximum Level (ppm) Date Comparison Value (CV) (ppm) Type Exceedences / Detections / Samples Location of Maximum
Tailings Piles (Tailings Pile #1, #2, #3)
Arsenic 25 2000 0.5 CREG //11 Unknown
Copper 6,600 2000 3,100 RBC-N 2/6/11 Tailings Pile #3
Iron 360,000 2000 23,000 RBC-N //11 Unknown
Tailings Piles (Tailings Pile #1, #2, #3)
Arsenic 15.8 11/01/00 0.5 CREG 3/3/3 Tailings Pile #3
Iron 170,000 11/01/00 23,000 RBC-N 3/3/3 Tailings Pile #3
Other on-site (Tailings Pile #3, base of solvent storage shed, inside transformer storage building, and near large outdoor transformers)
Arsenic 20.83 1991 0.5 CREG 4/4/4 Base of solvent storage shed
Source: ATSDR 2000b; Weston RF 2000a; USGS 2000

Key:
C-EMEG-child = Environmental Media Evaluation Guide for Chronic exposure to a child (ATSDR)
CREG = Cancer Risk Evaluation Guide (ATSDR)
MCL = Maximum Contaminant Level
ppm = parts per million
RBC-C = Risk-Based Concentration for Cancer effects (EPA)
= number of samples is unknown


Table C-6.

Air sampling contaminants for the Elizabeth Copper Mine Site
Chemical Maximum Level (µg/m3) Date Comparison Value (CV) (µg/m3) Type Detections / Samples Location of Maximum
Aluminum 0.67 11/2/2000 0.37 RBC 2/4 194 Old Mine Road (South)
Chromium 0.56 11/2/2000 0.00008 CREG 2/4 190 Old Mine Road (South)
Iron 0.92 11/2/2000 1,100 RBC 3/4 190 Old Mine Road (North)
Lead 0.18 11/2/2000 None 3/4 190 Old Mine Road (North; South)
Phosphorus 2,300 11/2/2000 None 1/4 190 Old Mine Road (South)
Source: Lockheed Martin 2001

Key:
CREG = Cancer Risk Evaluation Guide (ATSDR)
µg/m3 = micrograms per cubic meter
RBC = Risk-Based Concentration (EPA)


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