PUBLIC HEALTH ASSESSMENT
KENNECOTT (SOUTH ZONE)
COPPERTON, SALT LAKE COUNTY, UTAH
Figure 2a. Bingham Creek -- Copperton to 4800 West
Figure 2b. Bingham Creek -- 4800 West to Jordan River
APPENDIX B DEMOGRAPHICS, LAND AND NATURAL RESOURCE USES
Demographics, Land Use and Natural Resource Use
C. Demographics, Land Use, and Natural Resource Use
Bingham Creek Operable Unit
Downstream from 4800 West downstream to nearly the Jordan River, the areas adjacent and near the creek are largely residential. ATSDR staff's review of census block data for that area shows there are about 13,000 people residing within 1500 feet of the creek; of these, about 5,000 are age 5 or less (19). The census indicates the population is about 94 percent white; a few percent are Hispanic.
ATSDR staff saw no residences close to this segment of the creek. In the part of Bingham Flats beyond Kennecott's property, staff saw a large electrical substation and a large water tank; the remainder of the area appeared to have been used for agriculture at one time. Downstream, the creek crosses a remote southern corner of the brick plant property at a point far from the production area and then passes through the county's gravel quarry property.
ATSDR staff saw that residential development near the creek begins at 4800 West. The first 2,700 feet of creek downstream is bounded on the north by residences and on the south by a golf course. The next 4,100 feet is primarily residential, with some vacant property to the north. Along those two segments, the channel bottom is 25 to 40 feet lower than the surrounding topography. Lot boundaries do not extend into the channel (17).
For the next 2,000 feet observed downstream, residences border the south side of the creek, and the land immediately north is predominately vacant. Most of the next 1,100 feet (up to 9000 South) has homes on the north side and predominately vacant land on the south. Along these segments, the channel bottom is 10 to 15 feet below surrounding topography, and some lot boundaries extend into the channel (17).
From 9000 South to the Utah Lake Distribution Canal (1,400 feet) (Figure 2B), the north side of the creek is dominated by Jordan Valley Hospital parking lots and then by vacant land. The south side of the creek within that segment is bordered by residential property. For the next 1,600 feet (to 3200 West), the land immediately north and south of the creek is vacant (17).
The first 2,100 feet of channel (from 3200 West to 8600 South) lies within Jordan View Estates, is concrete lined (since 1986) and fenced on both sides, and has residences on both sides (43). The next 1,100 feet of channel (from 8600 South to 2700 West) is enclosed in a pipe and crosses large tracts of undeveloped property. ATSDR staff saw that those properties are fenced along the street edge.
ATSDR staff saw that, from 2700 West to Sugar Factory Road (Figure 2B), the first 1,700 feet of creek has residences on one side of the channel and a golf course the other. The creek then is carried within a pipe for about 1,600 feet (18). The channel then reappears and crosses about 1,700 feet of undeveloped land that is bounded on the southwest by residential properties. ATSDR observed that a high fence is present between the channel and the residences.
From Sugar Factory Road up to Brookside Trailer Park (1,500 feet), the channel crosses properties that are predominantly undeveloped. Within the trailer park, ATSDR staff saw that the channel segment (about 1,500 feet) is very close to many homes. Within that reach the channel is shallow and narrow.
The channel is essentially a dry creek bed throughout most of the year, and is accessible at many points throughout the residential areas. Evidence such as bicycle tracks, caves in the channel banks, and slide marks on the banks shows children use the channel as a recreational area. Children also have been observed in the channel (3). The ball park at Skye Drive and playgrounds at Brookside Trailer Park and the Meadow Greens subdivision also are locations for children's activities.
The creek, being essentially dry, is not likely to be used for fishing or swimming. Intermittent, localized wading is plausible following runoff episodes. Fishing does occur in the Jordan River; swimming also is plausible there.
ATSDR staff observed several schools in the creek vicinity, but none lie within the affected areas. The nearest school is approximately 2,000 feet from the channel.
The Jordan Valley Hospital property on 9000 South lies along the creek. ATSDR staff saw that the South Valley Care Center, a nursing facility on 9000 South adjacent to the hospital property, is several hundred feet west of the creek channel, on land that has not been shown to have been affected by creek flooding.
Copperton Soils Operable Unit
ATSDR staff's review of census block data for the Copperton vicinity indicates that the town has a 1990 total population of about 550 and about 40 children age 5 or less (19). The population is about 97 percent white.
The former Bingham High School on the north edge of town is now a middle school. A large community park with children's play areas is on the south side of town. The area on the east side of town on which homes were relocated from the Lark community was formerly a play area for children (2). No hospitals or nursing care facilities are in the community. Copperton obtains its public water supply from two deep wells (44). ATSDR staff learned from the water improvement district chairman that the town has been in existence since 1928 and every residence is connected to the system, which was installed in 1932.
Butterfield Creek Operable Unit
ATSDR staff's review of census block data for the Herriman vicinity indicates that the area has a 1990 total population of about 916 and about 110 children age 5 or less (19). The population is estimated to be 98 percent white, 1 percent Hispanic, and 1 percent other racial designations.
Southwest Salt Lake County Groundwater Operable Unit
Southwest Salt Lake County encompasses 3 incorporated cities (West Jordan, South Jordan and Riverton) and 3 unincorporated communities (Copperton, Herriman, and High Country Estates). The following table summarizes 1992 population estimates for the cities and communities.
Table B1. 1992 Community Population Estimates
| West Jordan | 45,000 |
| South Jordan | 14,000 |
| Riverton | 11,700 |
| Herriman | 800 |
| Copperton | 700 |
| High Country Estates | 795 |
Land Use
The 1990 predominant land use categories were mining, industrial, non-irrigated agriculture, residential, irrigated agricultural and commercial. The majority of the residential areas, which includes typical suburban shopping areas and schools, is in the eastern half of the area closer to the Jordan River but spreading westward toward the Oquirrh Mountains. In 1995, residential and commercial are rapidly replacing agricultural lands.
Natural Resource Use
Groundwater is the source of domestic water for the majority of the people living in Southwest Salt Lake County. Table B2 summarizes the groundwater usage by communities in southwest Salt Lake County.
Table B2. Community Groundwater Use
| Community | 1992 Annual water use in millions of gallons (mg) | 1992 Groundwater use from study area in mg | Number of Municipal Wells | Per cent of Groundwater pumped from study area |
| West Jordan | 3, 373 | 1,676 | 6 with 4 in use | 50% |
| South Jordan* | 1, 174 | N/A | none | N/A |
| Riverton | 780.2 | 780.2 | 6 | 100% |
| Herriman | 75 | 75 | 3 | 100% |
| Copperton | 90 | 90 | 3 with 2 in use | 100% |
| High Country Estates | 35 | 35 | 7 | 100% |
Kennecott Corporation completed a detailed well inventory of southwest Salt Lake County in
1995. Wells within a 120 square mile area were surveyed for location and use. This information
is summarized in Table 8
| TABLE 9. 1994-1995 Southwest Jordan Valley Well Inventory | |
| Drinking water wells | 347 |
| Non-drinking water wells | 219 |
| Kennecott Utah Copper (KUC) monitoring wells | 427 |
| Non-KUC monitoring wells | 90 |
| Not in use water wells | 601 |
APPENDIX C DESCRIPTION OF EVALUATION PROCESS
Selection of Key Contaminants for Public Health Evaluation
ATSDR reviews contaminant data and selects those that warrant subsequent further evaluation for public health implications. Identification of these contaminants does not imply that human exposure does occur or that exposure would actually result in adverse health effects.
Contaminant selection considers the following factors:
The soil contaminants selected for further evaluation and the media in which sampling shows they have occurred are summarized in the data tables in Appendix D. The data tables also identify specific public health assessment comparison values ATSDR considered in the selection process. An Environmental Media Evaluation Guide (EMEG) is an estimated comparison concentration that is based on information determined by ATSDR from its toxicological profiles for a specific chemical. Reference Dose Media Evaluation Guide (RMEG) comparison concentrations are based on EPA's estimates of the daily exposure to a contaminant that is unlikely to cause adverse health effects. An Action Level (AL) is an EPA regulatory concentration that, if exceeded in a public water system, requires the system operators to initiate specified response actions. Cancer Risk Evaluation Guide (CREG) is a comparison concentration that is based on an excess cancer rate of one in a million persons and is calculated using EPA's cancer slope factors. The Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) standards for air in the workplace have been divided by 400 to develop a conservative comparison value for community exposure. Ambient Air Quality Standard (NAAQS) was also selected as a comparison value. An estimated (Est.) comparison value is based on ATSDR staff review of toxicologic data for a contaminant.
ATSDR also reviewed the EPA Toxic Chemical Release Inventory (TRI) for 1992 to learn whether that database would disclose any supplemental information about contaminant releases in the area.
Identification of Exposure Pathways
ATSDR identifies human exposure pathways by examining environmental and human components that might lead to contact with contaminants of concern. A pathway analysis considers five elements: a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population. Completed exposure pathways are those for which the five elements are evident, indicating that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. ATSDR regards people who come in contact with contamination as exposed; for example, people reside in an area with contaminants in air, or who drink water known to be contaminated, or who work or play in contaminated soil are considered exposed. Potential exposure pathways are those for which exposure seems possible, but one or more of the elements is not clearly defined. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future.
Only exposure situations associated with completed pathways are discussed in this assessment; evaluations did not disclose any potential pathways likely to be of public health significance.
Determination of Public Health Implications
Determining the public health implications of a site is a two-track process: a toxicological evaluation, and, where appropriate, health outcome data evaluation.
Typically, the toxicological evaluation in a public health assessment is a comparison of the exposure dose (i.e., the amount of a substance individuals in an exposure pathway are exposed to daily) to an appropriate health guideline. If the contaminant being evaluated is a carcinogen, then the risk from exposure to that carcinogen is determined. The methodology for calculating exposure doses and cancer risk is described in Appendix E.
Health outcome data is information on the occurrence of cancer, birth defects, or other diseases or conditions; or the results of testing for the contaminants of concerns in humans. Health outcome data are evaluated if it is biologically plausible for a health outcome to occur or if the community is concerned about specific health outcomes; and if the appropriate data can be identified to evaluate a health outcome. For biological plausibility, the decision to evaluate health outcome data depends on whether a completed exposure pathway exists for a chemical suspected of causing the health outcome of concern (?). The selection of a noncarcinogenic health outcome is based on a review of the toxicologic literature for that contaminant of concern.
CONTAMINANT TABLES
List of Tables
LIST OF ACRONYMS
| AL | USEPA Action Level |
| CREG | Cancer Risk Evaluation Guide |
| EMEG | Environmental Media Evaluation Guide |
| Est. | estimated comparison value (by ATSDR) |
| J | value estimated (by laboratory) |
| NA | not applicable |
| NAAQS | National Ambient Air Quality Standards |
| ND | not detected |
| NIOSH | National Institute for Occupational Safety and Health |
| NI | no information |
| OSHA | Occupational Safety and Health Administration |
| PM10 | airborne particles 10 microns and smaller in diameter (relevant to inhalation exposure) |
| ppb | parts per billion |
| ppm | parts per million |
| RMEG | Reference Dose Media Evaluation Guide |
| µg/m3 | micrograms per cubic meter (ambient air) |
| < | less than the stated value |
| Table D1 | Bingham Creek Operable Unit On-site Data Preremoval Surface Soils (or Tailings), 4800 West to 9000 South |
| Contaminant | Maximum Concentration, Surface Samples (ppm) | Comparison Value | |||||
| Within Channel or Immediately Adjacent* | Off-channel Property** | Ball Field*** |
Park**** | Bike Path***** |
ppm | Source | |
| Arsenic | 630 | 480 | 110 | 40 and 70 |
187 | 0.4 | CREG |
| Cadmium****** | 3.1 | NI | 5.4 | NI | NI | 1 | EMEG |
| Lead | 54,000 | 1,260 | 4,890 | 620 and 1,700 |
2,230 | none | |
| Locations for some samples are not clearly described in reference texts and figures. Data noted as being "Within channel or
Immediately Adjacent" or "Off-channel" are based in part on ATSDR staff interpretations of available location information. * Values shown are for materials visually identified as tailings. Most samples from channel had less than 5,000 ppm lead. On adjacent properties, lead and arsenic in essentially all samples were close to, or equal to, expected background levels. About 150 samples taken in 1990 and 1991 reviewed (3,?,5,6,7,8) ** In 1990, on Tarbert Circle, on a nearby property that backs up to a ditch that drains into the creek, 1,260 ppm lead was from a backyard sample identified as "imported barrier"--seemingly implying the sample is of nonnative materials. A nearby sample on the property showed lead to be 480 ppm. (9) *** By Skye Drive. Seventeen samples taken in 1990 and 1991 (6,10). **** By Judd Drive. The 1,700 ppm lead and 70 ppm arsenic were the highest reported for two samples taken from the creek channel. The 620 lead and 40 ppm arsenic were for samples taken elsewhere in park. Ten samples taken in 1990 and 1991 (6,10). ***** Bike path by creek between 4800 West and Skye Drive. Nine samples taken, date not specified (11). ****** Few samples were analyzed for cadmium | |||||||
| Table D2 | Bingham Creek Operable Unit On-site Data Preremoval Surface Soils (or Tailings), 9000 South to 3200 West |
| Contaminant | Maximum Concentration, Surface Samples (ppm) | Comparison Value | |||
| Within Channel or Immediately Adjacent | Off-Channel "Plumes"* |
Residential Property |
ppm | Source | |
| Arsenic | 570 | 880 | 35 | 0.4 | CREG |
| Cadmium*** | 1.4 | 1.2 | 0.6 | 1 | EMEG |
| Lead | 20,000 | 20,700 | 977** | none | |
| Locations for some samples are not clearly described in reference texts and figures. Data noted as
being "Within channel or Immediately Adjacent" or "Off-channel" or "Residential Property" are based
in part on ATSDR staff interpretations of available location information.
Approximately 140 samples taken in 1990, 1991 and 1992 (3,5,6,7,8). Many samples within the
channel, immediately adjacent, and from off-channel plumes substantively exceed expected lead
background levels. Less than half of the samples were analyzed for arsenic. Of these, many exceed
expected background by a substantive margin. On residential property, it appears that lead and arsenic
levels were close to or equal to expected background levels. | |||||
| Table D3 | Bingham Creek Operable Unit On-site Data Preremoval Surface Soils (or Tailings) 3200 West to 2700 West |
| Contaminant | Maximum Concentration, Surface Samples (ppm) | Comparison Value | ||||||
| IRECO/Rigbye | ||||||||
| Jordan Viewa | Fahnian Ranchettesb |
Meadow Greensc | Bluegrassd | ppm | Source | |||
| Residences | Playground | |||||||
| Arsenic | 410 | 172 | 110 | 130 | 50 | 251 | 0.4 | CREG |
| Cadmiumf | 20.6 | NI | 5.9 | 6.9 | NI | NI | 1 | EMEG |
| Lead | 17,300 | 9,841 | 3,472 | 3,794 1,900; resampling 40; sandbox |
715 | 11,000 | none | |
| Samples taken in 1990, 1991 and 1992 (12,6,9,13). a 487 samples. About 80 per cent of residential lots sampled exceeded expected background lead levels; most by a substantive margin. Many arsenic levels exceeded expected background by a substantive margin. b 83 samples. All residential lots sampled exceeded expected background lead levels; most by a substantive margin. A few arsenic levels also exceeded expected background by a substantive margin. c 139 samples. Lead substantively exceeded background levels for about 1/3 of residential lots sampled (maximum 3,472 ppm) and some of the playground samples (maximum 3,794). Some arsenic levels exceeded expected background, but only a few did so by a substantive margin. Questions about playground values resulted in a second and third resampling there that showed a reduced lead level for general play areas (maximum 1,900 ppm)--sandbox samples showed lead to be a maximum of 40 ppm. d 26 samples. Lead at essentially all lots sampled was close to or equaled expected background levels. Arsenic did not exceed expected background by a substantive margin. e 10 samples. Lead in all samples substantively exceeded background lead levels. Two of the five samples analyzed for lead substantively exceeded background levels. f Relatively few samples were analyzed for cadmium. | ||||||||
| Table D4 | Bingham Creek Operable Unit On-site Data Preremoval Surface Soils (or Tailings) 2700 West to Brookside Trailer Park |
| Contaminant | Maximum Concentration (ppm) | Comparison Value | ||||||
| 2700 West to Sugar Factory Road |
Sugar Factory Road to Redwood Road Vicinity |
Brookside Trailer Park |
||||||
| Within Channela |
Off- Channel Propertyb |
Within Channelc |
Off- Channel Propertyd |
Within Channele |
Off- Channel Propertyf |
ppm | Source | |
| Arsenic | NI | 50 | NI | 80 | NI | 60 20g |
0.4 | CREG |
| Lead | 3,393 | 1,365 | 7,129 | 1,777 | 4,365 | 2,003 200g |
none | |
| Locations for some samples are not clearly described in reference texts and figures. Data noted as being
"Within Channel" or "Off-Channel Properties" are based in part on ATSDR staff interpretations of available
location information. No cadmium data. Sampling conducted in 1990, 1991 (6). a 5 samples. Lead exceeded expected background level for all samples. b 27 samples. Lead on residential properties exceeded expected background levels for about 50 percent of samples. c 37 samples. Lead exceeded expected background level for about 85 percent of samples. d 17 samples. Lead on residential and undeveloped properties exceeded expected background level for all samples. e 21 samples. Lead exceeded expected background level for all samples f 13 samples. Lead on residential properties exceeded expected background for about 50 per cent of samples. g Playground data. Lead does not exceed expected background levels. | ||||||||
| Table D5 | Copperton Operable Unit On-site Data Surface Soils |
| Contaminant | Maximum Concentration Surface Samples (ppm) |
Comparison Value | ||
| Residential Properties* |
Playground, School** |
ppm | Source | |
| Arsenic | 53.8 | 14.6 | 0.4 | CREG |
| Cadmium | 8.8 | 4.6 | 1 | EMEG |
| Copper | 2020 a 597 b |
230 | 80 | Est. |
| Lead | 253.4 | 252.6 | none | |
| Zinc | NI | NI | ||
| a 2020 ppm is the highest for nine samples taken on a residential
property closest to the conveyor. The highest copper was from a
sample taken at the downslope edge of the back yard by the Kennecott
property fence; copper was less than 500 ppm for the other eight
samples taken on the property. b 597 ppm is the highest found on other properties * Thirteen samples in 1994 and eight samples in 1993 (14,15,16). ** Three samples in 1994. (14) | ||||
APPENDIX E -- EXPOSURE DOSE AND CANCER RISK CALCULATIONS
Comparison of Exposure Dose to Health Guidelines
Soil Ingestion
The exposure doses for soil ingestion were calculated in the following manner. The minimum and maximum concentration for a contaminant were multiplied by the soil ingestion rates for adults, 0.0001 Kg/day; children, 0.0002 Kg/day, or pica children, 0.005 Kg/day. (The habit of ingesting large amounts of soil is called pica.) This product was divided by the average weight for an adult, 70 Kg (154 pounds) or for a child, 10 Kg (22 pounds). Those calculations assume that there is frequent daily exposure to soil contaminated at the specified level. The results of the actual calculations are recorded in Tables E1-E3 which follow.
Calculation of Risk of Carcinogenic Effects
Soil Ingestion
Carcinogenic risks from the ingestion of soil were calculated through the following. The adult exposure doses for ingestion of soil calculated as described previously, were multiplied by the EPA's Cancer Slope Factor for the contaminants of concern. The result represents the maximum risk for cancer after 70 years of exposure to the maximum concentration of the contaminant. A cancer slope factor was available only for arsenic. The results of the calculation of carcinogenic risk from exposure to arsenic can be found on Tables E1-E3 which follows. The results are discussed in the Public Health Implications portion of the Soils Exposure Situation Section.
Uncertainties in Calculating Cancer Risk
The actual risk of cancer is probably lower than the calculated number. The method used to calculate EPA's Cancer Slope Factor assumes that
there is no safe level for exposure (31). There is little experimental evidence to confirm or refute this assumption. Lastly, the method computes
the 95% upper bound for the risk, rather the average risk, which results in there being a very good chance that the risk is actually lower, perhaps several orders of magnitude (31).
| TABLE E1 - ESTIMATED EXPOSURE DOSES AND CANCER RISK FOR CONTAMINANTS IN UPPER CHANNEL SOIL EXPOSURE SITUATION COMPARED TO HEALTH GUIDELINES FOR INGESTION1 | |||||||
| Contaminant | Pre-Removal Concentrations in mg/kg |
Range of Estimated Exposure Doses in mg/kg/day | Health Guideline in mg/kg/day |
Source of Guideline |
Cancer Risk | ||
| Adult | Child | Pica Child | |||||
| Range of Arsenic Levels |
19 - 880 | 0.00003 - 0.001 | 0.0004 - 0.02 | 0.01 - 0.4 | 0.0003 | MRL2 | 5 in 100,000 to 2 in 1,0003 |
| Range of Lead Levels | 200 - 54,000 | 0.0003 - 0.08 | 0.004 - 1.1 | 0.1 - 27 | none | none | no cancer slope factor is available |
| Range of Cadmium Levels |
ND - 5.4 | 0 - 0.000008 | 0 - 0.0001 | 0 - 0.003 | 0.0007 | MRL2 | no cancer slope factor is available |
| 1 - An explanation of how these exposure doses and cancer risk was calculated can be found earlier in this appendix. 2 - MRL = ATSDR's minimal risk level. For more information on the MRL for arsenic and cadmium, see the ATSDR Toxicological Profiles for those chemicals. 3 - Maximum additional lifetime risk of cancer | |||||||
| TABLE E2 - ESTIMATED EXPOSURE DOSES AND CANCER RISK FOR CONTAMINANTS IN FLOOD PLAIN SOIL EXPOSURE SITUATION COMPARED TO HEALTH GUIDELINES FOR INGESTION1 | |||||||
| Contaminant | Pre-Removal Concentrations in mg/kg |
Range of Estimated Exposure Doses in mg/kg/day | Health Guideline in mg/kg/day |
Source of Guideline |
Cancer Risk | ||
| Adult | Child | Pica Child | |||||
| Range of Arsenic Levels |
ND - 410 | 0 - 0.0006 | 0 - 0.008 | 0 - 0.2 | 0.0003 | MRL2 | 0 to 9 in 10,0003 |
| Range of Lead Levels |
ND - 17,300 | 0 - 0.02 | 0 - 0.3 | 0 - 9 | none | none | no cancer slope factor is available |
| Range of Cadmium Levels |
ND - 20.6 | 0 - 0.00003 | 0 - 0.0004 | 0 - 0.01 | 0.0007 | MRL2 | no cancer slope factor is available |
| 1 - An explanation of how these exposure doses and cancer risk was calculated can be found earlier in this appendix. 2 - MRL = ATSDR's minimal risk level. For more information on the MRL for arsenic and cadmium, see the ATSDR Toxicological Profiles for those chemicals. 3 - Maximum additional lifetime risk of cancer | |||||||
| TABLE E3 - ESTIMATED EXPOSURE DOSES AND CANCER RISK FOR CONTAMINANTS IN LOWER CHANNEL SOIL EXPOSURE SITUATION COMPARED TO HEALTH GUIDELINES FOR INGESTION1 | |||||||
| Contaminant | Pre-Removal Concentrations in mg/kg |
Range of Estimated Exposure Doses in mg/kg/day | Health Guideline in mg/kg/day |
Source of Guideline |
Cancer Risk | ||
| Adult | Child | Pica Child | |||||
| Range of Arsenic Levels |
ND - 80 | 0 - 0.0001 | 0 - 0.002 | 0 - 0.04 | 0.0003 | MRL2 | 0 to 2 in 10,0003 |
| Range of Lead Levels |
ND - 7,129 | 0 - 0.02 | 0 - 0.3 | 0 - 9 | none | none | no cancer slope factor is available |
| 1 - An explanation of how these exposure doses and cancer risk was calculated can be found earlier in this appendix. 2 - MRL = ATSDR's minimal risk level. For more information on the MRL for arsenic, see the ATSDR Toxicological Profiles for thIs chemical. 3 - Maximum additional lifetime risk of cancer | |||||||
| TABLE E4 - ESTIMATED EXPOSURE DOSES AND CANCER RISK FOR CONTAMINANTS IN COPPERTON SOIL EXPOSURE SITUATION COMPARED TO HEALTH GUIDELINES FOR INGESTION1 | |||||||
| Contaminant | Concentration in mg/kg |
Range of Estimated Exposure Doses in mg/kg/day | Health Guideline in mg/kg/day |
Source of Guideline |
Cancer Risk | ||
| Adult | Child | Pica Child | |||||
| Maximum Arsenic Level |
ND - 53.8 | 0 - 0.00008 | 0 - 0.001 | 0 - 0.03 | 0.0003 | MRL2 | 0 to 1 in 10,0003 |
| Maximum Lead Level |
ND - 253.4 | 0 - 0.0004 | 0 - 0.005 | 0 - 0.1 | none | none | no cancer slope factor is available |
| Maximum Cadmium Level |
ND - 8.8 | 0 - 0.00001 | 0 - 0.0002 | 0 - 0.004 | 0.0007 | MRL2 | no cancer slope factor is available |
| Maximum Copper Level |
ND - 2,020 | 0 - 0.003 | 0 - 0.04 | 0 - 1 | none | none | not considered a carcinogen |
| 1 - An explanation of how these exposure doses and cancer risk was calculated can be found earlier in this appendix. 2 - MRL = ATSDR's minimal risk level. For more information on the MRL for arsenic and cadmium, see the ATSDR Toxicological Profiles for those chemicals. 3 - Maximum additional lifetime risk of cancer | |||||||
| TABLE E5 - ESTIMATED EXPOSURE DOSES AND CANCER RISK FOR CONTAMINANTS IN BUTTERFIELD CREEK SOIL EXPOSURE SITUATION COMPARED TO HEALTH GUIDELINES FOR INGESTION1 | |||||||
| Contaminant | Pre-Removal Concentrations in mg/kg |
Range of Estimated Exposure Doses in mg/kg/day | Health Guideline in mg/kg/day |
Source of Guideline |
Cancer Risk | ||
| Adult | Child | Pica Child | |||||
| Range of Arsenic Levels |
23 - 339 | 0.00003 - 0.0005 | 0.0002 - 0.007 | 0.01 - 0.17 | 0.0003 | MRL2 | 5 in 100,000 to 8 in 10,0003 |
| Range of Lead Levels | 35 - 27,988 | 0.00005 - 0.04 | 0.0007 - 0.6 | 0.02 - 14 | none | none | no cancer slope factor is available |
| 1 - An explanation of how these exposure doses and cancer risk was calculated can be found earlier in this appendix. 2 - MRL = ATSDR's minimal risk level. For more information on the MRL for arsenic, see the ATSDR Toxicological Profiles for thIs chemical. 3 - Maximum additional lifetime risk of cancer | |||||||
PUBLIC COMMENTS
EXPLANATION ON REPRODUCTION AND USE OF PUBLIC COMMENTS
As mentioned in the introduction to this document, ATSDR received comments on the public comment draft of the public health assessment from very few organizations and none from individual citizens. Comments from two of the organizations, Atlantic Richfield Company (via their legal counsel, Arnold and Porter) and the Kennecott Corporation, are reproduced in this appendix. The reproduced comments are incorporated into this document so that interested citizens may evaluate their effects upon the final document.
The Kennecott Corporation provided significant scientific references and information to support their concerns about the lack of health effects of sulfate below 1500 parts per million. ATSDR reviewed the information, including later reports from EPA Region VIII. Based upon evaluation of the information provided, ATSDR modified the draft document regarding ingestion of sulfate in drinking water at 500 ppm.
Comments from the University of Cincinnati, Utah Department of Environmental Quality (UDEQ), and the Utah Department of Health (UDC) are not reproduced. The University of Cincinnati comments were not reproduced for two reasons, the size of the comments and the concern about publishing information derived directly from University's health study without written permission of the authors. However, the University comments were carefully considered and the document modified as a result of the evaluation.
The comments from UDEQ and UDH were very helpful to the authors of PHA. As a result, some editorial changes were made in the document but no significant changes in conclusions or recommendations.
The comments presented by legal counsel, Arnold and Porter, on behalf of Atlantic Richfield Company were also carefully evaluated. Some editorial changes were made to clarify issues but no significant changes in conclusions or recommendations were deemed necessary.
ARNOLD & PORTER
August 20, 1996
Re: Public Health Assessment for Kennecott - Bingham (South Zone)
Dear Messrs. Howie and Mann:
The attached comments on the draft Public Health Assessment for Kennecott-Bingham (South Zone) are submitted on behalf of the Atlantic Richfield Company ("ARCO"). ARCO appreciates the opportunity to comment once again on this document.
Please call me if you have questions concerning our comments.
COMMENTS OF ARCO ON ATSDR PUBLIC HEALTH ASSESSMENT FOR KENNECOTT-BINGHAM (SOUTH ZONE)
Comment:
Page 1, paragraph 3: We fully agree that "present and future conditions of soils in the Bingham Creek area" present "no apparent public health concern." However, we do not believe that ATSDR has substantiated its statement that "some areas of Bingham Creek . . . did pose a public health hazard" in the past. At a minimum, this assertion is difficult to evaluate because the assessment does not define "public health hazard." The assessment certainly should make clear that a "public health hazard" is not equivalent to a risk to individuals.
To ARCO's knowledge, there is no instance of any human illness, disease or injury caused by the soils in the Bingham Creek area. Moreover, in light of the (i) findings of the environmental health study conducted in the area, (ii) studies conducted -- by ATSDR as well as by Potentially Responsible Parties -- at other mining sites, and (iii) associated animal bioavailability studies on lead and arsenic in soils, all of which demonstrate that soils mixed with mill tailings do not pose public health risks, the absence of any such illness, disease or injury is not surprising. We believe these studies constitute a strong, consistent body of evidence demonstrating that residential exposures to mill tailings do no result in public health hazards. In short, ATSDR has not documented or supported its assertion regarding the past existence of a "public health hazard" in "some" areas.
We also note that on page 7 the assessment asserts merely that "(t)he Bingham Creek situations may have been public health hazards in the past" (emphasis added), which is a considerably less emphatic position than that taken on page 1 of the assessment.
Page 8, first paragraph: It is misleading to suggest that tailings transport is a recent phenomena. Tailings impoundments diverted some or all of the tailings discharged into Bingham Creek beginning in 1906 or 1907. Tailings production itself in Bingham. Canyon ended in about 1930, and Bingham Creek stopped being a free-flowing drainage for the Canyon decades ago. In these circumstances -- where the asserted "public health hazard" has been present for virtually the entire century -- the absence of any human health problem caused by it should have received greater weight than it did.
Page 13, last paragraph: We agree with your conclusion that young children (who as a group have relatively higher rates of soil ingestion) are not likely to have played in the "Bingham Creek Upper Channel." ATSDR presents no reasons why this would not also be true at other locations in Bingham Creek.
Page 14, fourth paragraph: This paragraph suggests that Bingham Creek flooded until Kennecott built the reservoir system. In fact, the "delta" area appears on the first available aerial photograph -- from 1937 (Exhibit A) -- of what are now neighborhood areas. Moreover, historical evidence from the early years of the century -- regarding complaints due to tailings interference with agricultural activities -- strongly suggests that the "delta" area was formed even before World War I.
Page 15, last paragraph to Page 16, fourth full paragraph: We believe that the most serious deficiency in the draft assessment is the short shrift it gives to the data from the 1993 environmental health study. In providing our comments in march 1996, we noted that Dr. Bornschein had provided the results of the study to ATSDR in late 1994. We also offered to supply the data to ATSDR once again in computerized format for ease of analysis, and offered to respond to any questions or comments. Until ATSDR fully evaluates all the data from this study -- which was the most comprehensive of its kind ever conducted at a mining site in this nation -- its "public health assessment" cannot be scientifically valid.
ATSDR states that the "lack of systematic sampling . . . appears to be a problem" with the study (emphasis added). In fact, a comprehensive and systematic attempt was made in the Bingham Creek neighborhood areas to identify all young children and to sample their blood and urine. The fact that 75 properties in the pertinent area were not included is no proof of the absence of systematic sampling, but rather indicates strict compliance with study protocols due to the absence of young children at those properties (or children whose parents were not willing to fully participate in the study). In any case, any risks from exposures on these properties can be assessed from the slopes derived from the study. In this regard, the regression analyses show a near non-existent relationship between lead and arsenic in soils and biomarkers of exposure.
ATSDR next asserts that it received only a "partial" data set for the study and that certain "critical" data were not available. As indicated above, ARCO has offered before to assist ATSDR in identifying the "missing" data, to the extent it is unable to do so on its own, and we renew that offer, even to the point of facilitating a direct exchange between ATSDR and Dr. Bornschein, so that any questions regarding the data can be clarified.
In short, ATSDR has erred in ignoring the environmental health study, which demonstrated that the blood levels of children and participating adults who reside in the vicinity of the Bingham Creek channel are below the national average.
Furthermore, despite any limitations of the 1990 Utah Survey, we believe it should be given significant weight in evaluating risks, given the consistency of its results with many other mining site studies as well as the 1993 study.
Page 17, second full paragraph: We agree that arsenic in soil is significantly less bioavailable than arsenic in water. Bioavailability studies in a number of animal species consistently demonstrate that bioavailability of arsenic in soils is in the 15-20% range. These studies are referenced in our comments of March 1, 1996.
Page 18, second paragraph: We agree with your conclusions about the unlikelihood of cancer risks from lead exposure.
Page 18, final paragraph: Aerial photographs (which we have enclosed at Exhibit B) show that the Bingham Creek "floodplain" area was populated with only a few scattered houses during the 1962s with farmland present until that time. Thus, ATSDR's reference to the "long-term residency in the delta area" is without historical foundation, and its assumption that the 70-year, lifetime risk of cancer "may" have increased in this area is wholly unsupported. Given this and other evidence, including the data on the reduced bioavailability of arsenic in soils and the low urine arsenic levels demonstrated in the Bingham Creek study, conclusions about elevated risks from arsenic exposures (see also the fourth paragraph on p. 18 and p. 22) are not warranted.
Page 19, third paragraph: This paragraph fails to clearly distinguish the very low blood lead: soil lead slopes found at mining sites from other exposures, such as from operating smelters, which result in much steeper slopes. The notion that the blood lead: soil lead slope could be as high as 65 ug/dl per 1000 ppm increase in lead in soils, with an average of 4-5 ug/dl per 1000 ppm is wholly without evidentiary support at this site, or at any other mining site. In fact, the slope evidenced in the Bingham Creek study was less than 0.3 ug/dl per 1000 ppm. Such a minimal response makes clear that Bingham Creek children have not suffered ill effects from lead exposures at the site.
You also may be interested in the attached slide (Exhibit C), which shows there was no relationship whatsoever between blood lead levels and proximity of the children's homes to Bingham Creek.
Page 19, first paragraph and Page 22, fourth paragraph: The correct LOAEL for cadmium noted in the document is 0.0075 mg/kg-day, not 0.075 as stated. Further, and more important, the assertion that a child with pica for soil might be at risk for proteinuria from cadmium exposures is completely without scientific support. Proteinuria develops only when cadmium concentrations in the kidney accumulate to a critical level, typically after several decades of chronic exposures. Transient exposures like those resulting from childhood pica must be averaged over a lifetime before being compared to a LOAEL, NOAEL or MRL. When this is done, it is clear that there is no risk from the Bingham Creek exposures. This conclusion is supported by ATSDR's studies in Palmerton, Pennsylvania, among others.
We also note that short term, high level exposures which might conceivably produce kidney damage or other toxic effects are not likely in the exposure conditions at Bingham Creek.
Dear Mr. Howie:
Kennecott Utah Copper Corporation (KUC) has reviewed the Public Health Assessment conducted by the Agency for Toxic Substances and Disease Registry (ATSDR) for the Kennecott (South Zone), Copperton, Salt Lake County, Utah (Bingham Creek area) and is providing both general and specific comments on the June 28, 1996 draft released For Public Comment. KUC submitted comments (letters from Elaine Dorward-King to Max Howie dated February 19, 1996 and March 7, 1996) on a preliminary draft of this Assessment. ATSDR incorporated some of KUC's previous comments into the document, however, this draft still contains a number of inaccurate statements that will be misleading to the public if included in the Final Assessment. We therefore have included some of our previous comments in addition to providing comments on new sections of the document.
General Comments
The amount of discussion spent on pre-removal exposure seems unnecessary given that a public health assessment should focus on the current risks. The general statements that residents may be at risk from past exposures are not sufficiently substantiated.
Overall, all report describes risk and hazard in vague terms with little discussion/explanation of the uncertainty in the literature and toxicological assessments of the chemicals of concern. For example, the possibility of transient diarrhea is grouped under the same label (health hazard) as more serious effects such as cancer. More explanation of the process of the health evaluation should be made in the body of the text, because most members of the public are unlikely to read and understand the appendices. The calculations are more appropriate for a conservative screening for possible risk than for accurate calculation of actual risks for residents. Because of the lack of explanation, however, the public may believe the calculations estimate their actual risks.
The Public Health Assessment could be improved with a discussion of the forms of arsenic, cadmium, copper, and lead in the soil. The form of these constituents determines their bioavailability and toxicity. Specifically, arsenic and lead species in soil as a result of mining are typically less bioavailable than those derived from other sources. The U.S. Environmental Protection Agency's (EPA's) swine study of Bingham Creek soil reports 19% rather than the default 30% bioavailability for lead in soil (U.S. EPA, 1995c).
The lead and arsenic exposure analysis of the University of Cincinnati also provides valuable information for the relative impact of these constituents in soil on residents' exposure. The results indicate that soil is a relatively minor source for exposure, contrary to the implications in the risk calculations included in the Assessment.
The public health assessment concludes that Southwest Salt Lake County groundwater is a public health hazard because of sulfate levels in excess of EPA's proposed Maximum Contaminant Level Goal of 500 mg/L. This conclusion is inaccurate and misleading to the public and contrary to the statements of EPA (1994) on the lack of health affects associated with chronic exposure to sulfate. The public health assessment states that although residents may become accustomed to sulfate, they may be at risk for having kidney stones. This statement also implies more certainty than actually supported by the scientific and epidemiological data.
The assessment should state that EPA does not have a primary drinking water standard for sulfate because health effects are poorly understood. It should be stated that an EPA proposed sulfate standard of 500 mg/L was recently deferred for three years until additional study of sulfate health effects could be determined. The federal drinking water standards include only a secondary standard for sulfate which is based on aesthetic qualities and not health effects. The report should also include that the State of Utah does have a primary drinking water standard of 1,000 mg/L and that no drinking water wells in the study area exceed that value.
Specific Comments
Page 1, second paragraph: see comments above and below on the lack of "hazard" associated with sulfate below 1,200 ppm.
Page 1, third paragraph, page 27, second paragraph: Pre removal "hazards" are unlikely. At least some explanation of the likelihood and nature of this calculated "hazard" should be provided. There is no evidence to support the statement. "Before actions, some areas of Bingham Creek contained soils that did pose a health hazard."
Page 1, last paragraph, page 27 third paragraph: The last sentence seems to imply that the blood lead measurements are not representative and that exposures were previously higher before the family was notified about the contamination. Nevertheless, the University of Cincinnati found that notification of contamination had little to no measurable effect on blood lead levels in Bingham Creek (University of Cincinnati, 1996). See also comments on page 5.
Page 2, Paragraph 1 The following addition is suggested: EPA has deferred listing on the NPL the proposed Kennecott South Zone per a Memorandum of Understanding between Kennecott Utah Copper Corporation, Utah Department of Environmental Quality, and the U.S. Environmental Protection Agency dated September 27, 1995.
Page 2, Paragraph 2 The following addition is suggested: EPA has deferred listing on the NPL the proposed Kennecott South Zone per a Memorandum of Understanding between Kennecott Utah Copper Corporation, Utah Department of Environmental Quality, and the U.S. Environmental Protection Agency dated September 27, 1995.
Page 2, Paragraph 2 The Kennecott South Zone is not an NPL Site. It should be referred to as a proposed site.
Page 5, Table 2, Bingham Creek Floodplain Soils and Lower Bingham Creek Soils There is no evidence to support the statement made twice "Site did pose a public health hazard prior to removal and cleanup." A more accurate statement (used by ATSDR later in the text) would be "Site may have posed a public health hazard prior to removal and cleanup."
Page 7, Table 3 Frequency of Exposure; Page 13, Paragraph 4; Page 4, 5, 8; Page 15, Paragraph 2, and Page 17, Paragraph 2 and throughout document: Exposure estimates should include weather conditions. Exposure to soil contaminants would be unlikely on a daily basis due to typical weather conditions in this area. Exposure would be limited by snow and ice during portions of the fall, winter, and spring. Digging, tunneling, and bicycling would be next to impossible in these conditions.
Page 8, Paragraph 1: Should read "More recently, Kennecott Utah Copper Corporation (KUC) has been controlling mine and processing waters, and..."
Page 9-11, 13; Tables 4-7: The presentation of environmental data and exposure concentrations would benefit from more statistical description of the data, rather than just presenting ranges. For example, means, upper and lower confidence limits would indicate the distribution of the data and the more likely exposure for the community than the maximum and minimum. In addition, the casual reader would be confused by the comparison of the "Maximum post-removal levels in mg/kg" to the "Range of pre-removal levels in mg/kg."
Page 15, first sentence under "Public Health Implications": The first sentence describes how the public health assessment compared health guidelines with carcinogenic and non-carcinogenic effects. It appears Tables D1 through D5 should be referenced here, because Tables E1 through E4 (referenced later in the paragraph) do not examine non-carcinogenic guidelines.
When comparing chemical concentrations to an ATSDR Cancer Risk Evaluation Guide (CREG) or Environmental Media Evaluation Guide (EMEG), some mention should be made that exceeding these levels does not necessarily constitute a health threat because these levels are very conservative. Presentation of site concentrations in excess of these levels (e.g., Tables D1-D5) may seem to contradict the conclusion that a health hazard is not apparent. Soil concentrations for post-removal soils do not appear on these screening tables.
Page 15, second paragraph under "Public Health Implications" and thereafter: The University of Cincinnati Lead and Arsenic Exposure study included children 72 months (6 years) of age and younger, not 7 years of age and younger.
Page 16, first two full paragraphs: The public health assessment argues that sampling the blood lead or urinary arsenic levels of 1,300 children under the age of seven in the Bingham Creek area with blood lead levels from 284 children from the "contaminated" areas is not enough to reflect a true distribution because no children were recruited from 75 of the "contaminated" properties. Nevertheless, a statistically representative population that accurately predicts the mean and distribution of blood lead levels is certainly achievable without sampling every single child in a community. The University of Cincinnati calculated that only 100 participants were required to predict the geometric mean within 0.3 ug/dl with a 95% confidence. With a larger number of participants, the study is sufficient to represent an accurate estimate of the mean and distribution of blood lead levels. We therefore do not agree that these data are unusable for evaluating risk in the community. Actual, statistically valid biomonitoring and environmental data are far more accurate for assessing exposure than hypothetical risk calculations.
The geometric mean blood lead level is reported to be of 2.56 ug/dl with 0.8 percent (8 children) of blood lead levels over 10 ug/dl in the 971 children tested (University of Cincinnati, 1996). This is lower than other blood lead studies of mining or smelting areas in Utah (University of Cincinnati, 1990, 1996), Utah state or county blood lead studies (Schlenker, 1995), and the NHANES III national blood lead study either for all children or all middle-income suburban children (Pirkle, 1995). Therefore, pre-removal soil concentrations in Bingham Creek in 1993 did not result in blood lead levels elevated over state or national levels.
The University of Cincinnati study also shows through statistical analysis of their blood and environmental lead data that the influence of soil on blood lead is small, with only 3.2% of the variation in blood lead explained by soil concentration. In addition, of the eight children with blood lead levels over 10 ug/dl, five lived on properties already remediated or with soil lead levels under 400 ppm, and three were exposed to lead from family hobbies. Several of these children also were from the same family and therefore should not be counted as independent observations.
Page 16, second full paragraph: This paragraph indicates that ATSDR could not obtain the information on the number of children identified by census and tested in the University of Cincinnati's1993 study. This information is now available. Ninety-one percent of the occupants completed the census. The summary indicated a total of 1,157 families with children less than 72 months old and 1,706 children less than 72 months old. Of these, 971 children under 7 years of age in 728 families participated in the blood lead screening.
Page 17, first paragraph under "Cadmium": The text notes that for pica children, the dose for the pre-removal Bingham Creek Flood Plain exceeded the health guideline (Explained in Appendix D as the Environmental Media Evaluation Guideline (EMEG) and that this exposure might result in kidney effects (proteinuria). The next should also state that the EMEG for cadmium is very conservative because is based on a conservative Minimum Risk Level (MRL) that is even lower than the EPA reference dose. The MRL is inappropriate for assessing short-term exposure in a 10 kg child because it is based on average lifetime dose in adults that would result in proteinuria after cumulative lifetime exposure (as alluded to on page 18 but not clearly explained). This comment also applies to the fourth paragraph on page 18 and first paragraph on page 19. The exposure dose for the pica child was also compared to the LOAEL from drinking water. The exposure dose should be compated to a LOAEL from food or soil ingestion, because EPA has shown the LOAEL to be greater for cadmium in food than for cadmium in water.
Page 18, second paragraph under "Bingham Creek Floodplain Soil Exposure Situation" and Page 22, third paragraph of Section E: The phrase "resulted in a moderate increase in an individual's lifetime of cancer" should be quantified. The word "moderate" is vague and could be construed to mean a higher than acceptable increased risk.
Page 18, "Post-removal exposures". This paragraph indicates that "there is some chance of health effects...." "Some chance" is too vague and should also be quantified.
Page 18, last sentence under "Post-removal exposures". The statement that some chance exists for health effects for young children exposed where "contaminated" soil was not removed needs some explanation. Specifically, the likelihood of "some chance" for health effects and "contaminated soil" are not defined sufficiently to understand the magnitude of this risk and which residents might be affected. It is unclear whether the unremoved contaminated soil is below the 1,100 ppm removal target, properties yet to be cleaned up, or those that were missed for some reason. The University of Cincinnati study indicates that any such chance is likely negligible. Permanent health effects also do not necessarily occur at blood lead levels that exceed 10 ug/gl. The chance of such health effects depends on how high the blood lead is over an extended period of time.
Page 18, last paragraph: "increased lifetime risk of cancer" and "long-term residency" should be better explained as noted above. Given the numerous conservative assumptions of the risk calculations (e.g., daily exposure to the maximum and 100% bioavailability) the "increased lifetime risk" is likely negligible.
Page 19, first paragraph under "Lead": second sentence: This sentence states that lead levels in soil of 1,000 ppm could increase blood levels from 0.6 to 65 ug/dl with an average increase of 4 to k ug/dl. This statement lacks a summary of the calculations or supporting studies for both the baseline blood lead level of 0.6 ug/dl and for the increase to 65 ug/dl. Even if the conservative EPA Integrated Exposure/Biokinetic Model (1994) is used with EPA's calculated upper possible bioavailability factor (19%), dust concentration (0.43 x Soil Pb +90 ppm), and GSD (1.43) (U.S. EPA, 1995a,b) for Bingham Creek; the geometric mean blood lead level would be 6.3 ug/dl with an approximate maximum blood lead level of about 20 ug/dl. Statistical analysis of actual blood lead and environmental lead data from Bingham Creek (University of Cincinnati, 1996) shows children have only a very small direct exposure to lead in soil from playing in either their yards or along the channel (3.2% of the variation in blood lead is explained by soil concentration). Indirect exposure to soil through house dust is associated with an increase in blood lead levels of 0.6 ug/dl as soil increases from 100 to 1,100 ppm (University of Cincinnati, 1996).
Page 19, first paragraph under "Lead," last sentence, and page 20, second paragraph under "Lead," last sentence: Please reference the statement regarding decreased IQ and impaired hearing and growth associated with blood lead levels in children at or below ug/dl. This statement requires more explanation of uncertainties. Although some studies have shown negative correlations between blood lead levels and these health effects, other studies have not shown a significant effect particularly when confounding variables were accounted for (Schroeder el al., 1985; Schmitt and Anderson, 1992; Pocock et al., 1994). In addition, effects are generally extrapolated from large population studies in which such effects are measured over a large range in blood lead levels considerably in excess of 10 ug/dl. In these studies showing a correlation, the actual impacts of blood lead on IQ, for example, is very small compated to the large range in IQ among children in general (e.g., see summary graphs in U.S. EPA, 1990), and the impacts on cognitive development may not persist with age, perhaps due to the greater impact of social economic status, nutrition and other factors on cognitive development (Schroeder et al., 1985; Bellinger et al., 1990). Thus, any effects below 10 ug/dl are at best subtle and likely not of significant health consequence relative to the greater impacts of other influences on cognitive development such as the educational environment, socioeconomic status, and diet.
Page 22, second, third, and fourth paragraphs of Section E: These paragraphs indicate that arsenic, cadmium and lead may have been high enough to result in health effects if young children were exposed daily to lead and arsenic, and pica children were exposed to the maximum levels of cadmium. These risks are highly speculative, requiring many maximum exposure factors for the same individual (e.g., frequent exposure, living in the area for long periods of time, pica behavior, exposure to maximum soil levels, biological variability, near life time exposure to arsenic and cadmium) to produce a risk. This hypothetical situation is unlikely to have occurred. Moreover, actual biomonitoring and environmental data confirm that hypothetical exposures and risks are overstated. As EPA's response to Concern 2 indicates, children living in areas with elevated levels of lead tested very low for blood lead levels.
ATSDR acknowledges the unlikeliness of this hypothetical situation in Appendix E, page 55 of the Assessment. The discussion of uncertainties in calculating cancer risk states "The actual risk of cancer is probably lower than the calculated number." It goes on to say, referencing Paustenbach, 1989. "The method computes the 95% upper bound for the risk, rather than the average risk, which results in there being a very good chance that the risk is actually lower, perhaps several orders of magnitude (31)."
Pate 22, third paragraph of Section E: This paragraph states that a moderate increase in cancer risk may have resulted in the Bingham Creek flood plain area due to arsenic prior to removal of soil. This statement should be qualified by the numerous uncertainties in the arsenic slope factor (e.g., extrapolation of high dose data from Taiwan to the U.S.), and considerably lower bioavailability of arsenic in soil as compared to drinking water which is the basis of the slope factor. Considerable evidence indicates that arsenic is rapidly detoxified by the body at lower doses such as those associated with the estimated exposure doses for children and adults in Appendix E. Feeding studies in monkeys using Anaconda smelter soil have shown relative bioavailabilities of around 20 to 28% for soil and dust (Freeman et al., 1995). By contrast, the calculations in the Public Health Assessment do not appear to be corrected for the difference in bioavailability of arsenic in soil relative to water. In addition, the health assessment should note that residential exposure to arsenic in soil in the U.S. has never been shown to be associated with cancer. In fact, an ecological study of skin cancer in the areas around the former Anaconda smelter and Silver Bow mine (with 6,500 acres of soil with arsenic above 90 ppm compared to Bingham Creek's average concentration of 27 ppm; University of Cincinnati, 1996) found lower skin cancer rates than two control counties (Wong et al., 1992).
The biomonitoring and environmental data for the site also indicate that any arsenic exposure and associated cancer risk prior to soil removal is likely negligible. Soil arsenic does not appear to be the source of urinary arsenic levels measured in the Bingham Creek population. The University of Cincinnati found that soil arsenic was negatively correlated with urinary arsenic )r=-0.04). Moreover, because lead and arsenic concentrations in residential soils were strongly correlated (r=0.96), these arsenic results suggest that house dust lead has a different source than soil (e.g., lead-based paint).
The assessment of pica children based on an adult lifetime MRL is inaccurate (see above comment on page 17).
Pate 22, fourth paragraph of Section E: This paragraph claims lead levels in two segments of the lower channel may have been high enough to result in health effects. More discussion is needed to explain the basis of this statement. For instance, the exposure assumptions assumed should be stated.
Appendix D: The maximum concentrations of the metals were used to evaluate risk at the site. Although this may be appropriate for a screening study, evaluation of exposure should use an average concentration or an upper bound confidence limit of the mean. Children and adults are unlikely to be exposed constantly to the maximum concentration.
Page 22 through 25, "Evaluation of Groundwater Contaminants". In comparison to other chemicals, sulfate does not pose a toxic health hazard. As summarized by U.S. EPA (1994a), sulfates have more of a physical effect on increasing the retention of water in the gastrointestinal tract rather than a chemically toxic effect. Sulfates are naturally occurring substances and are an ingredient in over-the-counter laxatives. The human body is able to acclimate to the effects of sulfates in a relatively short amount of time. Accordingly, the expert panel convened by the U.S. concluded that "acute short-term effects are the appropriate focus for risk assessment." The benign nature of sulfate levels is demonstrated by numerous communities in the U.S. and Canada drinking water with sulfate levels in excess of 500 mg/L without a problem.
Visitors and infants have been the concern of EPA's proposed sulfate regulations. Nevertheless, the occurrence of laxative effects due to sulfate is more complicated than represented and depends on a number of factors, as noted in part by EPA's expert panel, such as osmolarity, presence of cations such as calcium and magnesium, and physiological and dietary conditions. In addition, infants and visitors have been assumed to be sensitive to sulfate levels above 500 mg/L, but such an assumption is not supported by the recent scientific or epidemiological data. In fact, if acclimation occurs by turn over of intestinal cell mucosa (U.S. EPA, 1997a), infants may be able to acclimate faster to the effects of sulfate because of their higher cell turn-over rates.
Levels of sulfate in wells currently at the Bingham Creek Site are reported in the Public Health Assessment to be relatively low: maximum levels of 500 to 1,000 ppm in 6 out of 35 private wells currently in use. At these sulfate levels, whether laxative effects would occur even in visitors of infants is questionable, and according to recent studies, doubtful (McGeehin, 1995; Heizer et al, 1994).
The data base considered by the U.S. EPA in proposing the 500 mg/L level is extremely weak. The few studies considered are generally old with small samples sizes and lack of controls for other confounding factors (U.S. EPA, 1994a). The results of recent studies in humans and piglets, which were not part of the data base considered by the EPA in proposing the 500 mg/L level, indicate that sulfate levels considerably in excess of 500 mg/L are required to cause laxative effects. A study by the Centers for Disease Control and Prevention, the South Dakota Department of Environment and Natural Resources, and the National Center for Environmental Health tracked the health of 276 newly born infants in homes with high sulfate levels throughout South Dakota to assess whether the infants were experiencing increased incidence of negative health effects (McGeehin, 1995). No increase in negative health effects was found with consumption of water with sulfate levels in excess of 500 mg/L (maximum level = 2,787 mg/L) as compared to those with lower sulfate levels. Sulfate intake was also not associated with a significant increase in risk for diarrhea. Heizer et al. (1994) investigated the effects of high sulfate in drinking water in human volunteers and in piglets; the piglets were used as a model for human infants which are assumed to be a sensitive subpopulation. Diarrhea, the critical toxicological endpoint, was not observed in the piglet study at concentrations less than 1,600 mg/L nor in the adult human volunteers at concentrations up to 1,200 mg/L.
The South Dakota report also summarizes results from other recent studies. The North Carolina human studies, which were in part funded by the U.S. EPA, involved four adult volunteers ingesting increasing levels of sulfate from 0 to 1,200 mg/L (increases occurred in 48 hours increments and a follow up study of six volunteers ingesting sulfate levels of 1,200 mg/L for six days. Neither study reported diarrhea in the subjects, although sample sizes of these studies are small. The South Dakota Department of Health also conducted its own study in 1992 at an institute for the mentally retarded and reported no health effects associated with sulfate unless levels above 1,200 mg/L were ingested over a considerable period of time (Bureau of National Affairs, 1996). Two piglet studies in North Carolina were also funded by the EPA. These studies showed no affect on normal weight gain. Sulfate levels of 1,600 mg/L caused slightly more soft and liquid stools, whereas sulfate levels at 1,800 mg/L and above were associated with significant diarrhea.
Collectively, these recent studies indicate that the onset of laxative effects occurs at sulfate levels on the order of 1,600 to 1,800 mg/L rather than 500 mg/L.
Page 23, third paragraph: This paragraph states that the highest concentration of sulfate reported in a private well was 2,270 mg/L (well W337 in 1985). It should be noted that this well was abandoned in 1986 and was replaced by paired wells P247A and P847B. Well P247A is screened in the upper 30 feet of the aquifer and sulfate concentrations have decreased from 2,200 mg/L in 1986 to 1,000 mg/L in 1995. Well P247B is screened approximately 400 feet below the water table and sulfate concentrations have remained less than 500 mg/L since 1986. Therefore, the report should state that sulfate concentrations in this area are decreasing and that long term exposure to sulfate concentrations exceeding 1,000 mg/L do not exist.
It is unclear what is meant by the statement that some wells have had persistent high levels of sulfate for more than one year. Does this refer to drinking water wells or monitoring wells and how is high defined in terms of sulfate concentrations? The report concludes that exposures to sulfate in drinking water are or were greater than 500 mg/L but less than 1,000 mg/L.
Page 24, Table 9 Exposure to Contaminants in Groundwater: This table contains inaccurate information. Under the heading of key contaminant, sulfate concentrations from 505 - 2,270 mg/L are listed. The report has stated previously that exposure to sulfate was greater than 500 mg/L but less than 1,00 mg/L. In reality, sulfate concentrations in drinking water wells do not exceed 600 mg/L (see comment #5). Therefore, the 505 - 2,270 mg/L range should be replaced with the actual range of 536 - 558 mg/L (see comment below, Page 24).
Page 24, first paragraph: This paragraph states that ATSDR has estimated that 35 existing private drinking water wells lie within or adjacent to a sulfate ground water plume. It is not possible to evaluate the correctness of this number because a map or a list of the well locations has not been included with the document.
Page 24: Ground water quality data used by ATSDR for this Public Health Assessment was being collected by Kennecott Utah Copper (KUC) as part of the Southwest Jordan Valley Well Inventory. The well inventory was ongoing while ATSDR was performing the health assessment. KUC supplied ATSDR with ground water quality data in April, 1995 and with an updated database in January, 1996. The database supplied to ATSDR by KUC in April, 1995 included the most recent analyses as of December, 1994. Seven drinking water wells from the April, 1995 database (W41A, W322, W347, W396, W408, W415, and W417) were identified as having sulfate concentrations greater than 500 mg/L. As part of the ongoing well inventory it was determined that two of the wells (W41A and W417) are being used for purposes other than drinking water. An additional well (W347) is located outside of the well inventory study area and is outside of the influence of the sulfate plume. Therefore, only four drinking water wells (W322, W396, W408, and W415) in the well inventory study area exceeded sulfate concentrations greater than 500 mg/L.
The database supplied to ATSDR by KUC in January. 1996 included the most recent analyses as of
December, 1995. Five drinking water wells (W322, W415, EVG2233, W396, and W347) were identified
as having sulfate concentrations over 500 mg/L. As stated previously well W347 is outside of the
influence of the sulfate plume. Well EVG2233 was inventoried after the April, 1995 database was
submitted to ATSDR. Well EVG2233 is located east of the Jordan River, however, and is most likely
affected by other sources. Therefore, only three drinking water wells (W322, W415, and W396) are
located within the influence of any KUC's sources and exceed 500 mg/L of sulfate. The following
summarizes the latest measured sulfate concentrations in wells W415, W396, and W322:
| Well # | Last Date Sampled | Sulfate Concentration |
| W415 W396 W322 |
March 8, 1996 February 22, 1996 September 26, 1995 |
558 mg/L 236 mg/L 544 mg/L |
Well W322 is located in the Herriman area and wells W415 and W396 are located down gradient of the South Jordan Evaporation ponds.
Page 24, first paragraph: This paragraph states that some of the wells listed as currently not in use may have been used as drinking water supplies before contaminants were measured. This assumption is speculative and no justifiable conclusion can be made from this assumption.
Page 25: The third paragraph mentions that although residents consuming high sulfate water may be acclimated to the laxative effects, sulfate increases the excretion of calcium in the urine and decreases the pH of the urine, both of which "some researchers have hypothesized" increase the risk of kidney stones. These statements are without documentation or reference and imply more risk than may actually exist.
Although there is published evidence that an increase in sulfate ingestion is associated with an increase in urinary calcium excretion and a decrease in urinary pH in humans and other animals (Tschope & Ritz, 1985; Singh et al., 1993; Oetzel el al., 1994; Greger et al., 1991; Whiting et al., 1986 and 1991, cited in Greger et al., 1991) the physiological control mechanisms regulating calcium and sulfate levels are highly complex and affected by electrolyte and hormone levels and diet. The formation of kidney stones is also a multifactorial process that may occur, depending on the type of stone formed, with high or low urinary pH (Robertson, 1986). Summarizing the literature, Robertson (1986) stated that "the current consensus is that the formation of abnormally sized particles of calcium-containing salts is due to the combination of a number of chemical fores which between them control the relative rates of nucleation, growth and agglomeration of crystals of calcium oxalate and calcium phosphate in urine." Furthermore, we could find no evidence in human subjects of a link between sulfate ingestion alone and the development of kidney stones. In fact, sodium thiosulfate has been successfully used as a treatment for recurrent kidney stones (Yatzidis, 1985).
Even if sulfate ingestion were a definite risk factor for kidney stone formation, it is unclear whether the magnitude of the effects of sulfate in the 500 to 1,000 mg/L range would be sufficient to significantly affect the formation of kidney stones. Any effects of sulfate on the formation of kidney stones are likely subtle as no increases in the incidence of kidney stones have been reported for populations ingesting naturally elevated sulfate levels. EPA (1994a) has also stated that "there was no evidence of adverse health effects in animals or humans from chronic exposure to sulfate in drinking water. The available health data indicate that chronic exposure to sulfate is not harmful to health."
Page 26, last paragraph: There may be a typographical error in the first sentence. The two blood lead samples described as ">5 ug/dl" are likely less than 5 ug/dl based on the other blood lead levels stated. The last sentence states that it is not possible to determine whether the results reflect typical exposure conditions. Nevertheless, the representativeness of the samples can be estimated based on several factors which unfortunately are not provided in this paragraph. These factors include the ages of the family members, their length of residency, whether they were mostly home prior to testing, and the time of the year blood lead levels were tested. If the family members tested included young children, the test conducted in summer or fall, and the family had sufficient residence time, the results should be fairly representative of cumulative exposure. Although blood lead results are generally considered representative of the past months' exposure, researchers at the University of Cincinnati have found blood lead levels of individual children to be relatively stable over time with respect to other children.
Summary
KUC appreciates the opportunity to provide these comments and requests that they be strongly considered for inclusion in the Final Assessment. KUC agrees with ATSDR's conclusion that the present and future conditions of soils in the Bingham Creek area are no public health concern. KUC disagrees that a public health hazard was present in some areas of the Bingham Creek area prior to removal of contaminated soils. There is no toxicological or epidemiological evidence of adverse health effects due to arsenic, cadmium, or lead in soils. Actual biomonitoring results, in fact, indicate no risk to public health. ATSDR's references to potential risk from past exposures to contaminants in soil are not substantiated in this Assessment, and appear to be qualitatively drawn using maximum soil concentrations and conservative exposure assumptions, even when actual exposure data are available.
Risk to public health from ingestion of sulfate in drinking water is over-stated and contradictory in the Assessment. ATSDR concludes that "one exposure situation is still considered a public health hazard because a few people still using private drinking water wells within the path of the ground water contaminant plumes may be ingesting high sulfate concentrations present in the drinking water aquifer." "High sulfate concentrations" are not defined, and ATSDR goes on to say that "there is no information that indicates anyone is currently ingesting ground water contaminated with sulfate greater than 1000 ppm." Based on the research results currently available, sulfate levels between 500 - 1000 ppm should not be considered "high". It is doubtful whether even infants and transients experience laxative effects at these levels. As detailed in our comments above, EPA has deferred establishing a drinking water standard for sulfate until additional research regarding sulfate health effects is completed. Also note that the State of Utah does have a primary drinking water standard of 1000 mg/L, and no drinking water wells exceed this value.
In conclusion, while KUC largely agrees with the overall conclusions presented in the Assessment, it is troubling that much of the language in the body of the document alludes to potential exposures and risks that are not realistic, cannot be substantiated, and have the potential to unnecessarily alarm the public. KUC considers this unfortunate and inappropriate, and hopes that these deficiencies are remedied in the final draft.
Please do not hesitate to call me if you have any questions regarding KUC's comments or suggestions.
Sincerely,
Elaine J. Dorward-King, Ph.D.
Director, Environmental Affairs
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1. ATSDR Staff (John Crellin, Don Gibeaut, John Mann, and Glenn Tucker) visited the site vicinity during the weeks of September 4 and October 23, 1994. Pertinent information obtained during those visits is described in appropriate sections of this document.
