ATSDR - PHA - KENNECOTT (NORTH ZONE), MAGNA, SALT LAKE COUNTY, UTAH

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PUBLIC HEALTH ASSESSMENT

KENNECOTT (NORTH ZONE)
MAGNA, SALT LAKE COUNTY, UTAH

PUBLIC HEALTH EVALUATION OF CONTAMINANTS IN SOIL

The possibility of public health impact by soil contaminants is evaluated in this portion of the assessment for one exposure situation (Magna soils). Table 5 summarizes the results of these evaluations.

The evaluation results lead ATSDR to conclude that the Magna soils exposure situation poses no apparent public health hazard.

TABLE 5 - EXPOSURE TO SOIL CONTAMINANTS*
Situation	Key Contaminants**	Exposed Population	Route of Exposure	Frequency of Exposure	Public Health Classification
Magna Vicinity	Arsenic, Cadmium Copper, Lead	About 18,000	Ingestion	Daily	No Apparent Health Hazard
* The source for these metals is probably a combination of natural and human activities ** Key Contaminants--contaminants which initial evaluations showed had some potential to be a public health hazard

B. Background--Overview

Kennecott's operations near Magna (Figure 2, Appendix A) have released metals to air that subsequently deposit on the ground. During high winds, substantive particulates (including some of the key contaminants) eroded from the surface of the tailings pond and migrated by air until modifications were made in the tailings discharge system and operations and maintenance procedures. Wind-blown tailings deposition has caused some metals concentrations in affected surface soils to be somewhat greater than their concentrations in unaffected natural soils.

C. Environmental Contamination

Soil sampling data were reviewed, and several contaminants were selected for further, more detailed, evaluation of public health significance. A description of the process for selecting the several contaminants can be found on page 37 in Appendix C. Those several were further evaluated, yielding four that were identified as key contaminants, as summarized below:

Arsenic, cadmium, copper and lead were found to be key contaminants for soils. Zinc was also detected in soil; but concentrations are not great enough for this metal to warrant further evaluation.

Table 6 summarizes concentration data for key soil contaminants.

TABLE 6--KEY CONTAMINANTS FOR MAGNA SOIL EXPOSURE SITUATION¹
Contaminant	Range in mg/kg	Comparison Value (See Appendix C)	Source
Arsenic²	nondetect - 40	0.4	CREG³
Cadmium⁴	nondetect - 6.5	1	EMEG⁵
Copper⁶	nondetect - 600	none	none
Lead⁷	nondetect - 560	none	none
1 There is a more detailed list of contaminants in Tables 14A and 14B starting on page 46 in Appendix E. The process for selecting contaminants is described in Appendix C starting on page 37. 2 This is the range in milligrams of arsenic per kilogram of soil (mg/kg) for 256 samples taken in Magna. 3 CREG is cancer risk evaluation guide. See Appendix C for an explanation. 4 This is the range in milligrams of cadmium per kilogram of soil (mg/kg) for 28 samples taken in Magna. 5 EMEG is environmental media evaluation guide. See Appendix C for an explanation. 6 This is the range in milligrams of copper per kilogram of soil (mg/kg) for 256 samples taken in Magna. 7 This is the range in milligrams of lead per kilogram of soil (mg/kg) for 256 samples taken in Magna.

Arsenic, cadmium, copper, lead, and zinc were the principal metals analyzed for during extensive investigation of surface soils in Magna (Tables 14A and 14B, Appendix E) (13,14). Review of the data suggests that levels of copper and possibly lead and zinc in some Magna surface soils may be somewhat elevated above the concentrations for samples taken of soils in adjoining West Valley--also shown in those tables (14).

D. Exposure Pathway Analyses

Only a small portion (5 percent or less) of the approximately 18,000 residents of Magna are being exposed to concentrations of arsenic, cadmium, copper, and lead at levels above background, based on the results of the soil sampling. For example, as indicated in Table 14A in Appendix E, 11 of 256 samples had arsenic concentrations above a background level of 20 ppm. These individuals could be exposed daily through activities such as gardening and playing which result in contact with contaminated soil. The approximate boundaries of Magna, an unincorporated community, are shown on Figure 2. Ninety four percent of the population is of the white race.

E. Public Health Implications

Public health implications decisions made in the public health assessment process primarily are based on toxicological evaluations that compare exposure dose (i.e., the amount of a substance individuals in an exposure pathway are exposed to daily) to appropriate health guidelines for carcinogenic and noncarcinogenic effects. There are health guidelines for noncarcinogenic and carcinogenic effects for arsenic and for noncarcinogenic effects for cadmium, but copper and lead have no guidelines. The methodology for calculating exposure doses and cancer risk, along with the results of those calculations (Table B), are found on pages 51 and 54.

It is unlikely that the exposures to arsenic, cadmium, copper, and lead in Magna soil will result in health effects in area residents. Levels of arsenic, cadmium, and lead identified in sampling of Magna soil are considered too low to result in noncarcinogenic effects or a significant increase in risk for cancer. The copper present in Magna soils is not likely to result in health effects because the human body has a effective mechanism to limit the amount of ingested copper moving into the bloodstream to well below toxic effect levels.

Although the child and pica child (child who ingests 5 grams or more soil per day) exposure doses for the maximum arsenic concentration in soil exceed the health guideline for arsenic, further evaluation indicates that it is unlikely that these exposures will result in health effects. The exposure dose for children is about equal to the lowest no observed adverse health effect level (NOAEL) of 0.0008 mg/kg/day found in humans and 18 times lower than the lowest observed adverse health effect level (LOAEL) of 0.014 mg/kg/day (11). The exposure dose for pica children is slightly higher than the LOAEL. However, the exposure dose is for the maximum arsenic soil level; about 95% of the soil levels are lower. Thus, it is unlikely that health effects would occur.

Arsenic is considered a known carcinogen, based on human epidemiological studies (11). The overall range of arsenic concentrations found in Magna soil is not likely to present an increased lifetime risk of cancer to the residents of Magna.

The pica child exposure dose for cadmium exceeds the health guideline, but further evaluation indicates that these exposures are not likely to result in adverse health effects. The exposure dose for pica children is about equal to the lowest no observed adverse health effect level (NOAEL) of 0.0021 mg/kg/day found in humans and 3 times lower than the lowest observed adverse health effect level (LOAEL) of 0.075 mg/kg/day (12). In addition, the exposure dose is for the maximum cadmium soil level; about 95% of the soil levels are lower. Given those factors it is unlikely that health effects would occur.

Cadmium is a probable human carcinogen based on animal data (12). However, there is no cancer slope factor for cadmium, so it is not possible to evaluate carcinogenic risk. In addition, the data indicate that cadmium probably causes cancer in animals only through inhalation and not through ingestion which appears to be the principle route of exposure in the Magna area.

There is no health guideline for copper, but a comparison of the exposure doses to a lowest observed adverse health effect level (LOAEL) and a consideration of the metabolism of copper in humans, indicates that health effects are unlikely (15). The adult and child exposure doses are about 70 and 6 times lower, respectively, than a LOAEL of 0.06 mg/kg/day, which is based on exposures of humans to copper in water. The exposure dose for pica children is about 5 times greater than the LOAEL. However, it is unlikely that this exposure would result in adverse health effects because a large portion of the copper in soil is not available to be absorbed from the gastrointestinal tract into the bloodstream. In addition, the body has an effective mechanism to limit the amount of copper that is absorbed.

Copper is not considered a carcinogen (15).

While there is no health guideline for lead, it is unlikely that health effects would have occurred based on the infrequency of exposure of children under 7 years old and the relatively low concentrations of lead. Only 4 of 256 samples were above 400 ppm, the current EPA action level, with a high concentration of 560 ppm. Thus, only a small number of children would have the opportunity to be exposed to soil lead levels which might cause health effects. A review of the literature indicates that even the maximum level of soil lead (560 ppm) found would not result in health effects unless there were also other sources of exposure (17).

A blood lead study done in Magna by the University of Cincinnati and the Salt Lake City/County Health Department provides some support to this conclusion (16). In this study, the mean blood lead level of the 162 children under 7 years tested was 4.8 micrograms of lead per deciliter (µg/dL). Ten of the children tested (10/162; 6.2%) had blood lead levels above 10 µg/dL. All the children under 7 in Magna were identified and offered testing. However, because the main purpose of the study was to determine the mean blood lead level for children under 7 in the community, only a participation rate of 50% of the children under 7 was considered necessary. Therefore, it is possible that some areas or populations within the community could be over or under represented. Besides blood lead samples, tap water, soil, and house dust samples from the household of each participant were tested for lead.

Lead is a probable human carcinogen based on animal data (17). However, there is no cancer slope factor for lead, so it is not possible to evaluate carcinogenic risk. In addition, the conclusion that lead causes cancer in animals is based on experiments with a form of lead not found in Magna soil.

F. Conclusions, Recommendations, and Public Health Actions

Conclusions--ATSDR believes the Magna Vicinity soil exposure situation poses no apparent public health hazard.
Recommendations--ATSDR's evaluations did not identify any issues that warrant recommendations.
Public health actions--Public health action information for all exposure situations is summarized in the Public Health Actions Section, found on Page 21.

PUBLIC HEALTH EVALUATION OF CONTAMINANTS IN SURFACE WATER

A. Overview

The possibility of public health impact by surface water contaminants is evaluated in this portion of the assessment for one exposure situation (Great Salt Lake Park). Table 7 summarizes the results of these evaluations.

The evaluation results lead ATSDR to conclude that the Great Salt Lake Park surface water exposure situation poses no apparent public health hazard.

TABLE 7 - EXPOSURE TO CONTAMINANTS IN SURFACE WATER*
Situation	Key Contaminants**	Exposed Population	Route of Exposure	Frequency of Exposure	Public Health Classification
Great Salt Lake Park	Arsenic, Cadmium, Copper, Lead	About 10% (70,000) of 676,000 Annual Visitors	Ingestion	A Few Times a Year	No Apparent Health Hazard
* The source for these metals is a combination of human and natural activities. ** Key Contaminants--contaminants which initial evaluations showed had some potential to be a public health hazard.

B. Background--Overview

The Great Salt Lake is a closed basin that drains a large part of northeastern Utah and parts of Wyoming and Idaho. The lake is a repository for inorganic materials both suspended and dissolved that are carried by streams or groundwater. Some of the salts are concentrated by several orders of magnitude in the lake over the natural concentration present in inflowing waters (18). Kennecott's operations contribute to lake contaminant levels to a limited extent via runoff and C-7 ditch outflow, and through releases to shallow groundwater that drains into the lake.

C. Environmental Contamination

Lake water sampling data were reviewed, and several contaminants were selected for further, more detailed, evaluation of public health significance. A description of the process for selecting contaminants for evaluation can be found on page 37 in Appendix C.

Arsenic, cadmium, copper and lead were found to be key contaminants for the exposure situation. Zinc was also detected in surface water; but concentrations are not great enough for this metal to warrant further evaluation.

Table 8 summarizes surface water contaminant concentration data.

TABLE 8 - KEY CONTAMINANTS FOR GREAT SALT LAKE PARK SURFACE WATER EXPOSURE SITUATION¹
Contaminant	Range in µg/L	Comparison Value (See Appendix C)	Source
Arsenic²	nondetect -192	0.02	CREG³
Cadmium⁴	>26	7	EMEG⁵
Copper⁶	nondetect -1,100	400	Est.⁷
Lead⁸	<153	15	AL⁹
1 There is a more detailed list of contaminants in Table 15 on page 47 in Appendix E. The process for selecting contaminants is described in Appendix C starting on page 37. 2 This is the range in micrograms of arsenic per liter of water (µg/L) for 8 samples taken at the Great Salt Lake Park Beach. 3 CREG is cancer risk evaluation guide for drinking water. See Appendix C for an explanation. 4 This is the range in micrograms of cadmium per liter of water (µg/L) for 8 samples taken at the Great Salt Lake Park Beach. 5 EMEG is environmental media evaluation guide for drinking water. See Appendix C for an explanation. 6 This is the range in micrograms of copper per liter of water (µg/L) for 8 samples taken at the Great Salt Lake Park Beach. 7 Estimated comparison value for drinking water 8 This is the range in micrograms of lead per liter of water (µg/L) for 8 samples taken at the Great Salt Lake Park Beach. 9 AL is the U.S. Environmental Protection Agency (EPA) action level for lead in drinking water.

Arsenic, cadmium, copper, lead, and zinc were the principal metals analyzed for during investigations of surface water that included samples at widely spaced locations in the southern part of Great Salt Lake (Table 15, Appendix E) (19,18). Review of the data shown indicate that levels of arsenic, cadmium, copper, and lead in lake water exceed comparison values (see discussion in Appendix C) and thus will be evaluated further.

D. Exposure Pathway Analyses

Based on the surface water sampling done (Table 15, Appendix E), any of the individuals that annually visit the Great Salt Lake Park (676,000) and swim, wade, or otherwise contact the surface water at the park beach are being exposed to arsenic, cadmium, copper, and lead. Park officials estimate that not more than 10 percent of visitors enter the water. These exposures would probably be no more than 10 times a year for some repeat visitors and would be of relatively short duration. It is unlikely that very much water would be ingested due to the very salty taste of Great Salt Lake water.

E. Public Health Implications

Public health implications decisions made in the public health process primarily are based on toxicological evaluations that compare exposure dose (i.e., the amount of a substance individuals in an exposure pathway are exposed to daily) to appropriate health guidelines for carcinogenic and noncarcinogenic effects. There are health guidelines for noncarcinogenic and carcinogenic effects for arsenic, and noncarcinogenic effects for cadmium. There are no health guidelines for copper and lead. The methodology for calculating exposure doses and cancer risk, along with the results of those calculations (Table C), are found on pages 51 and 55, respectively.

It is extremely unlikely that incidental ingestion or other exposures to arsenic, cadmium, copper, and lead in surface water at Great Salt Lake Park will result in health effects in park visitors. Levels of arsenic, cadmium, copper, and lead are far too low for lake water exposure doses to result in noncarcinogenic effects or any increase in risk for cancer.

As indicated in Table C of Appendix F, the adult and child ingestion exposure doses for arsenic and cadmium are well below health guidelines indicating that it is extremely unlikely that health effects would occur. For arsenic, there is no increase in the risk of cancer.

It is also very unlikely that health effects would occur due to ingestion exposure to copper in surface water. The child exposure dose is 860 times and the adult exposure dose is 6,700 times lower than the lowest observed adverse health effect level (LOAEL) of 0.06 mg/kg/day which is based on exposures of humans to copper in water (15).

Adverse health effects due to lead in lake water at the park also appear unlikely based on a comparison of the ingestion exposure doses to results from EPA's Integrated Exposure Uptake Biokinetic .99d (IEUBK) model for lead. The child exposure dose is about 100 times lower than the acceptable uptake level generated by the model's default values, which are the typical/average lead concentrations to which children are exposed. The results of the model did not substantially change even when the Great Salt Lake surface water exposure scenario was entered into the model.

F. Conclusions, Recommendations, and Public Health Actions

Conclusions--ATSDR believes the Great Salt Lake Park surface water exposure situation poses no apparent public health hazard.
Recommendations--ATSDR did not identify any issues that warrant recommendations.
Public health actions--Public health action information for all exposure situations is summarized in the Public Health Actions Section, found on Page 21.

COMMUNITY HEALTH CONCERNS

Through the September and October 1994 site visits, two public availability sessions, and phone calls and letters, ATSDR staff solicited community health concerns from the Magna Area Neighborhood Groups, Salt Lake City/County Health Department, Utah Department of Environmental Quality, Utah Department of Health, Kennecott Corporation, and individual citizens. The community health concerns identified and ATSDR's response to them are:

CONCERN: A former teacher thought that there were an excessive number of children with learning disabilities at the Magna elementary school nearest to the Kennecott facilities.

Response: The available soil, air, and blood lead data, already evaluated in this public health assessment, indicate that any sort of Kennecott-related health effects in children are unlikely. Only 10 of 162 children under 7 had blood lead concentrations above the health concern level of 10 µg/dL with a mean level of 4.1 µg/dL. One of the air monitoring stations in Magna was on top of this school and soil samples were collected from the school grounds.

CONCERN: A resident's husband and many coworkers at Kennecott died of cancer.

Response: Workers at Kennecott prior to 1980 have a greater risk of lung cancer, based on a number of studies of workers at smelters including Kennecott's (11). These investigations are the basis of the conclusion that arsenic is a known human carcinogen. There is not conclusive evidence that arsenic in air causes other types of cancer. It is also well documented by studies of human exposures in Taiwan and elsewhere, that arsenic in water causes skin cancer and probably liver, lung, bladder, and kidney cancer.

CONCERN: A Magna resident, who was 40-50 years old asked whether eight cases of multiple sclerosis in her high school class of 165 would be considered an excess.

Response: There is no indication that MS is caused by lead, arsenic, or cadmium (20). MS is a disease where the myelin coating around the nerves disappears over time. This usually results in a gradual loss of neural function. The average onset of MS is at about 30 years old.
There is a strong association between the occurrence of MS and latitude (20). Disease rates increase with distance to the north or south of the equator. At the equator, the rate of MS is 1 per 100,000, in the southern United States it is 6-14 per 100,000, and 30-80 per 100,000 in Canada, northern Europe and the northern United States. The rates in women are three to four times greater than men, and the rates in whites are greater than in blacks. However, all show an association with latitude. Individuals who migrate from a high risk area to one with low risk have the same rate of MS as the high risk area if they move when they are 15 years or older. If they move to the low risk area before they are 15, their rate of MS is the same as the area they move to. Another pertinent piece of epidemiological data is the occurrence of epidemics of MS in the Faroe Islands and in Iceland starting after British troops were based there during World War II.
All this epidemiologic data point to a relationship between MS and exposure to environmental agents in childhood (20). Viral agents are suspected but there is no strong evidence supporting any specific virus. There is no good evidence for an association with any chemical or with radiation.

CONCERN: A resident living next to the Kennecott tailings pond inquired about the risk the contaminants in the tailings pond may pose to their private drinking water wells and what the results of testing of their wells and soils meant.

Response: ATSDR responded to these concerns through verbal and written health consultations with the resident; a summary of those is included here (21).
Regarding the risk posed by the tailing ponds, the chemical concentrations reported for the well water appear to be within a natural range of concentrations for the aquifer and unaffected by the tailings pond. Groundwater contaminants from the tailings pond are unlikely to reach the resident's wells for two reasons. First, the wells draw water from a deep aquifer with a vertically upward flow pressure that prevents downward seepage of contaminants from the shallow zones. And second, the groundwater flow from the tailings pond is northward, away from the resident's wells. Both the upward flow pressure and the northward flow pattern have been determined from the studies performed by the Kennecott Utah Copper Corporation and reviewed by the Utah Department of Environmental Quality, U.S. Environmental Protection Agency, and the U.S. Geological Survey.
Regarding the meaning of well and soil testing, the concentrations of chemicals reported for soils and well water do not exceed safe levels.

CONCERN: Visitors at Great Salt Lake Park sometimes complain of odors and respiratory irritation.

Response: The respiratory irritation could be due to sulfur dioxide, but results of daily air monitoring indicate that any irritation should be short-term. The highest 24-hour average for monitoring done from 1990 to 1994 is 0.05 parts per million (ppm) while the permissible level is 0.14 ppm. The highest annual average of 0.01 ppm is also lower than the permissible level of 0.03 ppm as established by EPA. It is possible that within a 24-hour period sulfur dioxide levels might rise for a time to a level where irritation might occur, but based on the monitoring results, this time should be short.
At least one source of the odors at the Great Salt Lake Park could be the organic matter (decaying vegetation, etc.) in the lake itself.

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Department of Health and Human Services

CONCERN: A former teacher thought that there were an excessive number of children with learning disabilities at the Magna elementary school nearest to the Kennecott facilities.
Response:	The available soil, air, and blood lead data, already evaluated in this public health assessment, indicate that any sort of Kennecott-related health effects in children are unlikely. Only 10 of 162 children under 7 had blood lead concentrations above the health concern level of 10 µg/dL with a mean level of 4.1 µg/dL. One of the air monitoring stations in Magna was on top of this school and soil samples were collected from the school grounds.
CONCERN: A resident's husband and many coworkers at Kennecott died of cancer.
Response:	Workers at Kennecott prior to 1980 have a greater risk of lung cancer, based on a number of studies of workers at smelters including Kennecott's (11). These investigations are the basis of the conclusion that arsenic is a known human carcinogen. There is not conclusive evidence that arsenic in air causes other types of cancer. It is also well documented by studies of human exposures in Taiwan and elsewhere, that arsenic in water causes skin cancer and probably liver, lung, bladder, and kidney cancer.
CONCERN: A Magna resident, who was 40-50 years old asked whether eight cases of multiple sclerosis in her high school class of 165 would be considered an excess.
Response:	There is no indication that MS is caused by lead, arsenic, or cadmium (20). MS is a disease where the myelin coating around the nerves disappears over time. This usually results in a gradual loss of neural function. The average onset of MS is at about 30 years old. There is a strong association between the occurrence of MS and latitude (20). Disease rates increase with distance to the north or south of the equator. At the equator, the rate of MS is 1 per 100,000, in the southern United States it is 6-14 per 100,000, and 30-80 per 100,000 in Canada, northern Europe and the northern United States. The rates in women are three to four times greater than men, and the rates in whites are greater than in blacks. However, all show an association with latitude. Individuals who migrate from a high risk area to one with low risk have the same rate of MS as the high risk area if they move when they are 15 years or older. If they move to the low risk area before they are 15, their rate of MS is the same as the area they move to. Another pertinent piece of epidemiological data is the occurrence of epidemics of MS in the Faroe Islands and in Iceland starting after British troops were based there during World War II. All this epidemiologic data point to a relationship between MS and exposure to environmental agents in childhood (20). Viral agents are suspected but there is no strong evidence supporting any specific virus. There is no good evidence for an association with any chemical or with radiation.
CONCERN: A resident living next to the Kennecott tailings pond inquired about the risk the contaminants in the tailings pond may pose to their private drinking water wells and what the results of testing of their wells and soils meant.
Response:	ATSDR responded to these concerns through verbal and written health consultations with the resident; a summary of those is included here (21). Regarding the risk posed by the tailing ponds, the chemical concentrations reported for the well water appear to be within a natural range of concentrations for the aquifer and unaffected by the tailings pond. Groundwater contaminants from the tailings pond are unlikely to reach the resident's wells for two reasons. First, the wells draw water from a deep aquifer with a vertically upward flow pressure that prevents downward seepage of contaminants from the shallow zones. And second, the groundwater flow from the tailings pond is northward, away from the resident's wells. Both the upward flow pressure and the northward flow pattern have been determined from the studies performed by the Kennecott Utah Copper Corporation and reviewed by the Utah Department of Environmental Quality, U.S. Environmental Protection Agency, and the U.S. Geological Survey. Regarding the meaning of well and soil testing, the concentrations of chemicals reported for soils and well water do not exceed safe levels.
CONCERN: Visitors at Great Salt Lake Park sometimes complain of odors and respiratory irritation.
Response:	The respiratory irritation could be due to sulfur dioxide, but results of daily air monitoring indicate that any irritation should be short-term. The highest 24-hour average for monitoring done from 1990 to 1994 is 0.05 parts per million (ppm) while the permissible level is 0.14 ppm. The highest annual average of 0.01 ppm is also lower than the permissible level of 0.03 ppm as established by EPA. It is possible that within a 24-hour period sulfur dioxide levels might rise for a time to a level where irritation might occur, but based on the monitoring results, this time should be short. At least one source of the odors at the Great Salt Lake Park could be the organic matter (decaying vegetation, etc.) in the lake itself.