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PUBLIC HEALTH ASSESSMENT

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


PUBLIC HEALTH EVALUATION OF CONTAMINANTS IN SOIL

A. Overview

The possibility of public health impact by soil contaminants is evaluated in this portion of theassessment 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*
SituationKey**
Contaminants
ExposedPopulationRouteof ExposureFrequencyof ExposurePublicHealthClassification
MagnaVicinityArsenic,Cadmium
Copper, Lead
About 18,000IngestionDaily No ApparentHealthHazard
* The source for these metals is probably a combination of natural and humanactivities
** Key Contaminants--contaminants which initial evaluations showed hadsome 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 someof the key contaminants) eroded from the surface of the tailings pond and migrated by air untilmodifications were made in the tailings discharge system and operations and maintenanceprocedures. Wind-blown tailings deposition has caused some metals concentrations in affectedsurface 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, moredetailed, evaluation of public health significance. A description of the process for selecting theseveral contaminants can be found on page 37 in Appendix C. Those several were furtherevaluated, 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 alsodetected in soil; but concentrations are not great enough for this metal to warrant furtherevaluation.

Table 6 summarizes concentration data for key soil contaminants.

Table 6.

KEY CONTAMINANTS FOR MAGNA SOIL EXPOSURE SITUATION1
ContaminantRange in mg/kgComparison Value
(See Appendix C)
Source
Arsenic2nondetect - 400.4CREG3
Cadmium4nondetect - 6.51EMEG5
Copper6nondetect - 600nonenone
Lead7nondetect - 560nonenone
1 There is a more detailed list of contaminants in Tables 14A and 14Bstarting on page 46 in Appendix E. The process for selectingcontaminants 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 anexplanation.
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 foran 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 extensiveinvestigation of surface soils in Magna (Tables 14A and 14B, Appendix E) (13,14). Review ofthe data suggests that levels of copper and possibly lead and zinc in some Magna surface soilsmay be somewhat elevated above the concentrations for samples taken of soils in adjoining WestValley--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 beingexposed 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. Theseindividuals could be exposed daily through activities such as gardening and playing which resultin contact with contaminated soil. The approximate boundaries of Magna, an unincorporatedcommunity, 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 arebased on toxicological evaluations that compare exposure dose (i.e., the amount of a substanceindividuals in an exposure pathway are exposed to daily) to appropriate health guidelines forcarcinogenic and noncarcinogenic effects. There are health guidelines for noncarcinogenic andcarcinogenic effects for arsenic and for noncarcinogenic effects for cadmium, but copper andlead have no guidelines. The methodology for calculating exposure doses and cancer risk, alongwith 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 resultin health effects in area residents. Levels of arsenic, cadmium, and lead identified in sampling ofMagna soil are considered too low to result in noncarcinogenic effects or a significant increasein risk for cancer. The copper present in Magna soils is not likely to result in health effectsbecause the human body has a effective mechanism to limit the amount of ingested coppermoving 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) exposuredoses 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 effectlevel (NOAEL) of 0.0008 mg/kg/day found in humans and 18 times lower than the lowestobserved adverse health effect level (LOAEL) of 0.014 mg/kg/day (11). The exposure dose forpica children is slightly higher than the LOAEL. However, the exposure dose is for themaximum arsenic soil level; about 95% of the soil levels are lower. Thus, it is unlikely thathealth effects would occur.

Arsenic is considered a known carcinogen, based on human epidemiological studies (11). Theoverall 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 evaluationindicates that these exposures are not likely to result in adverse health effects. The exposure dosefor pica children is about equal to the lowest no observed adverse health effect level (NOAEL) of0.0021 mg/kg/day found in humans and 3 times lower than the lowest observed adverse healtheffect level (LOAEL) of 0.075 mg/kg/day (12). In addition, the exposure dose is for themaximum cadmium soil level; about 95% of the soil levels are lower. Given those factors it isunlikely that health effects would occur.

Cadmium is a probable human carcinogen based on animal data (12). However, there is nocancer 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 lowestobserved adverse health effect level (LOAEL) and a consideration of the metabolism of copper inhumans, indicates that health effects are unlikely (15). The adult and child exposure doses areabout 70 and 6 times lower, respectively, than a LOAEL of 0.06 mg/kg/day, which is based onexposures of humans to copper in water. The exposure dose for pica children is about 5 timesgreater than the LOAEL. However, it is unlikely that this exposure would result in adversehealth effects because a large portion of the copper in soil is not available to be absorbed fromthe 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 occurredbased on the infrequency of exposure of children under 7 years old and the relatively lowconcentrations of lead. Only 4 of 256 samples were above 400 ppm, the current EPA actionlevel, with a high concentration of 560 ppm. Thus, only a small number of children would havethe opportunity to be exposed to soil lead levels which might cause health effects. A review ofthe literature indicates that even the maximum level of soil lead (560 ppm) found would notresult 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/CountyHealth Department provides some support to this conclusion (16). In this study, the mean bloodlead 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. Allthe children under 7 in Magna were identified and offered testing. However, because the mainpurpose of the study was to determine the mean blood lead level for children under 7 in thecommunity, 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 orunder 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 cancerslope factor for lead, so it is not possible to evaluate carcinogenic risk. In addition, theconclusion that lead causes cancer in animals is based on experiments with a form of lead notfound in Magna soil.

F. Conclusions, Recommendations, and Public Health Actions

  1. Conclusions--ATSDR believes the Magna Vicinity soil exposure situation poses no apparentpublic health hazard.

  2. Recommendations--ATSDR's evaluations did not identify any issues that warrantrecommendations.

  3. Public health actions--Public health action information for all exposure situations issummarized 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 portionof the assessment for one exposure situation (Great Salt Lake Park). Table 7 summarizes theresults 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*
SituationKey**
Contaminants
ExposedPopulationRouteofExposureFrequency ofExposurePublicHealthClassification
GreatSaltLakeParkArsenic,Cadmium,Copper,LeadAbout 10%(70,000) of676,000AnnualVisitorsIngestionA FewTimes aYear No Apparent HealthHazard
* The source for these metals is a combination of human and naturalactivities.
** Key Contaminants--contaminants which initial evaluations showed hadsome 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 ofWyoming and Idaho. The lake is a repository for inorganic materials both suspended anddissolved that are carried by streams or groundwater. Some of the salts are concentrated byseveral 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 exposuresituation. 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
ContaminantRange in µg/LComparison Value
(See Appendix C)
Source
Arsenic2nondetect -1920.02CREG3
Cadmium4>267EMEG5
Copper6nondetect -1,100400Est.7
Lead8<15315AL9
1 There is a more detailed list of contaminants in Table 15 on page 47 in AppendixE. The process for selecting contaminants is described in Appendix C starting onpage 37.
2 This is the range in micrograms of arsenic per liter of water (µg/L) for 8 samplestaken at the Great Salt Lake Park Beach.
3 CREG is cancer risk evaluation guide for drinking water. See Appendix C for anexplanation.
4 This is the range in micrograms of cadmium per liter of water (µg/L) for 8 samplestaken 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 samplestaken 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 samplestaken at the Great Salt Lake Park Beach.
9 AL is the U.S. Environmental Protection Agency (EPA) action level for lead indrinking water.

Arsenic, cadmium, copper, lead, and zinc were the principal metals analyzed for duringinvestigations of surface water that included samples at widely spaced locations in the southernpart of Great Salt Lake (Table 15, Appendix E) (19,18). Review of the data shown indicate thatlevels of arsenic, cadmium, copper, and lead in lake water exceed comparison values (seediscussion 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 thatannually visit the Great Salt Lake Park (676,000) and swim, wade, or otherwise contact thesurface water at the park beach are being exposed to arsenic, cadmium, copper, and lead. Parkofficials estimate that not more than 10 percent of visitors enter the water. These exposureswould probably be no more than 10 times a year for some repeat visitors and would be ofrelatively 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 ontoxicological evaluations that compare exposure dose (i.e., the amount of a substance individualsin an exposure pathway are exposed to daily) to appropriate health guidelines for carcinogenicand noncarcinogenic effects. There are health guidelines for noncarcinogenic and carcinogeniceffects for arsenic, and noncarcinogenic effects for cadmium. There are no health guidelines forcopper and lead. The methodology for calculating exposure doses and cancer risk, along with theresults 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 toresult 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 arsenicand cadmium are well below health guidelines indicating that it is extremely unlikely that healtheffects 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 insurface water. The child exposure dose is 860 times and the adult exposure dose is 6,700 timeslower than the lowest observed adverse health effect level (LOAEL) of 0.06 mg/kg/day which isbased 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 acomparison of the ingestion exposure doses to results from EPA's Integrated Exposure UptakeBiokinetic .99d (IEUBK) model for lead. The child exposure dose is about 100 times lower thanthe acceptable uptake level generated by the model's default values, which are the typical/averagelead concentrations to which children are exposed. The results of the model did not substantiallychange even when the Great Salt Lake surface water exposure scenario was entered into themodel.

F. Conclusions, Recommendations, and Public Health Actions

  1. Conclusions--ATSDR believes the Great Salt Lake Park surface water exposure situationposes no apparent public health hazard.

  2. Recommendations--ATSDR did not identify any issues that warrant recommendations.

  3. Public health actions--Public health action information for all exposure situations issummarized 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 phonecalls and letters, ATSDR staff solicited community health concerns from the Magna AreaNeighborhood Groups, Salt Lake City/County Health Department, Utah Department ofEnvironmental Quality, Utah Department of Health, Kennecott Corporation, and individualcitizens. 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 withlearning disabilities at the Magna elementary school nearest to the Kennecott facilities.

Response:The available soil, air, and blood lead data, already evaluated in this publichealth assessment, indicate that any sort of Kennecott-related health effectsin children are unlikely. Only 10 of 162 children under 7 had blood leadconcentrations above the health concern level of 10 µg/dL with a mean levelof 4.1 µg/dL. One of the air monitoring stations in Magna was on top of thisschool 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, basedon a number of studies of workers at smelters including Kennecott's (11). These investigations are the basis of the conclusion that arsenic is a knownhuman carcinogen. There is not conclusive evidence that arsenic in aircauses other types of cancer. It is also well documented by studies of humanexposures in Taiwan and elsewhere, that arsenic in water causes skin cancerand probably liver, lung, bladder, and kidney cancer.

CONCERN: A Magna resident, who was 40-50 years old asked whether eight cases ofmultiple 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 overtime. This usually results in a gradual loss of neural function. The averageonset 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 theequator. At the equator, the rate of MS is 1 per 100,000, in the southernUnited 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 arethree to four times greater than men, and the rates in whites are greater thanin blacks. However, all show an association with latitude. Individuals whomigrate from a high risk area to one with low risk have the same rate of MSas the high risk area if they move when they are 15 years or older. If theymove to the low risk area before they are 15, their rate of MS is the same asthe area they move to. Another pertinent piece of epidemiological data is theoccurrence of epidemics of MS in the Faroe Islands and in Iceland startingafter British troops were based there during World War II.

All this epidemiologic data point to a relationship between MS and exposureto environmental agents in childhood (20). Viral agents are suspected butthere is no strong evidence supporting any specific virus. There is no goodevidence for an association with any chemical or with radiation.

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

Response:ATSDR responded to these concerns through verbal and written healthconsultations with the resident; a summary of those is included here (21).

Regarding the risk posed by the tailing ponds, the chemical concentrationsreported for the well water appear to be within a natural range ofconcentrations for the aquifer and unaffected by the tailings pond. Groundwater contaminants from the tailings pond are unlikely to reach theresident's wells for two reasons. First, the wells draw water from a deepaquifer with a vertically upward flow pressure that prevents downwardseepage of contaminants from the shallow zones. And second, thegroundwater flow from the tailings pond is northward, away from theresident's wells. Both the upward flow pressure and the northward flowpattern have been determined from the studies performed by the KennecottUtah Copper Corporation and reviewed by the Utah Department ofEnvironmental Quality, U.S. Environmental Protection Agency, and theU.S. Geological Survey.

Regarding the meaning of well and soil testing, the concentrations ofchemicals reported for soils and well water do not exceed safe levels.

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

Response:The respiratory irritation could be due to sulfur dioxide, but results of dailyair monitoring indicate that any irritation should be short-term. The highest24-hour average for monitoring done from 1990 to 1994 is 0.05 parts permillion (ppm) while the permissible level is 0.14 ppm. The highest annualaverage of 0.01 ppm is also lower than the permissible level of 0.03 ppm asestablished by EPA. It is possible that within a 24-hour period sulfurdioxide 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 theorganic matter (decaying vegetation, etc.) in the lake itself.



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