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PUBLIC HEALTH ASSESSMENT

KENNECOTT (SOUTH ZONE)
COPPERTON, SALT LAKE COUNTY, UTAH


SUMMARY

The Kennecott, South Zone, site comprises approximately 150 square miles in southwest SaltLake County, west of Salt Lake City, Utah. Agency for Toxic Substances and Disease Registry (ATSDR) staff members toured the site and met with staff members from Utah Department ofEnvironmental Quality (UDEQ), the U.S. Environmental Protection Agency (EPA) andKennecott Utah Copper (KUC) Corporation. ATSDR staff members also held open publicavailability sessions in October 1994 to meet individual citizens and gather community concerns. ATSDR staff members evaluated environmental health information provided by KUC, UDEQ,EPA, and information from other organizations.

ATSDR has identified seven exposure situations for theKUC South National Priorities List(NPL) site (Table 2 on page 5). Though undergoing removal and remediation, one exposuresituation, Butterfield Creek, is considered a past and current public healthhazard until removal iscomplete because people may still be exposed to high levels of lead from surface soils.

Present and future conditions of soils in the Bingham Creek area are considered no apparentpublic health concern because Kennecott, EPA, and ARCO successfully removed highlycontaminated soils. Before removal actions, two areas of Bingham Creek containedcontaminatedsoils that may have posed a public health hazard. The surface soils inthe Copperton area areclassified as no apparent health hazard because the contaminant concentrations,frequency andduration of exposure, and opportunity for human exposure are not sufficient to generate adversehealth effects in the residential population.

Though mitigated, one exposure situation (Southwest Jordan Groundwater), is considered apast public health hazard because a few people used a private drinking water well with concentrationsabove the 1500 ppm EPA Region VIII recommended risk level. In addition toprovidingalternative water supplies, Kennecott's comprehensive well inventory, groundwater monitoring,and private well testing programs have greatly reduced the potential for human exposure toconcentrations of sulfate above 1500 parts per million

Investigators did not have sufficient information to determine the public health hazard statusoneof the exposure situations (Pine Canyon groundwater). This area is identified as indeterminatepublic health hazard.

In response to a resident's concern about his family's exposure to the lead-contaminated soils,ATSDR evaluated the soil-lead levels and the family's blood lead measurements. The soil leadlevels may have been high enough to result in health effects if there were frequent exposure to thecontaminated soil. However, the results of the blood lead testing indicate that significantexposures were not occurring at that time. It is not possible to determine whether significantexposures could have occurred at another time.

INTRODUCTION

Purpose

In this public health assessment, the Agency for Toxic Substances and Disease Registry (ATSDR)evaluates the public health significance of the proposed Kennecott South Zone National PrioritiesList (NPL) site in southwestern Salt Lake County and eastern Tooele County. More specifically,ATSDR has reviewed available environmental and health outcomedata and community healthconcerns to determine whether adverse health effects are possible. In addition, this public healthassessment recommends actions to reduce, prevent, or further identify the possibility forsite-related adverse health effects.

Comments on the Public Comment Draft of the Public Health Assessment

A draft of the Public Health Assessment for the Kennecott South Zone NPL Sitewas released forpublic review and comment in June 1996 with the comment period extended through August1996. ATSDR did not receive any comments from citizens living in the communities in thevicinity of the proposed NPL site. ATSDR did receive comments from the Utah Department of Health, the Utah Department of Environmental Quality (UDEQ), the Kennecott Utah Copper(KUC) Corporation, the Atlantic Richfield Company (ARCO), and the University of Cincinnati. Comments from KUC and ARCO are reproduced in Appendix F. Comments from University ofCincinnati were not reproduced because of concern because of massive among of informationassociated with the comments.. Some changes in the public health assessment were made inresponse to the comments received. In particular, the public health hazard category for theSouthwest Salt Lake County Groundwater plume was changed inresponse to informationprovided by Kennecott Corporation and later, EPA Region VIII.

Site Description

In January 1994, the EPA proposed that the Kennecott South Zone site be added to the NPL.TheKennecott (South Zone) site covers portions of Salt Lake County (southwest of Salt Lake City)and eastern Tooele County, Utah. Comprising approximately 150 square miles, the site areaencompasses the communities of Copperton, Herriman, South Jordan, Riverton, and West Jordan. The site area includes a majority of the historic mining area in the Oquirrh Mountains that liealong the boundary between Salt Lake and Tooele counties. It also includes certain properties ofKUC and ARCO. EPA has tentatively divided the NPL site into 14 operable units, which arelisted in Table 1 (the majority are depicted in Figure 1 in Appendix A).

Table 1.

EPA designated Operable Units for Kennecott South NPL site.
NameNumberDescription
Bingham CreekOU1Includes the channel and floodplain of Bingham Creekeast of the Large Bingham Reservoir to Brookside TrailerCourt.
Southwest Salt Lake County(SWSLC) Groundwater Plume OU2This includes the contaminated groundwater pollutantsand contaminants originating at or near Bingham Creek,Lark, and the Evaporation Ponds and extendingdowngrade (generally eastward to Jordan River). Sourceareas are in separate operable units.
Butterfield MineOU3Includes Butterfield Mine and Butterfield Creekwatershed.
Large Bingham ReservoirOU4Includes Large Bingham Reservoir and other reservoirs inimmediate vicinity.
ARCO TailsOU5Includes the ARCO Tailings and drainage ditchesdownstream.
Lark Waste Rock and TailingsOU6Includes all mining waste areas in and near former Larkcommunity.
South Jordan Evaporation PondsOU7Includes the evaporation ponds and associated canals andditches.
Copperton SoilsOU10Contaminated soils in town of Copperton.
Bingham Canyon and MineOU11Watershed of Bingham Canyon upstream of the LargeBingham Reservoir.
Eastside Collection SystemOU12Eastside Leachate Collection System and StormwaterCollection System associated with waste dumps south ofBingham Creek.
Bingham Canyon UnderflowOU16Groundwater plume originating in Bingham Canyonupstream of the Large Bingham Reservoir.
Bastian Area and CanalsOU17Bastian Sink area and nearby properties; may be mergedwith OU5.
Acid Mine DrainageOU18Includes all the drainages from underground mine portalsand tunnels; may be handled with other operable units inthe vicinity as appropriate.
Pine Canyon in Tooele CountyOU20Includes the International Smelter operations and wastepiles in Pine Canyon in eastern Tooele Valley; soils andgroundwater contamination issues downstream anddownwind from Pine Canyon may be associated with thisoperable unit.

Historic mining and ore milling practices in the area included dumping waste rock and tailingsintodrainages and streams. From the later part of the nineteenth century into the twentieth century,waterborne mine tailings migrated from the Oquirrh Mountains into area streams. This migrationresulted in contamination of Bingham Creek channel and an associated floodplain located between3200 West Street and 2700 West Street. Residential and commercial buildings have beenconstructed adjacent to contaminated channel segments; in the floodplain area, residences wereconstructed on top of contaminated materials. Removal of substantively contaminated materialsby EPA, KUC, and ARCO has been underway in Bingham Creek since about 1990 and will soonbe completed.

Mining and milling operations also leaked acidic waste waters into the drinking water aquiferinsouthwest Salt Lake County. Plumes with high sulfate concentrations have spread eastward fromthe mining area and associated evaporation ponds. In response to private well contaminationproblems, KUC has an ongoing program for providing alternative drinking water supplies forresidences with contaminated water supply wells.

Public Health Evaluation Methodology and Scope--Overview

ATSDR staff members evaluated public health implications through a sequential process thatconsiders contaminant concentrations, plausible human exposure pathways, health concernsexpressed by community members, and plausibility of related carcinogenic andnoncarcinogenichealth effects.

Evaluations included a visit to the operable units(1) and site vicinity to help ATSDR staff membersdevelop an understanding of the geographic, physical, and demographic settings and therelationships between sources of contaminants and the people living and working nearby. Exposure evaluations considered multiple contaminant origins, including the following:

  • Process equipment contaminant releases to ambient air and subsequentdeposition onsurface soils,
  • Process unit and waste contaminant releases to groundwater,
  • Undefinable sources, and
  • Naturally occurring metals in environmental media.

Those evaluations and observations helped investigators to identify community members thatmight experience exposure. They used that information, together with environmental samplingdata, in further evaluations to decide whether exposures are likely to have any associated publichealth implications. Further description of major components of the evaluation process is inAppendix C.

The key exposure situations and the public health classification for each are listed in Table 2.

Table 2.

KEY EXPOSURE SITUATIONS AND THEIR PUBLIC HEALTH HAZARD CATEGORIES
Exposure SituationPublic Health Classification
Upper Bingham Creek Soils
4800 west to 3200 West
(OU1)
No apparent public health hazard
Bingham Creek Floodplain Soils
3200 West to 2700 West
(OU1)
For present and future site conditions,
no apparent public health hazard
(Some areas may have posed a public health hazard prior to removal and cleanup.)
Lower Bingham Creek Soils
2700 West through Brookside Trailer Court*
(OU1)
For present and future site conditions,
no apparent public health hazard
(Some areas may have posed a public healthhazard prior to removal and cleanup.)
Copperton Soils
(OU10)
No apparent public health hazard
Butterfield Creek Soils
(the floodplain portion of OU3)
Past and future public health hazard, nofuture public health hazard anticipated afterremoval is complete. (Kennecott sponsoredhealth study underway may determine extentof exposure)
SWSLC Groundwater
(OU2)
Past public health hazard
(The drinking water problems have beenmitigated by provision of alternative water)
Pine Canyon Groundwater
(groundwater from OU20)
Insufficient data to classify hazard
(indeterminate public health hazard)
* EPA has not included the segment from the trailer court tothe Jordan river in this operableunit at this time. EPA staff members advise that the segment will be examinedlater.

Exposure situations were identified for operable units 1, 2, 10, 20, and the Butterfield Creekportion of OU3. Operable units 4, 6, 7, 11, 12, 16, 17, 18, and the Butterfield Mine portion ofOU3 were excluded from further evaluation because the community has no or very limitedaccess, and any exposures that might occur to workers at those operable units (e.g., employeesand contractors) or visitors would be within the jurisdiction of state and federal occupationalhealth agencies.

This public health assessment focuses on six of the seven exposure situations summarized inTable 2. We do not have sufficient information at this time to make a public healthdeterminationfor one of the exposure situations listed ( Pine Canyon Groundwater). Preliminary reports forPine Canyon groundwater are unavailable for review. ATSDR will make a public healthdetermination after reviewing additional information anticipated from EPA and UDEQ.

In addition to those situations listed in Table 2, ATSDR has evaluated sampling and removalinformation and potential health consequences for properties at the intersection of 3200 West and9000 South, where materials excavated from the creek may have been deposited. Theseproperties are not described further because we concluded that there are not likely to have beensignificant human exposures. Bingham Creek from its source to 4800 West is also excludedbecause, within that reach, it traverses industrial- and municipal-owned properties wherecommunity members have no or very limited access. Likewise, Bingham Creek from theBrookside Trailer Court to the Jordan River is not part of the operable unit and has not beenaddressed; EPA staff members advised ATSDR that the agency plans to consider that segmentlater.

EVALUATION OFCONTAMINANTS IN SOIL

In this portion of the Kennecott Utah Copper (KUC) South public health assessment, weevaluatethe possible health impacts of five exposure situations (three along Bingham Creek, Coppertonsoils, and Butterfield Creek soils) involving soil contaminants. Table 3 summarizes the results of these evaluations.

We divide the segments of Bingham Creek that go through residential areas into threeexposuresituations: upper channel soils, floodplain soils, and lower channel soils. For the Bingham Creeksituations, the term "soils" applies to any combination of soil, sediment, or tailings. The upperchannel soil exposure situation extends from 4800 West Street to 3200 West; there, the streambed is mostly channelized (i.e., the stream bed typically is well below ground level). Thefloodplain soil exposure situation is located between 3200 West and 2700 West. There, thestream bed (now mostly contained in a culvert) has been at about the same level as thesurrounding terrain (i.e., the creek is in a floodplain). The lower channel soil exposure situationextends from 2700 West through the Brookside Trailer Court; there, the steam bed is largelychannelized.

As previously mentioned, Bingham Creek from the Brookside Trailer Court to the JordanRiver isnot part of the operable unit and has not been addressed. The majority of the properties in thisstretch of Bingham Creek appear to be agricultural with very limited opportunity for currenthuman exposure. The Agency for Toxic Substances and Disease Registry (ATSDR) will addressthis segment if additional investigations by the Environmental Protection Agency (EPA) or theUtah Department of Environmental Quality (UDEQ) indicate significant potential for adversehuman health problems.

The Copperton soil exposure situation is the community of Copperton. For this situation, theterm "soils" has been used for any combination of soil and tailings. The Butterfield Creekexposure situation is in the Herriman community area.

ATSDR does not consider the Bingham Creek or Copperton soils exposure situations tobeongoing public health hazards. The Bingham Creek situations may have been public healthhazards in past. Highly contaminated soils are currently being removed at the Butterfield Creekexposure situation. Until removal is complete and follow up studies, such as the health studysponsored by Kennecott Corporation, the Butterfield Creek exposure situation is considered acurrent public health hazard, as well as, a past public health hazard.

Table 3.

EXPOSURE TO SOIL CONTAMINANTS
SituationContaminantsExposed
Population
Route of
Exposure
Frequency of
Exposure
Public Health
Classification
Upper Bingham
Creek Channel
Arsenic Cadmium
Lead
1,100 residentswithin 500meters of creek(1990)ingestionNever to Daily For present and future,
no Apparent PublicHealth Hazard
Bingham Creek
Floodplain Area
Arsenic Cadmium
Lead
332 residentswithin 500meters of creek(1990)IngestionSeldom toDailyFor present and future,
no apparent publichealth hazard
Lower Bingham
Creek
Channel
Arsenic Cadmium
Lead
980 residentswithin 500meters of creek(1990)IngestionSeldom toDailyFor present and future,
no apparent publichealth hazard
CoppertonArsenic Cadmium
Lead
550 residentsIngestionSeldom toDailyNo apparent publichealth hazard
Butterfield CreekArsenic, Lead120 residents
(1997 estimate)
IngestionSeldom toDailyPast and current publichealth hazard

Route ofexposure refers to how people might come in contact with contaminated soils. For theexposure situations listed in Table 3, individuals, primarily children, were probably exposed to thesurface soils via incidental consumption and skin contact with the soil on hands and food items,mouthing of objects, or the ingestion of nonfood items (pica). All children mouth or ingestnonfood items to some extent. The degree of pica behavior varies widely in the population and isinfluenced by nutritional status and the quality of care and supervision. Groups that are atincreased risk for pica behavior are children aged 1 to 3 years old, children from families of lowsocioeconomic status, and children with neurologic disorders (e.g. brain damage, epilepsy, andmental retardation).

A. Background

Bingham Creek Soil Exposure Situations

Bingham Creek originates in the Bingham Canyon (in the Oquirrh Mountains) (Figure 1) andis the primary natural drainage from the mine district. The creek flowed freely to the Jordan Riveruntil about 1853, when it was dammed or diverted to accommodate many different mining andprocessing enterprises. Before the 1930s, the entire runoff from the canyon watershed dischargedinto the natural Bingham Creek drainage. Historic mining and processing operations dischargedconsiderable quantities of tailings into the waterway. Some of those tailings deposited within thechannel, some flowed (via flooding) onto properties beyond the channel, and some dischargedinto the Jordan River. More recently, Kennecott Corporation (Kennecott) has been controllingmine and processing wastes, and the Bingham Reservoir and other control structures on thecompany's property now capture canyon flow and recycle it to help fulfill operational water needs. Presently, the creek channel downstream from the reservoir receives random inflow of snow melt,storm runoff, and irrigation water and is typically dry for most of its length (1).

Copperton Soil Exposure Situation

Copperton is on the north side of Bingham Creek, on the lower flank of Bingham Canyon,approximately 2 miles west of State Route 111 (Figure 2A). ATSDR staff members noted aconveyor transfer station at the west edge of town, and a segment of covered conveyor closelyparallels the west boundary of the community. Historic documents provide information thatsuggests tailings have been deposited in and around Copperton. An author described constructionin 1928 of homes that required installation of pillars to provide adequate foundation support. EPA has confirmed tailings on the east side of town through interviews with several current andformer residents. In 1980, 16 homes removed from Lark were relocated to that area (2). Acontinuous chain-link fence along the east, south, and west edges of town separates thecommunity from Kennecott property, nearby process facilities, and Bingham Creek.

Butterfield Creek Soil Exposure Situation

Butterfield Creek carried sediments from the mining areas within Butterfield Creek Canyon,located in the southern Oquirrh Mountains, eastward through the community of Herriman, Utah. Sediments containing elevated levels of lead and arsenic were deposited along the stream channel,banks, and associated irrigation canals in the community area. EPA and Kennecott Corporationare currently sampling and removing highly contaminated soils within the Herriman community. The extent of contamination is still being characterized.

B. Environmental Contamination

Soil contaminants were selected for evaluation in this public health assessment primarily bycomparison of contaminant levels with values for noncarcinogenic and carcinogenic endpoints. Appendix C contains a full description of the process for selecting contaminants for evaluation.

Upper Bingham Creek Channel Soil Exposure Situation

Arsenic, cadmium, and lead were identified as key contaminants.



Table 4.

summarizes pre- and post-removal concentrations.
TABLE 4 - KEY CONTAMINANTS FOR
UPPER CHANNEL SOIL EXPOSURE SITUATION1
ContaminantRange of pre-removallevels in milligrams perkilogramsMaximum post-removallevels in milligrams perkilogram
Arsenic19 - 88075 -100
CadmiumND - 5.4no data
Lead200 - 54,000500 - 1,000
1 There is a more detailed list of concentrations ofcontaminants intables D1 & D2 in Appendix D. Appendix C contains a description ofthe process for selecting contaminants.
Non-Detect is abbreviated as ND.

Contaminant Levels Prior to Removal of Contaminated Soil

From 4800 West to where Bingham Creek intersects 9000 South, contamination wasessentiallyconfined to the area within the creek banks. Within the banks, concentrations of lead and arsenicwere as much as 54,000 and 630 parts per million (ppm) respectively in materials visuallyidentified as tailings and were elevated for many other samples (Table D1, Appendix D, references3-11). On adjacent properties (e.g., a ball field, a park, a bike path, and a residential yard), leadand arsenic concentrations were somewhat elevated for some samples; for most samples,however, the metals were in the range of expected backgroundlevels.

From where Bingham Creek intersects 9000 South to where it intersects 3200 West,contaminants are found in the channel, and formerly occurring high waters also distributedcontaminants beyond the banks at some locations. Maximum concentrations in the channel and inthe off-channel "plumes" ranged from 20,000 to 20,700 ppm for lead and 570 to 880 ppm forarsenic (Table D2, Appendix D, references 3, 5-8). A few samples taken on residential propertiesshowed somewhat elevated lead and arsenic; for most samples, however, concentrations were inthe range of expected background levels.

Contaminant Levels after Removal of Contaminated Soil

Review of removal protocols and sampling information indicates that post-removal lead andarsenic levels are less than 1,000 and 100 ppm respectively. Kennecott staff members report thatfor most samples lead levels were below 500 and arsenic levels were below 75 ppm.

Bingham Creek Floodplain Soil Exposure Situation

Arsenic, cadmium, and lead were identified as key contaminants.

Table 5 summarizes pre- and post-removal concentration data.

Contaminant Levels Before Removal of Contaminated Soil

Between 3200 West and 2700 West, floods distributed tailings across a broad area. TheJordanView Estates and Fahnian Ranchettes subdivisions and the IRECO/Rigby property (undevelopedland) immediately north of Jordan View Estates were substantively affected. On subdivisionproperties, lead and arsenic concentrations were as much as 17,000 and 410 ppm, respectively(Table D3, Appendix D, references 6,9,12,13), and many samples showed elevatedconcentrations. On the IRECO/Rigby property, lead and arsenic levels ranged up to 11,000 and251 ppm respectively. Farther north, a small segment of the Meadow Greens Subdivision,including a playground, was moderately affected. At the Bluegrass Subdivision still farther north,a few lots had concentrations slightly above expected background levels and might also have beenaffected.

Table 5.

KEY CONTAMINANTS FOR FLOODPLAIN SOIL EXPOSURE SITUATION1
ContaminantRange of pre-removallevels in milligrams perkilograms Maximum post-removal levels inmilligrams per kilograms
ArsenicND - 410Residential: 100
(100 is removal target level; removalis ongoing)
IRECO property: 75
CadmiumND - 20.6no data
LeadND - 17,300Residential: 1,100
(1,100 is removal target level;removal is ongoing)
IRECO property: 2,000
1 There is a more detailed list of concentrations ofcontaminants in Table D3 inAppendix D. Appendix C contains a description of the process for selectingcontaminants.
Non-Detect is abbreviated as ND.

Contaminant Levels After Removal of Contaminated Soil

Early removals within the subdivisions targeted areas where sampling showed lead levels weregreater than 2,500 ppm. The final removal phase, which is expected to be completed bymid-1996, reevaluates all residential properties for new removal actions. This phase is expectedtoachieve average soil concentrations in the surficial zone of 1,100 ppm or less for lead and 100ppm or less for arsenic. The current program includes residential properties where removals hadbeen conducted earlier, residential properties that had not been sampled previously, and residentialproperties for which access could not be obtained during earlier phases.

Sampling conducted after removal at the undeveloped IRECO/Rigby property showed leadlevelsin surface materials to about 2,000 ppm and arsenic levels to about 75 ppm.

Bingham Creek Lower Channel Soil Exposure Situation

Arsenic and lead were identified as key contaminants.

Table 6 summarizes pre- and post-removal concentration data.

Table 6.

KEY CONTAMINANTS FOR LOWER CHANNEL SOIL EXPOSURE SITUATION1
ContaminantRange of Pre-removallevels in milligrams perkilogramMaximum post-removal levels inmilligrams per kilogram
ArsenicND - 80most less than 90;
2 ranged up to 145
LeadND - 7,1292,000
1 There is a more detailed list of concentrations ofcontaminants in Table D4in Appendix D. Appendix C contains a description of the process forselecting contaminants.
Non-Detect is abbreviated as ND

Contaminant Levels Before Removal of Contaminated Soil

Downstream from 2700 West for 1,700 feet to a long culvert (which then encloses the creek),off-channel sampling on adjacent residential properties has shown lead present in surficialmaterials toas much as 1,365 ppm and arsenic to 50 ppm (Table D4, Appendix D [6]); most samplesexceeded the expected range of background levels. No samples are reported within the creekchannel within that reach.

From the downstream end of the culvert to Sugar Factory Road, a few samples taken withinthechannel near that road showed the surficial materials contained lead to about 3,400 ppm; thosesamples were not analyzed for arsenic. On nearby residential properties, lead was found to about800 ppm and arsenic to 50 ppm; about half of the samples exceeded the expected range ofbackground levels.

Within the channel from Sugar Factory Road to Redwood Road, lead was found in samples atlevels up to about 7,100 ppm; all samples exceeded the expected background levels (Table D4[6]). Arsenic data are not available for the channel samples. On adjacent and nearby residentialand undeveloped property, lead in surficial materials was up to about 1,800 ppm and arsenic to 80ppm. More than half of the samples exceeded the expected range of background levels.

In Brookside Trailer Court, sampling of channel materials showed lead present at levels up toabout 4,400 ppm; all samples exceeded the expected range of background levels (Table D4[6]). No arsenic analyses were performed on those samples. On the adjacent residential properties,lead was present in surface materials at concentrations as high as 2,000 ppm and arsenic to60 ppm. Lead exceeded the expected range of background levels for about half of thesamples. At the playground, lead occurred in surface materials at levels up to 200 ppm and arsenic to 20ppm; these are well within background levels.

Contaminant Levels After Removal of Contaminated Soil

Lead levels shown in surface materials after removal within this segment were less than 2,000ppm; arsenic levels were essentially less than 90 (2 samples ranged up to 145).

Copperton Soil Exposure Situation

Arsenic, cadmium, copper, and lead are key contaminants.

Essentially all samples of surface soils taken on several residential properties located invariousparts of the community show lead (maximum 253 ppm) to be close to or within the range ofexpected background levels (Table D5, Appendix D, references 14-16). For arsenic (maximum54 ppm), the concentrations for essentially all samples taken in residential areas exceed expectedbackground (based on arsenic being about 3% of lead values). Copper in one sample (maximum2,020 ppm) seems quite elevated and is clearly much more than is typically found in western soils. Values for metals at the playground and middle school seem to be within the range of expectedbackground concentrations.

Table 7.

KEY CONTAMINANTS FOR COPPERTON SOIL EXPOSURE SITUATION1
ContaminantRange of levels in milligrams per kilogram
ArsenicND -53.8
CadmiumND - 8.8
CopperND - 2,020
LeadND - 253.4
1 There is a more detailed list concentrations of contaminantsin TableD5 in Appendix D. Appendix C contains a description of the processfor selecting contaminants.
Non-Detect is abbreviated as ND

Butterfield Creek Soil Exposure Situation

Arsenic and lead are key contaminants.
Contaminant Levels Before Removal of Contaminated Soil
As of May, 1997, 5,000 soil samples had been analyzed, of which 1,000 were surface soils in theHerriman community. Bureau of Reclamation (BOR) data summary indicates that 84 propertieshave surface soil lead concentrations greater than 1200 ppm with some averaging as high as 4,000ppm of lead (32). Arsenic concentration is residential surface soils was reported as high as 236ppm with 6 residential properties having arsenic levels in the surface soils greater than 150 ppm.

Table 8.

KEY CONTAMINANTS FOR BUTTERFIELD CREEK SOIL EXPOSURE SITUATION1
ContaminantRange of Pre-removal levels in parts per million insurface soils
Arsenic23 - 339
Lead35 - 27,988
1 Appendix C contains a description of the process forselecting contaminants.
Source: July 1997 EPA Region VIII Endangerment Assessment for Herriman,Utah

C. Exposure Pathway Analyses

Bingham Creek Upper Channel Soil Exposure Situation

Ingestion of key contaminants in the Upper Channel Soil Exposure Situation occurred inthe pastwhenever residents went into the channel area of the creek. However, this likely happened onlyoccasionally because no homes are actually in the channel area and contamination was limitedto the channel. Current exposures are to much lower levels of contaminants.

Based on an estimate of residential properties (count of homes), indications are that about1,100people live within 500 meters of Bingham Creek in the area from 4800 West to 3200 West. The1990 census indicates the population is about 94% white; a small percentage are Hispanic.

Below 4800 West, for about 6,800 feet, the channel bottom is 25 to 40 feet lower than thesurrounding topography. Lot boundaries do not extend into the channel (17). For the next 3,100feet, to about 9000 South, the channel bottom is 10 to 15 feet below surrounding topography andsome lot boundaries extend into the channel. There are many homes near the creek within thesetwo reaches. Between 9000 West and 3200 West, the channel is shallower and portions haveflatter bank slopes. There are few residences between 9000 South and 3200 West, and none areclose to the creek. The channel 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 showschildren use the channel as a recreational area. Children also have been observed in thechannel (3).

However, daily exposure of children under 6 years old is unlikely because few residentialyardsactually extend into the channel. It is assumed that children under 6 would not routinely beallowed to leave their yards and go into the channel.

Before removal activities, lead concentrations ranged from 200 to 54,000 ppm. The arseniclevelranged from 19 to 880 ppm. After removal of contaminated soil, lead levels are below 1,000 ppmand arsenic levels below 100 ppm.

Bingham Creek Floodplain Soil Exposure Situation

Residents may have ingested lead, arsenic, and/or cadmium in the past in the manyresidentialyards with contaminated soil in the area described as Floodplain Soil Exposure Situation. Current levels of contaminants are much lower on properties where removals have beenconducted in recent years. After the ongoing final removal is completed in 1996, exposures onall residential properties are expected to be to substantively lower levels of contaminants. Pre-removal exposures on the undeveloped IRECO/Rigby property may have involved highconcentrations but probably occurred infrequently. Current exposures, following removal, areat much lower levels of contaminants and are likely to continue to occur infrequently, unless the property is developed for residences.

Based on an estimate of residential properties (count of homes), indications are that about332people live within 500 meters of Bingham Creek in the area from 3200 West to 2700 West. The1990 census indicates the population is about 94% white; a small percentage are Hispanic.

The creek now flows in a culvert through residential areas. Before culvert installation, thecreekbed was quite shallow, and flood conditions that occurred before the Bingham Reservoir systemwas in place resulted in extensive contaminant deposition in areas beyond the creek. Unlike theupper channel exposure situation, much of the population in the floodplain situation area has hadthe opportunity for daily contact with soils containing elevated levels of arsenic and lead at theirresidences.

Before removal activities, lead concentrations ranged from not detected to 17,300 ppm, andarsenic ranged up to 410 ppm. The ongoing final removal is targeted to reduce lead to below1,100 and arsenic to below 100 ppm in surface soils on all residential properties. Post-removal levels in surface soils on the undeveloped IRECO property range up to 2,000 ppm for lead and 75for arsenic.

Bingham Creek Lower Channel Soil Exposure Situation

Ingestion of key contaminants in the Lower Channel Soil Exposure Situation may haveoccurredin the past in those yards contaminated with lead and arsenic. Current exposures are to muchlower levels of contaminants in the areas where removal has occurred.

Based on an estimate of residential properties (count of homes), indications are that about980people live within 500 meters of Bingham Creek in the area from 2700 West to the Jordan River. The 1990 census indicates the population is about 94% white; a small percentage are Hispanic.

The opportunity to have daily contact with soil contaminated with arsenic and lead in thelowerchannel area appears to be greatest on residential properties within the first 1,700 feet below 2700West and in Brookside Trailer Court. ATSDR staff members saw that, from 2700 West to SugarFactory Road (Figure 2B), the first 1,700 feet of creek has residences on one side of the channeland 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 onthe southwest by residential properties. ATSDR investigators observed that a high fence ispresent between the channel and those residences. From Sugar Factory Road to BrooksideTrailer Court (1,500 feet), which is on the eastern side of Redwood Road, the channel crossesproperties that are predominantly undeveloped. Within the trailer court, ATSDR staff memberssaw that the channel segment (about 1,500 feet) is narrow, shallow, and very close to manyhomes.

Prior to removal activities, lead concentrations in the channel ranged from not detected to7,129ppm. There was no analysis for arsenic in channel samples. The highest levels where dailyexposure is probable were for samples obtained within the Brookside Trailer Court. Leadoccurred there as high as 2,003 ppm on a residential property. Lead levels within the channelthere were as much as 4,365 ppm. Arsenic levels there were up to 60 ppm.

Copperton Soil Exposure Situation

Ingestion of the key contaminants in the Copperton Soil Exposure Situation may haveoccurredin the past in those yards contaminated with lead, copper, cadmium, and arsenic.

ATSDR staff members' review of census block data for the Copperton vicinity indicates thatthetown has a total population of about 550 and about 40 children age 5 or less (19). Thepopulation is about 97% white. Sampling showed arsenic up to 54 ppm, cadmium to 9 ppm,copper to 2,020 ppm, and lead to 254 ppm. Although there were only a few samples taken, allsoils in Copperton are expected to contain those contaminants to at least background levels.

Butterfield Creek Exposure Situation

Ingestion of key contaminants in the Butterfield Creek Exposure Situation may haveoccurred inthe past and may still occur on residential properties with high concentrations of arsenic andlead until current removal and remedial actions by Kennecott and EPA are complete.

Based on the information provided in the EPA Endangerment Assessment (32), 30 residentialproperties in the Herriman community are contaminated with high levels arsenic and lead in thesurface soils. Assuming an average of 4 persons per household, 120 people are estimated to bepotentially exposed to arsenic and lead.

Before the current removal actions began, the concentrations of lead in residential surfacesoilsranged from 35 to 27,988 ppm for lead and 23 - 339 ppm for arsenic.

D. Public Health Implications

Typically, the toxicological evaluation in a public health assessment is a comparison of theexposure dose (i.e., theamount of a substance individuals in an exposure pathway are exposed todaily) with appropriate health guidelines for carcinogenic and non-carcinogenic effects. Therewere health guidelines for non-carcinogenic and carcinogenic effects for arsenic andnon-carcinogenic effects for cadmium but no guidelines for copper or lead. Appendix E containsa description of the methodology for calculating exposure doses and cancer risk, along with theresults of those calculations (tables E1 - E5).

Blood Lead and Urine Arsenic Studies of Area Residents

Health surveys of Bingham Creek area residents were conducted in 1990 and 1993. In 1990,theUtah Department of Health tested the blood of 157 children and 12 adults from the BinghamCreek area for lead (20). None of the participants had a lead level above the Centers for DiseaseControl and Prevention's (CDC) concern level of 10 micrograms of lead per deciliter of blood(µg/dL). As indicated in the Utah Department of Health's report, the survey was limited inthat,"The population of this area (i.e., Bingham Creek) was not systematically sampled, and somepersons with higher blood lead levels may not have volunteered for testing."

In 1993, the University of Cincinnati conducted a study of Bingham Creek area childrenunder 6years old (less than 72 months old) (21-23). Overall, this investigation evaluated lead and arsenicconcentrations for residential soil and interior dust from 728 homes and blood lead and urinearsenic levels for 971 children under age 6 (22). As part of their study, University of Cincinnatiinvestigators identified the total number of children under 6 in the study area as 1,706, so about57 % of area children participated in the study (24).

The study found that 2 of 284 children, whom the investigators identified as being fromcontaminated areas, had blood lead levels above 10 µg/dL and 1 of 174 had urine arseniclevelsabove 20 µg/L. All the children under 6 in the Bingham Creek area (the specific area ofconcernwas identified by EPA) were identified and offered testing. However, because the main purposeof the study was to determine the mean blood lead level for children under 6 in the community,only a participation rate of 50% of the children under 6 was considered necessary. Therefore, itis possible that some areas or populations within the community could be over or underrepresented. An EPA comparison of results for residences included in this study withenvironmental sampling results indicates that there were about 75 properties with lead levelsabove 500 ppm from which no study participants were recruited (22).

ATSDR received a data set from the University of Cincinnati for the 284 children who lived inwhat were identified by EPA as contaminated areas (21). Our analysis identified mean andmaximum blood lead levels for children from the Bingham Creek upper channel exposure situationof 2.5 µg/dL and 7.1 µg/dL, respectively; for the Bingham Creek Floodplainsituation, the meanand maximum were 2.6 and 7.6 µg/dL; and for the Bingham Creek lower channel, the meanwas2.7 µg/dL and the maximum was 13.1 µg/dL. This study was conducted before theremovalaction in the upper channel area, but after the removals in the floodplain and lower channel areas.

Bingham Creek Upper Channel Soil Exposure Situation

It is very unlikely that ongoing exposures to arsenic, cadmium, and lead in upperchannel area soil will result in health effects in area residents.

Exposure to arsenic and lead before removal of contaminated soil from the upperchannelprobably did not result in health effects in area residents because exposure was not frequentenough. Few, if any, small children, had regular access to the channel. This conclusion isfurther supported by ATSDR's analysis of the University of Cincinnati which identified meanand maximum blood lead levels (2.5 and 7.1 µg/dL) which were below the Center forDiseaseControl and Prevention (CDC) action level of 10 µg/dL.

Post-Removal Exposures

Post-remediation sampling data indicate that it is very unlikely that ongoing exposures toarsenic,cadmium, and lead in upper channel area soil will result in health effects in area residents.

Pre-Removal Exposure

Arsenic

While the adult, child, and pica child exposure doses for the maximum pre-removal arsenicconcentration in soil exceeded the health guideline for arsenic, further evaluation indicates that itis unlikely that these exposures will result in adverse health effects. The maximum exposuredoses for adults, children, and pica children vary from about equal to about 29 times greater thanthe lowest observed adverse health effect level (LOAEL) of 0.014 milligrams per kilogram perday (mg/kg/day) for humans (21). However, the LOAEL is based on long-term exposure toarsenic in water, not soil. Arsenic appears to be less available in soil than in water. In addition,these exposure doses are for daily exposures to the maximum arsenic soil level. Few, if any,individuals were exposed daily because people would have to travel to encounter contaminatedsoil; few residential yards extend into the channel. We assumed that small children would not beallowed to go into the channel very often or for very long. Given those two factors, it is unlikelythat health effects would occur. This conclusion is further supported by ATSDR's analysis of theUniversity of Cincinnati which identified mean and maximum urine arsenic levels (7.8 and 8.7 µg/L) well below the maximum background level of 20 µg/L (21).

Arsenic is considered a known carcinogen, based on human epidemiological studies (25). Themaximum arsenic concentrations found in the upper channel soil would present an increasedlifetime risk of cancer if exposures were daily for 70 years. However, daily exposure to themaximum arsenic levels is unlikely because the most-contaminated soil has been removed, andmost of the homes in the upper channel area were probably built in the last 20 years. A morereasonable "worst case" estimate is 100 milligrams a week for a 10 years duration. We conclude be no apparent increased risk of cancer if the average ingestion of soil were 100 milligrams aweek and for 10 years.

Cadmium

The pica child exposure dose for cadmium exceeded the health guideline, but furtherevaluationindicates that these exposures will not result in health effects. The exposure dose for pica childrenis about 2½ times less than the LOAEL of 0.0075 mg/kg/day (22). Also, as discussed in theArsenic Section, it is unlikely that exposure was daily. Given those factors, it is unlikely thathealth effects would occur.

Animal data indicate that cadmium is a probable human carcinogen (26). However, there isnocancer slope factor (see Appendix E for explanation of term) for cadmium, so it was not possibleto evaluate carcinogenic risk. In addition, the data indicate that cadmium probably causes cancerin animals only through inhalation and not throughingestion, which appears to be the principalroute of exposure in the Bingham Creek area.

Lead

It is unlikely that health effects would have resulted from the infrequency of exposure ofchildrenunder age 6. As discussed earlier, few, if any, small children, had regular access to the channel. This conclusion is further supported by ATSDR's analysis of the University of Cincinnati whichidentified mean and maximum blood lead levels (2.5 and 7.1 µg/dL) which were below theCenterfor Disease Control and Prevention (CDC) action level of 10 µg/dL (21).

Animal data indicate that lead is a probable human carcinogen (27). However, there is nocancerslope factor for lead, so it was 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 at Bingham Creek.

Bingham Creek Floodplain Soil Exposure Situation

It is unlikely that ongoing exposures to arsenic, cadmium, and lead in the floodplain areasoilwill result in health effects in area residents. Arsenic, cadmium, and lead soil concentrationsare too low to result in noncarcinogenic effects or a significant increase in risk for cancer.

Exposure to arsenic before removal of contaminated soil from the floodplain area mayhaveresulted in a moderate increase in an individual's lifetime risk of cancer. Also, lead levels atleast some locations may have been high enough to result in health effects if children under 6years were exposed daily. Health effects due to exposure to cadmium are very unlikely because5 grams of contaminated soil would have to ingested for over 50 years before health effectswould occur.

Post-removal Exposures

It is unlikely that ongoing exposures to arsenic, cadmium, and lead in the areas of thefloodplainwhere contaminated soil has been removed will result in health effects, because levels of arsenic,cadmium and lead are too low. This conclusion is further supported by ATSDR's analysis of theUniversity of Cincinnati which identified a mean urine arsenic level (4.6 µg/L) well belowthemaximum background level of 20 µg/L and a mean blood lead level (2.5 µg/dL)below CDC's action level of 10 µg/dL(21).

Pre-Removal Exposure

Arsenic

While the adult, child, and pica child exposure doses for the maximum pre-removal arsenicconcentration in soil exceeded the health guideline for arsenic, further evaluation indicates that itis unlikely that these exposures will result in noncarcinogenic health effects. The maximumexposure doses for adults, children, and pica children vary from about 24 times lower to 14 timesgreater than the LOAEL of 0.014 mg/kg/day for humans (25). However, the LOAEL is based onlong-term exposure to arsenic in water, not soil. Arsenic appears to be less available in soil thanin water. Given this factor, it is unlikely that health effects would occur.

Human epidemiological studies indicate that arsenic is a carcinogen (25). The maximumarsenicconcentrations found in the floodplain soil would present a low increased lifetime risk of cancerassuming that maximum exposure was 30 years. It appears that residential development of thisarea began in the 1960s.

Cadmium

The pica child exposure dose for the maximum soil cadmium concentration exceeded thehealthguideline. The exposure dose for pica children is about 1.3 times greater than the LOAEL of0.0075 mg/kg/day. The LOAEL is from a study of a population in Japan exposed for many yearsto cadmium in drinking water (26). However, health effects appear very unlikely based on areview of how cadmium causes damage to the kidney. The study from Japan and other studies ofhuman exposures to cadmium indicate that damage occurs only after prolonged exposure. It isestimated that 2,000 mg of cadmium have to be ingested before the kidney is harmed. At themaximum concentration of cadmium in the floodplain exposure situation (20.6 ppm), it wouldtake over 50 years for someone to ingest enough soil to result in a total cadmium exposure of2,000 mg. This is assuming that 5 grams of contaminated soil would be ingested daily. Thus,cadmium-related health effects are very unlikely.

Animal data indicate that cadmium is a probable human carcinogen (26). However, there isnocancer slope factor for cadmium, so it was not possible to evaluate carcinogenic risk. In addition,the data indicate that cadmium probably causes cancer in animals only through inhalation and notthrough ingestion, which appears to be the principal route of exposure in the Bingham Creek area.

Lead

The levels of lead in floodplain soil could have resulted in health effects in children under age6. Soil lead levels of 1,000 mg/kg could increase concentrations in blood from 0.7 to 68µg/dL, withan average increase of 4-5 µg/dL (27). This wide range resulted from the presence ofdifferentsources of lead, exposure conditions, and exposed populations. A recent EPA evaluation of the1993 University of Cincinnati Exposure Study described on page 16 indicates that contaminatedBingham Creek soil and house dust can elevate blood lead levels (22). The health effectsassociated with such an increase would depend partly on the existing body burden of lead. Exposure to lead causes a wide range of effects. The level of lead in blood is a good measure ofrecent exposure and also correlates well with health effects. Children are especially sensitive tolead, and many of its effects are observed at lower concentrations in children than in adults.Levels of 10 µg/dL and perhaps lower in children's blood have been associated with smalldecreases in IQ and slightly impaired hearing and growth (27).

Animal data indicate that lead is a probable human carcinogen (27). However, there is nocancerslope factor for lead, so it was 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 at Bingham Creek.

Bingham Creek Lower Channel Soil Exposure Situation

It is possible that the highest lead levels found within the channel from the first 1700feet of thelower channel area and the Brookside Trailer Court could result in health effects in childrenunder age 6 if they were exposed daily. It is unlikely that ongoing exposures to arsenic and leadin lower channel area soil will result in health effects in area residents. Arsenic and lead soilconcentrations are too low to result in noncarcinogenic effects or a significant increase in risk for cancer.

Post-Removal Exposure

It is unlikely that ongoing exposures to arsenic and lead in the areas of the lower channel,wherecontaminated soil has been removed, will result in health effects, because levels of arsenic,cadmium and lead are too low. This conclusion is further supported by ATSDR's analysis of theUniversity of Cincinnati which identified a mean urine arsenic level (4.6 µg/L) well belowthemaximum background level of 20 µg/L and a mean blood lead level (2.7 µg/dL)below CDC's action level of 10 µg/dL(21).

Pre-Removal Exposure

Arsenic

While the child and pica child exposure doses for the maximum arsenic concentration in soilexceeded the health guideline for arsenic, further evaluation indicates that it is unlikely that theseexposures will result in noncarcinogenic health effects. The maximum exposure doses for childrenand pica children vary from about 7 times lower to 3 times greater than the LOAEL of 0.014mg/kg/day for humans (25). However, the LOAEL is based on long-term exposure to arsenic inwater, not soil. Arsenic appears to be less available in soil than in water. Given this factor, it isunlikely that health effects would occur.

Human epidemiological studies indicate that arsenic is a known carcinogen (25). The arsenicconcentrations found in the lower channel area do not represent a significant increased lifetimerisk of cancer.

Lead

The highest levels of lead found within the creek channel from the first 1,700 feet of this area(3,393 ppm) and the Brookside Trailer Court (4,365 ppm) may have resulted in health effects inchildren under age 6, if regular exposure occurred.

Soil lead levels of 1,000 mg/kg could increase lead concentrations in blood from 0.7 to 68µg/dLwith an average increase of 4-5 µg/dL (27). This wide range resulted from the presence ofdifferent sources of lead, exposure conditions, and exposed populations. The health effectsassociated with such an increase would depend partly on the existing body burden of lead. Exposure to lead causes a wide range of effects. The level of lead in blood is a good measure ofrecent exposure and also correlates well with health effects. Children are especially sensitive tolead, and many of its effects are observed at lower concentrations in children than in adults. Levels of 10 µg/dL and perhaps lower in children's blood have been associated with smalldecreases in IQ and slightly impaired hearing and growth (27).

Animal data indicate that lead is a probable human carcinogen (27). However, there is nocancerslope factor for lead, so it was 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 at Bingham Creek.

Copperton Soil Exposure Situation

It is unlikely that exposures to arsenic, cadmium, copper, and lead in the soil tested inCopperton will result in health effects in area residents. Arsenic, cadmium, copper, and lead soilconcentrations are too low to result in noncarcinogenic effects or a significant increase in the riskof cancer.

Arsenic

While the child and pica child exposure doses for the maximum arsenic concentration in soilexceeded the health guideline for arsenic, further evaluation indicates that it is unlikely that theseexposures will result in noncarcinogenic health effects. The maximum exposure doses for childrenand pica children vary from about 14 times lower to 2 times greater than the LOAEL of 0.014mg/kg/day for humans (25). However, the LOAEL is based on long-term exposure to arsenic inwater, not soil. Arsenic appears to be less available in soil than in water. Given this factor, it isunlikely that health effects would occur.

Human epidemiological studies indicate that arsenic is a known carcinogen (25). The arsenicconcentrations found in the Copperton yards tested do not present an increased lifetime risk ofcancer.

Cadmium

The pica child exposure dose for cadmium exceeded the health guideline, but furtherevaluationindicates that these exposures will not result in health effects. The exposure dose for pica childrenis about 2 times less than the LOAEL of 0.0075 mg/kg/day (26).

Animal data indicate that cadmium is a probable human carcinogen (26). However, there isnocancer slope factor for cadmium, so it was not possible to evaluate carcinogenic risk. In addition,the data indicate that cadmium probably causes cancer in animals only through inhalation and notthrough ingestion, which appears to be the principal route of exposure in the Bingham Creek area.

Copper

There was no health guideline for copper, but a comparison of the exposure doses to aLOAELand a consideration of the metabolism of copper inhumans indicates that health effects areunlikely (28). The adult and child exposure doses for the highest copper concentrations from soilsamples are about 19 and 1.4 times lower, respectively, than a LOAEL of 0.06 mg/kg/day, whichis based on exposures of humans to copper in water. The exposure dose for pica children is about18 times greater than the LOAEL. However, all the other soil samples had copper concentrationsless than 500 ppm. Another factor in determining whether adverse health effects might occur isthat a large portion of the copper in soil is not available to be absorbed from the gastrointestinaltract into the bloodstream. In addition, the body has an effective mechanism to limit the amountof copper absorbed.

Copper is not considered a carcinogen (28).

Lead

While there is no health guideline for lead, a review of the literature indicates that themaximumsoil level of 253 ppm found in testing of some Copperton locations is too low to result in adversehealth effects (27).

Animal data indicate that lead is a probable human carcinogen (27). However, there is nocancerslope factor for lead, so it was 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 at Bingham Creek.

Butterfield Creek Exposure Situation
It is possible that the highest lead levels found in residential surface soils could result inhealtheffects in children under age 6 if they were exposed daily.

Pre-Removal Exposure

Arsenic

While the child and pica child exposure doses for the maximum arsenic concentration in soilexceeded the health guideline for arsenic, further evaluation indicates that it is unlikely that theseexposures will result in noncarcinogenic health effects. The maximum exposure doses for childrenand pica children vary from about 29 times lower to 12 times greater than the LOAEL of 0.014mg/kg/day for humans (25). However, the LOAEL is based on long-term exposure to arsenic inwater, not soil. Arsenic appears to be less available in soil than in water. Given this factor, it isunlikely that health effects would occur.

Human epidemiological studies indicate that arsenic is a known carcinogen (25). Themaximumarsenic concentrations found in the Butterfield Creek area do not represent a low increasedlifetime risk of cancer.

Lead

The highest levels of lead found in residential surface soils may have resulted in health effectsinchildren under age 6, if regular exposure occurred. The current health study in the Herrimancommunity may indicate if elevated blood lead levels are evident in children in the area.

Soil lead levels of 1,000 mg/kg could increase lead concentrations in blood from 0.7 to 68µg/dLwith an average increase of 4-5 µg/dL (27). This wide range resulted from the presence ofdifferent sources of lead, exposure conditions, and exposed populations. The health effectsassociated with such an increase would depend partly on the existing body burden of lead. Exposure to lead causes a wide range of effects. The level of lead in blood is a good measure of recent exposure and also correlates well with health effects. Children are especially sensitive tolead, and many of its effects are observed at lower concentrations in children than in adults. Levels of 10 µg/dL and perhaps lower in children's blood have been associated with smalldecreases in IQ and slightly impaired hearing and growth (27).

Animal data indicate that lead is a probable human carcinogen (27). However, there is nocancerslope factor for lead, so it was 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 at Butterfield Creek.

E. Conclusions, Recommendations, and Public HealthActions

ATSDR does not consider the Bingham Creek upper channel, floodplain, and lower channelandCopperton soil exposure situations to be current public health hazards. Until removal andremediation of residential properties are complete, the Butterfield Creek soil exposure situation is considered a current public health hazard.

Exposure to arsenic and lead before removal of contaminated soil from the Bingham Creekupperchannel probably did not result in health effects in area residents because exposure was notfrequent enough. Few, if any, small children, had regular access to the channel. This conclusionis further supported by ATSDR's analysis of the University of Cincinnati which identified meanand maximum blood lead levels (2.5 and 7.1 µg/dL) which were below the Center forDiseaseControl and Prevention (CDC) action level of 10 µg/dL.

Exposure to arsenic before removal of contaminated residential soils from the Bingham Creekfloodplain may have resulted in a moderate increase in an individual's lifetime risk of cancer. Also, lead levels at some locations may have been high enough to result in health effects ifchildren under 6 years old were exposed daily. Health effects due to exposure to cadmium arevery unlikely because 5 grams of contaminated soil would have to ingested for over 50 yearsbefore health effects would occur.

Lead levels in two segments of the lower channel soil exposure situation--the first 1,700 feet of the lower channel area and within the Brookside Trailer Court--may have been high enough to result in health effects if children under 6 years old were exposed daily.

Exposure to arsenic in Butterfield Creek Residential soils may have resulted in a low increase inan individual's lifetime risk of cancer. Lead levels in the residential surface soils in the ButterfieldCreek exposure situation may have been high enough to result in health effects if children under 6years old were exposed daily. The health study sponsored by Kennecott and performed byUniversity of Utah is designed to provide the information on presence of elevated blood leadlevels in the area.

No public health actions or recommendations were identified at this time.


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