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PUBLIC HEALTH ASSESSMENT

ASARCO INCORPORATED (GLOBE PLANT)
DENVER, DENVER COUNTY, COLORADO


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The tables in this section list the contaminants of concern. We evaluate these contaminants inthe subsequent sections of the Public Health Assessment and determine whether exposure tothem has public health significance. ATSDR selects and discusses these contaminants basedupon the following factors:

  • comparison of concentrations of contaminants on and off site with values for noncarcinogenic and carcinogenic endpoints,

  • sampling plan and field and laboratory data quality,

  • Comparison of on-site and off-site concentrations with background concentrations, if available, and

  • community health concerns.

In the data tables that follow under the On-site Contamination subsection and the Off-siteContamination subsection, the listing of a contaminant does not mean that it will cause adversehealth effects from exposures. Instead, the list indicates which contaminants will be evaluatedfurther in the Public Health Assessment. Once a contaminant has been identified in oneenvironmental media (e.g., groundwater), the contaminant's concentration in other environmentalmedia is evaluated for possible combined exposures above a comparison value. If those areidentified, that will be reported and evaluated further (20).

Comparison values used during the preparation of a public health assessment are compared tocontaminant concentrations in specific media on site and off site. Contaminants that exceedcomparison values are further evaluated in the Public Health Implication Section. Those valuesinclude Environmental Media Evaluation Guides (EMEGs) based on ATSDR's Minimal RiskLevels (MRLs) and are the estimated contaminant concentrations in water, soil, or air at whichthere is no noncarcinogenic health effects expected to occur at this or lower levels (GuidanceManual). Reference Dose Media Evaluation Guide (RMEGs) are the same as EMEGs, exceptthat they are based on EPA's Reference Dose (RfD) rather than MRLs. Exceeding the EMEGsand RMEGs does not mean that health effects will occur, just that further evaluation is needed(20).

EMEGs and RMEGs for soil are calculated using soil ingestion rates of 100 milligrams/day(mg/d) for adults, 200 mg/d for children, and 5000 mg/d for pica (the habit of eating soil)children (20). EMEGs and RMEGs for water are computed using 2 liters/day for adults and 1liter/day for children. For both water and soil calculations, a bodyweight of 70 kilograms isassumed for adults and 10 kilograms for children. The bodyweight of 10 kilograms is used toprotect the very young children and infants with extreme soil pica behavior (commonly seen inchildren especially from low socioeconomic homes). For air, the MRL for air is used as the airEMEG (20).

CREGs are estimated contaminant concentrations in water, soil, or air based on one excesscancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancerslope factors (20). Comparison values and Health Guidelines are further described in the Toxicological Evaluation Section latter in this document.

    The data tables and discussion include the following abbreviations:
  • CREG
  • = Cancer Risk Evaluation Guide
  • EMEG
  • = Environmental Media Evaluation Guide
  • IEMEG
  • =Intermediate EMEG
  • RMEG
  • =Reference Dose Media Evaluation Guide
  • MCL
  • = Maximum Contaminant Level
  • RfD
  • = Reference Dose
  • ppm
  • = parts per million
  • ppb
  • = parts per billion
  • µm3
  • = micrograms per cubic meter of air
  • mg/m3
  • = milligrams per cubic meter of air

    A. On-site Contamination

    Air

    Past operations at the Globe Plant have introduced numerous sources of metals in air throughpoint sources from stacks and fugitive dust emissions from trucks, batch transfer and storage,partially vegetated soils, and surface slag. The principal source of airborne cadmium at theGlobe Plant was the cadmium circuit which included the retort baghouses. The cadmiumrefining operation was basically a batch process, except for cadmium oxide production (10). The Globe plant received cadmium oxide in 1800 pound sacks from ASARCO's El Paso smelter. Cadmium oxide and cadmium powders were produced in the retort department. Six baghouses(dust collectors) controlled cadmium and cadmium oxide production. There were point sourceemissions from the baghouse stacks and fugitive emissions during powder transfer operations(10). The principal lead source is the Litharge Department, where refined lead metal is oxidizedto form litharge or lead oxide. The Litharge Department was the only production department inoperation during our site visit in November 1993. Fugitive emissions come from cleaning of thebag houses. According to ASARCO's representatives, the cadmium circuit is unlikely to becomeoperational again due to a deteriorated market and bismuth oxide may replace lead oxide.

    The US EPA National Enforcement Investigation Center conducted an air study in September1982. The study indicated that lead, cadmium, and arsenic, exhibited the greatest health riskwhile organic compounds were not detectable. Stack tests were conducted in 1985 and thelitharge stack was tested in 1989. ASARCO completed an air emission inventory and dispersionmodeling investigation in order to evaluate alternatives to further control existing metal sourcesfor cadmium, arsenic, and lead at the Globe Plant (6). The State is conducting an AirEngineering Design Study to evaluate options for additional emission reductions from the GlobePlant (6).

    Ambient outdoor air quality is addressed below through a review of air monitoring stations nearthe Globe plant. The quality of indoor air in buildings on the site is addressed through a reviewof OSHA records.

    Outdoor Air

    ASARCO began a meteorological monitoring program at the Globe Plant site in 1988. Themonitoring system tower is located in the northwest corner of the site. The system monitorswind speed, wind direction, temperature, relative humidity, and barometric pressure on acontinuous basis (11, 21). This meteorological data was not available for this draft of theassessment. The CDPHE operates the Welby meteorological system which is located 3.2 milesnorth of the plant. Welby data, collected in 1987, indicates that predominant wind directions are southwest, north, and northeast (2).

    Three air monitoring stations at ASARCO were used for on-site outdoor ambient air quality:Bookstore site, Nutech site, and Old Office site (2). The Forklift site was considered in thisassessment to be off-site because it is located in a mixed residential and commercial area and in an area of prevailing winds (north) from the site (2). Although the Old Lab station has always been on-site, the Bookstore and Nutech monitoring locations were near the west and eastproperty boundaries, respectively, and then moved on site in 1988 (2). Although the Bookstoresite is influenced by both plant emissions and the Interstate 25, it typically is upwind of plantemissions (2). Likewise, based on the 1987 wind data, Nutech is typically upwind. Therefore,local off-site data may be more typical of plant emissions than on-site data (see the Off-siteContamination section). The on-site monitoring program consists of high volume samplersoperating over a 24 hour period every six days (about 58 samples per year). Air quality wasmonitored at the site by analyzing samples for Total Suspended Particulates (TSP), cadmium,lead, and arsenic from 1986 through 1992 (2).

    ATSDR has summarized on-site and off-site air data in Tables 1 and 2 (2,6,22). A year-by yearsynopsis can be found in Tables 3 and 4 in Appendix B. It should be noted that nocomprehensive valid data set was found for air data prior to 1987. The data presented may notrepresent maximum levels during the operation of the plant because of controls andimprovements implemented after 1986. In May 1986, a cap was placed on the formerneutralization pond thereby reducing blowing of contaminated particles and after 1989improvements were made at the Globe Plant to control stack emissions (2).

    Air quality data indicate maximum annual averages for contamination in on-site air to be 0.080µg/m3 cadmium, 0.012 µg/m3 arsenic, 0.23 µg/m3 lead, and 123 µg/m3 TSP (Table 1) (2,22). TheOld Office monitoring station is the location for these on-site maximums with the exception ofTSP which was highest at the Bookstore station. TSP is also high off site as the Denver area is anonattainment area (can not meet the standard) for TSP (2,22). The maximum on-site annualaverage for lead is about half that for the off-site Forklift City station. Both on site and off sitelead maximums were calculated for 1988 data (Appendix B) (2,22). The higher off-site leadaverage may be due to station location, prevailing wind directions, stack heights, and multiplelead sources. Monthly monitoring results show that average lead concentrations are below thefederal lead standard (2). The federal standard for lead is a quarterly (three month) averageconcentration not to exceed 1.5 µg/m3. In general, airborne cadmium concentrations have decreased on site since 1989 (2,22).

    Table 1.

    AIR QUALITY MAXIMUM ANNUAL AVERAGES (1988 - 1992)

    ON SITEOFF SITE
    ContaminantConcentration
    µg/m3*
    StationConcentration
    µg/m3*
    Station
    Cadmium0.080Old Office0.092ForkliftCity
    Arsenic0.012Old Office& Nutech0.006ForkliftCity
    Lead0.23Old Office0.50ForkliftCity
    TSP123 Bookstore106Clinicare
    * Concentrations were usually below the detection limit so half of the minimal detectableactivity was used in averaging.
    TSP = Total Suspended Particulates
    The Clinicare station began data collection in 1990, therefore some of the earliermaximums were probably missed.
    Additional information is provided in Appendix B.



    Table 2.

    AIR QUALITY MAXIMUM OVERALL CONCENTRATION 1987-1992

    ON SITEOFF SITE
    ContaminantConcentration
    µg/m3
    StationConcentration
    µg/m3
    Station
    Cadmium0.879Nutech3.900Clinicare
    Arsenic0.098Nutech0.300*Clinicare
    Lead1.64Nutech6.34ForkliftCity
    TSP739Bookstore368Clinicare
    TSP = Total Suspended Particulates
    Additional information is provided in Appendix B.
    *Appears to be a spurious result.

    The maximum concentrations from all single monitoring events from 1987 through 1992 arereported in Table 2 (2,22). The on-site maximum concentrations for cadmium, arsenic, and leadwere detected at the Nutech monitoring station, which is on the eastern border of the site. Higher concentrations were detected at off-site locations. The TSP maximum was found at theBookstore location, near the highway. Although arsenic was usually below the detection limit at these stations, occasional maximums were highest at Nutech. There are no ambient standards for cadmium or arsenic, which were elevated at and near the site, compared to background CDPHEcontrol stations (2). The results of air monitoring suggest that the highest concentration levels, both on and off site, usually occur during the winter months and under inversion conditions (11,21).

    Indoor Air -Worker Exposure

    Records of violations (12/88 through 6/89) cited by OSHA (Occupational Safety and HealthAdministration) were reviewed for insight into worker exposure (23). The OSHA citationsindicate that employees were not properly trained in the use of respirators or for confined spaceentry. Employee training did not include the physical and health hazards of the chemicals in thework/lunch area during this time period. Feasible administrative or engineering controls werenot determined and implemented to reduce employee exposures. Workers took contaminatedpersonal clothing home for laundering. OSHA-recommended abatements included improvinghousekeeping, eliminating dry sweeping, redesigning the ventilation systems, and institutingplans for ventilation maintenance (23). Since this time period of violations, ASARCO hascovered outside bins, raised stack heights, and improved some ventilation and housekeeping. AGeneral Health and Safety Plan was revised for the Globe Plant in August 1993 (24). This plan addresses health and safety considerations during activities associated with tasks to be performed during the Remedial Design (24).

    The OSHA records (23) indicate that employees were exposed to cadmium, lead, tellurium, andantimony in the pre-melt, retort, litharge and production lab process areas. Specifically, achemist in the production lab was exposed to antimony at a time weighted average (TWA) of0.55 mg/m3, exceeding the permissible exposure limit (PEL) of 0.5 mg/m3 and to telluriumexceeding the PEL of 0.1 mg/m3. At least six workers were reported to be exposed to lead abovethe PEL of 0.050 mg/m3. An employee in the Shipping Department was exposed to cadmiumdust over the PEL of 0.2 mg/m3. Employees working at the Globe plant were exposed tohazardous levels of airborne cadmium as indicated through personal air sampling and a review ofbiological monitoring and medical records. Their symptoms were consistent with cadmiumtoxicity: beta-2-microglobulinuria, proteinuria, decreased pulmonary function and loss of smell. Eighteen employees had signs consistent with cadmium toxicity (23).

    Soil

    Soil samples were collected by the State in 1985 and during the Remedial Investigation (2) in 1986 and 1987. ATSDR summarized some of these soil sampling results in Table 5 in AppendixC (2). This table summarizes surface soil (0-2") contamination and other maximum levels ofon-site contamination. The highest on-site levels of metals were found primarily in the upper 6" of soil or in the subsurface of the former neutralization pond (2).

    Soils on the Globe Plant site contain antimony, arsenic, cadmium, lead, manganese, selenium,and zinc at levels above ATSDR comparison values for ingestion by a child (Table 5). The onlymetals exceeding ATSDR comparison values for soil ingestion by an adult were arsenic andcadmium. High purity metals, such as thallium and indium, were processed in small quantitiesbut are generally at low to non-detectable levels. Most antimony and arsenic concentrations inupper 2" of soil exceed a comparison value of 20 ppm for ingestion by a child (Table 5). Themaximum concentrations in the upper 2" of soil are 104 ppm antimony and 6770 ppm arsenic. The highest arsenic value on site, 15,250 ppm, was found 16' in the subsurface in the area of the former neutralization pond. The maximum concentration for antimony was found in the farnorthwest corner of the site (levels were highest off-site). Maximum concentrations of cadmium(14,708 ppm) and lead (16,000 ppm) were detected in upper 6" of soil near the lead slag depositand terrace escarpment in the center of the site. The majority of soil samples in the upper 2"exceeded the background lead concentration of 413 ppm and the comparison value of 40 ppmcadmium for ingestion by a child. The maximum surface soil level for manganese, 1000 ppm,was found in the Industrial Drainage Ditch. However, 1525 ppm of manganese was recorded inthe northwest corner of the site at a depth of 2-6". Two surface samples slightly exceed theselenium comparison value of 100 ppm. Only one sample in the upper 2" of soil exceeded thezinc comparison value of 20,000 ppm. The highest on-site value for zinc was found in thesubsurface of the former neutralization pond (2).

    Surface Water/Sediment

    Seepage from the Globe Plant site has elevated the cadmium, arsenic, and zinc concentrations in water and sediment of the Industrial Drainage Ditch (IDD). An interceptor trench was dugadjacent to the former neutralization pond in 1974 and is located entirely within the fence aroundthe Plant property. Groundwater discharging to the interceptor trench contain high cadmiumconcentrations of approximately 10 to 15 ppm (2). Water is pumped from the interceptor trench(to the Plant wastewater treatment system) to control groundwater levels so that contaminatedgroundwater flows away from and does not discharge to the IDD. Since groundwater flow iscontrolled, the IDD water does not contain elevated levels of metals. The IDD, on the westernedge of the Plant property, was fenced in 1985. Sediments in the IDD and retention ponds arecontaminated from historic groundwater discharge to the ditch (2).

    The Farmers and Gardeners Ditch is used for irrigation/agricultural and industrial purposes (2). Part of this underground pipe runs through the site. The water is used by one truck farm and for cooling water by Cherokee Power Station. Repairs were made to the Farmers and Gardeners Ditch pipe in 1987 and 1988 so that concentrations of cadmium would meet the State irrigation water standard of 0.01 mg/l (2).

    Groundwater

    There are two principal areas of metals contamination in shallow groundwater on site, onedowngradient of the former neutralization pond and the second in the northeastern portion of theproperty near a former sedimentation pond. Shallow groundwater at the Globe Plant has elevatedlevels of dissolved cadmium, zinc, and arsenic but not of lead (2). On-site cadmiumconcentrations in groundwater generally exceed the maximum contaminant level (MCL) of 5ppb. The maximum on-site concentration of cadmium in groundwater is 128 ppm. Dissolvedzinc concentrations reach 1650 ppm and generally exceed 10 ppm; the EPA's Lifetime HealthAdvisory for drinking water values (LTHA) is 2 ppm. Arsenic concentrations are high (with amaximum of 127.5 ppm) near the former arsenic production facilities. Deep bedrock aquifershave not been affected by site contaminants (6). Shallow groundwater on site is not used for drinking water. There are approximately 33 on-site monitoring wells (1988 value) (6).

    B. Off-site Contamination

    Air

    The off-site air monitoring stations currently operating near the Globe Plant site are Clinicare(a-half block north/northeast), and Forklift City (one block north). Both of these stations are inareas that are predominantly downwind of Globe Plant emissions according to the 1987meteorological data. Air quality data from these stations are presented in Tables 1 and 2 andAppendix B (Tables 3 and 4) (2,22). The Garden Place School and the Globeville CommunityHealth Clinic monitoring stations were installed in Fall 1989 by CDPHE but are no longeroperating. Both of these stations are located several blocks south/southwest of the Globe Plant site and are also frequently downwind of Globe Plant emissions. The CDPHE operated sixstations representing background air quality in the Denver urban area. Of the six stations onlytwo, Adams City and Gates, are currently operating. They are located about three miles northand seven miles south of the site, respectively. The Adams City data has been summarized inAppendix B. The Forklift City station is monitored by ASARCO. Moreover, Clinicare station ismonitored on a daily basis by CDPHE (2,22).

    Air quality data indicate maximum annual averages for contamination in off-site air to be 0.092µg/m3 cadmium, 0.006 µg/m3 arsenic, 0.50 µg/m3 lead, and 106 µg/m3 TSP (Table 1). TheClinicare and the Forklift City stations consistently show annual average cadmiumconcentrations similar to on-site readings (Table 1 and Appendix B) (2,22). The annual averagelead concentrations are highest at Forklift City, even higher than on-site values. There may bemultiple sources of lead contributing to the Forklift station. Clinicare and Forklift City stationsappear to be points of maximum air pollutant impact from the site. Outdoor air at Garden PlaceSchool was sampled from October 1989 through December 1990 and average concentrations inµg/m3 were found to be 0.004 arsenic, 0.008 cadmium and 0.070 lead (25). Cadmium and lead concentrations were slightly elevated.

    Air quality data indicate maximum concentrations for contaminants in air to be 0.30 µg/m3arsenic, 3.90 µg/m3 cadmium, 6.34 µg/m3 lead, and 0.42 µg/m3 zinc (Table 2) (2,22). Themaximum concentration for lead was detected at the Forklift City monitor in 1988. The othermaximum concentrations were detected at the Clinicare monitor in the 1990's.

    ASARCO completed an air emission inventory and dispersion modeling investigation forcadmium, arsenic, and lead at the Globe Plant (6) and evaluated the potential excess risk ofcancer using the ISCLT (Industrial Source Complex, Long Term) dispersion model. Elevenmonths (May 1989-April 1990, excluding July) of on-site meteorological data were used as aninput to the model. The highest off-site predicted concentrations occurred at the north fence-line of the Globe Plant (6).

    Soil

    Soil samples were collected by the State in 1985 and during two phases of the RemedialInvestigation (2); Phase I samples were collected in August of 1986 to delineate the extent andmagnitude of metals contamination and Phase II samples were collected in July 1987 to provideadditional data in residential neighborhoods and outlying areas (2). Generally, soil sampling was conducted within a two mile radius of the site. The RI contains contour maps depicting theextent and magnitude of shallow soil contamination in the Globe Plant area. Surface soil (0-2") contamination and other maximum levels of off-site contamination are summarized in Table 6 in Appendix C (2). Most of the highest off-site levels of metals were found in the upper 6" of soil (2).

    Off-site soils contain antimony, arsenic, cadmium, lead, manganese, and selenium at levels aboveATSDR comparison values for ingestion by a child (Table 6). Additionally, all or nearly allsamples for these metals exceed comparison values for pica children. Zinc concentrations werebelow the comparison value for ingestion by children but not pica children. Background levelsof most metals for the Globe area are above comparison values for pica children. Backgroundhas been estimated at 28 ppm arsenic, 8 ppm cadmium, 413 ppm lead, and 280 ppm zinc (2).

    In general, metals in surface soils off-site are highest immediately adjacent to the site to the north, east, and south of the Plant (2). An exception to this is antimony which has maximumlevels east of Franklin street, about half-a mile east of the site. An additional source of antimonybesides the Globe Plant site is indicated. High surface soil concentrations of manganese andselenium are located primarily to the east of the site in a non-residential area, the former Annex(2). The maximum manganese concentration of 860 ppm is immediately south of the site. Leadexceeds background immediately south and east of the site. In addition to elevated arsenic nearthe site, levels in surface soils exceed 50 ppm near Highway 70 and the South Platte River. Thereare high levels of cadmium and arsenic at two to six inches in the subsurface north of East 58thAvenue or about a-half mile northeast from the site. Arsenic is also elevated in the subsurface (2-6") between the site and Highway 70 (2).

    Soil sampling to determine off-site soil removal areas began in October 1993. Some residentialyards, Argo Park, Stapleton Recreation Center, Laradon Hall, and licensed day care centers weresampled. Sampling and removal activities are being conducted by ASARCO, with oversight bythe state. Contaminated residential soil will be used to cover the on-site slag pile (11, 21).

    Vegetable Gardens

    Garden surveys were conducted during the remedial investigation. Less than 10% of residencesare estimated to have gardens. Vegetables and soils from twelve gardens were sampled in 1986and leafy vegetables from two of these gardens and four additional gardens were sampled in 1987(2). A garden/farm survey was conducted in August 1986. The results of the survey indicatedthat most respondents used their gardens for 25% of their total food supply (5). Metals analyses were conducted on zucchini, carrots, tomatoes, lettuce, spinach, beets, and cucumbers. Metals in grasses were also analyzed (5).

    The soils of gardens within one mile radius of the plant site had elevated arsenic, cadmium, lead,and zinc. Maximum levels (dry weight) of metals in garden vegetables were found in lettuce: 4ppm arsenic, 32 ppm cadmium, 60 ppm lead, and 151 ppm zinc (2). Based on the gardensampling data, CDPHE advised gardeners in the Globeville community not to grow green leafyvegetables without taking other precautions to minimize their potential exposures to cadmium, in leafy vegetables, from plant uptake (2). This recommendation will remain in effect until garden soil remediation has been completed.

    A community garden adjacent to the Globeville Community Health Clinic was established in1987. Clean soil was added to the plots and residents were encouraged to use these garden plots (2).

    Surface Water/Sediment

    The Globe Plant site contributes only negligible amounts of metals to the South Platte River via groundwater discharge and detention pond water and sediment as previously discussed. Dewey and Copeland Lakes are northwest and north of the Globe Plant site, respectively. Theyare not located in areas of contaminated groundwater or surface run-off from the site. Theselakes were not sampled as part of the investigation at the site and their use is unknown toATSDR at this time (2). However, the Environmental Protection Division of the Denver PublicHealth Department with ASARCO's consultant sampled sediments at the North Side SewageTreatment Plant detention pond. Subsequently, there is an agreement between the City of Denverand ASARCO that if the pond is drained and sediments are exposed, the soil action levels wouldbe used as cleanup levels to remediate the exposed sediments.

    Groundwater

    Well surveys were conducted in 1985 (2) and summer 1992 (2,6). No private wells were foundto be contaminated as a result of migration from the Globe plant (6). City water was provided toone residence south of the Globe plant but the source of the shallow groundwater contaminationwas undetermined (2). Private wells in contaminated areas could be used for irrigation, bathing,or laundering. Under the Consent Decree, ASARCO is required to do a comprehensivedoor-to-door water use survey, with annual updates (3).

    The plumes of groundwater contamination around ASARCO have been defined byapproximately 18 monitoring wells outside of the property boundaries of the ASARCO Globeplant (1988) (2,6). The three plumes are discussed below.

    A narrow band of contaminated groundwater extends northeastward from the site and intersectsthe South Platte River about 1.25 miles from the site. This plume exists primarily in the floodplain of the South Platte River. The groundwater contains cadmium, zinc and arsenic at lowconcentrations throughout most of the plume. The plume in general contains less than 5 ppmcadmium, 1 ppm zinc, and 0.03 ppm arsenic. Maximum off-site cadmium and zincconcentrations are 2.62 ppm and 7.6 ppm respectively for this plume (2). Maximum off-sitearsenic is 24 ppm and is immediately adjacent to the ASARCO site. The contribution of metalsto the River from the plant site are negligible compared to other sources and probably has little impact on water quality (2).

    A small off-site plume directly west of ASARCO may originate from the former BennettChemical site. The contamination in this area may be related to the ASARCO site since in thepast, spent electrolyte solution was conveyed from the Globe plant to the chemical plant by aburied PVC pipe. The plume contains much higher off-site zinc concentrations (maximum of 72ppm) than the northeastern plume. Cadmium concentrations in this plume are less than 0.1 ppm(2).

    There is a separate groundwater plume south of the site in the vicinity of Argo Park. This plumecontains minor concentrations of dissolved cadmium, zinc, and arsenic. No evidence exists thatthe Globe Plant contributed to this contamination. It is near the location of the former Argo lead smelter (2).

    C. Quality Assurance and Quality Control

    Quality Assurance/Quality Control (QA/QC) information on the field and laboratory data qualitywas obtained for this public health assessment. Field blanks, trip blanks, duplicate samples, andsplit samples were run for groundwater and surface water. Split samples were taken forsediment, soil, and vegetation samples. The ASARCO Globe laboratory was not included in theQuality Assurance Project Plan (QAPP). The Globe lab ran some of the 1985 samples (seeAppendix 5 (6)). Samples were analyzed by four other labs participating in the QAPP:ASARCO Department of Environmental Sciences, Rocky Mountain Analytical, Core, andCDPHE. Environmental data from all of the above laboratories were used in this assessment.

    D. Physical and Other Hazards

    The spent process solutions that were discharged to the former neutralization pond wereoriginally acidic but through the addition of lime became basic. There were solutions andprecipitates of a caustic or acidic nature in this pond in the past;however, the pond was taken outof service in May 1986, capped with six inches of clayey top soil, and vegetated (6). The site isfenced so access to the Industrial Drainage Ditch in the plant vicinity has been has beenrestricted. A slurry wall and capping system are proposed for the former neutralization pond toprevent migration of contaminated groundwater from the pond. After installation of a drainsystem to control direction of groundwater flow, if necessary, the interceptor trench will bebackfilled. If access to the site does not continue to be limited, process buildings not currently in use could become physical and chemical hazards (6).

    E. Review of Toxic Chemical Release Inventory (TRI) Data

    During the assessment of the ASARCO site, the preparers of this document searched the ToxicChemical Release Inventory (TRI) (27). TRI is an on-line database, maintained by EPA,containing information (self-reports from chemical manufacturers and other companiesthroughout the United States) about more than 320 different substances released from facilitiesinto the environment (27). This database serves as a record of major chemical releases to the air, water, and land. TRI information was available from 1987 through 1991 and was searched by the 80216 zip code.

    Most of the releases to the Globeville area were air releases. The air data were primarily specialestimates and not actual measurements. Consequently, this assessment reviews the TRI data forgeneral information regarding the rough order of magnitude of the releases and to identify themore prevalent species of chemicals emitted to the air. The air data was reported as point sourceemissions (releases from a stack or vent) and non-point air releases (accidental releases or spills,releases during material handling or storage, or other releases not considered point sources) (27).

    The TRI search indicates that ASARCO emitted cadmium, lead, manganese, thallium, zinc,sulfuric acid, and sodium sulfate to land and air. However, according to ASARCO the GlobePlant does not produce thallium. There were no land releases reported in 1991. Most landreleases consisted of approximately 250 pounds of each contaminant. Air and land releases ofthallium were reported for 1988 and 1989 only. The majority of air emissions of metals or metalcompounds were point releases at 885 pounds or below. Cadmium was the primary metalreleased followed by lead, zinc, and manganese, respectively. The non-point releases of sulfuricacid (1987 - 1990) and sodium sulfate (1987) were 263 pounds or less (27).

    Companies, other than ASARCO, reported only air emissions. TRI shows ten companies in the80216 zip code that emitted one or more chemicals in common with ASARCO. Thesecompanies reported air emissions of lead, manganese, zinc, and sulfuric acid. Two majorreleases of manganese occurred in 1988 and 1989 from a steel fabricator north of ASARCO. These manganese releases were orders of magnitude above those released by ASARCO (230,000and 260,000 pounds compared to 18 and 2 pounds, respectively). Several companies reportedlead releases comparable to or higher than ASARCO's. One company reported emitting zinc in1990. Several companies showed multiple releases of sulfuric acid at quantities comparable to or below ASARCO's (27).

    The industries in the Globeville area contribute heavily to air toxins. In addition to the above aircontaminants, Globeville general air quality was also affected by releases of other heavy metalsand metal compounds, additional acids, volatile organic compounds, and polynuclear aromatichydrocarbons (27). Although not required to report releases, the Cherokee Power Plant locatednortheast of the Globe Plant is a significant contributor to air emissions in the area.

    PATHWAYS ANALYSES

    To determine whether nearby residents are exposed to contaminants migrating from the site,ATSDR evaluates the environmental and human components that lead to human exposure. Thispathways analysis consists of five elements: A source of contamination, transport through anenvironmental medium, a point of exposure, a route of human exposure, and an exposedpopulation (20).

    ATSDR categorizes an exposure pathway as a completed or potential exposure pathway if theexposure pathway cannot be eliminated. Completed pathways require that the five elements existand indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. Potential pathways, however, require that at least one of the five elements is missing, but could exist. Potential pathways indicate that exposure to a contaminantcould have occurred in the past, could be occurring now, or could occur in the future. Anexposure pathway can be eliminated if at least one of the five elements is missing and will neverbe present. Table 7 identifies the completed exposure pathways, and Table 8 identifies the potential exposure pathways.

    A. Completed Exposure Pathways

    Air Pathway

    Air monitoring results indicate that people residing in neighborhoods north/northeast andsouthwest of the site were exposed to airborne metals (cadmium, arsenic, lead) from Globe Plantemissions. Additionally, our TRI search and evaluation of air quality data indicate other sourcesof metals in this area. Inhalation of metals via particulates in air is a major route of humanexposure for this site. ATSDR can not completely characterize this pathway because most airdata was collected after remedial measures and controls were implemented at the site. Inparticular, there was no monitoring prior to capping of the former neutralization pond whichcould have elevated levels via airborne soil/precipitates. However, the stacks are likely to havecontributed metals farther into the community. Since most metallurgical processes involvingthese metals have been closed or emissions reduced, significant future exposures to these metals in air via the Globe Plant are considered unlikely.

    To determine an approximate number of the community exposed or potentially exposed to the air pathway would be extremely difficult to determine; however, a very rough estimate of thoseexposed or potentially exposed in the past could range from the 1,055 number of those exposedto soil to approximately 4370 people (number of community in Globeville, Census Tract 15 andpeople north of the Globe plant located in Adams County) (13,28,29). In the present and future,the number of individuals could be much lower since the ASARCO plant is currently notoperating the cadmium process; however, dust from ASARCO or community soils may be blowninto the air from areas not vegetated.

    Indoor Air

    From conversations with employees from the ASARCO Plant during the ATSDR site visit,approximately 100-200 individuals worked at the plant during peak capacity in the past. However, presently less than 50 employees currently work at ASARCO who may be potentiallyexposed to contamination from the soil and air pathway with emphasis on the air pathway ifproper safety equipment is not used during metal process work. As explained in the On-siteContamination section of this document, approximately 18 employees were exposed orpotentially exposed (12/88 through 06/89) (23).

    Surface Soil Pathway

    Soils contaminated with cadmium, arsenic, lead and zinc were found in residential areassurrounding the Globe Plant site. Children are at greatest risk for exposure via this pathwaybecause of hand to mouth activities. Ingestion of soil and inhalation of wind blown soil isconsidered to have occurred due to the extent of off-site contamination and its presence insurface soils near the site. Exposure to contaminants in soil are expected to continue untilremedial measures are taken.

    To determine an approximate number of the community exposed or potentially exposed to thecontaminants described in this Public Health Assessment, the authors used the maps ofcontamination (cadmium, lead, arsenic and zinc) found in the top two inches of soil on- andoff-site located in the Remedial Investigation (2) to determine the approximate population. With the use of 1990 census data on computer, census tract 15 (Globeville) in Denver County andCensus tract 89.52 (Adams County) were accessed at the city block level cadmium, lead, arsenic, and zinc from the 0-2 inch soil level was roughly overlaid on the blocksto determine an approximate number of people exposed or potentially exposed in the past,present, and future (2). Approximately 1,055 persons resided in this area in 1990 (2,28,29). Ofthese 1,055 people, 538 were White (51%), 123 Black (12%), and 394 Other (37%). Other refersto those individuals who did not specify their race or filled in other. In addition, some of thecommunity may have filled in only the ethnic space and not the race space which would bereported as Other in the 1990 Census (28,29). This population of 1,055 persons was furthersubdivided to explain the age breakdown which was composed of 386 people under 18 years ofage (37%), 581 people 18 to 64 years of age (55%), and 88 people 65 years of age and older(8%).

    Garden Vegetable Pathway

    Metals analyses of vegetables from gardens within a one-mile radius of the former neutralizationpond at the Globe Plant indicate elevated levels. The metals may be elevated due to airbornedeposition of metals or from irrigation with contaminated water. Ingestion of the vegetables maycontribute to exposures, however, there are a limited number of gardens (less than 10% ofresidences have gardens) surrounding the plant.

    To determine the number of individuals possibly exposed in the past to the garden vegetablepathway, one could use the information acquired during a community survey about garden usewhich determined that less than 10% of those people living near the Globe Plant had vegetablegardens (2,5). If we apply this percentage to the 1990 Census data estimates (28,29) used forthose exposed to soil off-site, less than 100 people would have been exposed in the past. For thepresent and future, this number would be less than the above number since the community wasinformed in October, 1987 by the Colorado Department of Health and ASARCO and receivedbrochures on recommended garden practices (2).

    Additional Considerations

    The Stapleton Homes public housing which was composed of 234 units was closed in 1990. Thenumber of individuals exposed in the past was 300 children who were less than 18 years old. However, a total number can be derived by using the average number of people per residence inDenver County (2.17) times the 234 units which would give a number of 508 people (30).

    The Laradon Hall Training School may have had as many as 400 youths who could have beenexposed to air and off-site surface soil; however, after observation of the training school during the ATSDR site visit, very few areas where children or young adults could be exposed to surface soils was observed.

    B. Potential Exposure Pathways

    Groundwater

    There is no known exposed population to groundwater contaminated by the Globe Plant site. However, ATSDR will address the groundwater pathway further when additional water useinformation is provided. Currently, there are no known users of contaminated groundwater asdrinking water, and annual water surveys are planned. In addition, future use of groundwater is precluded by the ASARCO consent order. The contaminated groundwater plume on the terracewill continue to migrate to the flood plain unless remedial measures are taken.

    There is currently no known exposed population to the groundwater potential exposure pathway(2,26). This pathway may still remain a potential pathway for the future if groundwater in the contaminated aquifers is used for drinking, bathing, and/or irrigation (2).

    Surface Water/Sediment

    The Industrial Drainage Ditch and the Farmers and Gardeners Ditch are not sources of drinkingwater. Children may have been exposed to contaminated water and sediment in the IndustrialDrainage Ditch prior to fencing. They could have incidentally ingested the water or sediment. Dermal absorption of metals is unlikely to be significant. Moreover, the Farmers and GardenersDitch has been shown to contain contaminated water. According to the CDPHE, the Farmers andGardeners Ditch water quality is now below irrigation standards.

    The surface water/sediment pathway may have been a potential exposure pathway in the past;however, the extent of children who may have played or used the Industrial Drainage Ditch orFarmers and Gardeners Ditch is unknown. Currently, the Industrial Drainage Ditch is fenced andposted (2).

    PUBLIC HEALTH IMPLICATIONS

    A. Toxicological Evaluation

    Introduction

    In this section, we will discuss the health effects in persons exposed to specific contaminants, evaluate state and local health databases, and address specific community health concerns.

    To evaluate health effects, ATSDR has developed Minimal Risk Level (MRLs) for contaminantscommonly found at hazardous waste sites. If an ATSDR MRL is not available, then EPA'sReference Dose (RfD) is used (20). The MRL and RfDs are estimates of daily human exposureto a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLsare developed for each route of exposure, such as ingestion and inhalation, and for the length ofexposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greaterthan 365 days). However, for exposure doses above a MRL or RfD, there is a wide zone ofuncertainty about whether adverse health effects will occur (20). ATSDR presents these MRLsin Toxicological Profiles. These chemical-specific profiles provide information on healtheffects, environmental transport, human exposure, and regulatory status. In the followingdiscussion, we used ATSDR Toxicological Profiles for antimony (31), arsenic (32), cadmium(33), lead (34), manganese (35), selenium (36), and zinc (37). In addition, ATSDR usesinformation contained in available medical references and databases to evaluate contaminants forwhich there no toxicological profiles. Examples of such databases are the Hazardous SubstanceDatabase (38), EPA's Integrated Risk Information System (39), and ATSDR's Case Studies inEnvironmental Medicine for arsenic (40), cadmium (41), and lead (42).

    EPA's Cancer Slope Factor for a contaminant is used to calculate the maximum risk from 70years of exposure. The actual risk of cancer is probably lower than the calculated number. Themethod used to calculate EPA's Cancer Slope Factor assumes that high dose animal data can beused to estimate the risk for low dose exposure in humans (43,44). There is little experimentalevidence to confirm or refute those two assumptions. Lastly, the method computes the 95%upper bound for the risk, rather than the average risk, which results in there being a very good chance that the risk is actually lower, perhaps 10 to 1,000 times lower (45).

    Antimony, manganese, selenium and zinc have not been classified by EPA in any cancer class. However, inorganic arsenic is classified by EPA as a human carcinogen (39). Cadmium does notcurrently have a slope factor but is considered by EPA as a probable human carcinogen due tolimited human data but sufficient animal studies which demonstrate increased lung tumors afterinhalation (41). Lead is considered by EPA as a probable human carcinogen due to inadequatehuman studies but sufficient animal studies which demonstrate renal tumors in rats after injection (42). Carcinogenic effects will be further explained under each contaminant of concern.

    Antimony

    Antimony is a silvery white metal. It is absorbed slowly from the gastrointestinal tract, and manyantimony compounds are gastrointestinal irritants (31). Antimony is a common air pollutantfrom industrial emissions, but exposure for the general population is largely from food (31). Thepossible routes of exposure are through inhalation, oral, and dermal contact. Inhalation studiesprimarily focused on factory workers who are exposed to high levels for long periods of time. Inthe literature, the primary effects noted were problems with lungs (pneumoconiosis), heartproblems (altered electrocardiograms), stomach pain, diarrhea, vomiting, and stomach ulcers. Although human and animal health effects have been noted in the literature from oral exposurestudies, the information is limited.

    A chemist and any other laboratory personnel in the production laboratory at ASARCO wereexposed to 0.55 mg/m3 (TWA) of antimony in indoor air (23) which is not substantially differentfrom the permissible exposure limit (PEL) of 0.5 mg/m3 set by the Occupational Safety andHealth Administration (OSHA). That level of exposure at ASARCO was about 100 times lowerthan the level of antimony that caused less serious/minor respiratory problems (such aspneumoconiosis and upper airway inflammation) in humans after 9-31 years of exposure (31). Moreover, that level of antimony in the air is about 10 times lower than the level of antimony inair that caused less serious/minor heart and stomach problems (such as altered EKG, elevatedblood pressure, and stomach ulcers) in humans after 5 weeks to two years of exposure (49). It isunlikely that any adverse health effects would occur in persons exposed to that low amount ofantimony alone in air. However, the same workers at ASARCO were also exposed to telluriumin indoor air at levels that exceeds OSHA's PEL of 0.1 mg/m3 for tellurium in workplace air (23). It is possible that the presence of an elevated level of tellurium in the air might cause a slight increase in and the manifestation of minor respiratory problems for the laboratory staff.

    Maintenance, and any construction workers on site, and nearby residents were and may currentlybe exposed to antimony in soils (Tables 5 and 6). However, the estimated exposure dose foradults does not exceed the RfD (Table 10). Although the estimated dose of antimony inresidential soils for pica children exceeds the RfD, the estimated exposure dose is about 10,000times lower than the lowest dose of antimony that caused no adverse health effects in laboratoryanimals after more than three years of exposure (31). Therefore, noncarcinogenic adverse healtheffects are unlikely to occur because of exposure to low levels of antimony in on- and off-sitesurface soils. The carcinogenicity of antimony has not yet been evaluated by EPA.

    Arsenic

    Arsenic is a naturally occurring element. Pure arsenic is a gray metal-like material, but that formis not common in the environment. Rather, arsenic is usually found combined with otherelements such as oxygen, chlorine, and sulfur. Most arsenic compounds are pure white orcolorless with no smell, and most have no particular taste. The most common uses of arsenic andarsenic compounds are for wood preservatives and agricultural chemicals (32). Most cases ofarsenic-induced toxicity in humans are due to exposure to inorganic arsenic. The average dailydiet in the United States for adults contains 0.05 mg/day. Diet is the largest source of arsenicexposure. Exposures of humans could also involve food grown on contaminated soils. There islittle quantitative data on noncancer effects in humans exposed to inorganic arsenic by theinhalation route. However, it appears that such effects are unlikely below a concentration in air of about 0.1-1.0 mg arsenic/m3 (32).

    Workers at the old office and Nutech areas on site, and nearby residents in Forklift city andClinicare were exposed to arsenic in ambient air through inhalation (Tables 1 and 2). Theselevels in air are lower than the 200 µg/m3 (0.2 mg/m3) guideline set by the American Conferenceof Governmental Industrial Hygienists (ACGIH) or the 2 µg/m3 recommended exposure limit foroccupation exposure set by NIOSH. In addition, the off site levels are either lower than orsimilar to acceptable ambient air levels established by most states in the United States. Noncancer effects for arsenic in air are unlikely since the maximum annual average and theoverall maximum for arsenic are over 8000 and 1000 times smaller than the 100 g/m3 (0.1 mg/m3) value at which arsenic in air may cause harmful effects in humans (32).

    Maintenance, and any construction workers in close contact with soils, were and may becurrently exposed to arsenic in surface soils (Table 5). The estimated exposure dose for suchworkers exceed the MRL or RfD for arsenic (Table 10). In addition, the highest estimated dosefor workers is similar to the doses of arsenic that caused minor skin problems in humans after 45years of exposure (32). Any Worker who eats homegrown vegetables containing arsenic (4 ppmdry weight or 0.2 ppm wet weight) on a long term basis received additional exposure fromvegetables (2). Any worker in close contact with soils and who was also exposed to arsenic in air(and vegetables) for a long period of time, and the other group of workers who are in closecontact with soils, and who were also exposed through inhalation, are two groups of ASARCOworkers most at risk for arsenic exposure. It is possible that they might experience minornoncarcinogenic skin, blood, or stomach problems. This evaluation is supported by the findingsof the health hazard evaluation conducted by NIOSH in 1989 which concluded that of the 45medical records reviewed, 18 (40%) had biological monitoring tests indicating excessiveexposure and with either symptoms consistent with metal poisoning, or signs of metal poisoning.

    The total estimated exposure dose of arsenic from soils and vegetables for adult residentsexceeds either the MRL or the RfD (Table 10). The group of adult residents exposed to arsenicin soils, air, and who also eat home grown vegetables are those residents most at risk for arsenicexposure. This group of residents might experience minor forms of these health effects becauseof their exposure to arsenic in soils, air, and homegrown vegetables. However, the vegetablepathway is not currently a source for exposure to metals in soils.

    The estimated doses of arsenic for both pre-school children and the very few young children aged1-3 years who show a craving for nonfood items (pica children) exceed either the MRL or theRfD (Table 10). The children might experience some enlargement of the deep layer of the skinand an increase skin pigmentation if they are exposed to the highest levels of arsenic in soils. However, these effects might be seen only among the very few pica children who live withincontaminated areas.

    The Department of Health and Human Services/ National Toxicology Program (DHHS/NTP),the International Agency for Research on Cancer (IARC), and the United States EnvironmentalProtection Agency (EPA) consider arsenic to be a human carcinogen. Based on this information,workers exposed to arsenic in air or in soil for more than 10 years may have a moderate increasedrisk of developing lung, skin, gastrointestinal or kidney cancer during their lifetime. However,nearby residents have no apparent increased risk of developing additional cancer in their lifetime because of exposure to arsenic at the site.

    Cadmium

    Cadmium is currently used for the production of nickel-cadmium batteries and for metal plating. It is also used for pigments, plastics, synthetics, and for alloys (33). Foods are the mostimportant source of cadmium exposure for the general population. Low levels of cadmium arefound in basic foodstuffs, especially grains, cereals, and leafy vegetables (41). The greatestsource of airborne cadmium are burning fossil fuels such as coal or oil, and incineration ofmunicipal waste.

    Available information in OSHA records indicate that an employee at the Shipping Department ofASARCO plant was exposed to cadmium dust in indoor air at levels that exceed OSHA's PEL of0.2 mg/m3. In addition, eight other employees showed symptoms includingbeta-2-microglobulinuria, proteinuria, decreased pulmonary function and loss of smell which areconsistent with cadmium toxicity (23). These nine workers have been probably over-exposed tocadmium and are likely to suffer permanent damage to kidney tubules, pulmonary function, andloss of the sense of smell. Although the cadmium circuit has stopped production, additionalexposure to cadmium may be occurring from residual cadmium from indoor dust, and soils. Other small groups of long-term employees who have not experienced harmful effects may stillbe exposed to residual cadmium in air and dusts, and from contaminated soils, and mightexperience minor forms of these health effects. However, recently employed workers and officeworkers at the site are less likely to experience adverse health effects although the potential for adverse health effects occurring in the future is possible.

    Maintenance, and construction workers on site were and may be currently exposed to cadmiumin soils (Tables 5). The estimated exposure dose for the workers exceed the RfD (Table 10). Inaddition, these workers were also exposed to cadmium in air, and dust. Moreover, cigarettescontain cadmium and will lead to higher levels in the body for people who smoke (15,41). Homegrown lettuce contains 32 ppm dry weight or 1.6 ppm wet weight of cadmium (2). This level ofcadmium is about 100 times the typical level of cadmium in leafy vegetables grown in the UnitedStates. It is possible that any worker exposed to cadmium in air, and soils (and eats homegrownvegetables) for more than 10 years might experience some respiratory and kidney problems. According to ASARCO only one worker lives in Globeville and that worker does not have agarden.

    Nearby adult residents were and may currently be exposed to cadmium either in soils, vegetables,and/or cigarettes. The total estimated doses for adults who eat contaminated vegetables but donot smoke, and those who smoke and eat contaminated vegetables exceed the RfD (Table 10). Itis possible that the group of people exposed through ingestion might experience some kidneyproblems, while those exposed through inhalation and ingestion might experience somerespiratory as well as kidney problems after more than 10 years of exposure. It is also possiblethat the exposed people who also smoke cigarettes might be at greater risk of developing thesehealth effects. However, adults who do not eat homegrown vegetables, and who are nonsmokersare unlikely to develop adverse health effects. This is plausible because in humans, no more than5% of ingested cadmium is absorbed from the gut into the blood; chromium and zinc (and zinc ispresent in the residential soils) can decrease cadmium uptake (41).

    The estimated exposure dose of cadmium for young children exceeds the RfD (Table 10). However, the very small group of soil-pica children (who may or may not also eat vegetablesgrown on contaminated soils) are those probably at risk of experiencing respiratory and kidneyproblems. Pre-school children who get their exposure from soil ingestion and also from eatingcontaminated vegetables might only experience minor forms of these health effects, although thelikelihood of this occurring is unlikely since by 1987 CDPHE had recommended that Globevillegardeners reduce or eliminate their ingestion of home-grown leafy green vegetables. Normalpre-school children who occasionally receive their exposure from soil ingestion alone are notlikely to experience adverse health effects.

    DHHS (NTP), IARC, and EPA have concluded from animal experiments that cadmium mightcause cancer in humans when it is inhaled. Based on that information, workers and residentsexposed to cadmium at the maximum concentration detected in outdoor air through inhalationmay have a slightly increased risk of developing lung cancer over a lifetime.

    Lead

    Lead is a naturally occurring element. People living in areas surrounding hazardous waste sitesmay be exposed to lead via ingestion of contaminated water or soils or by inhalation of leadparticles in the air. For the general population, the major route of exposure to lead is ingestion oflead-contaminated drinking water, food, soil, lead-based paint chips, or dust (last two routes mostrelevant to children in lower-income urbanized populations). The lead from dust in automobileemissions is deposited in soil. For occupationally exposed individuals, the predominant route of exposure is the inhalation of lead particles (34).

    Workers at ASARCO are exposed to lead in much the same way as they are exposed tocadmium, that is, via accidental soil and dust ingestion while working and breathingcontaminated air. According to OSHA records (23), six workers at ASARCO were exposed tolead in indoor air at levels that exceed OSHA's PEL level of 0.05 mg/m3 or the REL of 0.1 mg/m3set by NIOSH for air concentrations to be maintained so that worker blood lead remains <0.06mg/100 ml of whole blood. In addition, ambient air levels (based on 24-hour readings)monitored on the site between 1987 and 1992 exceed the National Ambient Air Quality (NAAQ)of 1.5 µg/m3 recommended by the EPA. A review of the literature shows that levels of lead inambient air range from 7.6 x 10-5 µg/m3 in remote areas such as Antarctica to >10 µg/m3 nearstationary sources such as smelters, with an average annual concentration below 1.0 µg/m3 for urban monitoring sites (34).

    Any worker who eats home grown vegetables containing 60 ppm (dry weight) or 3 ppm (wetweight) of lead receives additional lead into her/his body. Although according to ASARCO onlyone worker lives in Globeville and that worker does not have a garden. It is probable that the sixworkers who were shown by OSHA to have been exposed to elevated levels of lead, and anyother group of workers in close contact with soils might experience health effects consistent with exposure to high lead levels.

    Lead has been shown to affect virtually every organ and/or system in the body in both humansand animals. The most sensitive target organs of lead appear to be the nervous system, the bloodsystem, and the cardiovascular system. There is also evidence in both humans and animals tosuggest that the kidney and the immune system are also adversely affected by lead. Lead has alsobeen shown to be carcinogenic in animals. No minimal risk levels have been developed for leadbecause a threshold has not been defined for the most sensitive effects of lead (neurotoxicity)(34). Women in the work force are particularly at greater risk and might experience theseproblems because the hematopoietic system (bone marrow responsible for making red bloodcells) in women is more lead-sensitive than men's.

    Nearby residents were exposed to lead in air, and soils. In addition, those who eat vegetablesgrown on contaminated soils within one radius of the site were also additionally exposed to leadin vegetables. Lead levels in outdoor air in residential areas were monitored between 1987 and1992 and exceed the NAAQ level of 1.5 ug/m3 recommended by the EPA or the average annualconcentration of 1.0 µg/m3 for urban monitoring sites (34). Denver is a nonattainment area whichmeans total suspended particulates exceed the regulations, in other words, the air quality is poor(2). It is possible that the few adults, especially women who receive their exposures from soils,air, and vegetables are those who might experience some of these health effects because of theirmultiple exposures which might result in exposures to high levels of lead.

    Pre-school children who occasionally swallow small amounts of soil, and very young children, 1- 3 years old, with pica behavior for soil, and who live within a one mile radius north of the sitemight have the highest exposure to lead in soils, air, and vegetables. Inhaled lead deposited inthe lower respiratory tract is completely absorbed. The amount of lead absorbed from theingestion route for an adult is typically 10% to 15% of the ingested amount while for pregnantwomen and children, the amount absorbed can increase to as much as 50%. The quantityabsorbed depends on diet, especially on iron or calcium deficiency (42). It is possible that these groups of children might experience minor forms of nervous system, blood system, andcardiovascular system problems.

    The Globeville Childhood Metals Study showed that about eight percent of the children tested in all four neighborhoods including control area have blood lead levels greater than 10 µg/dl, the current 1991 Colorado Department of Health and the Centers for Disease Control and Prevention (CDC) level of concern. In addition, the study found that a child at Globeville is more likely than other children from the comparison areas to be in the 5 - 10 ug/dl range of blood lead levels. However, the source of the lead exposure is unknown. Further medical monitoring planned for the community would perhaps better explain the significance of lead exposure at this site.

    Manganese

    Manganese and its compounds are used in making steel alloys, dry-cell batteries, electrical coils,ceramics, matches, glass, dyes; in fertilizers, welding rods; and as animal food additives (46). Manganese is an essential element and is a cofactor for a number of enzymatic reactions,particularly those involved with cholesterol and fat acid production in the body (35,46). Dailymanganese intake ranges from 2 - 9 milligrams/day. Gastrointestinal absorption is less than 5%(35). While manganese is beneficial in small amounts, inhalation or oral exposure to high levels can cause adverse effects (35).

    Workers who are in close contact with soils at the site, and nearby residents were exposed tomanganese in surface soils (Tables 5 and 6). However, the estimated exposure doses for workersand adult residents do not exceed the RfD (Table 10). In addition, the estimated doses wereabout 100 to 1000 times lower than the lowest dose that causes less serious mild neurologicalsigns in humans after 50 years of exposure. Moreover, manganese taken orally is only absorbedto a very low degree, 3% (35). Adverse health effects are unlikely to occur because of exposureto low levels of manganese. The estimated exposure dose of manganese from residential soilsfor pica children is also similar to the RfD (Table 10). However, the estimated doses exceed theintake of manganese that caused less serious/mild neurological signs in humans after 50 years ofexposure (35). It is possible that the very small number of children (1-3 years old) who exhibitpica behavior are those who might experience mild neurological signs later in their lifetime. However, the manifestation of this health effect would depend on many other factors (includingdietary practices).

    Selenium

    Selenium is an essential trace element. Selenium is a naturally occurring substance that is widelyfound in the earth (36). Selenium deficiency is known to cause a disease state known as KeshanDisease that causes heart problems (46). Selenium is an essential part of an enzyme (glutathioneperoxidase) that helps prevent cells from destroying themselves. Selenium interacts with arsenicand may protect against its adverse effects. Selenium is found in a wide variety of foods,especially fish, meat, poultry, beans, and cereal. Because selenium is an essential element, thechronic MRL is approximately three times the recommended daily allowance for adults (0.0009mg/kg/day) (47).

    Workers in close contact with surface soils, and nearby residents were and may currently beexposed to selenium in soils (Tables 5 and 6). However, the estimated exposure doses ofselenium for workers and residents including children do not exceed the MRL (Table 10). Adverse health effects are unlikely to occur because of exposure to low levels of selenium.

    Zinc

    Zinc is one of the most abundant trace metals in humans. It is found normally in all tissues andtissue fluids and is a cofactor in over 200 enzyme systems. Together, muscle and bone containapproximately 90% of the total amount of zinc in the body. Other organs that contain high levelsof zinc are the liver, gastrointestinal tract, kidney, brain, skin, lung, heart, and pancreas (37). Theprincipal route of excretion of zinc in humans is through the intestine. Urinary excretion isusually very low. Acute ingestion of large doses of zinc cause zinc intoxication manifested bygastrointestinal distress and diarrhea. However, it is unlikely that large acute doses of zinc are absorbed and distributed to other tissues (37).

    Data in Table 5 show that workers in close contact with surface soils were and may currently beexposed to zinc in soils. However, the estimated ingestion dose for workers does not exceed theRfD (Table 10). In addition, any worker who eats homegrown vegetables also receivedadditional zinc from vegetables which contained 151/7.6 ppm dry/wet weight. However,according to ASARCO only one worker lives in Globeville and that worker does not have agarden. It is unlikely that the group of workers in close will experience any adverse healtheffects because of their exposure to zinc in soils.

    Nearby residents were also exposed to zinc in soils (Table 6). The estimated exposure dose foradult residents does not exceed the RfD (Table 10). However, zinc in residential soils is about20 times higher than the estimated mean for zinc (65 ppm) in Western U.S. soils. Residents whoeat vegetables grown in contaminated soils within a one mile radius of the site also received zincfrom homegrown vegetables (2). Residents most at risk are therefore those who eat home grownvegetables, and live within the one mile radius of the site. It is possible that this group ofresidents might experience mild eye and skin irritations because of their multiple exposures tohigh levels of zinc through several pathways.

    The estimated dose of zinc in soils for pica children exceeds the RfD (Table 10). In addition, theestimated dose slightly exceeds the estimated intake from the RDA (0.62 mg/kg/day) forchildren. Children who eat homegrown vegetables also received additional zinc from vegetables(2). The highest concentration of zinc (151/7.6 ppm dry/wet weight) found in lettuce) exceedsthe 5 mg/day of zinc recommended by the NRC as a dietary allowance for 1 year old infants. The allowance for children 1-3 years old is 10 mg/day. The very small group of children withpica for soil, and who also eat homegrown vegetables are those most at risk. It is possible thatthe very small number of pica children might experience eye and skin irritations, and mildanemia because of their multiple exposures to zinc which might result in exposures to high levels of zinc.

    Total Suspended Particulates (TSP)

    All Asarco workers and area residents were exposed to levels of TSPs above the annual and24-hour TSP primary standards of 50 and 150 µg/m3 (Tables 1 and 2). The TSP problem inDenver is predominantly due to several industrial sources within the Denver area, as well asautomobile traffic. It is probable that the city-wide problem of TSP levels occasionallyexceeding the TSP standard could contribute to the occurrence of respiratory conditions reported and diagnosed among workers and area residents.

    B. Health Outcome Data Evaluation

    Cancer Registry

    The Colorado Central Cancer Registry examined cancer data on two separate occasions,December 1985 and May 1989, for census tracts surrounding the Globe Plant site. Both thesestudies compared the ASARCO area average annual age-adjusted incidence rates per 100,000population for both sexes combined and separately with rates for the Denver Metropolitan areaand for the United States Surveillance, Epidemiology and End Results program (SEER). Thelung and kidney cancer rates in the ASARCO area tended to be higher than the rates in theDenver Metropolitan area, especially for the period 1980-83 (16,17), although those rates did notdiffer significantly between the two areas for lung and kidney cancer types. The December 1985report (using 1980-1983 data) is based on combined data from all 13 census tracts includingsubstantial areas west of I-25, south of I-70, east of the South Platte River, and some parts ofcommerce City which is a highly industrialized area. The May 1989 report which is a summaryof a followup study concluded that census tracts 15, 35, and 89.59 were those Globeville areasmost likely to have been affected by emissions from the ASARCO site. However, as part of theConsent Decree (4), the Colorado Central Cancer Registry will evaluate the cancer levels in thearea surrounding the ASARCO Globe Plant site to determine if cancer rates are higher thanexpected as compared to the city, state, and country (SEER).

    Childhood Metals Study

    On November 15, 1993, the CDPHE, Division of Disease Control and EnvironmentalEpidemiology released the Globeville Childhood Metals Study (12). The study was funded byATSDR, and was done in the summer of 1990 to assess potential exposure of young children (6months-6 years) living in Globeville to lead, arsenic, and cadmium compared to two populationsof young children living in two areas similar in socioeconomic status to Globeville. The resultsindicate that 37 of the 443 young children tested from four neighborhoods including control areahave blood lead levels equal to or greater than 10 µg/dl which is the CDC's action level forcommunity intervention. In addition, young children in Globeville are more likely to have bloodlead levels in the range of 5-10 µg/dl although the source of the lead exposure is unknown. Moreover, while urine arsenic levels were within the non-toxic range, the urine cadmium levelswere greater than the 2 µg/dl level of concern set by the CDPHE. A retest of the children inNovember did not confirm these results since none of the children had levels of cadmium above2 µg/dl, probably because most samples in the previous study were contaminated. In addition, thestudy only shows a window in time, and in different seasons, regarding a child's exposure. Therefore, medical monitoring program planned in the community (48) prior to and after soilcleanup should correlate each child's blood lead, and urine arsenic and cadmium levels with soil metal levels from each child's yard, especially in the target areas (where soil and any other environmental media might show high contamination).

    C. Community Health Concerns Evaluation

    We have addressed each of the community concerns about health as follows:

    • Has there been an increase in cancer in the area?

    There is no significant increased level of cancer rates in the area according to the limitedinformation from the Colorado Central Cancer Registry for 1985 (16) and 1989 (17) reports. However, for the period 1980-83, the incidence of lung and kidney cancers in the ASARCO areaappear to be slightly increased over the Denver metropolitan area, although these rates did notdiffer significantly. The CDPHE as part of the Medical Monitoring Program will be performinga cancer incidence survey for the Globe area using census tract information and Colorado CancerRegistry data to determine if the population in the ASARCO area has a greater incidence ofcancer than comparable populations in the Denver metro area.

    • Is there an increase in children with asthma?

    In the Globeville and Stapleton Homes, 9 out of 238 children participating in the metals studyreported asthma as a diagnosed condition compared to 11 out of 210 children surveyed in theSwansea and Baker/Valverde areas (12). Denver is a non-attainment area for particulate airpollution which means that on occasion when air pollution is worse due to either high automobiletraffic or weather inversion conditions where the air is trapped low to the ground, may lead toaggravation of asthmatic condition. Many irritant stimuli bring on asthma attacks in people whohave the disease (49). One such study performed in Denver on people ages 18 to 70 years of agedemonstrated that asthmatic people were more likely than those who did not have asthma to beaffected by airborne acids from air pollution in the city (50).

    ATSDR has requested the CDPHE to bring the reported cases of childhood asthma and otherrespiratory diseases to the attention of local health officials in the area. [The CDPHE hasacknowledged that representatives of the local health departments have been actively involved in site activities, and have been provided with copies of the public health assessment].

    • Will the state tell people the results of the yard sampling?

    Yes. The CDPHE will insure that community members receive their individual soil samplingresults and explain the public health significance of those results (11, 21,19).

    • Why did the City tear down the Stapleton Homes Housing Project?

    According to the CDPHE (3) the Stapleton Homes Housing Project was demolished in 1990 forseveral reasons, including lead paint in the homes, new laws by the city for dispersed housing,widening of the highway, and the poor status of construction of the housing.

    • Can the chemicals of concern depress the immune system and make people moresusceptible to disease such as tuberculosis?

    Toxicological evaluation presented in this document indicates that some workers and residentsexposed to some of the contaminants might experience some blood problems including milddepression in the immune function, and possibly other heath problems. In addition, animal andhuman studies suggest that cadmium and lead can cause changes in the immune system afterchronic or high level exposures (32,33,34). However, it is difficult to determine whether theexposed people would be more susceptible tuberculosis because of their exposures to high levelsof these chemicals alone.

    • What recourse do people who have respiratory problems have when they start thecleanup? Will there be a telephone hotline number?

    The CDPHE will supervise the cleanup of soil in the areas around the site. The air will bemonitored and techniques will be used to control the dust so that it does not get into the air (19). When community soil cleanup begins, anyone having health concerns such as respiratoryproblems can contact CDPHE or the Globe Medical Monitoring Program field office to make anappointment with the program physician to discuss their concerns. A telephone hotline will beavailable for this purpose.

    • Does the contamination from the site cause breast cancer?

    No. Arsenic, cadmium and lead as reviewed in the literature are not known to cause cancer of the breast.

    • Does any of the contamination cause kidney malformations?

    Yes. Kidney malformation is known to be related to occupational exposure to high levels ofcadmium and arsenic. Evaluation of workers at ASARCO site by OSHA and NIOSH discoveredkidney problems that were consistent with exposure to cadmium.

    • Could kidney problems of my parents who lived for 15 years near the Globe plant berelated to the contamination?

    As explained in the toxicological evaluation, some residents and workers who are exposed tohigh levels of arsenic, cadmium and lead in soils, air, and by eating vegetables might experiencesome forms of kidney problems. However, it is difficult to determine whether the manifestationof their kidney problems would be due solely to exposure to these metals. Therefore, it ispossible that the kidney problems of your parents might be partly related to exposure to thesecontaminants, although their medical history, dietary, smoking and other social behaviors, andracial backgrounds are important to confirm this. Another issue which must be explained is theprevalence of diabetes in Mexican Americans which can affect the kidney, nervous system, eyes,and heart. Although the rate for diabetes for the Denver area was not investigated, studies haveshown that the prevalence of and mortality from diabetes is two to five times greater amongMexican Americans than among the general United States population (53). In addition, MexicanAmericans with diabetes are more likely to suffer more severe complications of the disease (53). Obesity in low socioeconomic groups increases the risk of diabetes (53).

    • Could the contamination from the ASARCO Globe plant cause respiratory problems such as difficulty with breathing, emphysema, or asthma?

    In the past, air quality may have been bad enough to make existing respiratory conditions worsenaround the ASARCO site. However, other industries in the area, the main freeway systemlocated south and west, and the poor air quality of the area would also lead to increased breathingproblems. Therefore, when community soil cleanup begins, anyone having health concerns suchas respiratory problems can contact CDPHE or the Globe Medical Monitoring Program fieldoffice to make an appointment with the program physician to discuss their concerns. In addition, blood cadmium will also be tested under the Medical Monitoring Program.

    • Is cancer of the larynx or kidney in the community surrounding the Globe plant area higher than expected?

    The 1980-83 average annual age-adjusted cancer incidence rates for kidney and lung cancers are slightly higher (although not statistically significant) in the ASARCO area than the Denvermetropolis area (19). However, the 1985 and 1989 rates did not show increased cancer rates forcancers of the larynx and kidney. In addition, further evaluation of the rates of cancer in the ASARCO Globe area will be performed in the next year or two.

    • If the soil on my property is cleaned up (topsoil replaced), what happens if I dig a hole for a tree or for my garden?

    The CDPHE plans to have ASARCO remove and replace all surface and part of the subsurfacesoils in residential areas. When this is done, residents who dig to plant a tree on residentialproperties are not likely to have contact with contaminated soils. In addition, soils below the surface rapidly fall in metal concentration.

    • Who is eligible to participate in the Medical Monitoring Program?

    The Medical Monitoring Program will focus on residents who live in areas of knowncontamination around the ASARCO site, and any others who can be identified to have beenexposed to site-related contaminants.

    • What type of tests will be performed for the Medical Monitoring Program?

    Blood lead and urine arsenic and cadmium will be studied in all participants. In addition, bloodhematocrit and hemoglobin will be done to screen for anemia, or iron deficiency. Chronic orlong-term exposure and any adverse health effects will be monitored by testing for site-relatedcontaminants including cadmium and beta-2 microglobulin in urine.

    • Could my dizziness be related to exposure to site-related contaminants?

    No. Although some of the site-related chemicals are known to cause dizziness at certainconcentrations, the cause of your dizziness is unrelated to exposure to site contaminants. Yourdizziness is probably caused by inhalation exposure to chemicals in the oil paints you apply tovarious drawings (of landscapes, portraits, etc.) in the basement of your home. Many otherhousehold products may also cause problems at home if not properly used or if instructions onthe labels are not correctly followed. The use of pesticides on gardens or in the house which may have arsenic based compounds could also cause such problems.


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