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PUBLIC HEALTH ASSESSMENT

CLEBURN STREET WELL SITE
GRAND ISLAND, HALL COUNTY, NEBRASKA


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

This section of the public health assessment identifies contaminants of concern found in specificenvironmental media at the Cleburn Street Well site. The contaminants of concern will beevaluated later in the health assessment to determine if exposure to them will affect the public'shealth.

ATSDR selects and discusses contaminants of concern using the following information:

  • concentrations of contaminants on and off site;
  • the quality of field and laboratory data and sample design;
  • comparison of on- and off-site contaminant concentrations with comparison values for noncancer and cancer endpoints; and
  • community health concerns.

It is emphasized that the listing of a contaminant in the following tables does not mean that itwill cause adverse health effects if people are exposed at the reported concentrations. Rather,the listing of a contaminant indicates that the contaminant will be evaluated further in this publichealth assessment. When a contaminant is selected as a contaminant of concern in one medium,its presence or absence in all media sampled will be discussed.

The data tables presented in this section include the following abbreviations and/or acronyms:

Comparison Values (CVs)

  • CREG
  • =Cancer Risk Evaluation Guide
  • EMEG
  • =Environmental Media Evaluation Guide
  • RMEG
  • =Reference Dose Media Evaluation Guide
  • LTHA
  • =Lifetime Health Advisory
  • MCLG
  • =Maximum Contaminant Level Goal
  • MCL
  • =Maximum Contaminant Level
  • PMCLG
  • =Proposed Maximum Contaminant Level Goal
    Data Clarifiers
  • ppb
  • =parts per billion
  • ND
  • =not detected
  • J
  • =associated numerical value is an estimated quantity
  • M
  • =compound was qualitatively identified; however, numerical valueis less than the contract-required quantitation limit or less than theEPA limit of quantitation and, therefore, is an estimated value

    EMEGs are media-specific values developed by ATSDR for use in selecting environmentalcontaminants of potential health concern. EMEGs are calculated using noncancer healthendpoints and do not consider potential carcinogenic effects. RMEGs are media-specific valuesdeveloped by ATSDR from EPA Reference Doses (RfDs). RfDs are EPA's estimates of thedaily exposure to a contaminant that is unlikely to cause adverse health effects. CREGs areestimated contaminant concentrations expected to cause no more than one excess cancer in amillion persons exposed over a lifetime (70 years). Maximum Contaminant Level Goals(MCLGs) are EPA-developed drinking water health goals. EPA believes that MCLGs representlevels that no known or anticipated adverse effect on the health of persons should occur whichallows an adequate margin of safety. Proposed Maximum Contaminant Level Goals (PMCLGs)are MCLGs that are being proposed. Maximum Contaminant Levels (MCLs) representcontaminant concentrations that EPA deems protective of public health (considering theavailability and economics of water treatment technology) over a lifetime (70 years) at anexposure rate of 2 liters of water per day. EPA's Lifetime Health Advisories (LTHAs) representthe level of a contaminant in drinking water (with a margin of safety) at which adversenoncarcinogenic health effects would not be anticipated during a lifetime (70 years) exposure. While MCLs are regulatory concentrations, PMCLGs, MCLGs, and LTHAs are not.

    A. On-Site Contamination

    As previously discussed, sampling data have been collected from various environmental mediaat the Cleburn Street well site, primarily during the 1988 Site Investigation and the 1992-1993Remedial Investigation. Relevant contaminant data from these and other sampling events, whichwere described earlier in the Background section, are discussed and evaluated below.

    Available sampling data show that VOCs have been released from multiple sources togroundwater in the vicinity of the Cleburn Street well. VOCs, primarily PCE, have beendetected in soils, soil gas, groundwater monitoring wells, municipal water supply wells, and/orwater supply reservoirs at the site.

    For the purpose of this public health assessment, "on-site" refers to those areas within the generalsite boundary shown in Figure 1. This includes the Cleburn Street, Pine Street, and LincolnStreet wells, the Pine Street reservoir, and the following potential contamination sources: theformer One Hour Martinizing cleaners, Ideal Cleaners, Liberty Cleaners, former Oil DealersAssociation, and former Nebraska Solvents Company.

    It should be noted that the sampling data evaluated by ATSDR do not include information aboutinorganic compounds or semi-volatile organic compounds. However, other informationreviewed by ATSDR indicates that the groundwater contamination at the site is limited to VOCsonly. Therefore, inorganic and semi-volatile organic compounds will not be discussed further in this assessment.

    Soil Gas

    In March 1988, a soil gas investigation was conducted in the Cleburn Street well area to estimatethe extent of PCE groundwater contamination and identify potential source areas. Sampleswere taken at a depth of about 5 feet below ground service at more than 70 locations andanalyzed in the field for PCE (12). The sampling results indicated four areas with significantPCE soil gas levels - One Hour Martinizing, former Nebraska Solvents Company, LibertyCleaners, and Ideal Cleaners (see Figure 3). The highest PCE soil gas concentration (1,560,000ppb) was found on the east side of the One Hour Martinizing dry cleaners building. Maximumsoil gas levels at the other three areas were as follows:94,800 ppb at the former Nebraska Solvents Company; 59,000 ppb at Liberty Cleaners; and36,800 ppb at Ideal Cleaners. Based on the high PCE soil gas concentrations, these four areaswere identified as potential sources of VOC groundwater contamination (1,12).

    Trace amounts of PCE were found in soil gas samples at four other areas - former Oil DealersAssociation, Vintage Body Shop, Sink and Baer Cleaners, and Peavey Company. (PCE was notdetected at the Grand Island Oil Company.) Since it is reported that these businesses never usedPCE, the positive soil gas values were likely due to groundwater contamination associated withthe four potential source areas previously discussed (1,12).

    Soil

    During Phase I of the RI, which was conducted in May and June 1992, soil samples werecollected from 19 soil borings at eight areas based on the results of the 1988 soil gasinvestigation. The Phase I soil boring locations are shown in Figure 4. Samples were collectedfrom the 0-1 foot and the 4-5 foot depth intervals in the shallow borings, and the 6-8 foot and the12-14 foot depth interval in the deep borings. Soil samples were also collected from boringsused in the installation of the 11 Phase I monitoring wells (Figure 5). Depth discrete soilsamples for the shallow monitoring well borings were collected from depths of 0-1 foot and 4-5feet, while samples for the deep monitoring well borings were collected at various depthintervals ranging from 0-1.5 feet to 25.0-26.5 feet. All Phase I soil samples were analyzed for VOCs (1).

    During Phase III of the RI (June 1993), an additional 53 soil samples were collected from 17 soilprobe locations at the One Hour Martinizing source area (Figure 6) and analyzed in the field forPCE and trichloroethylene (TCE). Thirteen (13) of the soil probe locations were vertical profileborings, collected at depth intervals of 1-3, 6-8, 12-14, and 18-20 feet, with the remaining 4boring locations angled under the building to a depth of 8.5 to 10.5 feet below the building slab (7).

    Analysis of the RI soil samples (Table 1) indicated the presence of VOCs, primarily PCE, at thefour potential source areas previously identified - One Hour Martinizing, Liberty Cleaners, IdealCleaners, and former Nebraska Solvents Company. In general, soil contamination was greatestat the One Hour Martinizing location.

    PCE was found in samples from all four potential source areas at levels ranging from aminimum of 6.5 ppb at Ideal Cleaners to a maximum of 11,000,000 ppb in a soil sample from adepth interval of 25 to 26 feet at One Hour Martinizing. Significant levels of PCE (2,800 ppb)were also found in shallow (0 to 1 foot deep) soil samples underneath a concrete and/or asphaltparking area at One Hour Martinizing.

    TCE was found in soil samples at Nebraska Solvents Company and One Hour Martinizing at amaximum concentration of 16 ppb and 4,400 ppb, respectively. The highest TCE level wasdetected at a depth of 25 to 26 feet at One Hour Martinizing.

    Other VOCs, specifically 1,1-Dichloroethylene (1,1-DCE), 1,1,1-Trichloroethane (1,1,1-TCA),and 1,1,2-Trichloroethane (1,1,2-TCA), were also found at the One Hour Martinizing locationwith the greatest concentrations occurring at the 25-26 foot depth interval. 1,2-Dichloroethylene(1,2-DCE) was found at both One Hour Martinizing and Nebraska Solvents at 48 ppb and 83ppb, respectively.

    It should be noted that the contaminant levels in site soils were all below ATSDR comparisonvalues except for PCE in deep subsurface soils at the One Hour Martinizing location.

    No VOCs were detected in soil samples from the other four areas investigated (Grand Island OilCompany, Vintage Body Shop, Sink & Bear Cleaners, and former Oil Dealers Association).


    Table 1.

    Contaminant Concentrations in Soil (various depths)1
    ContaminantConcentration Range (ppb)Comparison Value
    Liberty Cleaners21-Hr Martinizing3NE Solvents2Ideal Cleaners2 ppbSource
    1,1-DichloroethyleneND780NDND1,000CREG
    1,2-DichloroethyleneND4883ND40,000 (trans-)RMEG
    Tetrachloroethylene (PCE)13 - 1108 - 11,000,000J16 - 8106.5 - 27010,000 CREG
    1,1,1-TrichloroethaneND3,100NDNDNone
    1,1,2-TrichloroethaneND33NDND10,000CREG
    Trichloroethylene (TCE)ND50 - 4,40016ND60,000CREG
      1 Source: References 1 and 6
      2 Data from samples collected in 5/92-6/92
      3 Data from samples collected in 5/92-6/92 and 6/93

    Groundwater -- Monitoring Wells

    During Phase I (May/June 1992) of the RI, 11 monitoring wells were installed at 7 locations atthe Cleburn Street Well site. Eight of the wells (MWs 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B) wereinstalled as 2-well nests, consisting of a shallow (30 to 34 feet) "A" well and deep (88 to 96 feet)"B" well, at the four potential source areas previously discussed. The three remaining wellsconsisted of two deep wells (MWs 5B and 6B) northeast of the Cleburn Street well and ashallow well (MW 7A) at the location of the former Oil Dealers Association. The well at theformer Oil Dealers Association was installed based on the results of an earlier sampling conepenetrometer survey which indicated potential groundwater contamination at that location (1). The Phase I monitoring well locations are shown in Figure 5.

    Following installation, each of the 11 monitoring wells was sampled for VOCs. In November1992, all of the wells were re-sampled for VOCs as part of the Phase II field activities (1).

    In June 1993, 7 additional monitoring wells were installed downgradient of the former One HourMartinizing building as part of the Phase III RI field investigation (see Figure 6). Six of thewells (MWs 8A, 8B, 10A, 10B, 11A, and 11B) were installed in three, 2-well nests. Each nestcontained a shallow (about 30 feet deep) "A" well and a deep "B" well (approximately 85-90 feetdeep). The seventh well (MW 9A) was a single shallow monitoring well. Followinginstallation, groundwater samples were collected from all 7 of the new monitoring wells as wellas from 8 of the 11 existing monitoring wells (7).

    Analysis of the groundwater samples revealed the presence of VOCs in most of the monitoringwells (Table 2). PCE was found in samples from monitoring wells at Liberty Cleaners, OneHour Martinizing, Nebraska Solvents Company, Ideal Cleaners, and former Oil DealersAssociation (see Figures 7 and 8 for PCE concentration contours in the shallow and deepmonitoring wells, respectively.) The highest PCE concentrations (170,000 ppb) were measuredin samples from the shallow (32 feet deep) monitoring well at One Hour Martinizing. Theestimated horizontal and vertical extent of PCE contamination originating from the One HourMartinizing source, based on Phase III groundwater sampling data, is presented as PCE iso-concentration maps in Figures 7 and 8.


    Table 2.

    Contaminant Concentrations in Groundwater from Monitoring Wells1
    ContaminantConcentration Range (ppb)Comparison Value
    Liberty Cleaners21-HrMartinizing2NESolvents3IdealCleaners2Oil DealersAssoc.3 ppbSource
    BenzeneNDNDNDND201CREG
    BromodichloromethaneND2 - 3NDND20.6CREG
    Bromoform1.1NDNDNDND4 CREG
    ChlorodibromomethaneNDNDNDNDND

    ChloroformND11 - 171.6NDND6 CREG
    Total Trihalomethanes 1.113.1 - 201.6ND2100MCL
    ChloromethaneNDNDND12ND3LTHA
    1,1-DichloroethaneND3.4 - 54 - 9.1NDNDNone
    1,1-DichloroethyleneND11 - 372 - 4.6NDND0.06CREG
    1,2-DichloroethyleneND1.5 - 85160NDND70 (cis)LTHA
    Tetrachloroethylene (PCE)1.1 - 686 - 170,00080 - 4,1005.3 - 953.20.7 CREG
    1,1,1-TrichloroethaneND400 - 5408 - 30NDND200LTHA
    1,1,2-TrichloroethaneND7.9 - 12ND2ND0.6CREG
    Trichloroethylene (TCE)ND1.3 - 4101.1 - 75NDND3CREG
      1 Source: References 1 and 6
      2 Data from samples collected in 5/92 & 6/92, 11/92, and 6/93
      3 Data from samples collected in 5/92 & 6/92 and 11/92

    A number of other VOCs, including TCE, 1,1,1-TCA, 1,1-DCE, 1,2-DCE, and THMs, such aschloroform and bromodichloromethane, were also found at significant levels in the shallow OneHour Martinizing monitoring well. Many of these same contaminants were present in samplesfrom the monitoring well at Nebraska Solvents Company but generally at lower levels. At theformer Oil Dealers Association location, low levels of PCE and one THM were detected alongwith benzene, ethyl benzene, toluene, and xylene (BTEX), compounds usually associated withgasoline or petroleum contamination. However, since the ethyl benzene, toluene, and xyleneconcentrations did not exceed ATSDR's comparison values, these contaminants were notselected as contaminants of concern. At Liberty Cleaners and Ideal Cleaners, other than PCE,only a few low-level VOCs were found in the monitoring well samples.

    Groundwater -- Public Wells

    Samples from the Pine Street, Lincoln Street, and Cleburn Street municipal wells have beencollected on numerous occasions since 1984 when PCE contamination was discovered in theLincoln Street well. (See Figures 2 and 5 for the location of these three wells.) The CleburnStreet and Lincoln Street wells have been disconnected from the municipal water distributionsystem since 1986 and 1995, respectively. However, the Pine Street well is still usedperiodically (during periods of high water demand) to supplement the municipal water supply. As previously discussed, water from this well is pumped into the Pine Street reservoir where itmixes with water from the Platte River well field prior to entering the municipal waterdistribution system.

    Sampling data for the Pine Street, Lincoln Street, and Cleburn Street wells are presented inTables 3 and 4 below. Table 3 shows sampling results for the Pine Street well and for theLincoln Street and Cleburn Street wells while they were connected to the municipal system. Table 4 presents sampling data for the Cleburn Street well after it was taken off-line and,therefore, was not contributing water to the municipal water system.

    As shown in Table 3, low levels of trihalomethanes and PCE were found in the Pine Street welland in the Lincoln Street and the Cleburn Street wells while they were connected to themunicipal distribution system. In recent years, much higher levels of PCE have been detected inthe Cleburn Street (Table 4), while VOC levels in the Pine Street well have been mostly not-detectable. PCE levels in the Lincoln Street well have also reportedly increased the last fewyears; however, ATSDR has no recent sampling data to confirm this. Since the Cleburn Streetand Lincoln Street wells are inactive, VOCs in these wells are not currently entering themunicipal water supply. However, the VOC plume may eventually spread to the downgradientPine Street well and impact the municipal water system.



    Table 3.

    Contaminant Concentrations in Pine Street Well, Cleburn Street Well (before takenoff-line in 1986), and Lincoln Street Well (before taken off-line in 1995)1
    ContaminantConcentration
    Range (ppb)
    Year Detected2Comparison
    Value
    ppbSource
    Bromodichloromethane0.01M - 1.0880.6CREG
    Bromoform4.6884 CREG
    Chlorodibromomethane0.02M - 2.7880.4CREG
    ChloroformND


    Total Trihalomethanes0.03 - 8.388100MCL
    Tetrachloroethylene (PCE)1.3 - 26.584,86,87,88,910.7 CREG
      1 Source: References 1, 4, 6, and 12
      2 Based on sampling conducted in 84, 86, 87, 88, 90, 91, 92, and 93 at Pine Street and Lincoln Street wells and in 84 and 86 at Cleburn Street well



    Table 4.

    Contaminant Concentrations in Cleburn Street Well (after taken off-line in 1986)1
    Contaminant Concentration
    Range (ppb)
    Year
    Detected2
    Comparison
    Value
    ppb Source
    Tetrachloroethylene (PCE) 10.0J - 19,000 86,87,88,92,93 0.7 CREG
    1,1,1-Trichloroethane 2 - 14.8 91,92 200 LTHA
    1,1,2-Trichloroethane 8 92 0.6 CREG
    Trichloroethylene (TCE) 3.8 - 17.8 91,92 3 CREG
      1 Source: References 1, 4, 6, 12, and 13
      2 Based on sampling conducted in 86, 87, 89, 91, 92, and 93

    Groundwater -- Public Water Supply Reservoirs

    Water samples from the Pine Street reservoir were collected during Phases I and II of the RI andon several previous occasions. The purpose of these samples was to evaluate the quality ofwater leaving the reservoir for distribution to municipal water users.

    As previously discussed, the Pine Street reservoir stores water from the Pine Street well as wellas other Grand Island municipal wells. Water is withdrawn from the reservoir, chlorinated, andthen pumped into the water distribution system.

    As shown in Table 5, low concentrations of THMs (bromoform, bromodichloromethane,chloroform, chlorodibromomethane) and 1,1,2-TCA were found in water samples from the PineStreet reservoir. No other VOCs, such as PCE, were detected in the reservoir. These datasuggest that VOCs which have impacted the Cleburn Street, Pine Street, and Lincoln Streetmunicipal wells have not significantly contaminated the municipal drinking water supply.


    Table 5.

    Contaminant Concentrations in Municipal Water Supply Reservoirs (Pine Street Reservoir)1
    ContaminantConcentration
    Range (ppb)
    Year
    Detected2
    Comparison
    Value
    ppbSource
    Bromodichloromethane1.1 - 10.686,87,88,920.6CREG
    Bromoform2 - 12.886,87,88,92,934 CREG
    Chlorodibromomethane2.7 - 9.086,87,88,920.4CREG
    Chloroform1.0M - 9.187,886 CREG
    Total Trihalomethanes2 - 30.686,87,88,92,93100MCL
    1,1,2-Trichloroethane3920.6CREG
      1 Source: References 1, 4, 6, and 12
      2 Based on sampling conducted in 86, 87, 88, 92, and 93

    Groundwater -- Private Wells

    During Phase III of the RI field activities, a groundwater sample was collected from a privatewell located at a residence upgradient of One Hour Martinizing. This well is reported to beabout 60 feet deep and to be used only for outdoor uses such as lawn and garden watering. Analysis of the sample for VOCs detected very low levels of three contaminants - bromoform,bromodichloromethane, and chlorodibromomethane. These compounds, commonly referred toas THMs, are likely to be naturally occurring and unrelated to the Cleburn Street well sitecontamination.

    Sampling data for other private wells in the site area were not available to ATSDR during thedevelopment of this health assessment. ATSDR considers this a significant data gap becausearea private wells, especially those located near the One Hour Martinizing location or theCleburn Street well, may be affected by site-related groundwater contaminants.

    Surface Water

    No significant surface waters are present within the Cleburn Street well site boundaries. Thenearest major water body is the Wood River, which is located about 2.5 miles southeast of thesite. At the present time, water pumped intermittently from the Cleburn Street well for floodcontrol is discharged to the municipal wastewater treatment plant (WWTP) which, in turn,discharges to the Wood River. ATSDR does not have sampling data for VOCs from the WWTPdischarges or from the Wood River near the WWTP. However, it is unlikely that VOCsdischarged from the Cleburn Street well would significantly impact the Wood River since thecontaminant concentrations would rapidly decrease due to volatilization and dilution duringtransport through the sewer system, treatment in the WWTP, and mixing with the river.

    Standing Water

    In 1988, two separate samples were taken of standing water (accumulated stormwater runoffand/or shallow groundwater) in an underground traffic light box located just east of the OneHour Martinizing building. This traffic light box tends to intercept stormwater draining from theOne Hour Martinizing area to the bottom of the Eddy Street underpass. As shown in Table 6,the first sample, which was collected by the City of Grand Island in March 1988 and heldapproximately six months before being analyzed, contained very high levels of PCE, 1,1,1-TCA,and TCE. The second sample, obtained during the September 1988 site investigation, showedmuch lower levels of PCE and 1,1,1-TCA and non-detectable levels of TCE. The September1988 sample also contained 1,2-DCE and low levels of two THMs - bromodichloromethane andchloroform (5).

    Ambient Air

    No sampling data for VOCs in ambient air (indoor or outdoor) at the site were available duringthe development of this public health assessment. For indoor air, this is considered to be asignificant data gap since VOCs in soil gas may accumulate inside buildings (e.g., residences,businesses) at areas with significant groundwater and soil contamination (e.g., near One HourMartinizing location).



    Table 6.

    Contaminant Concentrations in Standing Water in Underground Traffic Light Control Box1
    Contaminant March 1988 Sample Sept. 1988 Sample Comparison
    Value
    Concentration (ppb)Concentration (ppb)ppbSource
    BromodichloromethaneND1.0M0.6CREG
    BromoformNDND

    ChlorodibromomethaneNDND

    ChloroformND13.0J6 CREG
    Total TrihalomethanesND14.0100 MCL
    1,2-DichloroetheneND110J70 (cis)LTHA
    Tetrachloroethylene (PCE)50,000,000440J0.7 CREG
    1,1,1-Trichloroethane320,0003.0M200LTHA
    Trichloroethylene (TCE)180,000ND3 CREG
      1 Source: Reference 4

    B. Off-Site Contamination

    Except as discussed below, all sampling data evaluated in this public health assessment werefrom areas inside the defined site boundaries. These areas include the Cleburn Street, LincolnStreet, and Pine Street wells, and the five potential source areas previously discussed. Since no site-related contamination was found outside the site boundaries, no off-site data are presented in this public health assessment.

    As previously discussed, traces of VOCs (primarily THMs) have been found in a number ofGrand Island municipal water supply wells outside the site boundaries. However, contaminantsin these wells, which are a generally several miles south of the site, are not related tocontamination at the Cleburn Street and are not present at levels of health concern. As such, the contaminants are outside the scope of this public health assessment and will not be further evaluated.

    C. Toxic Chemical Release Inventory (TRI) Review

    ATSDR conducted a search of the EPA Toxic Chemical Release Inventory (TRI) database forfacilities in Grand Island. The search showed that some facilities in the area release PCE, 1,1,1-TCA, and xylene compounds to the air. TRI records indicated that no VOCs were disposed of inthe ground during the reporting period. However, it should be noted that information in the TRIdatabase is reported only by large companies that handle certain quantities of hazardouschemicals. Therefore, it is not possible to determine from the TRI records whether any smallbusinesses have dumped contaminants (such as VOCs) onto the ground in the site area.

    The TRI database does not provide sufficient information to estimate airborne concentrations,either at an individual source or downwind of a source. Also, airborne VOC releases are notlikely to contribute significantly to groundwater VOC contamination. Therefore, airbornereleases identified in the TRI search are not considered further in this assessment.

    D. Quality Assurance and Quality Control

    The reports and laboratory data sheets ATSDR reviewed indicate that laboratory proceduresused to analyze samples from the site included quality control measures. However, thatinformation does not show whether sampling procedures, transport, holding times, and storagewere in accordance with accepted quality assurance requirements. For example, one sampletaken from the underground traffic light control box was reportedly held for several monthsbefore being analyzed. ATSDR has presumed that appropriate protocols were generallyfollowed, and that analytical data are generally accurate. The validity of ATSDR's evaluations,conclusions, and recommendations is contingent upon the completeness and reliability of theavailable site data and information.

    E. Physical and Other Hazards

    The main physical hazard at the Cleburn Street Well site is the former One Hour Martinizingbuilding. EPA officials report that the dilapidated building has been several holes in its walls,due to neglect and vandalism, which allow unlimited access to the inside. Furthermore, thebuilding has a partially collapsed roof which could endanger anyone entering it. EPA and cityofficials have received numerous complaints from local residents about the hazardous conditionof the building. It is anticipated that the building will either be demolished or repaired in the near future (4).

    A less conventional hazard associated with the Cleburn Street Well site is the possibility that soilgases released below ground from contaminated groundwater could rise to the ground surfaceand accumulate in buildings at levels that could support combustion (explosion). ATSDR'sconclusions about combustible gases in structures are discussed later in this assessment.

    PATHWAYS ANALYSES

    To determine whether persons are exposed to contaminants from the Cleburn Street well site,ATSDR has evaluated the environmental and human components, or pathways, that lead tohuman exposure. This pathway analysis considers five elements: 1) a source of contamination;2) an environmental medium in which contaminants may be present or through whichcontaminants may be transported; 3) a point of exposure; 4) a route of human exposure; and 5)an exposed population.

    ATSDR classifies pathways as completed or potential. For a completed pathway to exist, allfive elements must exist, and there must be evidence that human exposure to a contaminant hasoccurred in the past, is currently occurring, or will occur in the future. A potential pathwayexists when at least one of the five elements is missing, or is not clearly defined, but could exist(e.g., exposure to a contaminant could have occurred in the past, could currently be currentlyoccurring, or could occur in the future). A pathway is eliminated when at least one of the fiveelements is missing and will never exist (e.g., there is no evidence that people have been, are, orwill be exposed).

    Completed and potential exposure pathways for the Cleburn Street well site are summarized inTables 7 and 8, respectively. Estimates of the number of exposed persons for completedexposure pathways and the number of potentially exposed persons for potential exposurepathways are shown in Tables 9 and 10, respectively. The discussion that follows these tablesincludes those exposure pathways considered important or relevant to the site. However,exposure pathways that have been eliminated are also discussed.



    Table 7.

    Completed Exposure Pathways
    PATHWAY
    NAME
    EXPOSURE PATHWAY ELEMENTS TIME
    SourceMediumPoint of
    Exposure
    Route of
    Exposure
    Exposed
    Population
    Public Water
    Supply
    Chemical use,disposal, spillage,and/or leakageGroundwaterResidences
    Businesses
    Industry
    Ingestion
    Inhalation
    Skin contact
    Residents
    Workers
    Visitors
    Past
    Present
    Future



    Table 8.

    Potential Exposure Pathways
    PATHWAY
    NAME
    EXPOSURE PATHWAY ELEMENTSTIME
    SourceMediumPoint of ExposureRoute of
    Exposure
    Exposed
    Population
    Private Well Water Chemical use,disposal, spillageand/or leakageGroundwaterResidences
    Businesses
    Industry
    Ingestion
    Inhalation
    Skin contact
    Residents
    Workers
    Visitors
    Past
    Present
    Future
    Soil gas/
    indoor air
    Chemical use,disposal, spillageand/or leakageSoil to airInterior of buildingsInhalationResidents
    Workers
    Visitors
    Past
    Present
    Future
    Worker/
    Sourcechemicals
    Chemical use,disposal, spillageand/or leakageChemicalscontaining VOCs(such as PCE)Businesses wherechemicals were used,disposed, spilled, orleakedSkin contact
    Inhalation
    Ingestion
    WorkersPast
    Present
    Future
    SoilChemical use,disposal, spillageand/or leakageSoilAreas with contaminatedsoils (e.g., One HourMartinizing)Incidentalingestion;InhalationWorkers involvedin digging, drilling,or excavationactivitiesPresent
    Future
    Worker/
    Traffic lightbox
    Chemical use,disposal, spillageand/or leakageSurface waterrunoff and/orgroundwaterUnderground trafficlight control box (nearEddy St. underpass)Inhalation
    Skin Contact
    Utility workers;Sampling personnelPast





    Table 9.

    Estimated Population for Completed Exposure Pathways
    EXPOSED POPULATIONSAFFECTED BY A COMPLETED EXPOSURE PATHWAY* FOR:
    LocationEstimated
    Number
    1,1,2-TCATHMsOther VOCs
    (e.g., TCE, PCE)
    Persons in Grand Islandusing the municipal watersystem38,000Unknown Public water supplyUnknown/Potential exposure
      * Refer to Table 7 for a summary of completed exposure pathways.





    Table 10.

    Estimated Population for Potential Exposure Pathways
    POTENTIALLY EXPOSED
    POPULATIONS
    AFFECTED BY A POTENTIAL EXPOSURE PATHWAY* FOR:
    LocationEstimatedNumberBenzenePCE1,1,1-TCA,
    1,1,2-TCA
    TCE1,1-DCA1,1-DCE,
    1,2-DCE
    Chloro-
    methane
    THMs
    Private well users insite areaUnknownPrivate wellwater**Private wellwater**Private wellwater**Private wellwater**Private wellwater**Private wellwater**Private wellwater**Private wellwater**
    Persons who live orwork in areas of thesite underlain by
    VOC-contaminatedgroundwater
    UnknownSoil gas/
    indoor air**
    Soil gas/
    indoor air**
    Soil gas/
    indoor air**
    Soil gas/indoor air**Soil gas/indoor air**Soil gas/indoor air**Soil gas/indoor air**Soil gas/indoor air**
    Workers in businesseswhere chemicalscontaining VOCswere used, stored,spilled, or leaked UnknownWorker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Worker/
    Source
    chemicals**
    Workers involved indigging, drilling, orexcavation activitiesUnknownNot exposedSoilSoilSoilNot exposedSoilNot exposedNot exposed
    Persons accessingunderground trafficlight control boxUnknownNot exposedWorker/
    Traffic lightbox
    Worker/
    Traffic lightbox
    Worker/
    Traffic lightbox
    Worker/
    Traffic light
    box
    Worker/
    Traffic light
    box
    Not exposedWorker/
    Traffic light
    box
      * Refer to Table 8 for a summary of potential exposure pathways.
      ** Sampling data are unavailable or insufficient to confirm the presence of this contaminant at the potential point of exposure.

    A. Completed Exposure Pathways

    Public Water Supply Pathway

    As previously discussed, VOCs, primarily THMs and PCE, have been found in the Pine Street,Lincoln Street, and Cleburn Street municipal wells since the mid-1980s (see Tables 3 and 4). VOCs (THMs and 1,1,2-TCA) have also been detected at low levels in the Pine Street reservoir(see Table 5) which is used to store water from the Pine Street well and other Grand Islandmunicipal wells. The Pine Street reservoir also received water from the Cleburn Street andLincoln Street wells until 1986 and 1995, respectively, when the wells were disconnected fromthe municipal water system. Water in the Pine Street reservoir is withdrawn as needed,chlorinated, and pumped into the municipal water system for distribution to city water users.

    VOC contamination of the Cleburn Street well is believed to originate from the area surroundingthe former One Hour Martinizing building. High levels of PCE and other VOCs have beenfound in soil (see Table 1) and groundwater (see Table 2) at that area which is just upgradient ofthe Cleburn Street well. The source of contamination at the Lincoln Street well is likely theformer Nebraska Solvents Company, while contaminants at the Pine Street well may beassociated with the Cleburn Street groundwater plume or some unknown source.

    Residents, workers, and visitors who use the public water system are subject to exposure toTHMs, 1,1,2-TCA, and possibly other VOCs (such as PCE or TCE) in their drinking water. Although PCE and TCE have not been detected in the municipal water supply, thesecontaminants have been found in the Cleburn Street well and nearby monitoring wells and couldappear in the public water supply in the future.

    Exposure to VOCs in the municipal water system is possible by drinking contaminants in thewater (ingestion), by breathing contaminants evaporating from the water during showering orother indoor water uses (inhalation), and by absorbing contaminants through the skin duringbathing, showering, etc. (dermal contact). It is estimated that up to 38,500 people - theapproximate number of persons served by the municipal water system - could be exposed to lowconcentrations of VOCs from using municipal water. However, since no sampling data areavailable for VOCs at the users' taps, the actual number of persons exposed and the actualexposure levels are not known. For VOCs such as PCE and 1,1,2-TCA, the levels at the tap arelikely much lower than those measured in the municipal water supply wells because of dilutionwith water from other non-contaminated municipal wells in the Pine Street reservoir. The VOClevels at the tap would also tend to be lower than the levels found in the Pine Street reservoir dueto volatilization in the water distribution system. For THMs, however, the levels at the tap maybe higher than the levels found in the water supply wells or water supply reservoir because waterpumped from the reservoir undergoes chlorination which commonly results in the formation ofTHMs.

    B. Potential Exposure Pathways

    Private Well Water Pathway

    A few private water supply wells have been identified in the immediate site vicinity. Althoughmost of these wells are reported to be used just for outdoor watering, some of them may be usedfor indoor water uses, including drinking water. PCE and other VOCs found in groundwateraround the Cleburn Street well (see Table 4), the former One Hour Martinizing location, and, toa lesser extent, the former Nebraska Solvents Company location (see Table 2) could impactsome of these private wells. If any impacted wells were used for outdoor uses, such as lawnwatering or irrigation of home vegetable gardens, significant human exposure to VOCs would benot expected since VOCs tend to evaporate rapidly from water and do not accumulatesignificantly in fruits or vegetables. However, if such wells were used for household waterneeds, such as drinking or showering, human exposure to VOCs could occur (see Public WellPathway discussion).

    During the RI, one private well located upgradient of the former One Hour Martinizing cleanerswas sampled for VOCs. This well, which was reportedly used for outdoor watering, did notcontain any site-related contaminants at levels of concern. Since no other private wells in thesite vicinity were sampled, it is not known whether any private wells are actually impacted bysite contamination and, if so, to what extent Therefore, at this time, ATSDR cannot fullyevaluate potential exposure pathways associated with use of private well water.

    Soil Gas/Indoor Air Pathway

    At the Cleburn Street well site, PCE has been detected in soil gas at areas where groundwater iscontaminated by VOCs. This indicates that PCE is volatilizing from the water table and enteringthe void spaces of the overlying soil. The highest PCE soil gas levels were found around theformer One Hour Martinizing building where groundwater is heavily contaminated with PCEand other VOCs.

    PCE and other volatile contaminants migrating upward in soil gases may enter buildings (e.g.,residences, businesses) through basement walls, crawl spaces, or foundation cracks, andaccumulate inside. Persons living or working in these buildings could then be exposed to theVOCs by breathing the contaminated indoor air. However, since no indoor air data for VOCsare available, it is not known to what extent soil gas VOCs are entering residences andbusinesses at the site. Therefore, the potential for inhalation exposure to VOCs in indoor air, especially PCE, cannot be evaluated at this time.

    No soil gas sampling data are available for estimating potential for combustion. PCE data areavailable, but that contaminant is not combustible (15). After analyzing potential water/airequilibria, ATSDR estimates that combustible VOCs released from groundwater to theunsaturated soil zone are not likely to be at concentrations at which they would ignite if theysubsequently accumulated in overlying structures. Only one water sample, taken from the trafficlight control box early in 1988, had concentrations of combustible VOCs great enough tosupport ignition in ambient air. However, that sample was held for several months before beingtested. Because of that departure from protocol, and because a later sample taken at the boxcontained much lower VOC levels, ATSDR believes the initial sample should not be givensubstantial weight in this assessment. Ambient air monitoring data are not available, however,to confirm whether explosion potential is an important issue for residences and businesses thatare located over areas of groundwater contamination.

    Worker/Source Chemicals Pathway

    People who worked in businesses where PCE or other volatile chemicals were used orinappropriately disposed of could have been exposed to those contaminants through skin contactand inhalation. Such exposures were especially likely at the One Hour Martinizing cleanerssince 1) PCE was used in the dry cleaning operations, 2) PCE spillage inside the business wasreported on at least one occasion, and 3) PCE is present at high levels in soil and groundwaterbeneath the buildings. However, the extent of past exposures (while the business was operating)cannot be evaluated with currently available information. Note: Recent exposures are not likelysince this business has been closed and the building vacated for several years.

    Soil Pathway

    VOCs, primarily PCE, have been found in site soils at the following four locations: One HourMartinizing, Liberty Cleaners, NE Solvents, and Ideal Cleaners. However, none of the contaminants were present at levels of concern except for PCE in subsurface soils at the OneHour Martinizing location. Moreover, the areas where PCE and other VOCs were found aregenerally covered by buildings or pavement (asphalt and/or concrete) which prevent directcontact with the contaminated soils. For these reasons, area residents are not likely to besignificantly exposed to PCE or any other VOCs in site soils.

    Persons involved in extensive digging, drilling, or excavation activities, such as utility personnelor remedial workers, near the One Hour Martinizing building might be exposed to PCE andother VOCs, through incidental ingestion of contaminated soil or through inhalation ofcontaminants volatilizing from the soil. However, such exposures are expected to be limitedsince site workers are not likely to come in contact with the most heavily contaminated soils,which are found at a depth of 25-26.5 feet below ground surface. In addition, it is assumed thatsite workers will take appropriate protective measures when conducting any extensive soil-disturbing activities in significantly contaminated areas.

    Worker/Traffic Light Box Pathway

    High levels of PCE, 1,1,1-TCA, and TCE have been found in standing water in an undergroundtraffic light control box (see Table 6) just east of and downhill from the former One HourMartinizing building. Stormwater runoff draining from the One Hour Martinizing area towardthe Eddy Street underpass tends to collect in the underground box. In addition, groundwaterfrom the shallow water table may seep into the underground box when the water table is high(e.g., after heavy rains.) Therefore, it is likely that the contaminants found in the traffic lightbox migrated from the One Hour Martinizing area through stormwater runoff and/orgroundwater infiltration.

    People who have accessed the traffic box in the past, such as utility maintenance workers orenvironmental sampling personnel, without proper respiratory or skin protection may have hadshort-term exposure to PCE, 1,1,1-TCA, and TCE via inhalation and dermal contact. Althoughsuch exposures were likely to be brief and infrequent, available information is insufficient toevaluate the extent of these potential exposures.

    Groundwater/Surface Water Pathway

    As previously discussed, a groundwater extraction well near the former One Hour Martinizingbuilding is being used to prevent groundwater contamination at that location from migrating todowngradient areas. Groundwater pumped from the well is discharged to a sanitary sewer andthen to the municipal WWTP which, in turn, discharges to the Wood River. Although waterfrom the well is likely to contain significant levels of PCE and other VOCs, the contaminantlevels will decrease rapidly, due to dilution and volatilization, as the water passes through thesewer system, undergoes treatment in the WWTP, and mixes with the Wood River. As a result,the discharges from the extraction well should have little impact on the water quality of the riverand should not cause anyone using the river to be significantly exposed to VOCs.

    Although the groundwater extraction well helps to control groundwater seepage into the EddyStreet underpass, flooding of the underpass after significant rainfall events has been reported. Flooding of the underpass is caused by accumulated stormwater runoff, which drains from thearea surrounding the old One Hour Martinizing building, and excess seepage from the highgroundwater table. Since shallow groundwater near One Hour Martinizing and the CleburnStreet well is contaminated with PCE and other VOCs, standing water at the Eddy Streetunderpass may also contain such contaminants. However, since the flooding occurs on a busycity roadway, and since heavy rainfall will tend to dilute any contamination coming from theOne Hour Martinizing area, significant human exposure to contaminants at the underpass isunlikely and will not be evaluated in this public health assessment.

    PUBLIC HEALTH IMPLICATIONS

    Introduction

    This section discusses health issues for persons exposed to specific site contaminants, discusseshealth outcome data, and addresses specific community health concerns.

    A. Toxicological Evaluation

    To evaluate noncancer health effects, ATSDR has developed a Minimal Risk Level (MRL) forcertain contaminants commonly found at hazardous waste sites. The MRL is an estimate ofdaily human exposure to a contaminant below which noncancer adverse health effects areunlikely to occur. MRLs are developed for routes of exposure and for the length of exposure: acute (less than 14 days), intermediate (15 to 364 days), and chronic (equal to or greater than365 days). ATSDR presents these MRLs in Toxicological Profiles. These chemical-specificprofiles provide information on health effects, environmental transport, human exposure, andregulatory status. If an ATSDR MRL is not available, then EPA's Reference Dose (RfD) isused. The RfD is an estimate of daily human exposure to a contaminant for a lifetime belowwhich (noncancer) health effects are unlikely to occur.

    ATSDR estimates cancer risks using EPA's cancer slope factors. EPA has estimated cancerslope factors (CSF) for certain chemicals. CSFs are estimates of a chemical's potency to causecancer and are used in conjunction with exposure dose to estimate cancer risk of a lifetime of 70 years.

    In calculating estimates of exposure to contaminants in water, intake rates of 2 liter/day for adults and 1 liter/day for children were used.

    Tetrachloroethylene (PCE)

    PCE is a colorless, nonflammable liquid with an ether-like odor. It is practically insoluble inwater. PCE is used in dry cleaning and textile processing. It is also used as a cooling gas, aninsulating fluid, and in the manufacture of other chemicals and products includingfluorocarbons, paint, adhesives, aerosols and coatings. PCE may be formed in small quantitiesduring chlorination of water. It has also been detected in rainwater, sea water, rivers, fruits andvegetables, dairy products, oils, fats, fish, meats, and fresh bread. Potential consumer exposureto PCE may occur through use of coin-operated laundromats containing dry cleaning machinesand freshly dry-cleaned clothing (16).

    Grand Island residents who used public water before 1986 were probably exposed to low levelsof PCE in their drinking water, even though PCE was not detected in the Pine Street reservoir. Prior to 1986, water pumped from the Cleburn Street well was mixed with clean water fromother municipal wells in the Pine Street reservoir, thereby diluting any contaminants in theCleburn Street well water. This may explain why PCE discharged from the Cleburn Street wellwas never found at detectable levels in the reservoir. Using the highest PCE levels detected inthe Cleburn Street well (Table 3), the estimated exposure doses for children are 4 times lowerthan the chronic RfD and for adults are 13 times lower than the RfD (Table 11) (16). Therefore,adverse health effects are unlikely to occur in children or children exposed to PCE in themunicipal water system.

    The International Agency for Research on Cancer (IARC) has classified PCE as probablycarcinogenic to humans. EPA has classified PCE between a "probable human carcinogen"(based on sufficient evidence in animals and inadequate or no evidence in humans) and a"possible human carcinogen". Using EPA's cancer potency factor for PCE, ATSDR's evaluationindicates that persons exposed to PCE in their drinking water at the levels detected in theCleburn Street well (Table 3) would have no apparent increase risk of developing cancer (16).

    High levels of PCE were detected in the Cleburn Street well after it was taken off-line in 1986(Table 4) and in soils (Table 1) at the One Hour Martinizing location. (Note: PCE was alsofound in soils at three other locations - Liberty Cleaners, NE Solvents, and Ideal Cleaners - but at much lower levels.) However, since the Cleburn Street well is no longer connected to the municipal water supply system, exposure to PCE from the well is not a concern. In addition,PCE in site soils is generally confined beneath buildings or paved parking areas. Therefore,Grand Island residents are unlikely to be exposed to PCE in site soils. Persons involved inextensive digging, drilling, or excavation activities, such as utility personnel or remedialworkers, in areas where soil contamination is present (e.g., around the One Hour Martinizingbuilding) might be exposed to VOCs. Such exposures should not pose a health hazard ifappropriate protective measures are used during the soil-disturbing activities.

    PCE was also found at high levels in groundwater (Table 2) at the One Hour Martinizing andNE Solvents locations, and to a much lesser extent at Liberty Cleaners, NE Solvents, and IdealCleaners. Although few people in the site area use private wells for their water needs, it is notknown whether any private wells are actually in use near the areas of PCE groundwatercontamination and, if so, to what extent such wells have been impacted by the contamination. Therefore, at this time, ATSDR cannot evaluate whether potential exposure to PCE poses ahealth threat to private well users at the site.

    Although air quality data are not available for the underground traffic light control box, it ispossible that fumes from the very high levels of PCE (50,000,000 ppb) detected in standingwater inside the box could have posed a short-term inhalation health risk to environmentalsampling staff or utility workers who may have opened the box without proper respiratoryprotection. However, it is difficult to determine the potential health effects of such an exposure in the absence of ambient air samples.

    Bromodichloromethane (BDCM)

    BDCM is a colorless liquid that is not readily flammable. It is soluble in water, alcohol, ether,acetone, benzene and chloroform. BDCM is used in the manufacturing of organic chemicals andas a reagent in laboratory research. It has been used to separate minerals and salts, as a fireretardant, in fire extinguishers, and as a solvent for waxes, fats, and resins. However, it is notcurrently listed as an ingredient in solvents, fire extinguishers, or other commercial products(17).

    Since BDCM is not produced or used on a large commercial scale it is unlikely that significantrelease into the environment will result from industrial processes. The major environmentalsource of BDCM (and other trihalomethanes) is its formation as a result of the chlorination ofdrinking, waste, or cooling waters. Consumers are also potentially exposed to BDCM fromcontaminated food and beverages prepared with chlorinated water containing low levels ofBDCM. Exposure can also occur from dermal contact with and ingestion of chlorinatedswimming pool water (17).

    Grand Island residents using public water have been and may currently be exposed to low levelsof BDCM in their drinking water. The estimated exposure doses for adults and children, basedon the highest BDCM levels measured in the Pine Street reservoir (Table 5), are 20 times lowerthan the MRL or the RfD (Table 11). Therefore, adverse health effects are not likely to occur in adults and children exposed to the low levels of BDCM in municipal water.

    Although BDCM is classified as a probable human carcinogen by EPA, exposure to BDCM atthe levels found in the municipal water system should not present an increased cancer risk.

    Potential exposure to the trace amounts of BDCM detected in standing water inside the underground traffic light control box (Table 6) is insignificant.

    Low levels of BDCM have also been found in groundwater at the One Hour Martinizing and OilDealers Association locations (Table 2). However, significant exposure is not likely based onthe low groundwater levels detected and the fact that few people in the site area use private wells for their water needs.

    Bromoform

    Bromoform (also known as tribromomethane or methyl tribromide) is a colorless to yellowliquid with a chloroform-like odor. Bromoform is used in pharmaceutical manufacturing, as aningredient in fire-resistant chemicals and gauge fluid, and as a solvent for waxes, greases, andoils. Currently, bromoform is only produced in small amounts for use in laboratories and ingeological and electronics testing. When chlorine is added to drinking water to kill any disease-causing organisms which might be present, the chlorine reacts with natural substances present inthe water, producing low levels of bromoform as undesired by-product. In the environment,bromoform is either dissolved in water or evaporated in air where it can cause other chemicals tobreakdown slowly. Any bromoform in water or soil may also be broken down by bacteria,although the extent of this process is not known (18).

    Grand Island residents using public water have been and may still be exposed to low levels of bromoform in their drinking water. The estimated doses for adults and children, using thehighest levels of bromoform detected in the Pine Street reservoir (Table 5), do not exceed theMRL or the RfD (Table 11). Therefore, no adverse health effects are expected to occur fromexposure to low levels of bromoform in municipal water.

    Although bromoform is classified as a probable human carcinogen by EPA, if residents ingestedthe maximum level of bromoform detected in the municipal water system for 70 years, theywould have no significant increased risk of cancer.

    Low levels of bromoform have also been found in groundwater at the Liberty Cleaners location(Table 2). However, significant exposure is not likely based on the low groundwater levelsdetected and the fact that few people in the site area use private wells for their water needs.

    Chlorodibromomethane (CDBM)

    CDBM is a colorless, heavy, nonflammable liquid with a sweetish odor. CDBM was used to inthe past to make chemicals such as fire extinguisher fluids, spray can propellants, refrigeratorfluid, and plasticides. Currently it is produced only in small quantities for use in laboratories. When chlorine is added to drinking water to kill any germs, the chlorine reacts with the naturalsubstances in the water to produce CDBM as undesired byproduct. Small amounts of CDBM arealso produced by plants the ocean. In the environment, CDBM like all trihalomethanes (THMs),is found dissolved in water or evaporated in air. When CDBM enters soil or water, it is brokendown by bacteria, although the extent of this process has not been adequately determined (18).

    Grand Island residents using public water have been and may still be exposed to low levels ofCDBM in their drinking water. The estimated doses of CDBM, using the highest levels detectedin the Pine Street Reservoir (Table 5), are far lower than the chronic MRL or the RfD (Table11). Therefore, adverse health effects are unlikely to occur from exposure to low levels of CDBM in municipal water.

    Although the EPA considers CDBM to be a possible carcinogen based on animal studies only,the International Agency for Research in Cancer (IARC) has not classified CDBM as acarcinogen. People exposed to the low levels of CDBM found in the municipal water systemshould have no increased risk of cancer.

    Chloroform

    Chloroform, which is also known as trichloromethane, methane chloride, or methyltrichloride, isa colorless, volatile, nonflammable liquid. It is slightly soluble in water and has a pleasant, non-irritating odor. Chloroform was used as an anaesthetic in the past but its use has beendiscontinued. Chloroform enters the environment from chemical companies, paper mills, wastewater from sewage treatment plants, and drinking water that contains chlorine. Potential humanexposure may occur from breathing air contaminated with chloroform, eating food or drinkingwater containing chloroform, or by absorption of chloroform through the skin. Chloroform isvery persistent in both air and groundwater (19).

    Grand Island residents using public water have been and may be currently exposed to low levelsof chloroform in their drinking water. However, the estimated ingestion doses for children andadults, based on the highest chloroform levels detected in the Pine Street reservoir (Table 5), aresubstantially lower than the chronic oral MRL or RfD (Table 11). Therefore, adverse healtheffects are unlikely to occur from exposure to low levels of chloroform in municipal water.

    Chloroform detected in the municipal water system is unlikely to cause any increased risk ofcancer in residents who use municipal water.

    Potential exposure to chloroform detected inside standing water in the underground traffic lightcontrol box (Table 6) is insignificant.

    Low levels of chloroform have also been found in groundwater at the One Hour Martinizing andNE Solvents locations (Table 2). However, significant exposure is not likely based on the lowgroundwater levels detected and the fact that few people in the site area use private wells fortheir water needs.

    1,1,2-Trichloroethane (1,1,2-TCA)

    1,1,2-TCA is a colorless, sweet-smelling liquid that does not burn easily. 1,1,2-TCA is usedmostly where 1,1-dichloroethane (vinylidene chloride) is made. 1,1,2-TCA may also be formedin landfills when 1,1,2,2-PCA is broken down. When 1,1,2-TCA is released into theenvironment, most of it finally ends up in the air, but some may enter groundwater. Breakdownin air, soil, and groundwater is slow (20).

    Grand Island residents who use municipal water are probably exposed to low levels of 1,1,2-TCA in water from the Pine Street water supply reservoir (Table 5). However, the estimateddoses for children and adults are substantially lower than the chronic RfD (Table 11). Therefore, adverse health effects are unlikely to occur because of exposure to low levels of1,1,2-TCA in municipal drinking water.

    Although the EPA considers 1,1,2-TCA a possible human carcinogen based on animal studiesalone, IARC and the National Toxicology Program (NTP) of the U.S Department of Health andHuman Services (DHHS) have not classified 1,1,2-TCA as a carcinogen. Residents exposed to1,1,2-TCA in municipal water should not have an increased risk of developing cancer.

    Low levels of 1,1,2-TCA have also been found in groundwater at the One Hour Martinizing andIdeal Cleaners locations (Table 2). However, significant exposure is not likely based on the lowgroundwater levels detected and the fact that few people in the site area use private wells fortheir water needs.

    Other Volatile Organic Compounds (VOCs)

    1,1,1-Trichloroethane (1,1,1-TCA) (320,000 ppb) and trichloroethylene (TCE) (180,000 ppb)were other VOCs detected in water in the underground traffic control box (Table 6). As amixture, these contaminants could have posed a short-term inhalation health risk toenvironmental sampling staff or utility workers who may have opened the box without properrespiratory protection (21,22). However, the potential health effects of such exposures cannot bedetermined because air quality data from inside the box are unavailable.

    1,1,1,-TCA, TCE, and a number of other VOCs were detected in soil (Table 1) and ingroundwater (Table 2) at One Hour Martinizing, and to lesser extent, at one or more of thefollowing locations: NE Solvents, Ideal Cleaners, and Oil Dealers Association. Grand Islandresidents are unlikely to be exposed to such VOCs in site soils since the contaminants aregenerally confined beneath buildings or paved parking areas. Persons involved in extensivedigging, drilling, or excavation activities, such as utility personnel or remedial workers, in areaswhere soil contamination is present might be exposed to VOCs. Such exposures can beminimized through the use of appropriate protective measures (where required by specific siteconditions).

    Few people in the site area use private wells for their water needs; however, it is not knownwhether any private wells are actually in use in those areas where groundwater is contaminatedwith VOCs (such as the One Hour Martinizing location) and, if so, to what extent such wellshave been impacted by the contamination. Therefore, at this time, ATSDR cannot evaluatewhether potential exposure to 1,1,1-TCA, TCE, and other VOCs poses a health threat to privatewell users at the site.



    Table 11.

    Comparison of Estimated Exposed Dose to Health Guidelines for Municipal Water System Users
    Contaminant Exposure
    Pathway
    Health Guideline for Ingestion - mg/kg/day
    Value Source Exceeded by Estimated
    Exposure Dose
    Bromodichloromethane Municipal water system 0.02 MRL*/ RfD** No
    Bromoform Municipal water system 0.2
    0.02
    MRL
    RfD
    No
    No
    Tetrachloroethylene Municipal water system 0.01 RfD No
    Chlorodibromomethane Municipal water system 0.03
    0.02
    MRL
    RfD
    No
    No
    Chloroform Municipal water system 0.01 MRL/RfD No
    1,1,2-Trichloroethane Municipal water system 0.004 RfD No
      *MRL = Minimal Risk Level (ATSDR)
      **RfD = Reference Dose (EPA)

    B. Health Outcome Data Evaluation

    Review of the Nebraska cancer incidence and mortality records for the period 1985 to 1990(Tables 12 and 13) did not show any statistically significant excess cancer incidence or mortalityrates in Hall County compared with either state or national rates. The rates for Hall County areprobably considered representative of Grand Island because its population of approximately39,400 is about 80% of the county's 49,500 resident population.



    Table 12.

    Total Cancer Incidence (1987-1989) and Cancer Mortality Rates (1985-1989) for Colon/Rectal and Bladder Cancers in Hall County, State of Nebraska, and United States (1987)
    Area of
    Consideration
    Colon/rectalBladder
    IncidenceRate*Mortality
    Rate*
    Incidence
    Rate*
    Mortality
    Rate*
    Significant
    Excess
    Compared
    To:
    Hall County 46.1 15.8 12.0 2.2
    Nebraska 45.8 18.5 14.2 3.0 No
    United States 49.0 19.9 9.4 6.3 No
      * Age-adjusted rates per 100,000 population.



    Table 13.

    Total Cancer Incidence (1987-1990) and Cancer Mortality Rates (1986-1990) for Liver/Gallbladder Cancer and Combined Cancer Sites in Hall County, State of Nebraska, and United States (1987)
    Area of
    Consideration
    Liver/GallbladderAll Sites Combined
    Incidence
    Rate*
    Mortality
    Rate*
    Incidence
    Rate*
    Mortality
    Rate*
    Significant
    Excess
    Compared
    To:
    Hall County 2.2 1.6 306.0 173.1
    Nebraska 3.2 3.4 336.2 157.3 No
    United States 2.7 4.3 377.2 169.3 No
      * Age-adjusted rates per 100,000 population.

    C. Community Health Concerns Evaluation

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

    1. Is the increased incidence of cancer in the area related to the Cleburn Street wellcontamination? Is this why the hospital added a cancer treatment unit last year?

      No, the addition of a cancer treatment center to the hospital is in response to therecognition of cancer as the second leading cause of death in the United Statesincluding Nebraska. Mortality rates have continued to increase nationwide duringthe 1980s, almost entirely as a result of the rising number of lung cancer deaths(9). Analysis of cancer data for the period between 1985 and 1990 (Tables 12and 13) indicates that incidence and mortality rates of all cancer types or specificcancer types did not differ significantly when the rates for Hall county arecompared with those for state or federal rates. The Nebraska Cancer Registrywhich began collecting data in 1987 is relatively new and is incomplete in yearsand data necessary to determine trends in cancer incidence.

      In addition, toxicological evaluation of the available environmental data for the CleburnStreet well site does not indicate that residents have been exposed to contaminants indrinking water at levels which might cause adverse health effects such as cancer. However, environmental data and other pertinent information for private wells and otherpathways through which people might be exposed to site contaminants are presentlyunavailable.

    2. Is it safe to use the municipal water for canning and vegetable gardening?

      Yes, it is safe to use the water for all domestic purposes including canning and vegetablewatering. Public supply wells that were found to contain low levels of VOCs weredisconnected from the municipal water distribution system in 1986. Plants do notsignificantly take up or bioaccumulate VOCs. In addition, VOCs volatilize readily,especially when aerated or heated, which would also reduce their presence in the water. As discussed in the Pathways Analyses section, the potential for people to be exposed to contaminants via the food chain is not significant.


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