PUBLIC HEALTH ASSESSMENT
TUCSON INTERNATIONAL AIRPORT AREA
TUCSON, PIMA COUNTY, ARIZONA
The purpose of this document is to summarize the body of environmental health investigationwork that has been developed for the Tucson Internatinal Airport Area (TIAA) Superfund Site. The report includes a summary of previous reports and new data.
Contaminated groundwater was discovered in the area in 1981. The pollution includedtrichloroethylene (TCE). Investigations revealed the TCE was moving in a north to northwestdirection.
TCE was also discovered in production wells used by Tucson Water in 1981. These wells wereshut down shortly after the contamination was discovered. No groundwater data exist prior to1981. Since historical exposure levels are unknown prior to 1981, exposure to contaminatedgroundwater posed an unknown public health hazard. Municipal groundwater posed no publichealth hazard after the contaminated municipal wells were closed.
Currently the levels of contamination in private wells are not of public health concern. However,no regulation prevents persons from installing private drinking water wells in the contaminatedgroundwater, or from converting contaminated irrigation wells to drinking water wells. Becausethe pollutants in the groundwater may be of public health concern if it were used for drinkingwater, the site may pose a public health hazard unless actions are taken to prevent such use.Because of this potential pathway, ADHS finds the TIAA site may pose an indeterminatepublic health hazard unless further actions are taken. It should also be noted that a groundwateraquifer is a dynamic system, and pollution levels can and do vary over time. Consequently,private drinking wells should be monitored to ensure that contaminant levels remain below levels of health concern.
The Tucson International Airport Area (TIAA) Superfund Site is located on the south side ofTucson, Arizona. The site is approximately bounded by Ajo Way to the north, Hughes AccessRoad to the east and south, and Highway 89 to the west (Appendix: Figure 1). In May 1981,contaminated groundwater was discovered beneath part of the site, beginning a number ofinvestigations evaluating the nature and extent of contamination in the area. From theseinvestigations, at least three separate areas of contamination, potentially from different sources,have been identified. The TIAA Superfund Site was officially added to the National Priorities List (NPL) in 1983.
Various environmental sampling reports and health evaluations have been conducted over theyears (for example - Hargis & Montgomery, 1982; PCDEQ, 1994; D.B. Stephens, 1995; BaselineRisk Assessment ADHS, 1996; ATSDR, 2000a; ATSDR, 2000b; ATSDR, 2000c). In addition toreports focusing on individual areas of contamination, the Agency for Toxic Substances andDisease Registry (ATSDR) released a Public Health Assessment (PHA) for the TIAA in 1988and a draft version of a subsequent Public Health Assessment Addendum for the TIAA in 1996.
This PHA is prepared by the Arizona Department of Health Services (ADHS) in cooperativeagreement with the ATSDR. Because this current document is able to make use of a substantialbody of public health evaluations previously unavailable, it is laid out differently than the 1996ATSDR document. This PHA is essentially a new document (rather than a revised version of a previous document).
The purpose of this document is to summarize the body of environmental health investigationwork that has been developed regarding the TIAA site. The report includes data available sinceprevious documents were created, and develops and presents the overall public health findingsfor the TIAA site based on the current body of available data.
The Tucson Airport and surrounding area has been the site of various aviation, aerospace, and industrial facilities that have occupied portions of the site since 1942. The TIAA site includes one main contaminated groundwater plume with smaller areas of groundwater contamination located east of the main plume. Areas of contaminated soil have also been identified as part of the site. Figure 1 in the Appendix shows the location of the site and specific areas mentioned in this text.
Approximately 20 facilities have operated at various times in the TIAA vicinity. Known waste handling activities related to the TIAA site consisted of:
- surface discharge of waste liquids, containing several organic compounds, into soils,disposal ponds, and unlined landfills, and
- burning of wastes for use in fire training exercises (flammable wastes ignited in unlined fire pit areas, followed by application of water to extinguish the blaze).
Main Plume Area
In May 1981 contaminated groundwater was discovered at the site beneath Air Force Plant No. 44 (AFP44), which was operated for the Air Force at that time by Hughes Aircraft Corporation. This area is currently operated by Raytheon Corporation. Further investigations of the site revealed a sizable area of groundwater contamination, called the main plume, containing several organic compounds, including trichloroethylene (TCE), and chromium. Investigations revealed the contaminated groundwater plume was moving off-site in a north to northwest direction.
In 1987, the area of the plume was approximately 4 miles long and 3,000 feet wide covering anarea located from the northwest corner of the AFP44 facility to near Irvington Road. Acooperative agreement between the USEPA and the United States Air Force (USAF) divided theplume into two major remedial areas with Los Reales Road as the dividing point. The portions ofthe main plume south of Los Reales Road are treated with a reclamation well field and full-scaleair stripping facility that began operation in 1987 at the AFP44 site. North of Los Reales Road,the main plume is contained by extraction wells which feed the Tucson Aquifer RemediationProject (TARP) plant. Figure 1 in the Appendix displays a recent overview of the main plume.
Plume B Area
East of the main plume are smaller areas of contamination indicated by soil and water quality analyses from sampling programs conducted in the TIAA area. Based on the analyses conducted to date and a review of historical activities at the facilities in the area, the contamination (primarily TCE and chromium) may have resulted from operations of any of the following: the Tucson Airport, the Burr-Brown facility, the former West Cap property, General Electric, and the Arizona Air National Guard. In this report, these smaller areas of contaminated groundwater have been collectively referred to as "Plume B." The Plume B area is the subject of a separate Public Health Assessment (ATSDR, 2000c).
In addition to the areas of groundwater contamination, areas of soil and sediment contamination related to surface water runoff from the site were also identified during site investigations. A primary area was associated with the "Three Hangars" area of the airport. The Three Hangars area has been used for aircraft modification operations, general aircraft and vehicle maintenance, synthetic rubber and plastics manufacturing, charter services, and other industrial activities. Soil contaminated by runoff from this area has been discussed in a recent Public Health Assessment subtitled "El Vado Residential Properties"(ATSDR, 2000a).
In addition to numerous site visits, ADHS also obtained information about the area from theATSDR, the Pima County Department of Environmental Quality (PCDEQ), Arizona Departmentof Environmental Quality (ADEQ), USEPA, and from residents who attended numerouscommunity meetings over the last several years.
Additional groundwater data were obtained from the TCE library located at the El PuebloCommunity Center in south Tucson. The TCE library collects data and information that areprovided by various governmental and community sources relating to the TIAA Superfund Site.This information is available to the public at the TCE Library located at 101 W. Irvington, Tucson, Arizona.
Demographics and Land Use
The area around the TIAA site is an area of mixed commercial and residential usage. Areas closest to the airport tend to be more commercial than areas slightly further from the airport. The greatest concentrations of residences are west and north of the airport. Approximately 55,000 people live within one mile of the site (1990 census).
The climate of Tucson, Arizona is semi-arid with an average of between 10 and 11 inches of rainfall annually. Annual evaporation is about four times greater than the average annual precipitation. Summertime high temperatures average about 100 degrees Fahrenheit. Winter high temperatures average in the upper 60s.
Most of the residential community obtains their water supply from the Tucson municipal water system. However, there are some residences in the area which still use private wells for drinking or irrigation purposes. Surface water is not a significant source of water supply in the Tucson area.
Natural surface waters in the site area are intermittent and occur primarily as runoff from stormevents. The Airport Wash is the dominant surface water feature at the Tucson Airport, and islocated in the northeastern part of the airport. The other major surface water feature consists ofthe Diversion Channel, which flows from Aero Park Road to the Hughes Access Road on thewestern side of the main runway. Under current land use conditions, artificial surface coveringsincluding pavement and tarmacs essentially prevent soil or groundwater contaminants fromcoming into contact with surface water. These coverings do allow the potential for surface waterrunoff to contaminate soils in areas where surface waters pond during storm events.
The upper 200 feet of sedimentary materials within the area show a general coarsening trend from east to west. Predominately fine-grained material is interbedded with layers and lenses of sand and gravel in a complex manner exist east of the Nogales Highway (PCDEQ, 1998).
The regional aquifer system at the TIAA site is hydrogeologically complex due to lateral and vertical lithologic changes. Three units of the regional aquifer system (the upper zone, lower zone, and undivided regional aquifer) are present within the boundaries of the TIAA Site. The middle aquitard divides the regional aquifer into upper and lower zones under most of the TIAA site.
Transport and fate of groundwater contamination has been associated mainly with the upper zoneregional aquifer. The vertical extent of contamination has been limited by the presence of themiddle aquitard. In this area, the upper zone regional aquifer is about 70 - 100 feet thick,extending from the water table, which occurs at depths of about 85 - 100 feet below the groundsurface (bgs), to the top of the middle aquitard at a depth of about 175 feet bgs. As a consequenceof the heterogeneous geology and groundwater pumpage, the depth to groundwater, nature of theaquifer system (unconfined versus confined), and direction of groundwater flow vary within the area depending on location and depth (ADEQ, 1998).
Several health studies have been conducted over the past 15 years to determine the health effectsto residents in the TIAA area from exposures to trichloroethylene (TCE) in drinking waterAlthough these studies focus on exposures to TCE in drinking water primarily from the largerMain Plume, they are also applicable to the Plume B area since it also is contaminated with TCEand chromium similar to the Main Plume (ADHS, 1996; ATSDR, 1994). In many cases, thestudies included participants or databases which covered both areas. These studies are as follows:
- Mortality Rates on Tucson's Southside. Caldwell G. ADHS. 1986.
- An Association of Human Congenital Cardiac Malformations and Drinking Water Contamination. Goldberg SJ, Lebowitz MD, Graver EJ, Hicks S. Journal of theAmerican College of Cardiology. 1990; 16;1:155-164.
- Maricopa and Pima County Birth Defects Study. ADHS. 1987.
- A Comparison of Homebound Program Admission Rates in the Tucson Unified and Sunnyside School Districts. K. Komatsu, ADHS. 1986.
- Historical Prospective Mortality Study of Hughes Aircraft Employees at Air Force Plant #44. ENSR. 1990.
- The Incidence of Childhood Leukemia and Testicular Cancer in Pima County,1970-1986. ADHS. 1990.
- Effects on Neurobehavioral Performance of Chronic Exposure to ChemicallyContaminated Well Water. Kilburn KH, Warshaw RH, University of SouthernCalifornia, Los Angeles, CA. 1994.
- Prevalence of Symptoms of Systemic Lupus Erythematosus (SLE) and of Fluorescent Antinuclear Antibodies Associated with Chronic Exposure to Trichloroethylene and other Chemicals in Well Water: Kilburn KH, Warshaw RH. Environmental Research.1992; 57:1-9.
These studies have been summarized and discussed in previous documents (ATSDR, 1996a;ATSDR, 2000c) and the reader is referred to those documents for further interest. A briefsummary of the findings from these is found in Section 4.3, "Health Outcome Data Evaluation."
Other available Health Outcome Data include a Disease and Symptom Prevalence Survey for partof the TIAA site area conducted by ATSDR (ATSDR, 1996b), and information emerging fromthe ongoing National Exposure Registry - Trichloroethylene (TCE) Subregistry developed byATSDR (see ATSDR, 1999 for a recent summary report of the Registry program). Informationfrom these projects is discussed in Section 4.3, "Health Outcome Data Evaluation."
This section describes general concerns voiced by community residents who live near the TIAAsite. Detailed descriptions of these concerns have been documented in previous reports (ATSDR,1988; ATSDR, 1996a; ATSDR, 2000c). These concerns have already been discussed in detail inthe 1996 PHA Addendum (ATSDR, 1996a).
Groundwater contamination in southwest Tucson has been a concern of residents living near the TIAA site for many years. The community includes many residents who understand the history of the site, the exposure scenarios, and what is happening with the remediation activities. Some believe that public drinking water is still contaminated. While many residents have switched over to City water, a few believe that drinking water out of a contaminated private well is safer than drinking the "contaminated Tucson Water" and have chosen not to hook up to city water (ATSDR, 2000c; PCDEQ, 1998). ADHS has made recommendations in previous documents (ATSDR, 2000c) to address potential exposure due to use of private wells.
In the past, residents in southwest Tucson have expressed concerns about the prevalence ofcongenital heart disease, lupus, and, cancer in their community that they associate with exposureto the contaminated groundwater (ATSDR, 1988, 1996a). Several studies have been conductedto address these concerns, as described in Section 1.5, "Health Outcome Data," and Section 4.3,"Discussion: Health Outcome Data Evaluation."
In addition, former workers from the AFP44 facility have expressed concerns about potentialworkplace exposures. ADHS was unable to locate environmental data to evaluate past conditionsinside the facility. Investigations of workplace health concerns are the authority of theOccupational Safety and Health Administration (OSHA) and the Occupational Safety and Health Division of the Arizona Industrial Commission, and are beyond the scope of this report.
In this section, contamination in the site area will be discussed based on the medium (air, soil,water) and where the chemicals are, or have been, found. For issues which have been addressed by previous documents, the reader will be referred to those documents for detailed discussion.
No air sampling data were located for public exposures in the site area. No significant air exposure pathway appears likely based on site contaminants and conditions and past public health evaluations did not find a need for any air sampling (ATSDR, 1988, 1996a). On-site soil gas samples have been collected and evaluated for part of the site (ATSDR, 2000b). The available data are discussed in section 4.1 "Environmental Data Evaluation."
Evidence of past off-site soil contamination related to drainage system runoff from the TIAA site has been detected. This contamination was evaluated in the PHA document subtitled "El Vado Residential Properties" (ATSDR, 2000a). Other areas of contaminated soil were found on-site and are discussed in section 4.1, "Environmental Data Evaluation."
As noted previously, no significant perennial surface waterways exist in the TIAA site area, and surface water is not considered to be a pathway of public health significance. However, the site has multiple areas of significant groundwater contamination associated with it, and groundwater is the main source of drinking water supply for the TIAA site area. For ease of discussion, groundwater contamination will be discussed in separate detail for the past and present timeframes.
Past Groundwater Data
Past groundwater conditions have been evaluated for the time period 1981 to 1999 in previous documents (ATSDR, 1988, 1996a, 2000c). No sampling data were located which indicate groundwater chemical conditions prior to 1981. ATSDR (1996a) did evaluate scenarios to estimate potential levels of groundwater contaminants prior to 1981 in the draft PHA. However, comments on that draft text indicated that the model oversimplified the complex hydrogeology of the site. ATSDR's text accompanying the modeling effort also indicated that the estimates were only for purposes of estimating approximate dates of contamination in wells and that the numbers should not be used to evaluate public health exposures. In addition, ADHS notes that the definition of multiple distinct areas of contamination (e.g., Main Plume and Plume B) is more complex than the model effort incorporated. Based on these comments, ADHS finds the existing database inadequate to evaluate groundwater exposures prior to 1981. The ADHS could not locate any actual data or detailed estimates suitable for use in public health evaluation of groundwater contaminant concentrations prior to 1981.
Present Groundwater Data
Groundwater sampling of the two plumes associated with the site continues at present. ADHS's most recent evaluation of this data was published in 2000 (ATSDR, 2000c). Additional data on groundwater conditions are routinely reported by USEPA and AFP44. These data are publicly available from USEPA or at the TCE Library at 101 W. Irvington, Tucson. USEPA drinking water regulations also require the Tucson Municipal Water authority to notify customers if any of the municipal drinking water is not meeting EPA standards for maximum contaminant levels. Current data indicate local drinking water contains less than 5 micrograms per liter (µg/L) of TCE.
ADHS evaluates a site by considering the level of exposure in potential or completed exposurepathways. An exposure pathway is the way chemicals may travel through the environment andenter a person's body to cause a health effect. It includes all of the steps between the release ofthe chemical and the population exposed: (1) a chemical release source, (2) chemical movement,(3) a place where people can come into contact with the chemical, (4) a route of human exposure,such an inhalation or ingestion, and (5) a population that is exposed. ADHS considers whichchemicals, if any, from a site are present at levels of public health concern (i.e., above anappropriate comparison value) through all five elements of a completed pathway whendetermining the public health implications of a site.
This section presents ADHS's evaluation of the available data based either on data listed in thesection titled "Environmental Contamination" or on previously published reports as identified inthe text.
Quality Assurance and Quality Control
Procedures for sampling, analysis, and data reporting were evaluated in the previous investigations that are summarized in this document. Quality assurance and quality control measures were determined to be adequate and no major problems with field or laboratory procedures were reported.
No data were found indicating large-scale chemical releases to the air which would affect the ambient air around the TIAA site. Limited data from a portion of the site were evaluated (ATSDR, 2000b) and are summarized in Table 1. Estimated indoor air concentrations of contaminants were determined by applying the Jury Model (Appendix) to the highest measured levels of contaminants in soil vapor. Modeled concentrations were then compared to ATSDR Environmental Media Evaluation Guide (EMEG) comparison values to determine potential for health risk. The EMEGs are media-specific chemical levels that do not represent a health concern. The modeled concentrations were well below the corresponding EMEG values, as shown in Table 1. Based on this limited available data, activities conducted at the TIAA site, and the nature of the soil and groundwater contamination, ADHS does not find any public health issues from ambient air exposures to site-related chemicals for either the past, present, or future timeframes.
|Contaminant||Concentration Range in Soil Vapor (µg/L)†||Maximum Concentration in Samples (µg/L)||Modeled Air Concentration* |
|ATSDR Air CV‡ |
|Exceed ATSDR CV?|
|TCE §||ND¶ - 387||387b||2.3E-05||5.4E-012||NO|
|PCE**||ND - 121||121b||8.6E-06||2.7E-011||NO|
|1,1-DCE††||ND - 140||140 c||7.5E-07||8.0E-022||NO|
|1,1,1-TCA‡‡||ND - 4.3||4.3 a||2.5E-07||3.82|| |
‡ CV = Comparison Values; ¶ ND = non-detect;
§ TCE = trichloroethylene; ** PCE = tetrachloroethene; †† 1,1-DCE = 1,1-dichloroethylene; ‡‡ 1,1,1-TCA = 1,1,1 trichloroethane.
a= 1996 sampling data; b= from sample WC-1, 2000 data; c= from sample WC-2, 1997 data.
1= ATSDR chronic Environmental Media Evaluation Guide (EMEG); 2= ATSDR intermediate EMEG
Previous investigations found that elevated levels of polychlorinated biphenyls (PCBs) in the drainage areas at the TIAA site had migrated off-site into residential areas. This contamination was evaluated in previous public health assessments (ATSDR, 1988, 1996a, 2000a). As presented in the document subtitled "El Vado Residential Properties," (ATSDR, 2000a), remediation of these areas has occurred to below Residential Arizona Soil Remediation Levels (SRLs). SRLs are levels of contaminants in soils promulgated by administrative rule that do not represent a health risk. A summary table of representative soil data is presented as Table 2.
Other areas of contaminated soil related to AFP44 and the airport itself have either beenremediated or are being remediated as part of ongoing TIAA site work (EPA, 2000). The AFP44and airport property soil sites are completely fenced to restrict site access and the fencing isroutinely monitored. Based on this restriction of access, ADHS finds no public health concernfrom on-site soil contamination because there currently is no completed pathway of exposure.Worker exposures to on-site soil contamination were evaluated in a previous investigation(ADHS 1996). PCBs were detected above screening levels in some areas, but were not found to pose a health threat to on-site personnel.
|Remediation Area||Number of Samples||Range of Polychlorinated Biphenyl (PCB) Concentrations in milligram per kilogram |
|Soil Remediation Levels (SRLs) for PCBs |
|12||0.643 - <0.033||0.32||2.5||NO|
|9||0.182 - <0.033||0.100||2.5||NO|
Backyards of Residences
|5||0.122 - <0.033||0.076||2.5||NO|
Vacant Area North of the Church
|3||0.120 - 0.045||0.07||2.5||NO|
Vacant Area West of the Church
|2||0.039 - 0.035||0.037||2.5||NO|
Results from Conestoga (1997) as reported in ATSDR (2000a).
Past Groundwater Conditions
As noted previously, insufficient data exist to evaluate groundwater contamination prior to 1981. Therefore, ADHS finds that pre-1981 groundwater exposure is an indeterminate public health concern.
Groundwater conditions since 1981 have been evaluated in previous public health reports(ATSDR, 1988, 1996a, 2000c). Summarizing these documents, ADHS finds that groundwateroffsite was contaminated with trichloroethylene (TCE) at levels above public health guidelinesprior to 1981. However, there have been no significant exposures since site monitoring andremedial activities began in 1981. A summary of past municipal well monitoring data ispresented in Table 3. Municipal supply well locations are depicted in Figure 2 in the Appendix.
|Well||Month/Year Removed from Use||trichloroethylene (TCE) parts per billion||Sample Date (month/year)|
MCL = current EPA drinking water standard (Maximum Contaminant Level)
Present Groundwater Conditions
Contaminated groundwater is currently being extracted, treated to remove pollutants, and placed into the Tucson municipal drinking water distribution system at the Tucson Aquifer Remediation Project Plant. No current private drinking water wells contain TCE at levels of health concern. A number of private irrigation wells and some private drinking water wells that are not in-use are contaminated with TCE. Potential exposures to contaminated irrigation well groundwater during both residential and occupational irrigation purposes were evaluated and found to pose no public health threat (ATSDR, 2000c). A summary of recent private drinking water well data is provided in Table 4. Figure 3 in the Appendix shows the location of the private wells that were sampled. The site currently poses no apparent public health concern from exposure to groundwater.
|Well ID #||Present Status||TCE† |
|12||Mobile Home Park||0.8||6.3 **||NO|
|9||Private residence||N.D.||3.0 **||NO|
|18||Private residence||N.D.||5.6 **||NO|
|21||Private residence||N.D.||5.8 **||NO|
|17||Private residence||N.D.||1.2 **||NO|
|7||Private residence||4 **||N.D.||NO|
|13||Mobile Home Park||3.6||7||NO|
|15||Private residence||3 **||6.3 **||NO|
** Indicates an increase in contaminant level between sampling periods (1994 samples to 1998 samples, or 1998 to 2000 samples)
Table from: ATSDR, 2000c
Future Groundwater Conditions
Levels of TCE and chromium did increase in some wells between sampling events, as shown in Table 4. Due to potential fluctuations in contaminant levels, private drinking water wells should be monitored to ensure that contaminant levels remain below levels of health concern. The presence of private irrigation wells contaminated with TCE and the possibility that these wells could be converted for drinking water use presents a potential public health concern. ADHS has recommended that safeguards be enacted to preclude private use of any contaminated irrigation well for drinking water purposes until site remediation has been completed (ATSDR, 2000c). ADHS affirms that recommendation in this current document.
As noted previously, a number of public health evaluations have been conducted over the lastseveral years regarding the TIAA site. Some of the key reports are listed below along with a brief summary of their public health findings:
- Public Health Assessment for Tucson International Airport Site (ATSDR, 1988) - Thisreport evaluated the (limited) available data and concluded that public drinking watersupplies posed no public health concern. The report also found a lack of adequateinformation on previous conditions which left past conditions as an indeterminate public health concern.
- Baseline Human Health Risk Assessment (ADHS, 1996) - This document used formal riskassessment methods following EPA's "Risk Assessment Guidance for Superfund" andfound that off-site soils posed a potential public health risk due to PCB contamination.These soils have since been remediated. No completed pathway of groundwater exposurewas identified, and no health risk was found from groundwater.
- Petitioned Public Health Assessment Addendum for Tucson International Airport Area(ATSDR, 1996a) - This document evaluated a large body of environmental data and foundthat groundwater and municipal drinking waterposed no apparent public health hazard.Soils in wash areas were of public health concern based on the presence of polychlorinatedbiphenyls (PCBs). Note that the wash areas have since been remediated and were discussedin the document regarding the "El Vado Residential Properties" (ATSDR, 2000a).
- Public Health Assessment for Tucson International Airport Area (a/k/a El Vado ResidentialProperties) (ATSDR, 2000a) - This public health assessment evaluated off-site soilcontamination west of the Tucson Airport property. The contamination was apparently theresult of surface water runoff from the western portion of the airport near the three hangarsarea. ATSDR found that soils had been remediated to an acceptable level and the site posedno public health hazard.
- Public Health Consultation for Tucson International Airport (a/k/a West Cap Facility)(ATSDR, 2000b) - This consultation evaluated specific concerns regarding soilcontamination and soil gas vapors inside buildings on the former West-Cap property. Indoorair concentrations modeled from soil gas data were found to present no public healthhazard.
- Public Health Assessment for Tucson International Airport Area (Plume B Area) (ATSDR,2000c) - This PHA evaluated private wells in the Plume B area north of the airport. Twelveprivate drinking water wells were evaluated and were found to pose no public healthhazard. In addition to private drinking water wells, a number of private wells used forirrigation purposes were also evaluated and three were found to contain TCE at levels abovedrinking water standards. Because it is possible to convert an existing irrigation well to adrinking water source or to install a new private well for drinking use in the area, this wasconsidered to be a potential public health concern for the future. Actions to prevent any exposures of public health concern were recommended.
ATSDR and ADHS have reviewed the eight studies listed in Section 1.4. A brief summary of thefindings of these studies is presented here. Readers are referred to the PHA - "Plume B Area"(ATSDR, 2000c), the 1996 PHA Addendum (ATSDR, 1996a), or the specific study documentsfor more details about the findings and limitations of each study.
No statistically significant results were found for the following outcomes studied: a) homeboundprogram admission rates in the Tucson Unified and Sunnyside school districts, b) mortality ratesof Hughes aircraft employees, and, c) childhood leukemia and testicular cancer incidence in PimaCounty.
In the reviewed studies, the reported results were suggestive, but not conclusive, for thefollowing outcomes: a) congenital heart disease, b) musculoskeletal birth defects (county-yearinteractions), c) mortality due to asthma, d) neurobehavioral performance, and, e) prevalence ofsystemic lupus erythematosus.
Numerous and significant limitations exist in the eight studies. These limitations preventdefinitive conclusions on the causal relationship between exposure and health outcomes. Almostno exposure information is available besides that of residence in the contaminated census tract orwork. This is a poor surrogate for exposure, since the contamination plume does not occupy thewhole census tract. Using the tract level for analysis rather than block level is likely to lead toexposure misclassification resulting in an underestimation of the outcome effect. It isrecommended that any further studies use block level analysis of morbidity and mortality data.
Although a number of serious limitations exist in the above studies, it is recommended that theoutcomes for which results were suggestive be included in any future studies of the Tucson TCEcontamination problem when possible. It is also recommended that a trend analysis be done todetermine if the elevations in specific birth defects or other outcomes were persistent after publicwater supply sources were used.
In addition to these studies, ATSDR has conducted two additional activities pertinent to thetrichloroethylene (TCE) in groundwater at the TIAA site. First, ATSDR conducted a "Diseaseand Symptom Prevalence Survey" (ATSDR, 1996b) in an area around the site. In addition to thesurvey, ATSDR has developed a National Exposure Subregistry of persons significantly exposedto TCE at various locations in the US. The TCE Subregistry began in 1989 and is ongoing. Themost recent report (ATSDR, 1999) covers data collected through 1997 and incorporatesinformation collected from nearly 5,000 persons.
The Disease and Symptom Prevalence Survey (ATSDR, 1996a) found "a statistically significantly greater proportion of residents from the target area than the comparison area reported having had most of the general and neurological-specific disease and symptoms with onset since moving into the home occupied at the time of the survey." The conclusions then note that "the association between the reported health outcomes and TCE exposure could not be determined without......more detailed exposure information."
ATSDR compares data from the TCE Subregistry to the National Health Interview Surveyconducted throughout the US (ATSDR, 1999). In the information reported to date, TCEregistrants reported some conditions at a higher rate than the general population. The healthconditions reported in excess at one or more interview time periods were: anemia, diabetes,hearing impairment, hypertension, kidney disease, liver problems, skin rashes, speechimpairment, stroke, and urinary tract disorders (ATSDR, 1999). ATSDR notes that these resultsdo not identify a causal relationship between TCE exposure and adverse health effect because theexcess reporting of some health conditions might be explained by methodological differences indata collection. ATSDR states it intends to continue the registry and follow-up evaluation(ATSDR, 1999).
ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants andchildren demand special emphasis in communities faced with contamination of their water, soil,air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardoussubstances emitted from waste sites and emergency events. They are more likely to be exposedbecause they play outdoors, they often bring food into contaminated areas, and the developingbody systems of children can sustain permanent damage if toxic exposures occur during criticalgrowth stages. ADHS has considered the special needs of children in the evaluation of the TIAA site.
Based upon the available data and previously published reports, ADHS has reached the followingconclusions regarding the potential public health hazards posed by the Tucson InternationalAirport Area (TIAA) site.
Since no groundwater sampling data exist for site-related contaminants prior to 1981, the TIAA site posed an indeterminate public health hazard prior to 1981. Groundwater represented no apparent public health hazard after the contaminated municipal wells were closed.
Soils in wash areas were a potential public health concern due to the presence of polychlorinatedbiphenyls (PCBs) prior to the soil remediaton activities conducted in 1996. However, after theclean up effort, the soils represented no apparent public health hazard.
ADHS finds no current completed exposure pathways at levels of public health concern. The TIAA site currently poses no apparent public health hazard.
ADHS notes that ongoing remedial activities (descriptions of activities presented in the Background Section of this PHA), should improve local environmental conditions. The potential currently exists for people to install private drinking water wells in currently contaminated groundwater. Because of this potential pathway, ADHS finds the TIAA site may pose an indeterminate public health hazard unless further actions are taken. ADHS will share these findings with EPA site managers and parties responsible for the ongoing remedial activities in an effort to prevent any future public health hazard from occurring.
ADHS recommends the following for the TIAA site:
- ongoing remedial efforts should continue at the TIAA site to reduce on-site contaminant levels;
- actions should be taken to prevent potential future use of contaminated groundwater by private well users;
- TCE and chromium levels should continue to be monitored in contaminated privatedrinking water wells to ensure that contaminants remain below levels of health concern; and
- health outcomes for which results were suggestive be included in any future studies of theTucson TCE contamination problem when possible. It is also recommended that a trendanalysis be done to determine if the elevations in specific birth defects or other outcomes were persistent after public water supply sources were used.
In the event additional data become available regarding the TIAA site, ADHS will consider modifying, or issuing an addendum to, this Public Health Assessment as appropriate.
ADHS has actively participated in regular site-related meetings with the local community(Unified Community Advisory Board - UCAB), regulatory agencies (USEPA and ADEQ), andparties responsible for site remediation activities (AFP44, Tucson Airport Authority, contractors)to provide public health evaluations throughout the site investigation and remediation process.ADHS will continue to participate as needed in site-related remedial activities to address publichealth concerns related to the TIAA site.
ADHS will also work to educate the local community about the use of private wells and healthconcerns that may be related to that use.
ATSDR will continue the TCE Subregistry and follow-up evaluation.
Agency for Toxic Substances and Disease Registry, 1988. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry; PublicHealth Assessment, Tucson International Airport Site, Tucson, Pima County, Arizona. March 8,1988.
Agency for Toxic Substances and Disease Registry, 1994. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry; Division ofHealth Assessment and Consultation. Review of Health Studies Related to TCE Contamination atTucson Superfund Site, Tucson Arizona. 1994.
Agency for Toxic Substances and Disease Registry, 1996a. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry; Division ofHealth Assessment and Consultation, Petitioned Public Health Assessment Addendum, TucsonInternational Airport Area, Tucson, Pima County, Arizona. September 6, 1996.
Agency for Toxic Substances and Disease Registry, 1996b. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry; Division ofHealth Assessment and Consultation Final Report - Disease and Symptom Prevalence Survey,Tucson International Airport Site, Tucson, Pima County, Arizona. September 1996.
Agency for Toxic Substances and Disease Registry, 1999. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry. NationalExposure Registry - Trichloroethylene (TCE) Subregistry, Baseline through Followup 3Technical Report. October 1999.
Agency for Toxic Substances and Disease Registry, 2000a. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry. PublicHealth Assessment, Tucson International Airport Area (a/k/a El Vado Residential Properties),Tucson, Pima County, Arizona. March 15, 2000.
Agency for Toxic Substances and Disease Registry, 2000b. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry; Division ofHealth Assessment and Consultation. Health Consultation, Tucson International Airport (a/k/aWest-Cap Facility), Tucson, Pima County, Arizona. July 11, 2000.
Agency for Toxic Substances and Disease Registry, 2000c. U.S. Department of Health & HumanServices, Public Health Service, Agency for Toxic Substances and Disease Registry. PublicHealth Assessment, Tucson International Airport Area (Plume B area), Tucson, Pima County,Arizona. October 10, 2000.
Arizona Department of Environmental Quality. Remedial Investigation Report. Phase II:Former West-Cap Property and Vicinity. Area B. Tucson International Airport Area, CERCLASite. File Report: OFR 98-2. June, 1998.
Arizona Department of Health Services. Baseline Human Health Risk Assessment; TucsonInternational Superfund Site. December 1, 1996.
Daniel B. Stephens & Associates, 1995. Field Reconnaissance Investigation Results, TucsonInternational Airport RI/FS, Volume 1. Albuquerque, NM. January 27, 1995.
Hargis & Montgomery, 1982. Phase I Investigation of Subsurface Conditions in the Vicinity ofAbandoned Waste Disposal Sites, Hughes Aircraft Company Manufacturing Facility, Tucson,AZ.
Pima County Department of Environmental Quality. South side TCE Private Well Investigationfor the Tucson International Airport Area Superfund Site (TIAASS), Tucson, Arizona. November,1994.
Pima County Department of Environmental Quality. South side TCE Private Well Investigationfor the Tucson International Airport Area Superfund Site (TIAASS), Tucson, Arizona. December1998.
U.S. Environmental Protection Agency, 2000. Tucson International Airport Area (TIAA)Superfund Site (newsletter), February 2000.
Arizona Department of Health Services, Office of Environmental Health
Douglas Gouzie, Ph.D., Environmental Program Specialist
Will Humble, M.P.H., Chief, Office of Environmental Health, Principal Investigator
ATSDR Technical Project Officer
Tammie McRae, M.S.
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
State Program Section
ATSDR Regional Representative
Regional Services, Region IX
Office of the Assistant Administrator