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PUBLIC HEALTH ASSESSMENT

TUCSON INTERNATIONAL AIRPORT AREA
a/k/a EL VADO RESIDENTIAL PROPERTIES
TUCSON, PIMA COUNTY, ARIZONA


EXECUTIVE SUMMARY

The Agency for Toxic Substances and Disease Registry (ATSDR) asked the Arizona Department of Health Services (ADHS), Office of Environmental Health, to conduct a public health assessment for the off-site residential area located adjacent to the Tucson Industrial Center (TIC), also known as the Three Hangars site, within the larger Tucson International Airport Area Superfund site (TIAA), in Tucson, Arizona. Previous investigations found that elevated levels of polychlorinated biphenyls (PCBs) in the drainage areas at the TIC site had migrated off-site into residential areas, presenting a health threat to residents. The purpose of this public health assessment was to evaluate if a public health hazard still existed, since the remediation activities were conducted at the off-site El Vado residential area.

Remediation activities occurred during the period from March through May, 1997. These activities consisted of the removal of contaminated surface soil in the backyards of three residential properties, vacant areas north and west of a church, and a vacant lot, all located west of Highway 89 between El Vado and East Corona Roads. The associated drainages west of the Three Hangars area were also remediated. The soils were replaced with clean fill dirt and were landscaped. In addition, voluntary removal actions conducted by the Tucson Airport Authority (TAA) at the Three Hangars site included removing PCB-contaminated pipe sludge from the inlets to the drain pipes in the Three Hangars area, and plugging the floor drains and other inlets to the drain pipe systems to prevent future surface water flow from entering the pipe systems and facilitating PCB migration to off-site areas.

Results from the 31 confirmatory soil samples taken in these remediated areas were found to be below the Arizona residential Soil Remediation Level (SRL) of 0.66 milligrams/kilograms for PCBs, indicating that all contaminated soil had been removed (Conestega 1997).

ADHS concluded that no current public health hazard exists as a result of ingestion, dermal, or inhalation exposures by residents, children, or transients to the remediated soil in the residential areas on El Vado Road. Replacement of the top soil with certified clean soil removed all chance of contact with the soil containing PCBs, thus eliminating any future public health hazard.


BACKGROUND

The Agency for Toxic Substances and Disease Registry (ATSDR) has asked the Arizona Department of Health Services, Office of Environmental Health, to conduct a public health assessment for the off-site residential area located adjacent to the Tucson Industrial Center (TIC) within the larger Tucson International Airport Area Superfund Site (TIAA), in Tucson, Arizona. Previous investigations found that elevated levels of polychlorinated biphenyls (PCBs) in the drainage areas at the TIC site had migrated off-site into residential areas, presenting a health hazard to residents. The purpose of this public health assessment was to evaluate if a public health threat posed by PCBs still exists, since the off-site remediation activities were conducted at the El Vado residential area.

A. SITE DESCRIPTION AND HISTORY

The TIAA Superfund Site has been the site of various aviation, aerospace, and electronic industrial facilities since 1942. In May 1983, the TIAA site was added to the National Priorities List (NPL) after the discovery of a major groundwater plume containing several organic compounds, including trichloroethylene (TCE), 1,1-dichloroethylene (DCE), trans-1,2-dichloroethylene, chloroform, and chromium (ADHS 1996). The TIC site, also known as the Three Hangars site, is located on the central western portion of the TIAA site and is zoned as industrial property suitable for several types of manufacturing activities. The Three Hangars area was used for aircraft modification operations from 1954 until 1960. All the time of this public health assessment, it was being used by a number of tenants performing a variety of industrial activities, including general aircraft and vehicle maintenance, synthetic rubber and plastics manufacturing, and charter services. Several other building structures located in this area included small businesses involved in, but not limited to, aircraft maintenance, overhaul and repair, sandblasting, and degreasing of aircraft parts prior to plating.

A remedial investigation (RI) of the Three Hangars site began in 1992. Samples were taken for metals, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), organochlorine pesticides, and PCBs throughout the Three Hangars area, and the adjacent drainage ditch located just east of Highway 89. Elevated levels of PCBs in the drainage ditch area led to additional sampling on the vacant lot west of Highway 89 and the wash areas behind the residences on El Vado Road. In February 1996, an investigation was conducted on the residential properties that had identified PCB concentrations ranging from less than 0.056 milligrams/kilograms to 6.2 mg/kg, posing a health threat to residents, children, and transients (USEPA, 1996). The waste-related activities at the Three Hangars site consisted of discharging waste fluids directly into floor drains inside Hangar One of the TIC site. These drains were connected to the storm water drain pipe that discharged to the adjacent Highway 89 drainage ditch. A culvert extended under Highway 89 from the drainage ditch, allowing the contaminants in the underlying soils in the drainage ditch to migrate into off-site residential properties (see Figure 1 in Appendix).

In 1996, voluntary removal actions were conducted by the Tucson Airport Authority (TAA) on the Three Hangars site. These activities included removing PCB-contaminated pipe sludge from the inlets to the drain pipes in the hangar area, and plugging the floor drains and other inlets to the drain pipe systems to prevent future surface water flows from entering the pipe systems and facilitating PCB migration. In March 1997, USEPA conducted soil remediation activities for the off-site residential areas. Contaminated soil on the off-site residential properties and vacant lot was removed and replaced with clean fill dirt and the area was landscaped. Replacement of the top soil with certified clean soil removed all contact with the soil containing PCBs, eliminating any future public health threat.

B. SITE VISIT

The El Vado residential site consists of a vacant lot, the backyards of three residences, and the vacant area north and west of a church, all of which are areas located on the north side of El Vado Road. The residences were built in the 1970s and 1980s.

Site visits were conducted by ADHS on January 7, 1999 and January 20, 1999. Activities included visiting the Three Hangars site and the surrounding residential areas. The following observations were made:

  1. The Three Hangars site is being leased to Tucson Industrial Centers, which subleases space to industrial operations (primarily aircraft-related firms). Buildings 24 and 25, which were located to the west of the Three Hangars site, have been torn down, but the foundations are still visible.

  2. The drainage outfall areas are located to the west of the Three Hangars site, next to the railroad tracks and Highway 89. They are covered with desert vegetation such as grass, bushes, and small trees. A culvert crosses under Highway 89 into a vacant lot on the west side of the railroad tracks.

  3. The off-site properties that were remediated include a vacant lot, the area behind three residences and a church, and an additional vacant lot to the west of the church. Two of the three residential properties are owned by one family. There are a total of three houses located on these two properties. The third residential property, which only has one house on it, is owned by another family. The remediated areas have been appropriately landscaped and successfully blended into the surrounding area.

  4. The residential backyards are covered primarily with dirt and gravel. There are horse stables, animal stalls, and a mobile home behind one residence.

  5. A church is located in the remediation area. A vacant lot, which was probably used for parking, is to the west of the church and was remediated.

ADHS obtained information about the El Vado site from the Pima County Department of Environmental Quality (PCDEQ), residents who live on El Vado, and from participants attending a community meeting on Wednesday, January 20, 1999. On January 7, 1999, soil data were obtained from the TCE library located at the El Pueblo Clinic. The TCE library collects data and information that is provided by various government and community sources relating to the larger TIAA Superfund Site. This information is available to the public.

C. DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCES

Demographics

The residential site is located on El Vado road directly west of the Three Hangars site, which is located in the central western portion of the larger TIAA Superfund Site. El Vado Road extends westward from Highway 89, which runs north and south. The two vacant lots on the northwest and southwest corners of El Vado and Highway 89 are covered primarily with dirt, gravel, and some grassy areas. Single-family homes are located on the north and south sides of El Vado Road to the west of the vacant lots and are landscaped with typical desert plants and trees. The drainage ditch areas located to the east of Highway 89 have typical native desert brush and trees (USEPA Memo, September 10, 1996).

Land Use and Natural Resources Use

The major residential area of contamination is located on the north side of El Vado Road. This includes the backyards of three residences, the vacant lot located on the northwest corner of El Vado Road and Highway 89, and the vacant areas north and west of the church. The backyards of the residences were covered primarily with dirt and desert vegetation. There were open spaces, horse stables, animal stalls, a mobile home, and parking areas throughout the remediated areas. Water for the site was supplied by the City of Tucson municipal water system. The climate of Tucson, Arizona is semiarid, with an average of 10 or 11 inches of rainfall annually (ADHS 1996a).

D. HEALTH OUTCOME DATA

In 1996, ADHS conducted residential serum PCB blood tests for residents who lived adjacent to the Three Hangars site. Results were as follows:

Residential Serum PCB Blood Tests

Upon finding elevated levels of PCBs in the residential area, ADHS was asked to conduct a health consultation to determine the health implications of the possible PCB exposure to the residents. A total of four houses are located on the three residential properties. Three houses are owned and occupied by members of the same family. The fourth house is owned and occupied by members of another family. In May 1996, ADHS staff arranged to have blood tests conducted for serum PCB levels on 16 members of the two families whose yards were found to have elevated levels of PCBs.

Interviews were conducted with the two families living on the properties, as well as the grown children who had lived on the properties during the past 10 years, and had children of their own while living on the site. Several members of one family expressed concerns regarding symptoms experienced over the years that could not be explained by their physicians. The symptoms ranged from severe acne to fainting spells. To address their concerns, ADHS made arrangements to have interviews and blood tests for PCBs conducted on the families (ADHS, 1996b). ADHS made arrangements with the Pima County Health Department to conduct the blood draw, and with Sonora Labs to perform the blood analysis. Twelve members of one family and four members of the second family were tested for PCBs in their blood. Results of these blood tests are shown in Table 1. Studies by the Centers for Disease Control and Prevention (CDC) have demonstrated that most people without occupational exposure have median blood PCB levels from 5 and 7 µg/L, with approximately 95% of these values being below 20 µg/L (ATSDR, 1999).

Table 1.

Polychlorinated Biphenyl (PCB) Blood Levels in 16 Residents Living Adjacent to the Three Hangars Site (1996).
Resident Number PCB Levels in microgram/Liter (µg/L)
1 Less than 3 µg/L
2 Less than 3 µg/L
3 Less than 3 µg/L
4 Less than 6 µg/L *
5 Less than 6 µg/L *
6 3.4 µg/L
7 Less than 3 µg/L
8 Less than 3 µg/L
9 Less than 3 µg/L
10 Less than 3 µg/L
11 Less than 3 µg/L
12 Less than 3 µg/L
13 Less than 3 µg/L
14 Less than 3 µg/L
15 Less than 3 µg/L
16 Less than 3 µg/L
* These two results were as accurate as the testing procedure and quality control criteria would allow on the samples submitted.

COMMUNITY CONCERNS

During the site visit on January 7, 1999, ADHS staff had the opportunity to speak with members of one of the families whose backyard had been remediated. They said that they were quite pleased with the outcome of the remediation activities and had no complaints or further concerns. They also stated that their neighbors whose backyards were also remediated were very pleased with the results. They showed ADHS staff around the backyards and pointed out the areas that were remediated. The areas had been blended into the natural landscaping, so there was no apparent area of differentiation. The areas are clean and have been well-kept. They were pleased that someone had followed up on the situation.

The following questions were expressed by some of the community residents:

A. How does USEPA know that all the PCBs have been found?

Sampling locations are determined by the geography, type of soil, and the contaminant that is being identified. These properties allow USEPA to choose the best sampling plan for a site. During the sampling of the yards at this site, PCBs were found to be concentrated in particular areas. The boundaries of those areas were determined when PCBs did not show up in samples taken further away from the areas. Additional soil sampling depended on how the PCB concentrations presented themselves. USEPA has told all the families that if there is still someconcern about the presence of PCBs that might have gone undetected, they should call or write to the USEPA and express their concerns.

B. Since the blood samples showed that the serum PCB levels were not elevated, and did not present a health threat, why did USEPA clean up the yards?

The decision to clean up the PCBs was not just to prevent any possible future exposures to the PCBs, but also to meet regulations and prevent further ecological damage. The previous ATSDR health consultation conducted in 1997 stated that, despite the presence of PCBs in the residential yards, no residents had elevated levels of PCBs in their blood. This shows that, even if people were being exposed to the PCBs, it was not enough to show up in the blood. If the blood levels had been high, this would indicate that people were being, or had been, exposed and their health could be affected. USEPA has a responsibility to make sure that any known contamination is below certain standards, and also to address ecological concerns.


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