PUBLIC HEALTH ASSESSMENT
TUCSON INTERNATIONAL AIRPORT AREA
TUCSON, PIMA COUNTY, ARIZONA
This public health assessment evaluates the potential public health hazard from exposure to contaminated groundwater in the vicinity of the Tucson International Airport. The Tucson International Airport Area (TIAA) superfund site consists of a main plume of contaminated groundwater and three smaller areas of groundwater contamination east of the main plume. This report focuses on one of these areas of contamination called Plume B and evaluates the public health hazard posed by Plume B to residents of the area of south Tucson bounded by Valencia Road, Campbell Avenue, Irvington Road, and 6th Avenue.
This assessment addresses potential current and future exposures to contaminated groundwater from private wells in the area of concern. Because insufficient data are available to evaluate potential past exposures, this document does not address past exposure. This document is part of a series of health consultations and health assessments evaluating all aspects of the TIAA site. Other areas of contamination and community concern have been or will be addressed by other documents.
For this evaluation, Arizona Department of Health Services, Office of Environmental Health (ADHS), considered 24 private wells which had been identified in the study area. Five of the wells were either non-operational or were not sampled by request of the owners, leaving a total of 19 private wells. Of the 19 private wells evaluated in this report, 12 were private drinking water wells and 7 were irrigation wells.
ADHS found that none of the drinking water wells exceeded appropriate comparison values while three of the irrigation wells were found to exceed USEPA's Maximum Contaminant Levels for trichloroethylene (TCE). ADHS considered the specific use of these three wells for irrigation water and found that the TCE levels present were not of public health concern for irrigation purposes (because only incidental ingestion and contact was likely for adults or children who may come into contact with the water on a limited basis).
Therefore, ADHS found that the groundwater currently poses no public health hazard. However, ADHS noted that there is nothing currently in place to preclude residents from turning an irrigation well into a drinking water well or installing new drinking water wells in the area of the plume. ADHS also notes that the plume is still being characterized and that chemical concentrations in some existing wells may increase beyond current levels. Because of these possibilities, ADHS has concluded that a future public health hazard may exist.
The United States Environmental Protection Agency (USEPA) asked the Arizona Department of Health Services (ADHS), Office of Environmental Health, to determine whether contaminated groundwater north of the Tucson International Airport Area (TIAA) has the potential to adversely affect human health in exposed persons. The USEPA asked that recent data contained in a 1998 private well study, conducted by the Pima County Department of Environmental Quality (PCDEQ), and the 1998 monitoring well data, obtained by the Arizona Department of Environmental Quality (ADEQ), be used to determine if adverse health effects would result from the use of private wells that have been identified near Plume B north of Valencia Blvd. The objective of this public health assessment is to evaluate if a public health hazard exists to residents who use the currently identified private wells over or near Plume B.
In 1981, contaminants were detected in several City of Tucson drinking water wells near the Tucson International Airport. Subsequently, the Tucson International Airport Area (TIAA) Superfund Site was officially added to the National Priorities List (NPL) in 1983. Figure 1 in the Appendix shows location of the TIAA.
The TIAA site consists of one main contaminated groundwater plume with three smaller areas of groundwater contamination located directly eastward. The three smaller areas of groundwater contamination will be referred to in this report by their approximate locations: one plume located at the Air National Guard facility, a plume associated with the Burr-Brown and West-Cap facilities, and Plume B, which is located just north of the Air National Guard facility and Valencia Road (ADEQ 1998). The groundwater in Plume B has been contaminated with the industrial solvent trichloroethylene (TCE) and chromium (ADEQ 1998). The source of the plume has not yet been determined. Possible sources have included the Air National Guard, the former West-Cap facility, and General Electric. Figure 2 in the Appendix shows the location of the larger and smaller contaminated groundwater plumes at the TIAA.
ADHS conducted site visits on November 18 and 19, 1998, and on January 20, 1999. Activities included visiting the West-Cap site, the Air National Guard, and the surrounding residential area near Plume B. The following observations were made:
- The residential area of concern begins approximately one-half mile north of the Air National Guard, and north of Valencia Blvd. There are several trailer parks, houses, one elementary school, and a few businesses located in this area. The elementary school is located on Drexel and is on the public water system.
- The area directly west of the residential area where Plume B is located is undeveloped and has little vegetation.
In addition to site visits, ADHS also obtained information about the area from the PCDEQ, ADEQ, USEPA, and from residents who attended a community meeting on Wednesday, November 18, 1998. Additional groundwater data were obtained from the TCE library located at the El Pueblo Clinic in South Tucson. The TCE library collects data and information that are provided by various governmental and community sources relating to the larger TIAA Superfund Site. This information is available to the public at the TCE Library located at 101 W. Irvington, Tucson, Arizona.
The area of groundwater contamination is within the TIAA Superfund Site, just north of Valencia Road. A residential area, which includes several trailer parks, small houses, an elementary school, and businesses, is located directly over the contaminated groundwater plume. The USEPA is continuing to install monitoring wells in the area to better define the plume boundaries. For purposes of this health assessment, boundaries have been chosen that will include the residential area located directly over the plume and an area extending beyond the current plume boundaries. The boundaries of the area considered for this report include Valencia Road to the south, Campbell Ave. to the east, Irvington Road on the north, and 6th Avenue to the west. Figure 1 shows these boundaries in relation to the TIAA site area.
Land Use and Natural Resources
Most of the residential community obtains their drinking and irrigation water from the City of Tucson municipal water system. However, there are some residences in the study area which still use private wells for drinking and/or irrigation purposes.
The upper 200 feet of sedimentary material within the area show a general coarsening trend from east to west. East of the Nogales Highway where the West Cap site is located, predominately fine-grained material is interbedded with layers and lenses of sand and gravel in a complex manner (ADEQ/USEPA 1998).
The regional aquifer system at the TIAA site is hydogeologically 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 zone regional aquifer because the vertical extent of contamination has been limited by the presence of the middle 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 bgs, to the top of the middle aquitard at a depth of about 175 feet bgs. As a consequence of the heterogeneous, layered geology, including lateral sedimentary facies changes, and local and regional groundwater pumpage, the depth to groundwater, nature of the aquifer system (unconfined versus confined), and direction of groundwater flow vary within the area depending on location and depth, making it difficult to characterize this groundwater plume (ADEQ 1998).
Several health studies have been conducted over the past 15 years to determine the health effects to residents in the TIAA area from exposures to trichloroethylene (TCE) in drinking water. Although these studies focus on exposures to TCE in drinking water primarily from the larger Main Plume, they are also applicable to Plume B since it also is contaminated with TCE and chromium similar to the Main Plume (ADHS 1996; ATSDR 1994). These studies are as follows:
- Mortality Rates on Tucson's Southside. Caldwell G. ADHS. 1986.
The objective of the study was to determine if an increase in mortality rates existed in certain census tracts in Tucson, Arizona. A 12-year review of all deaths in certain census tracts suspected to have unusual levels of serious illness (as reported by the press) was carried out in Tucson, Arizona. The number of deaths in census tracts 37, 38, and 39 (contaminated water area) were compiled by cause of death, sex, and age from computerized vital statistics death records.
Statistically significant excess crude mortality rates were found for the following diseases when compared to annual state or county rates: influenza/pneumonia in 1977; diseases of early infancy in 1973, 1975, 1976, 1980 and 1981; accidents in 1976; and homicide in 1978. Overall crude rates were not significantly different. No significant excess deaths were seen when compared to census tracts 24 and 25. With age-adjusted data, only 13 out of 84 comparisons were statistically significant. Of these, none were considered directly related to the trichloroethylene contamination. When compared to census tracts 24 and 25, no statistically significant mortality was apparent in census tracts 37, 38, and 39. No specific tests have been done to compare census tracts. (The report concludes that no pattern of mortality consistent with a marked increase in death is apparent and attributes the few excesses seen to behavior or chance rather than an environmental exposure).
- An Association of Human Congenital Cardiac Malformations and Drinking Water Contamination Goldberg SJ, Lebowitz MD, Graver EJ, Hicks S. Journal of the American College of Cardiology. 1990; 16;1:155-164.
The authors state that the investigation was designed to test the hypothesis that the proportion of offspring with congenital heart disease (CHD) is greater for parents who had contact with the contaminated water in the TIAA area before and through the first trimester of pregnancy than for parents who never had contact with the contaminated water area. The hypothesis is stated as if the study is a cohort study.
This is a registry-based case-control study investigating exposure to contaminated water among parents of children with certain types of CHD in Tucson, Arizona. The main contaminant was trichloroethylene, but dichloroethylene, chromium, and trace levels of other solvents were also present in the water supply. Seven hundred and seven families with children diagnosed with CHD were interviewed and compared to three different control groups. The authors conclude that the data show a significant association but no causality between parental exposure to the contaminated water and an increased proportion of CHD.
- Maricopa and Pima County Birth Defects Study. ADHS. 1987.
The objectives of this study were to determine if : 1) the observed differences in the birth defect rates between Pima County (Tucson) and Maricopa County (Phoenix) were real; 2) to compare the 2 county rates to the national and state rates; and 3) to determine if there were any unusual geographic distributions in either county.
A 5-year study of birth defects was conducted in Maricopa and Pima counties of Arizona. No consistent statistically significant differences in occurrence of birth defects was found between the two counties. The trend analysis, however, did show significant differences in the patterns of occurrence from defect to defect and between counties, but no evidence of a consistent county differential.
Of the 21 birth defect groups, none was found to be statistically significantly elevated, when compared either internally or externally to the Metropolitan Atlanta Birth Defects Registry. Only 11 of 282 census tracts were found to have a statistically significant excess in one or more defect groups, when 14 might have been expected by chance alone. Only one of these tracts was in Pima County. These data indicate that previously reported data may have resulted from reporting differences on birth certificates rather than real differences in the frequency of defects. Further surveillance and study are warranted for those tracts and birth defect groups where excesses were observed.
- A Comparison of Homebound Program Admission Rates in the Tucson Unified and Sunnyside School Districts. K. Komatsu, ADHS. 1986.
The purpose of the study was to examine the number and type of Homebound program admissions in the Sunnyside (close to the TCE-contaminated area) and Tucson Unified (unexposed) school districts to determine if there were significant differences which might be suggestive of a public health problem.
Results showed that: 1) Sunnyside Homebound admission rates were significantly higher for several diagnostic categories and specific diagnoses including overall number of cases, trauma, pregnancy, and infectious diseases. Rates for cancer, mononucleosis, Valley fever, and seizures did not differ significantly; 2) Among specific cancer diagnoses, there were no clusters, unexpected types, or unusual patterns of distribution in either district.
- Historical Prospective Mortality Study of Hughes Aircraft Employees at Air Force Plant #44. ENSR. 1990.
This report describes a cohort mortality study of 20,535 Hughes Aircraft employees. The observed mortality of the cohort, by cause, was compared with the expected based on U.S. mortality rates. For the entire cohort, mortality from all causes was 71.5% of that expected, a deficit that was statistically significant. In addition, a significantly lower mortality was found for all cancer combined, cancers of buccal cavity, pharynx, digestive system, larynx, female genital organs, circulatory system and several other nonmalignant disease. Though a significant increase in asthma mortality was observed when compared with U. S. mortality rates, there was no increase when compared with Pima County, Arizona rates.
- The Incidence of Childhood Leukemia and Testicular Cancer in Pima County, 1970-1986. ADHS. 1990.
This incidence study was conducted in 1990 to investigate the findings of the 1986 mortality study. It was designed to compare the incidence rates of childhood leukemia in the 0-19 age group and testicular cancer in males of all ages in the TIAA to the rest of Pima County during the years from 1970 through 1986. The incidence rates for childhood leukemia, testicular cancer, brain/CNS cancer and lymphoma, and other childhood cancers in the TIAA were not statistically elevated in comparison to the remainder of Pima County during the years from 1970 to 1986. The incidence rates were comparable to rates in other states and cities participating in the National Cancer Institute Surveillance Epidemiology End Results (SEER) Program.
- Effects on Neurobehavioral Performance of Chronic Exposure to Chemically Contaminated Well Water. Kilburn KH, Warshaw RH, University of Southern California, Los Angeles, CA. 1994.
This study was designed to determine whether there were adverse health effects, specifically neurobehavioral impairment, from living within an area served by wells known to have been contaminated with TCE and other chemicals for 25 years.
This is a study comparing neurophysiological (NPH) and neuropsychological (NPS) tests of 170 TCE- exposed residents of Tucson with two groups of subjects who had been studied for similar investigations. The NPH battery consisted of body balance, eye closure and blink reflex, simple and choice reaction time, and finger pad number recognition. The NPS battery consisted of immediate recall of stories, visual spatial memory, intelligence, attention span, psychomotor speed, dexterity, and affective status. Exposed subjects were significantly impaired compared to referents for both NPH and NPS tests.
- 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.
This study was designed to determine whether there was an increased prevalence of systemic lupus erythematosus (SLE) in the Tucson residents group who had been exposed to TCE. Results showed that the frequencies of each of 10 Antinuclear Antibodies (ANA) symptoms were higher in "exposed" subjects than in any comparison group, except those with clinical SLE. The prevalence of subjects with four or more symptoms was double in "exposed" group women and men compared to referent women and men.
The overall mission of ADHS and the ATSDR is to address the public health concerns of the residents who live near hazardous waste sites, such as the TIAA. Identifying and addressing public health concerns of the community near a Superfund site is crucial if the public health assessment is to satisfy its purpose of helping the public and health professionals understand the health risks posed by a site. This section describes the various concerns voiced by the community residents who live near the TIAA site.
Groundwater contamination in southwest Tucson has been a concern of the residents living near the TIAA site for many years. The community is made of residents who understand the history of the site, the exposure scenarios, and what is happening with the remediation activities as well as those who believe that the drinking water is still contaminated. Many residents do not trust Tucson City Water, or any governmental official. Much of the fear that residents have at this site is fueled from on-going problems created by the largest plume of contamination in the area and perceived lies told to community residents by various state, county, and city organizations and governmental personnel. Therefore, any news of a new plume tends to fuel the mistrust of Tucson Water and government officials.
PCDEQ conducted a private well study in 1994 and 1998 to identify the private wells in the TIAA area. During these investigations, PCDEQ employees informed all private well owners in the TIAA including the Plume B area of the groundwater contamination. They encouraged residents who had private wells to hook up to Tucson Water. While some 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 will not hook up to city water.
According to PCDEQ, there is currently a mild level of concern among the residents living near the Plume B area. However, in the past, residents in southwest Tucson have expressed concerns to ATSDR about the prevalence of congenital heart disease, lupus, and, cancer in their community that they associate with exposure to the contaminated groundwater. Several studies have been conducted to address these concerns, as described previously in Section 1.4, "Health Outcome Data."