PETITIONED PUBLIC HEALTH ASSESSMENT
KELLY AIR FORCE BASE
(a/k/a EAST KELLY AIR FORCE BASE)
SAN ANTONIO, BEXAR COUNTY, TEXAS
The Agency for Toxic Substances and Disease Registry has concluded the levels of contaminants detected at on- and off-site locations associated with East Kelly Air Force Base are not likely to cause adverse health effects. The current site conditions do not pose a public health threat. Contaminated surface soil at East Kelly was evaluated to determine if chemicals at levels of health concern could migrate off-site via stormwater runoff or wind-blown dust. Soil gas samples were also evaluated to determine if residents near East Kelly are being exposed to the volatile organic compounds that may get into their homes from the contaminated shallow groundwater. The on-site soil contamination does not pose a health threat to residential areas because of the low levels of contaminants detected. A review of volatile organic compounds in soil gas and indoor air modeling suggests that the shallow aquifer contamination does not pose a threat to human health since contaminants are not getting into residences at levels of health concern. There were no private well owners identified near East Kelly using the contaminated shallow groundwater for domestic purposes.
The East Kelly area is an annex located east of Kelly Air Force Base and has historically been used for aircraft maintenance and hazardous waste storage and transport. Leakage, spillage, and landfilling of these wastes have occurred throughout East Kelly and consequently contaminated the shallow groundwater and soil. The shallow groundwater is contaminated with chlorinated solvents and has migrated east and southeast into the surrounding community. The surface soil at East Kelly has been contaminated primarily with polyaromatic hydrocarbons (PAHs). Community members suspect contaminants in the shallow groundwater are getting into their homes through soil gas and causing adverse health effects. The Agency for Toxic Substances and Disease Registry (ATSDR) was initially petitioned by the late Congressman Frank Tejeda to evaluate the potential public health impact of contaminants released from Kelly Air Force Base and later requested to evaluate East Kelly [1]. ATSDR completed a public health assessment for Kelly Air Force Base in 1999. The purpose of this public health assessment is to identify potential human exposures to substances related to East Kelly activities by evaluating existing on- and off-site environmental data, community health concerns, and to recommend appropriate public health follow-up activities.
Kelly Air Force Base was commissioned in 1916 in Bexar County, Texas, approximately seven miles southwest of San Antonio. East Kelly (also called Zone 4) is a storage area comprising about 400 acres along the eastern edge of Kelly Air Force Base. The surrounding community is a mixture of residential, commercial, and light industrial areas (Appendix A, figure 1). In 1982, a restoration program was initiated to investigate and clean up hazardous waste at Kelly Air Force Base. This investigation determined that in addition to groundwater contamination from the main Kelly Air Force Base flowing southeast of East Kelly, leaking industrial waste pipe lines in the northern portion of East Kelly were also sources of environmental contamination. From the 1940s to the mid-1970s, engine repair facilities at East Kelly used a collection system to transport chemical wastes to a central location for disposal. Over the years, this network of underground waste collection pipe lines leaked, contaminating shallow groundwater with waste oils, solvents, and paint thinners [2]. Other wastes stored at East Kelly in the past contained herbicides, metals, PAHs, and volatile organic compounds (VOCs).
Specific health concerns expressed by community members pertaining to East Kelly are the release of soil gas into nearby homes from contaminated shallow groundwater and the possibility of contaminated soil found on-site reaching their homes by stormwater runoff. Residents are also concerned that contaminants from Kelly Air Force Base are causing a number of illnesses including: cancer, immune system disorders, nervous system disorders, birth defects, liver problems, skin problems, respiratory illnesses, muscular problems, nosebleeds, and headaches. These health concerns were addressed in the Kelly Air Force Base public health assessment which was released in 1999. In this public health assessment, ATSDR evaluates the environmental contamination related to East Kelly to identify any additional impact for these same health concerns.
There are 5,021 people living within a one mile radius of East Kelly (Appendix A, figure 1) [3]. The entire population is Hispanic. Of the total population, 18% are under age 6 and 27% are age 65 years and older. In 1990, there were about 900 females of reproductive age (15-44 years) in the area.
The following sections contain an evaluation of the environmental data available for East Kelly. In preparing this evaluation, ATSDR uses established methodologies for determining how people may be exposed to potential contamination related to East Kelly and what harmful effects, if any, may result from such exposure. Exposure pathways (or routes of physical contact with chemicals) that ATSDR evaluates are ingestion, inhalation, and skin contact. ATSDR uses comparison values (CVs), which are screening tools used to evaluate environmental data that are relevant to the exposure pathways. Comparison values are concentrations of contaminants that are considered safe levels of exposure. Chemicals detected below CVs are not likely to represent a health concern; chemicals that are detected above CVs require a more detailed evaluation of site specific exposure conditions. ATSDR also evaluates the public health implications of exposures to combinations of substances that may be present in one or more environmental media to which populations may be exposed. For a complete discussion of these criteria (quality assurance considerations, human exposure pathway analyses, health-based comparison values, and the methods of selecting contaminants above comparison values), refer to Appendix B.
East Kelly lies over a shallow aquifer and a deeper, confined aquifer, the Edwards Aquifer. The shallow aquifer is at depths below the surface ranging from approximately 15 to 30 feet. The leaking industrial waste lines at East Kelly contaminated the shallow aquifer with VOCs and PAHs [4]. There is a layer of clay below the shallow aquifer ranging from 50 to 450 feet in thickness. Under the clay layer is about 300 feet of a loose, crumbly rock material called marl and another 500 feet of limestone and shale. The Edwards aquifer is below about 1000 feet of clay, marl, limestone, and shale layers [5]. Most residences near East Kelly receive drinking water from Bexar Metropolitan Water District, a municipality that obtains its water from the Edwards Aquifer. There is one residence near East Kelly that has a private well used for drinking water (discussed in the next section Private Wells).
Municipal water has been supplied to residents east of Kelly AFB beginning in the 1950s [6]. Three private well surveys conducted in 1988, 1996, and 1998 (Appendix A, figure 2) identified 22 shallow aquifer private wells within a one mile radius of Kelly AFB [7] [8]. Most of the private wells identified were using groundwater from the shallow aquifer for gardening or lawn care. However, one private well on Quintana Road was identified as a drinking water source in 1988. Four private wells were dry or blocked by debris. Water samples from the remaining 18 usable private wells were collected and analyzed for VOCs, semi-volatile organic compounds (SVOCs), metals, and cyanide. Several contaminants were detected in the private well used for drinking water and were not at levels of health concern [9]. Several contaminants were also detected in some of the private wells not used for drinking water [8]. The chemicals detected in private wells are listed below:
Table 1: Chemicals detected in the shallow aquifer private wells in 1988, 1996, and 1998
| Chemical | Range of Chemical Concentration (ppb) | Number of Private Wells that Chemicals were Detected above Drinking Water Comparison Values1 |
| cis-1,2-Dichloroethene (DCE) | ND-190 | 1 |
| Tetrachloroethene (PCE) | ND-20 | 8 |
| Trichloroethene (TCE) | ND-82 | 7 |
| Chloroform | ND-4.61 | 3 |
| Lead | ND-64.1 | 1 |
| Thallium | ND-10.7 | 1 |
| Vinyl Chloride | ND-10 | 1 |
Residents near East Kelly have been notified of the shallow aquifer contamination and have been advised not to use water from their wells for consumption, showering, or cooking. The contaminants detected in the private well used for drinking water were not at levels of health concern.
Most of the functioning private shallow aquifer wells were used for irrigating or watering gardens in the past and may still be used for watering lawns and gardens. The contaminants detected in the private wells near East Kelly are mostly VOCs which are not easily taken up in plants and quickly volatilize during watering [10]. ATSDR evaluated the irrigation exposure pathway by comparing the VOCs levels in groundwater used for watering lawns and gardens with showering using water with the same levels of VOCs [11]. Showering represents a more conservative scenario than outdoor watering; even with this scenerio, ATSDR determined the VOCs would evaporate during watering and are not at levels of health concern.
Nearby residents are concerned that the contaminated surface soil left on-site may migrate into residential areas via stormwater runoff or wind-blown dust. Although ATSDR found no visible evidence that stormwater runoff is affecting the residential areas, the surface soil contamination (less than one foot deep) was evaluated to determine if contaminants are at levels above screening values. Stormwater runoff or wind is not likely to carry contaminated on-site soil that is deeper than one foot to residential areas. Samples of on-site soil were collected during remedial investigations throughout the 1990s to determine the extent of soil contamination [12]. Arsenic was detected in surface soil at a former storage yard (site S-7) at concentrations that exceeded closure guidelines [13]. Kelly AFB removed 1.2 acres of the arsenic contaminated surface soil in 1997 and disposed of it off-site in accordance with TNRCC guidelines to attain closure status. The storage yard is no longer in use and arsenic concentrations are below background levels [14]. In other areas of East Kelly, the four PAHs listed in Table 2 were detected in on-site surface soil at levels above their health-based comparison values. Therefore, these PAHs were selected for further evaluation [15]:
Table 2. East Kelly Soil Contaminants Detected above Comparison Values
| Chemical | Chemical Type | Estimated Risk | Risk-Based Comparison Value1 (mg/kg) | Maximum Concentration (mg/kg) |
| Benzo(a)pyrene | PAH | 9.7E-05 | 0.087 | 8.13 |
| Dibenzo(a,h)anthracene | PAH | 2.74E-06 | 0.087 | 0.23 |
| Benzo(a)anthracene | PAH | 1.01E-05 | 0.87 | 8.51 |
| Benzo(b)fluroranthene | PAH | 1.11E-05 | 0.87 | 9.35 |
The assumptions of the risk analysis for on-site surface soil are presented in Appendix C. Although the maximum concentrations were detected above health-based comparison values, the levels of these contaminants have not been shown to cause adverse health effects in scientific literature. The results indicate that incidental ingestion of on-site soil is unlikely to cause adverse health effects.
Soil gas consists of vapors within soil space that can potentially get in the air of an enclosed space. The soil gas can come from soil contaminants or groundwater migrating through these soil spaces. Residents living near East Kelly are concerned that vinyl chloride and other VOCs from the contaminated shallow aquifer are migrating into their homes. Soil gas samples were taken outside of homes that were identified where shallow groundwater contamination is highest, thus having the highest potential for gas migration to indoor air [16]. Five soil gas monitoring wells were installed west and south of East Kelly and three soil gas monitoring wells were installed east of East Kelly (Appendix A, figure 3). Soil gas was collected and analyzed in March 2000. Although vinyl chloride was not detected in the soil gas, several other VOCs were detected. The levels of VOCs detected directly in the soil gas are not expected to cause adverse health effects based on epidemiologic studies, even if they are inhaled directly [17] [18] [19] [20] [21] [22]. However, it is not likely that residents near East Kelly will inhale soil gas directly. ATSDR estimated the indoor air concentration of each VOC detected above screening values in the soil gas using EPA's Johnson and Ettinger model for subsurface vapor intrusion into buildings [23]. The indoor air concentrations of VOCs are estimated to be about 60,000 times lower than the concentrations detected in soil gas directly (Appendix D). Based on the levels of VOCs in the soil gas and the modeling analysis, no adverse health effects are expected to occur from exposure to the VOCs detected and estimated to be in the indoor air of homes located over contaminated shallow groundwater. Appendix D details the results of the soil gas sampling results and the modeling.
Children are at greater risk than adults from certain kinds of exposure to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed for several reasons; children play outside more often than adults, increasing the likelihood they will come into contact with chemicals in the environment. Since they are shorter than adults, they breathe more dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain damage if toxic exposures occur during certain growth stages.
Many children live in neighborhoods surrounding East Kelly. Even though these children do not have access to the site, ATSDR closely reviewed possible exposure situations to children while evaluating this site. Based on the available sampling and modeling data, ATSDR did not identify any chemical contaminants at levels of health concern to children living near East Kelly.
East Kelly is surrounded entirely by a fence and guarded 24 hours a day. Therefore, public access is controlled at this site. ATSDR did not identify any physical hazards to the public during the evaluation of the site and the site visit.
ATSDR uses one of five conclusion categories to summarize our findings of the site. These categories are: 1) Urgent Public Health Hazard, 2) Public Health Hazard, 3) Indeterminate Health Hazard, 4) No Apparent Public Health Hazard, and 5) No Public Health Hazard. A category is selected from site specific conditions such as the degree of public health hazard based on the presence and duration of human exposure, contaminant concentration, the nature of toxic effects associated with site related contaminants, presence of physical hazards, and community health concerns. Based on these criteria, ATSDR determined that the environmental contamination related to East Kelly presents a No Apparent Public Health Hazard based on levels of contaminants found in the on-site soil, the contaminants detected in the off-site soil gas, and the lack of human exposure to the contaminated shallow groundwater at levels of health concern.
Based upon the conclusions and information reviewed, ATSDR makes the following recommendation to TNRCC:
The actions described in this section are designed to ensure that this public health assessment identifies public health hazards and provides a plan of action to mitigate and prevent adverse health effects resulting from exposure to hazardous substances in the environment.
Actions Completed
Action Planned:
Preparer of Report:
Kimberly K. Chapman, MSEH
Environmental Health Scientist
ATSDR/DHAC/EICB/PRS
Contributing Author:
Gregory M. Zarus, MS
Atmospheric Scientist
ATSDR/DHAC/EICB/EI
Technical Assistance:
Andrew Dent, MA
GIS Programmer/Analyst
ATSDR/DHAC/PERIS
Reviewers of Report:
Donald Joe, PE
Section Chief
ATSDR/DHAC/EICB/PRS
John E. Abraham, PhD
Branch Chief
ATSDR/DHAC/EICB
Susan Moore, MS
Section Chief
ATSDR/DHAC/EICB/HC
Review and Approval of this public health assessment for East Kelly.
Concurrence:
Environmental Health Scientist, PRS, EICB, DHAC
Section Chief, PRS, EICB, DHAC
Branch Chief, EICB, DHAC
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