PUBLIC HEALTH ASSESSMENT
TRI-COUNTY PUBLIC AIRPORT
DELAVAN, MORRIS COUNTY, KANSAS
The proposed Tri-County Public Airport (TCPA) National Priorities List site is a former World War II Army Airfield. During its peak operating period the airfield consisted of more than 300 buildings and housed approximately 2,000 personnel. The airfield had a waste water treatment plant, a 200,000-gallon fuel storage tank, warehouse area, barracks, and a recreation area. The airfield was officially declared surplus in 1946 and deeded to the city of Herington, Kansas in 1948. Most of the 300 buildings and structures previously at the airfield have been removed, but two hangars, a water tower, several water supply wells, and a few small buildings remain.
From 1948 to the present, the site has been leased to a number of companies for various purposes. Operations at the site have included, but are not limited to, aircraft restoration, aircraft storage, the manufacturing of farm implements, black powder manufacture, and the manufacture of roofing materials.
The nature and extent of environmental contamination at the TCPA site are still being determined. The Agency for Toxic Substances and Disease Registry (ATSDR) has reviewed the available environmental data and found that people have been exposed in the past to drinking water from wells contaminated with carbon tetrachloride, 1,2-dibromoethane (EDB) and trichloroethylene (TCE). Presently, no one is being exposed to site-related contaminants, via drinking water, at levels above the Maximum Contaminant Level (MCL) established by the Safe Drinking Water Act. Carbon filtration units have been installed on all residences with carbon tetrachloride, EDB, or TCE levels exceeding the MCL. These carbon filtration units are being monitored periodically to ensure proper operation. Former workers and trespassers on the site may have been exposed to soils containing TCE, vinyl chloride, cadmium, lead, and manganese. ATSDR saw no indication of trespassing when visiting the site; however the TCPA site is not fenced and areas of contaminated soil are still present. Presently, on-site workers may be potentially exposed to contaminated on-site soils. For contaminants with an adequate amount of toxicological and epidemiological information, ATSDR believes adverse non-cancer health effects are unlikely for adults and children near the TCPA site due to past or present exposures. For those contaminants with known carcinogenic endpoints, ATSDR believes that there is no significant increased risk of developing cancer due to past or present exposures. However, the levels of some Volatile Organic Compounds (VOCs) in drinking water supply wells near the TCPA are similar to concentrations of VOCs found in drinking water studies that have shown possible increased risk of birth defects and higher incidence of childhood leukemia due to ingestion of VOC contaminated drinking water during the pregnancy period (12,13). Even though these studies suggest a possible association with VOC exposure and a possible increased risk of birth defects the results are not conclusive.
ATSDR has made recommendations to (1) provide a more permanent solution for drinking water that meets Safe Drinking Water Act regulations to residences with contaminated well water in the vicinity of the Tri-County Public Airport site, (2) continue periodic monitoring of the groundwater plume to ensure that private drinking water wells currently outside the plume do not become contaminated by the migration of the plume, (3) take appropriate preventive measures to mitigate exposure if these well do become contaminated, and (4) inform trespassers and present workers on-site through signs or by other means that they should avoid unnecessary contact with site soils and sediment, especially near Hangar 1, Hangar 4, the former potential burial area, and the sump in the north motor pool.
ATSDR has no data for the TCPA site prior to 1997. Therefore, it is difficult to assess past exposure. ATSDR believes exposure to site related contaminants via drinking water occurred in the past, but has no way to determine the length of exposure. Exposure to carbon tetrachloride, EDB, and TCE above the MCL has been stopped through the installation of carbon filtration units at residences with contaminated well water. ATSDR believes, on the basis of the review and analysis of available site related data, that there is presently no apparent public health hazard at the proposed TCPA National Priorities List site.
The Tri-County Public Airport site was proposed to the National Priorities List (NPL) by the United
States Environmental Protection Agency (EPA) 
in July 2000. The Agency for Toxic Substances and
Disease Registry (ATSDR), located in Atlanta, Georgia, is a federal agency within the United States
Department of Health and Human Services (DHHS). ATSDR, under the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) conducts public
health assessments for sites the EPA proposes to the NPL. Therefore, ATSDR has, under its
mandate, evaluated the public health significance of this site. The agency considered whether
adverse health effects are possible and has recommended actions to mitigate possible future
exposure.
The purpose of this public health assessment is to describe ATSDR's activities and to report the agency's conclusions, recommendations, and public health actions.
Community residents requested that ATSDR address the following issues in the public health assessment:
The TCPA is located 7 miles east of Herington, Morris County, Kansas. The facility comprises approximately 3.5 square miles.
The TCPA was originally constructed as the Herington Army Airfield (HAA) in 1942. During peak
operations the airfield contained more than 300 buildings and housed approximately 2,000
personnel. The airfield had a self-contained wastewater treatment plant , a 200,000-gallon fuel
storage tank, a warehousing area, and a barracks and recreation area.
HAA processed B-24 bombers between 1943 and the summer of 1944. The bombers arrived at the base from the production line. Mechanics at HAA inspected, and sometimes overhauled electrical systems, hydraulic systems, engines, and aircraft structures. Typically, an aircraft spent several weeks at the base. Flight crews arrived at HAA after flight training and were matched up with their particular aircraft. After a short training program, the B-24 aircraft and crew would depart for the European Theater of Operations.
In the summer of 1944, HAA's mission changed. It became the primary processing base for the new Boeing B-29 Super Fortress. Because HAA was located only a short distance from the Boeing plant in Witchita, it became the primary staging base for the B-29. Approximately 60 percent of the B-29's that flew to the Pacific Theater of Operations--about 74 aircraft per month--processed through Herington. Maintenance operations at HAA occurred 24 hours per day, 7 days per week. Base mechanics performed all types of maintenance on the B-29, including: engine repair, cylinder repair, engine replacements, and other types of heavy maintenance. Changing and cleaning spark plugs was an important function of the maintenance operation. The B-29 had 4 engines with 36 spark-plugs each, for a total of 144 spark-plugs. Army personnel used TCE and other solvents to clean spark-plugs and degrease aircraft parts during maintenance operations.
The HAA was officially declared surplus in 1946. The airfield property and buildings were deeded to the city of Herington, Kansas in 1948.
From 1948 to the present, the site has been used by a number of companies for various purposes.
Operations have included aircraft restoration and aircraft storage, as well as the manufacturing of
farm implements, black powder, and roofing materials. From the 1950's to early 1960's, Beech
Aircraft leased all four hangars and several other buildings at the site. In 1980, the Raytheon Aircraft
Company acquired Beech Aircraft. Operations conducted by Beech and Raytheon at the site
consisted of a chromium conversion coat process, vapor degreasing, painting, paint stripping, wing-tank manufacturing, aircraft refurbishing, aluminum processing, aircraft starter generator
manufacturing, and steel wing-tank shipping container manufacturing. A wastewater treatment
system was used by Beech Aircraft for treating chromium process solutions and rinse waters. Paint
stripping wastewater was transferred to a holding pond located north of Hangar 1, in or near an area
that is now considered a potential burial area. According to a former employee, both Hangar 1 and
Hangar 4 contained trichloroethylene (TCE) degreaser pits for cleaning aircraft parts. The vapor
degreaser in Hangar 4 was approximately 12 feet deep, 20 feet long, and 6 feet wide. Both degreaser
pits were filled in and paved over with concrete and are no longer visible.
Most of the 300 buildings and structures previously at the airfield have been removed, but two hangars, a water tower, several water supply wells, and a few small buildings remain. The main Tri-County Airport Authority office, pilots lounge, and buildings in the former barracks and recreation area leased to a black powder manufacturer were constructed after the airfield was declared surplus.
Currently, the eastern portion of the site is occupied by Black Diamond Custom Feeders, Inc., a large
manufacturer of cattle feedlot equipment. The southwest corner of the site is fenced and occupied by
the Pyrodex Corporation, a black powder manufacturer that utilizes the southernmost Hangar
(Hangar 4). The Pyrodex manufacturing process generates wastewater treatment sludges from the
manufacture and processing of explosives. KDHE determined in 1994 that these sludges were non-reactive and allowed Pyrodex to be delisted as a Resource Conservation and Recovery Act (RCRA)
hazardous waste generator. U.S. Stone, a custom limestone cutting operation, currently occupies the
northernmost Hangar (Hangar 1). Prior to U.S. Stone, Insulfoam, and the Carlisle Syntec Company,
a bonder of felt for roof underliners, operated in Hangar 1. The main north-south runway is
operational and is used by small commuter aircraft. The city of Herington maintains the pilots lounge
and on-site maintenance building.
EPA, KDHE, and the U.S. Army Corps of Engineers (USACE) have conducted numerous investigations on the site. USACE conducted an investigation at the TCPA from 1994 to 1997 and completed its final report in July 1998. The USACE concluded that ground water at the site, specifically that near the fuel storage area, had been impacted by BTEX (benzene, toluene, ethyl benzene and xylenes), 1,2-dibromoethane, total petroleum hydrocarbons, and lead. It also concluded that soils on site had not been contaminated except in the wash rack area. Because the USACE considered the solvent contamination (TCE and cis-1,2-dichloroethylene) outside the scope of Department of Defense responsibility, it deferred that contamination issue to EPA Region 7.
In May 1996, KDHE completed a preliminary assessment/screening site inspection of TCPA in response to the detection of TCE during the USACE investigation and concluded that the groundwater beneath the TCPA site had been contaminated with TCE, 1,1-dichloroethene (DCE), and carbon tetrachloride, but there was no apparent contamination of the surface water or soil pathways at the site. KDHE recommended that an Expanded Site Inspection/Remedial Investigation (ESI/RI) be conducted at the site.
In October 1997, EPA and KDHE sampled private groundwater wells in the area around TCPA. Forty-three groundwater samples were collected from private wells within Latimer and the surrounding area. All TCE concentrations detected in wells within Latimer exceeded the TCE Maximum Contaminant Level (MCL) of 5 µg/L. Six of the eight wells in the surrounding area had TCE concentrations that exceeded the MCL. None of the DCE concentrations exceeded the MCL.
The EPA completed an ESI/RI at the site in June 1999.
The results of completed investigations indicate that ground water has been contaminated with TCE and DCE within 3 miles to the north and northwest of TCPA. TCE has been detected in groundwater samples collected from private wells within this distance at concentrations ranging from 3 micrograms per liter (µg/L) to 280 µg/L. TCE concentrations in 21 of the 23 private wells sampled exceeded the 5 µg/L MCL established by the EPA as the highest permissible level of TCE allowed in drinking water.
In March 2001, ATSDR visited the site to get an overview of site conditions and gather additional data. During the visit, ATSDR noted that access to most of the site is unrestricted.
The full extent and characterization of site contamination is on-going. Therefore, the release of this public health assessment deals with information available to ATSDR as of October 2002. Information obtained by ATSDR following the release of this document will be evaluated separately, as needed.
The primary surface water bodies in the TCPA site area are Clarks Creek, a tributary of the Kansas River, and Level Creek, a tributary of the Neosho River. The TCPA site is on a topographically elevated area that serves as a surface water divide between the major drainage basins of Clarks Creek and the Neosha River. Clarks Creek is a perennial, north-northeast flowing creek that lies to the west and north of the site. The south flowing and north flowing reaches of the on-site drainage ditch flow into tributaries of Clarks Creek. The general geology beneath the site consists of a succession of shale aquitards and limestone aquifers. The shallowest aquifer is the Cresswell Limestone aquifer. The Stovall and Towanda aquifers lie below the Cresswell. According to ESI/RI data, a majority of private water wells in the vicinity of the site are completed into the Towanda aquifer.
The community consists of approximately 19 residents living within a one-mile radius of the site. The nearest residence is approximately 2,500 feet north of the site boundary. There are approximately 4 children six years old and younger living within a mile radius of the site. Homes near the site rely on groundwater sources for drinking water.
A. Nature and Extent of Environmental Contamination
Results of sampling activities are summarized as shown in Appendix B. The sampling data show that on-site soil is contaminated with metals and volatile organic compounds (VOCs) and on-site and off-site groundwater is contaminated with VOCs. These data will be discussed in more detail in the following sections of the document.
Six springs located to the north and northwest of TCPA were sampled for VOCs. These springs lie in the general direction of the groundwater plume. One spring had an elevated level of TCE (Appendix B, Table 1).
Data were analyzed by ATSDR for on-site and off-site drinking water supply wells that were sampled as part of the ESI/RI and the December 2000 and April 2001 quarterly sampling reports. On- and off-site drinking water supply wells were sampled for VOCs, 1,2-dibromoethane (EDB), and dibromo-3-chloropropane (DBCP) during each sampling event. Elevated levels of TCE, EDB, and carbon tetrachloride were detected in some wells (Appendix B, Table 2).
Data also were analyzed by ATSDR for groundwater monitoring wells that were sampled during the ESI/RI and the Quarterly Sampling Reports. The monitoring wells were sampled for VOCs and metals. Several of the VOCs and metals exceeded ATSDR screening values (Appendix B, Table 3).
Samples of on-site soil and sediment were tested for VOCs and metals. Elevated levels of VOCs were found in subsurface soils adjacent to the former locations of the TCE degreasers at both Hangar 4 and Hangar 1and near the former waste water treatment plant. Elevated levels of metals were found near Hangar 1 (north side) and at the former potential burial area and the north motor pool (Appendix B, Table 4).
ATSDR identifies human exposure pathways by examining environmental components and human practices that might lead to contact with contaminants of concern. A pathway analysis considers five principal elements: (1) a source of contamination, (2) transport through an environmental medium, (3) a point of exposure, (4) a route of human exposure, and (5) an exposed population. Completed exposure pathways are those for which the five elements are evident, and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. ATSDR regards people who come into contact with contamination as exposed. For example, people who reside in an area with contaminants in the air, or who drink water known to be contaminated, or who work or play in contaminated soil are considered to be exposed. Potential exposure pathways are those for which exposure seems possible, but one or more of the elements is not clearly defined. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. Identification of an exposure pathway does not imply that health effects will occur. Exposures may or may not be substantive. Thus, exposures may or may not cause adverse health effects.
ATSDR staff reviewed site history; information on past, current, and planned activities; and media sampling data. They identified various exposure pathways that warranted consideration. Those are discussed in this subsection.
The ESI/RI determined that three main areas of TCE contaminated soil are present on the TCPA site, and that TCE has impacted the three uppermost aquifers both on and off the site. TCE contamination was originally verified in 15 nearby private drinking water wells to the north and northwest of the site over an approximate 12 square-mile area. More recent data indicate that 22 private drinking water wells have carbon tetrachloride, EDB, or TCE contamination exceeding the MCL. KDHE provided 6 residences that had carbon tetrachloride, EDB, or TCE concentrations above the MCL in their drinking water with granulated activated carbon filtration units late in 1997. EPA also provided one residence with a carbon filtration unit and 15 residences with bottled water in 1997. Beginning in 2000, a potentially responsible party (PRP) utilized a phased approach to install carbon filtration units on all homes still using bottled water as the primary drinking water source. A PRP also replaced the carbon filtration units originally installed by KDHE. Presently, all homes with carbon tetrachloride, EDB, or TCE contamination above the MCL have carbon filtration units. EPA determined that to evaluate the continuing health threat presented by the groundwater plume and possible remedial/removal alternatives, quarterly sampling of selected water supply wells at the boundary of the plume and monitoring wells on and off the site was warranted. ATSDR reviewed analytical results for sampling activities from the ESI/RI, the April 2000 quarterly monitoring and the quarterly sampling conducted from May 1999 to April 2000.
C. Completed Exposure Pathways
Elements of completed exposure pathways are provided in Appendix C, Table 2.
The groundwater in the vicinity of the TCPA is contaminated with metals and VOCs (Appendix B, Table 3). The full nature and extent of groundwater contamination is still being characterized. The groundwater plume flows north and north west of the site over an approximate 12 square-mile area. Current testing indicates that there is TCE contamination in 22 nearby drinking water wells. How long people were exposed to VOCs in private wells is not known. The HAA was closed in 1946 and turned over to the city of Herington in 1948. If we assume that the groundwater contamination began during the airfield's operating days, it is possible for a resident of the area to have been exposed to site related contaminants for approximately 50 years. Conversely, it is possible that contamination of the groundwater occurred much later during the period when the HAA was leased to various companies,which would make the exposure period for residents much shorter.
D. Potential Exposure Pathways
Elements of potential exposure pathways are provided in Appendix C, Table 1.
From observations made during ATSDR's site visit, it is possible for trespassers to access the TCPA site. Most areas of the site are not fenced. The number of trespassers upon the site is not known, but is assumed to be less than 100 trespassers. It is possible that trespassers, as well as former and present workers, may have been intermittently exposed to contaminants present in soil. Surface-soil samples taken from areas around the site (Appendix B, Table 4) have been shown to be contaminated with various VOCs and metals. The maximum concentration of TCE was 2,100 parts per million (ppm) and the maximum concentration of vinyl chloride was 12 ppm. Metals found in soil samples were cadmium at a maximum concentration of 48 ppm, lead at a maximum concentration of 1,700 ppm, and manganese at a maximum concentration of 4,400 ppm. The principal route of exposure would be by direct contact with and possible intermittent ingestion of contaminants in the soil. Inhalation of contaminants in fugitive dusts is also possible.
Monitoring of on-site water wells has not shown contamination of TCE to date; however, there is potential for contamination to migrate into these wells in the future. A quarterly monitoring program is in place that should provide sufficient warning if site related contaminants do migrate into the on-site drinking water supply.
Three surface-water samples taken from eight springs and/or seeps to the north and north west of the site have shown contamination with TCE at levels above the MCL (Appendix B, Table 1). Persons who trespass upon the property with these springs may be exposed intermittently to these contaminants via direct contact or incidental ingestion.
The contaminants of concern released into the environment at the proposed TCPA NPL site have the potential to cause adverse health effects. However, for adverse health effects to occur, the pathway for exposure must be complete. A release does not always result in exposure. The health effects resulting from an interaction of an individual with a hazardous substance in the environment depend on several factors. One is the route of exposure; whether the chemical contacts the skin (dermal), is breathed in (inhaled), or consumed with food, soil, or water (ingestion). Another factor is the dose to which a person is exposed, and the amount of the exposure dose that is actually absorbed. Mechanisms that alter chemicals in the environment or inside the body, as well as combination (types) of chemicals are also important. Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the contaminants are absorbed, distributed, metabolized, and excreted. Together those factors and characteristics determine the health effects that may occur as a result of an exposure to a contaminant. Much variation in these mechanisms exists among individuals. For example, all children mouth or ingest nonfood items to some extent. This behavior is known as pica. The degree of pica behavior varies widely in the population, and is influenced by nutritional status and the quality of care and supervision (3). Groups that are at increased risk for pica behavior include children 1 to 3 years old and children with neurological disorders (e.g., brain damage, epilepsy, and mental retardation).
To ensure that the health of children is protected, ATSDR has implemented an initiative to protect children from exposure to hazardous waste. ATSDR recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Infants and children are usually more susceptible to toxic substances than are adults because of immature and developing organs. Children are more likely to be exposed to contaminants because they play outdoors and often bring food into contaminated areas. These activities may increase their exposure to toxicants in dust, soil, and air. Some children exhibit excessive pica behavior, which may increase their intake of toxicants. Children are smaller, which results in higher dose concentrations in their bodies. Most importantly, children depend completely on adults for risk identification, management decisions, housing decisions, and access to medical care. ATSDR's evaluation described in this document considered children as a susceptible subpopulation.
The methods for calculating and evaluating exposure doses from ingestion are presented in Appendix D.
Exact information about the habits of trespassers upon the site is unknown. To evaluate possible exposures ATSDR made certain assumptions about the possible sources of contamination.
Soil
- People who trespassed upon the site were adults and school-aged children.
- Intermittent exposure occurred at a maximum frequency of 3 days per week, 2-5 hours per visit, and not more than 30 weeks per year.
- Children displaying pica behavior (children between 0 and 5 years old) were not present upon the site.
- Exposures occurred at the maximum concentration detected.
- Exposure via incidental ingestion occurred (though minimal).
- The maximum period of time people could have been exposed was 30 years for non-carcinogenic compounds and 50 years for carcinogenic compounds.
- The main route of exposure was most likely by direct contact.
Springs and Seeps
- People who contacted spring or seep water on the site were adults and school children.
- Intermittent ingestion occurred at a maximum frequency of 3 days per week and not more than 30 weeks per year.
- Children ingested an average of 0.5 liter of water per day; adults ingested an average of 1 liter of water per visit.
- Exposures occurred at the maximum concentration detected.
- Exposure by direct contact and inhalation occurred (though minimal).
- The maximum period of time people could have been exposed was 30 years for non-carcinogenic compounds and 50 years for carcinogenic compounds.
- The main route of exposure was most likely by ingestion.
Drinking Water
- People who drank contaminated water were adults and children.
- Children ingested an average of 1 liter of water per day; adults ingested an average of 2 liters of water per day.
- Exposure occurred at a maximum frequency of 365 days per year.
- Exposures occurred at the maximum concentration detected.
- Exposure by inhalation occurred (though minimal).
- The maximum period of time people could have been exposed was 30 years for non-carcinogenic compounds and 50 years for carcinogenic compounds.
- The main route of exposure was most likely ingestion of drinking water.
ATSDR has no methodology to determine amounts of chemicals absorbed through the skin. Therefore, an exposure dose for this route of exposure was not calculated. Contaminants which are carcinogenic, at levels above health guidelines, and those for which there are no health guidelines available (Appendix E) will be discussed further.
Adults living in the vicinity of the TCPA were mainly exposed to VOCs by drinking water from private wells, but also may have been exposed to VOCs by occasional contact with spring and seep water and on-site soil and sediment. Laboratory animals have been exposed to these chemicals via contaminated air, drinking water, and food. The results of these studies indicate that the nervous system and liver, and to a lesser degree, the kidney and heart are the organs of adults and animals affected by VOCs. In these studies, however, the amount of VOCs needed to cause adverse health effects occurred at levels 50 to 200 times higher than those levels received by people who drank contaminated water or who were occasionally exposed to contaminated surface water, soil, and sediment (greater than 5 mg/kg/day vs. maximum of 0.086 mg/kg/day) at the TCPA site (6,7,10).
Trichloroethylene (TCE) was found in spring and seep water at a maximum concentration of 15 µg/L, in drinking water at a maximum concentration of 280 µg/L, and in on-site soil and sediment at a maximum concentration of 2100 ppm. TCE can enter the body by breathing air, by drinking water, or by skin contact. Health effects in people have been reported when exposed to levels of TCE at which its odor is noticeable. Animals exposed to moderate levels of TCE had enlarged livers, and high-level exposure caused liver and kidney damage. It is not known if these changes would occur in humans. The carcinogenicity of TCE has not been rated by EPA, but the International Agency for Cancer Research (IARC) considers it to be a probable human carcinogen.
ATSDR maintains a TCE exposure subregistry with approximately 4,300 participants. Information from the subregistry indicates that participants reported that they had more health problems than what is normally expected (10). The participants were exposed to TCE at levels of 2 to 19,380 ppbm in drinking water for up to 18 years. Only the rate for strokes was reported to increase with increasing concentration of TCE in drinking water. Therefore, this study suggests that there may be a relationship between exposure to TCE and an increased chance of having a stroke. However, these results do not prove a cause and effect relationship. This study did not confirm the health conditions (they were self reported) and the study did not completely identify the exposure levels. In addition, the current scientific literature does not document any known association of stroke and TCE exposure (10).
Besides strokes, the participants in the ATSDR TCE exposure subregistry reported other health problems (above the national averages, for various age and sex groups): hypertension, liver problems, anemia and other blood disorders, diabetes, kidney disease, urinary tract disorders, heart conditions and skin rashes. These other health problems were not related to the concentration of TCE in their drinking water (the occurrence of health problems did not increase with higher exposure levels) (10). If the health problems had been associated with exposure to TCE, the number of people with a specific health problem should have increased with higher exposure levels. This is not what was reported to ATSDR. Therefore, it is unlikely that the reported health problems (kidney disease, urinary tract disorders, heart conditions, and skin rashes) are associated with exposure to TCE.
ATSDR calculated adult TCE exposure doses for spring and seep water, drinking water, and soil pathways, on the basis of the exposure scenarios previously outlined. The estimated exposure doses were 100 to 1,000 times lower than the lowest observed adverse effect level (LOAEL) for animals (37 mg/kg/day) (10).
Carbon tetrachloride (CCl4) was detected in private drinking water wells at a maximum of 19 micrograms per liter (µg/L). The MCL is 5 µg/L, but EPA has proposed a MCLG of zero. Experiments have not been performed on the effects of long-term exposure of humans to low levels of CCl4, so human health effects are not known. Studies have shown that the kidney and liver are sensitive to CCl4. Fortunately, if injuries to the kidney and liver are not too severe, these effects disappear after exposure stops. Many cases of CCl4 toxicity are associated with drinking alcohol. The frequent drinking of alcoholic beverages increases the danger from CCl4 exposure. Studies in animals have shown that CCl4 given by mouth can increase the frequency of liver tumors in some species (6). Studies have not been performed to determine if breathing CCl4 causes tumors in animals or humans, but it should be assumed that CCl4 could produce cancer. CCl4 is considered possibly carcinogenic to humans. Estimated exposure doses slightly exceeded the minimal risk levels (MRL) (0.007 mg/kg/day), but were well below the no-observed-adverse-effect-level (NOAEL) (11 mg/kg/day) and the cancer effect level (CEL) (47 mg/kg/day) (6).
1,2-dibromoethane (EDB) was found in drinking water wells at a maximum concentration of 0.712 µg/L. The MCL for EDB is 0.05 µg/L. EDB is rapidly absorbed into the bloodstream by any method of exposure. Most of it builds up in the liver or kidneys where it is rapidly broken down into different substances. These substances leave the body quickly in the urine with smaller amounts passed in liver bile into the stool. In animal studies, rats and mice that repeatedly breathed, swallowed or had skin contact with EDB for long periods had cancer in many organs. Based on these studies, the DHHS has determined that EDB may be reasonably anticipated to be a carcinogen. ATSDR calculated an exposure dose for EDB based on the maximum concentration found in drinking water (0.712 µg/L). The calculated exposure dose was well below the LOAEL (4 mg/kg/day) and the CEL (37 mg/kg/day).
Vinyl chloride was found in on-site soil and sediment at a maximum concentration of 12 ppm. Vinyl chloride that enters the body through inhalation or ingestion enters the bloodstream rapidly. Studies in animals show that extremely high levels of vinyl chloride can damage the liver, lungs, and kidneys. Results from several studies suggest that breathing air or drinking water containing low levels of vinyl chloride may increase the risk of getting cancer; therefore, it is considered a human carcinogen. ATSDR calculated an exposure dose for vinyl chloride based on the maximum concentration found in soil. The estimated exposure dose was slightly above the MRL (0.00002 mg/kg/day), but more than 250 times lower than the LOAEL in animals.
Adults in the vicinity of the TCPA site also may have been exposed to some metals through occasional contact with on-site soil and sediment. The metals detected in on-site soil above ATSDR comparison values were cadmium, lead, and manganese.
Cadmium was detected in on-site soil and sediment at a maximum concentration of 48 ppm. Cadmium has the ability to cause dermal irritation. Some eczema patients patch-tested with 2% cadmium chloride showed some reaction. Cadmium is classified by EPA as a probable human carcinogen based upon epidemiological studies of humans. The epidemiological studies indicate that cadmium may be a carcinogen via the inhalation route of exposure with the resulting condition being lung cancer. These conditions occurred in occupational settings at concentrations much higher than those found in on-site soil and sediment samples (5). On considering the locations where the samples were taken, ATSDR believes that the inhalation route of exposure is not of significance in this pathway. ATSDR calculated an exposure dose for cadmium based on the exposure scenarios previously outlined in the PHA. The estimated exposure doses did not exceed ATSDR's MRL.
Lead was detected in on-site soil and sediment at a maximum concentration of 1,700 ppm in subsurface soil and a maximum concentration of 270 ppm in surface soil. Ingestion of lead at very high levels in soil may, over time, result in neurological impairment such as learning disabilities-- especially in children. Dermal exposures are not considered to be significant in humans because the dermal absorption rate for inorganic compounds of lead is low. Lead has been shown to cause cancer in animals. ATSDR has no MRL and EPA has no RfD for lead. ATSDR calculated exposure doses for lead. The estimated exposure doses were below the LOAEL for neurological effects in monkeys (0.05 mg/kg/day). The estimated exposure doses are approximately 20,000 times lower than the CEL in animals.
People who trespassed on the site and came into contact with on-site surface soils could have been exposed to manganese at a maximum concentration of 4,400 ppm. Dermal exposure is usually not a concern because manganese has not been found to enter the body through undamaged skin. No studies were found that reported cancer in humans associated with manganese. Few animal studies on this subject are available. Gastrointestinal absorption of manganese is approximately 3%-5%. The estimated exposure dose was below the EPA's reference dose (RfD) of 0.005 mg/kg/day.
On the basis of information reviewed, ATSDR believes that adults would have very infrequent exposure to areas at the TCPA site with elevated levels of soil contamination. The main route of exposure to the contaminants in the soil or surface water would be by direct contact or incidental ingestion. ATSDR calculated exposure doses in soil, sediment, and surface water for adults on the basis of the exposure scenarios previously presented in the PHA. ATSDR believes that these very infrequent exposures to metals or VOCs in soil, sediment, or surface water would not cause adverse non-cancer or cancer health effects.
The main exposure pathway for adults would be through ingestion of contaminated drinking water from private drinking water wells in the vicinity of the TCPA site. ATSDR calculated exposure doses for the ingestion of VOC contaminated drinking water, based on the exposure scenarios previously outlined in the PHA. From this analysis, ATSDR believes that exposure to VOCs in drinking water would not cause adverse non-cancer or cancer health effects to adults.
Children, particularly the fetus, are susceptible to the toxic effects of chemicals if the chemicals cross the placental barrier. Before birth, the fetus is forming the body organs that need to last a lifetime. This is the time when chemical injury might have the greatest effect. Laboratory animal and epidemiological studies indicate that VOC exposures to the fetus may result in adverse health effects. However, the amount of VOCs given to pregnant laboratory animals was higher than what people were actually exposed to by drinking water or through occasional exposure to surface water and on-site soil and sediment at the TCPA site. This indicates that VOC exposures to people near the TCPA site may not have been at levels that could affect children.
On the other hand, recent epidemiologic studies suggest that the exposures that occurred could possibly result in adverse health effects to children exposed as a fetus. The New Jersey Department of Health evaluated effects of VOCs in drinking water on birth outcomes in an area of northern New Jersey (13). Information on birth outcomes status and maternal risk factors was obtained from vital records and the New Jersey Birth Defects Registry. This study found that exposure to TCE during pregnancy increased the risk of the fetus developing central nervous system defects, neural tube defects (NTD), and oral cleft defects. The authors concluded that their study by itself cannot resolve whether the drinking water contaminants caused the reported adverse birth outcomes.
Two other studies have shown possible increased risk of birth defects [small for gestational age (SGA) and NTD] and higher incidence of childhood leukemia due to ingestion of drinking water contaminated with TCE and tetrachloroethylene (PCE) during the pregnancy period. In Woburn, Massachusetts, a 1979 drinking water sampling of two contaminated wells detected TCE at 267 ppb and PCE at 21 ppb. A cluster of childhood leukemia was linked to these drinking water contaminants (18). A study of birth outcomes parallel to the childhood cancer study found increased risks for several birth defects including NTD and an increased risk of SGA. It is unclear whether the increased risks were due to the TCE, PCE, or the mixture. Because TCE was the predominant contaminant, the focus has been on TCE (18). A study at Camp Lejeune, North Carolina, found a potential association with reduced birth weight and SGA in male infants from long-term exposure to TCE during pregnancy (12). However, the sample size was small and considerably weakens the evidence for a causal association.
Health effects seen in children from exposure to toxic levels of carbon tetrachloride could be expected to be similar to the effects seen in adults. No studies were located regarding reproductive effects or developmental effects in humans after oral or inhalation exposure to carbon tetrachloride (6).
1,2 dibromoethane (EDB) is not known to cause birth defects in people. No studies were located regarding developmental effects in humans after inhalation or oral exposure to EDB. No studies were located regarding reproductive effects in humans from oral exposure to EDB, but one showed a possible reduction in sperm count for male workers occupationally exposed by inhalation to EDB.
There is limited information available on the toxicity of vinyl chloride in children. Two studies of communities located near vinyl chloride polymerization facilities suggested there might be increased developmental toxicity or increased fetal loss when one of the parents had been occupationally exposed to vinyl chloride. However, both studies failed to demonstrate a statistically significant correlation (11).
In addition to VOC exposure at the TCPA site, there also was possible intermittent exposure of children to some metals. The metals found at the TCPA site that were above ATSDR comparison values were cadmium, manganese, and lead.
Health effects seen in children from exposure to toxic levels of cadmium are expected to be similar to the effects seen in adults. Children are most likely to be exposed to cadmium in food or water. Most ingested cadmium moves through the gastrointestinal (GI) tract without being absorbed. Cadmium has the potential to cause adverse neurological effects; however, only a few studies have reported an association between environmental cadmium exposure and neuro-psychological functioning. Endpoints that were affected included verbal IQ, acting-out, and distractibility. The placenta may act as a partial barrier to fetal exposure to cadmium. Long-term exposures of infants and children to cadmium may result in the accumulation of cadmium in the bone (5).
Although low levels of manganese are necessary for human health, chronic exposure (exposures occurring over a period of one year or longer) to high manganese levels may be harmful. Children-- especially neonates less than one month old--may be unusually susceptible to the effects of manganese. There is some limited evidence that prenatal or neonatal exposure of animals to elevated levels of manganese can lead to neurological changes in the newborn. A number of studies indicate that neonates retain a much higher percentage of ingested or injected manganese than adults, both in animals and in humans. The result of high retention is increased levels of manganese in tissues of exposed neonatal animals, especially in the brain. Dermal exposure is not a concern since manganese has not been found to enter the body through undamaged skin (9).
Exposure to lead is particularly dangerous for unborn children and young children (0-5 years old) because of their greater sensitivity during development. Studies have shown that lead contamination in exterior dusts and soil at concentrations of 500 to 1000 mg/kg can begin to influence blood lead concentrations in children residing in lead contaminated areas (8). Blood lead levels may be raised above background. Lead exposure is hazardous for unborn children and young children because they are more sensitive to lead during development. Unborn children can be exposed to lead through the placenta. Such exposures could cause premature births, smaller babies, and a decrease in mental ability.
Children are more likely to experience lead-induced adverse health effects because they absorb lead through the GI tract more readily than do adults. They also have immature detoxification enzyme systems which lead to an increase in body burden of ingested lead. Children also have lower thresholds for neurological and hematological adverse effects from lead exposure (8).
On the basis of reviewed information, ATSDR believes that children, especially those between one and five years old, would infrequently, if at all, play near the areas with elevated levels of soil contamination or near the off-site springs and seeps. If exposure occurs, the main route of exposure to the contaminants in soil or surface water would be by direct contact or incidental ingestion. ATSDR calculated exposure doses in soil, sediment, and surface water for children, according to the exposure scenarios previously presented. On the basis of this analysis, ATSDR believes that these very infrequent exposures to metals or VOCs in soil, sediment or surface water would not cause adverse health effects.
The main exposure pathway for children or an unborn fetus (via the mother) would be through ingestion of contaminated drinking water from private wells in the vicinity of the TCPA site. ATSDR calculated exposure doses for the ingestion of VOC contaminated drinking water, according to exposure scenarios previously outlined. On the basis of this analysis, ATSDR believes that exposure to VOCs in drinking water would not cause adverse health effects to children. However, as was suggested from cited studies, ATSDR does not know whether the levels of VOCs found in drinking water near the TCPA site might adversely affect an unborn child.
Increased risk of cancer is not expected to occur from intermittent exposures to cadmium and vinyl chloride in on-site surface soil and sediment, or from exposure to carbon tetrachloride, 1,2-dibromoethane, or trichloroethylene. It is not known if exposure to lead and manganese causes cancer in humans. Many of the adverse health effects described for lead exposure are the result of exposure to lead at high concentrations. Due to the rural nature of the site, it is not likely that children, especially 5 years old or younger, would play at the site. In addition, exposure to on-site contaminants by trespassers or former and present workers would have been minimal. Therefore, adverse health effects, although possible, are unlikely to have occurred.
Considering the data reviewed, exposure to contaminated on-site media would cause minimal effects, if any. However, direct contact with surface soils should be avoided, especially near the hangars where the higher levels of contamination were found. ATSDR recommends, to be safe, children should avoid contact with site contaminants, especially cadmium, lead, and TCE.
On the basis of reviewed data, exposure to contaminants in drinking water wells does not appear to have been at sufficient levels to have caused adverse non-cancer or cancer health effects. Although, as discussed in the child population section, some studies (Woburn, MA, and Camp Lejeune, NC) do suggest an association between long-term in utero exposure to VOCs (i.e., TCE) and possible fetal health effects. The level of TCE found in drinking water wells in the Woburn study was in the same range as that found in drinking water wells at the TCPA site. The TCE levels found in the Camp Lejeune study were 3 to 4 times higher than what was found at TCPA. Therefore, even though adverse fetal health effects may have been possible, they are not likely to have occurred.
ATSDR has no data for the TCPA site prior to 1997. Therefore, it is difficult to assess past exposure at the site. ATSDR based its analyses in this report on the highest levels of contaminants found in a particular medium (surface water, drinking water, soil, and sediment). Past contaminant levels may have been higher or lower. For some contaminants (i.e., TCE) much higher levels were found in ground water monitoring wells; however, ATSDR believes exposure at these higher levels to be unlikely.
Uncertainty exists in ATSDR's evaluation of VOC exposure and the possibility of harmful effects to residents. First, estimating exposure is uncertain. These uncertainties are listed here:
Second, uncertainties exist in comparing the estimated doses to animal and human studies and deciding whether or not harmful effects might occur. These uncertainties are described in more detail here:
G. Review of Health Statistical Data
Due to the small number of people living in proximity to the proposed TCPA NPL site, an evaluation of health statistical data and a comparison with local population health data would not provide useful or meaningful information. Therefore, no health outcome data evaluation was conducted.
Response:
According to cancer statistics from the Center for Health and Environmental
Statistics at the KDHE, Morris County had 93 cancer deaths for the years 1994
through 1998. The age-adjusted death rate from cancer for Morris County was
nearly equal (120.2 vs. 119.6) to the age-adjusted death rate for cancer for
the state of Kansas. Morris County's age-adjusted death rate for cancer was
below the age-adjusted rate for the U.S. population for the years 1994 through
1998. ATSDR contacted KDHE to request a breakdown by cancer type (specifically
liver, kidney, and leukemia) for cancer deaths that occurred in Morris County.
KDHE reported that for the years 1996 through 1999 there were no liver cancers,
four kidney cancers, and 3 leukemia's in Morris County.
Based on information received from KDHE and the local residents to this point, there is no evidence of any unusual cancer incidence patterns among persons living in the area of groundwater contamination from the TCPA site. The numbers and types of cancer identified are what we would expect given the age and sex distribution of the population in the area. We have not observed any "clustering" of specific types of cancers (especially cancer types theorized to be associated with contaminants found at this site, such as liver, kidney, or leukemia) that would suggest a potential association to the TCPA site.
[Good Housekeeping, The Mystery at Kelley Air Force Base, July 2001]
Response:
ALS is a disorder involving loss of the use and control of muscles. The nerves
controlling these muscles shrink and disappear, which results in loss of muscle
tissue due to the lack of nervous stimulation. The cause of ALS is unknown
and there is no known treatment or cure for the disease.
As is stated in the Good House Keeping article about Kelly Air Force Base, ATSDR is working in conjunction with other federal and state agencies to investigate cases of ALS reported in the vicinity of the base. ATSDR is presently conducting an extensive review of the scientific literature concerning ALS and exposure to environmental chemicals. Special attention will be given to what is known or suspected regarding environmental exposures at Kelly Air Force Base. Results of the literature review will be shared with the public when it becomes available.
ATSDR does not know whether exposure to chemicals from the TCPA site or other sites may contribute to ALS. Research and studies in this area are currently being conducted that will hopefully give us a better understanding of ALS and its possible cause in the future.
Response:
There is evidence from studies in humans that inhalation exposure to high
levels of manganese compounds can lead to a disabling syndrome of neurological
effects which resembles Parkinsonism and is referred to as manganism or manganese
induced Parkinsonism. The first signs of the disorder are usually subjective,
often involving generalized feelings of weakness, heaviness or stiffness of
the legs, anorexia, muscle pain, nervousness, irritability, and headache.
Typically, neurological effects from manganese exposure do not become apparent
until exposure has occurred for several years, but some sensitive individuals
may show signs after as little as 1-3 months of exposure. Manganism has been
documented in occupational type exposures for example, in welders who have
been exposed to high levels of manganese dust or fumes in mines or foundries.
There is only limited evidence that oral exposure to manganese leads to neurological
effects in humans (9).
The levels of manganese found at the TCPA site are much lower than exposures in an occupational setting. The highest level of manganese found in on-site soil and sediment was 4,400 ppm. ATSDR calculated an exposure dose for manganese in soil and sediment. The estimated exposure dose was well below the EPA RfD. Lifetime exposures to levels below the RfD are not likely to cause harmful effects in people.
Response:
ATSDR completed a health consultation in October 1997 addressing this question.
ATSDR reviewed data from wells that provided water to homes and/or cattle
and found that they contained a maximum of 391 ppb TCE and a maximum of 21
ppb carbon tetrachloride. It was assumed that the water samples were collected
either from the tap or from the actual well. Because, both TCE and carbon
tetrachloride are quite volatile some of the contaminants would be expected
to volatilize during the process of filling containers for cattle. Therefore,
the levels of TCE and carbon tetrachloride consumed by cattle were most likely
lower than the actual tap or well samples. In animals, TCE that is ingested
is absorbed and metabolized rapidly. Bioaccumulation studies of TCE have been
conducted in aquatic organisms and indicate a low tendency to bioaccumulate.
No studies regarding bioaccumulation in cattle were found, but more than likely
cattle would also have a low tendency for bioaccumulation. Like TCE, carbon
tetrachloride has little tendency to bioaccumulate in animals.
ATSDR reviewed additional data collected by EPA from wells used for watering livestock for this public health assessment. Data values for TCE ranged from none detected to 190 ppb and data values for carbon tetrachloride were all less than 1 ppb. On the basis of the levels found, bioaccumulation of compounds in beef or dairy products is not expected to be of health concern for consumers.
In addition, ATSDR conducted a literature search for information regarding health effects of TCE on cattle. ATSDR found no information specific to TCE and bovine health. One journal article was found which discusses research conducted with goats and milk-fed kids (14). The object of this particular study was to examine tissue distribution, secretion into milk and expiration to expired air after ruminal or gastrointestinal absorption of methyl chloroform (MCF), trichloroethylene (TCE), and tetrachloroethylene (PCE) which were intra-ruminally or orally distributed to lactating goats and milk-fed kids. The study results indicated that MCF is readily exhaled through alveolar breath; TCE is adaptatively metabolized to metabolites in the body; and PCE is the most significantly tissue-partitioning, as well as the most secreted substance in milk. The levels of TCE and PCE administered to goats in this study were much higher than those found in drinking water near the Tri-County Airport site. ATSDR does not expect that beef or dairy cattle consuming TCE or CCL4 at the concentrations measured in the water (391 ppb and 21 ppb, respectively) would result in adverse health effects to cattle.
The purpose of the public health action plan (PHAP) is to ensure that this public health assessment goes beyond presenting ATSDR's conclusions and recommendations about public health issues at the proposed TCPA NPL site. The PHAP describes the actions that are designed to stop or prevent harmful effects resulting from exposure to hazardous substances at the site.
A. Actions Undertaken
B. Actions Planned
Robert B. Knowles, M.S., REHS, Division of Health Assessment and Consultation
ATSDR Team Members for the Tri-County Public Airport Public
Health Assessment
Shawn Blackshear, ATSDR Regional Representative, EPA Region
VII
Dawn O'Connor, Division of Health Assessment and Consultation
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