PUBLIC HEALTH ASSESSMENT
U.S. DEFENSE GENERAL SUPPLY CENTER
RICHMOND, CHESTERFIELD COUNTY, VIRGINIA
ENVIRONMENTAL CONTAMINATION & OTHER HAZARDS
The contaminants discussed in subsequent sections of this public health assessment will be evaluated to determine whether exposure to them has public health significance. ATSDR selects and discusses contaminants based on their environmental concentrations with consideration for 1) field and laboratory data quality, 2) sample design and adequacy, and 3) comparison of on- and off-site concentrations. Environmental concentrations are evaluated using comparison values for non-carcinogenic and carcinogenic endpoints and community health concerns. The potential for adverse health effects from those contaminants of concern will be discussed in the Public Health Implications section of this document.
Comparison values for ATSDR public health assessments are contaminant concentrations in specific media (air, water, soil, etc.) used to select contaminants of concern for further evaluation. The values are developed by environmental and health agencies to provide an estimate of concentrations present in each environmental medium that should be evaluated for possible health effects if exposures to the contaminants occur. An explanation of comparison values and quantitative units used in this document are described in Appendix B.
The contaminants of concern at each site for which environmental data were available for review are listed in the site tables in Appendix A. The comparison value that is listed in a table was selected because a contaminant concentration exceeded that value in a particular environmental medium. In Table 5, for example, 1,1,1-trichloroethane is listed because it was detected in both groundwater and soil samples. Only the comparison value for groundwater concentrations was exceeded; therefore, the groundwater comparison value is used. The other media concentrations are included to identify those that may be continued sources of groundwater contamination at the site and to identify data that are lacking but would be useful in characterizing the site.
Likewise, a contaminant may have exceeded comparison values in more than one medium (e.g., groundwater and soil). Only one comparison value is provided in the table, but other media are considered when evaluating the public health implications.
Comparison values for a contaminant differ for each environmental medium. Therefore, comparison values used for a contaminant listed in one table may be different than those used in another table, particularly if the environmental medium is not the same.
An overview of the contamination of groundwater, soils, surface water, and other environmental media is presented to show how individual sites (source areas) may be affecting the installation as a whole and the surrounding communities. An overview is presented in the following paragraphs, followed by site-specific (source areas) information.
Groundwater
Groundwater contamination has been identified at five DGSC sites. Data for groundwater at other sites are not yet available. The shallow aquifer is contaminated at three of the five sites; the deep aquifer is contaminated at four sites. The primary contaminants are volatile organic chemicals (VOCs). Groundwater flow patterns and contaminant migration potential are discussed in the Pathways Analyses section of this document. The summary table that follows shows which sites are impacting each aquifer.
Summary of Groundwater Contamination
Contamination |
Contamination | |
| Open Storage Area | ||
| Area 50 | There is no shallow aquifer in this area.1 | |
| National Guard Area | ||
| Fire Training Area | ||
| Acid Neutralization Pits | The deeper aquifer has not been sampled.1 |
Contaminants of concern and their concentrations are listed in Tables 2-8 in Appendix A and are discussed in the site-specific sections.
Groundwater data were recently collected and analyzed for two additional sites, Building 112 and the Fuel Oil Storage Area (Law Environmental, Inc. 1993). Those results are discussed in the site-specific sections.
Soils
Soil samples from five sites have been collected and analyzed. Contaminants of concern have been detected only at the Fire Training Area. Both surface and subsurface soils at the site contain contaminants of concern, including heavy metals.
Soil samples from four additional sites have recently been collected and analyzed for Buildings 112, 202, 68 and the Fuel Oil Storage Area (Law Environmental, Inc. 1993). Those results are discussed in the site-specific sections.
Surface Water and Sediments
Surface water and sediment samples have been collected and analyzed for two streams at DGSC. Flow patterns and the individual sites that affect each stream are discussed in the Pathways Analyses section. Surface water and sediments are contaminated in the No-Name Creek that originates on the installation and in Kingsland Creek. Metals, VOCs, and PAHs were found in surface water; petroleum hydrocarbons were detected in sediments. Kingsland Creek is discussed in the Off-Site Contamination section.
Both creeks were recently sampled in October of 1992. Those results are discussed in subsequent site-specific sections (Law Environmental, Inc. 1993 ).
Air
No air monitoring has been performed at any of the sites. However, soil gas surveys were performed during the remedial investigations of the Open Storage Area/Area 50/National Guard Area and the Fire Training Area. VOCs were detected in soil gas assays at the National Guard Area and the Fire Training Area. Findings are further described in the Pathways Analyses section.
Biota
No edible animals or plants have been tested for contamination. The aquatic animals that were subjected to tests using water from creek systems at the installation (see site-specific discussions) were used as water quality indicators and not for contaminant uptake potential.
Site-Specific Contamination
The site-specific contamination which was detected in each environmental media is organized for each source area. Tables 2-8 in Appendix A list contaminants detected in the source areas at levels greater than comparison values.
Open Storage Area
The ranges of concentrations for contaminants of concern in the Open Storage Area are presented in Table 2. Volatile organic compounds are contaminants of concern. In some wells, the water was tested for a limited number of inorganic chemicals. Lead was analyzed for in only two wells (Dames and Moore 1989b). No lead was detected in water from either well above the detection limit of 5 parts per billion (ppb).
Area 50
National Guard Area
USGS also installed 68 monitoring wells on installation property outside the National Guard Area to the north and east. The wells are arranged in 10 clusters; each cluster contains four to five wells. At least one well in each cluster is in the upper aquifer and at least three wells are in the lower aquifer at varying depths. The deepest well in the lower aquifer is 72 feet below the ground surface (Dames and Moore 1989b).
Concentration ranges for contaminants of concern in the National Guard Area are shown in Table 4. Analyses for lead and other pertinent metals associated with the types of wastes generated at the facility were not conducted. Some upgradient wells were tested, and the water was analyzed for some metals, including lead (CH2M Hill 1991). The maximum level of lead detected in those upgradient wells was 13 ppb.
In October of 1992, sediment samples were collected both on and off site from the No-Name Creek and analyzed for VOCs, base neutral/acid extractable semi-volatiles (B/N/As), pesticides/PCBs, total metals, Total Organic Carbon (TOC), cyanide, hexavalent chromium, and grain size analysis (Law Environmental, Inc. 1993). Although some volatiles, semi-volatiles, pesticides, total metals, and TOC were occasionally detected, adverse health effects are not likely.
Ambient aquatic 7-day chronic toxicity tests were conducted using surface water samples from the No-Name Creek. Ceriodaphnia dubia (water fleas) and Pimephales promelas (fathead minnows) were used in the tests. A benthic macroinvertebrate study also was conducted on samples from the creek. Results of the studies indicate the creek has been moderately affected, possibly by the contaminants present in the stream. A definition of "moderately affected" was not provided in the report (Dames and Moore 1989b).
In October of 1992, surface water samples were collected both on and off site from the No-Name Creek and analyzed for volatile organics (VOCs), B/N/As, pesticides/PCBs, total metals, cyanide, hexavalent chromium, total dissolved solids (TDS), conductance and pH (Law Environmental, Inc. 1993). Although some volatiles and total metals were occasionally detected, adverse health effects are not likely.
Fire Training Area
Acid Neutralization Pits
Aluminum Phosphide Residue Disposal Area
Parker Pond
Building 112--Pesticide Generalization and Recycling Building
Building 68--Suspected PCB Spill Site
Transitory Shelter (Building 202)--Reported DDT Spill Site
Fuel Oil Storage Area
However, one well in the Rayon Area (on Congress Street) was sampled in June of 1992. The well water was analyzed for volatile organics, semi-volatile organics, metals, and pesticides/herbicides. No chemicals were detected above appropriate drinking water standards (DGSC 1993b).
Six private wells in the Kingsland Creek area (on Kingsland Road) were also sampled during June of 1992. The well water was analyzed for volatile organics, semi-volatile organics, metals, and pesticides/herbicides. One well had lead detected at a concentration above EPA drinking water standards; five other wells in the immediate area did not. The lead has been attributed to the resident's well piping (DGSC 1993a). That homeowner was referred to a health professional at the Virginia Department of Health (DGSC 1993ba , DGSC 1993b).
Ambient aquatic 7-day chronic toxicity tests were conducted on water fleas and fathead minnows using water from Kingsland Creek. A benthic macroinvertebrate study also was conducted. The creek was found to be moderately affected, possibly by the contaminants found in the creek (Dames and Moore 1989c). A definition of "moderately affected" was not provided in the report.
In October of 1992, surface water samples were collected both on and off site from Kingsland Creek and were analyzed for VOCs, B/N/A, pesticides/PCBs, total metals, Total Organic Carbon (TOC), cyanide, hexavalent chromium, and grain size analysis (Law Environmental, Inc. 1993). Although some volatiles and total metals were occasionally detected, adverse health effects are not likely.
In October of 1992, sediment samples were collected both on and off site from Kingsland Creek and analyzed for volatile organics (VOCs), base neutral/acid extractable semi-volatiles (B/N/A), pesticides/PCBs, total metals, cyanide, hexavalent chromium, total dissolved solids (TDS), conductance and pH (Law Environmental, Inc. 1993). Although some pesticides and total metals were occasionally detected, adverse health effects are not likely.
C. Quality Assurance and Quality Control
The data reviewed by ATSDR are consistent with EPA guidelines. Data appear valid and reliable. However, for one chemical, vinyl chloride, the detection limit (5 ppb) was higher than the MCL (2 ppb) for groundwater collected from monitoring wells in the Fuel Oil Storage Area. This sampling was conducted in October of 1992 (Law Environmental, Inc. 1993). For future sampling, the detection limits should be set lower than regulatory environmental comparison values. This public health assessment was prepared using the data presented in the Remedial Investigation reports and other available documents.
Although most drums stored at the Open Storage Area contain
lubricants with high flash points, some drums and containers,
especially in the recoupment area, contain products with lower
flash points. During the March 1991 site visit, ATSDR staff
heard some of the drums popping, and some of the drums were
unlabelled such that the flash points of the contents are
unknown. Therefore, a physical hazard may exist at the open drum
storage area because weather-exposed drums could explode, or
spills could result in fires. Only installation personnel have
access to those areas. EPA is currently working with the
installation to resolve this situation (DGSC 1992b).
An environmental exposure pathway consists of the following components: 1) a source of contamination, such as the National Guard Area; 2) an environmental medium in which the contaminants may be present or may migrate, such as soil and groundwater; 3) points of human exposure, for example, private wells; 4) routes of exposure such as inhalation, ingestion, or dermal absorption; and 5) a receptor population, including people who are exposed or potentially exposed. Pathways are considered to be complete when all pathway components exist or are likely to exist. Pathways for which one or more of the pathway components do not exist are considered 1) potential, if the missing component may be identified at a later point in time; 2) potential, if the missing component could occur at a later date; or 3) eliminated, if the missing component is likely never to occur. The past, present, and future exposure pathways that may present a public health hazard are discussed in this section. Exposure pathways associated with specific sites (source areas) may be completed, potential, or eliminated; therefore, each relevant medium is discussed in this section in relation to the sources of contamination.
A. Completed Exposure Pathways
Groundwater
The Open Storage Area and the National Guard Area have contributed to upper aquifer contamination. Some introduction of contaminants to the lower aquifer through monitoring wells constructed during earlier investigations may have taken place, but that has not been confirmed by the installation contractors (Dames and Moore 1989b). Contaminants in Area 50 appear to affect the lower aquifer. Contaminants from those three areas are believed to be linked to the off-post migration of contaminants to private wells in the northwestern corner of the Rayon Park community (Figure 4). Current plume data do not confirm if those three areas are also the source of other private well contamination in the community. Other potential sources of contamination exist in the community, such as the small body shop south of the installation in the Kingsland Creek area, but to date, no other source has been identified.
The private well contamination in Rayon Park resulted in a completed exposure pathway for residents who used the water for drinking and other household purposes. The exposure routes were by ingestion and inhalation of, and dermal contact with the contaminants. Contamination was first discovered in 1984; however, since 1987, wells with confirmed contamination have been connected to the municipal water supply. The exact duration and extent of exposure is unknown; the concentration of contaminants may have varied (i.e., higher or lower) over time. However, exposure has been confirmed for four years (1984 to 1987). Because the residents are using an alternate water supply, no exposures are believed to be taking place at this time. Past exposures are evaluated in the Public Health Implications section.
B. Potential Exposure Pathways
Groundwater
Groundwater contamination is still present at the Open Storage Area, the National Guard Area, and Area 50. The contaminant plume or plumes that migrated from the installation to Rayon Park continue to contaminate groundwater in that area and may migrate to other areas. In addition, at least three residences in that area have private wells that are still being used for drinking water and other household purposes. Those three wells were tested and showed no contamination in 1987, so the property owners elected to continue using those private wells. Although those three wells have not been regularly monitored, one well in that area was recently sampled in June of 1992. Well water was analyzed for volatile organics, semi-volatile organics, metals, and pesticides/herbicides. No chemicals were detected above EPA drinking water standards (DGSC 1993b). Currently, it appears that wells in that area are probably free of contamination and are not being affected by contaminant plumes. Future exposures are possible if contaminant plumes reach private wells that are still in use. People who use the potentially contaminated water would be exposed by ingestion, inhalation, and dermal contact. An interim plan for remediation of groundwater east of the National Guard Area is being proposed to prevent migration of contamination. It is expected to be released for public review in late April 1993 (DGSC 1993b).
Groundwater contamination in the Fire Training Area, according to the Remedial Investigation, may be migrating toward homes south of the installation in the Kingsland Creek area (Dames and Moore 1989c). In addition, there are other potential sources of contamination in that community such as a small body shop and a landscaping and nursery operation. Neighborhoods south of the installation appear to be topographically upgradient of Kingsland Creek and a steep incline separates the installation from the homes. However, analytical data in the Remedial Investigation suggest that groundwater may flow under the creek toward the homes. Some of those homes use private wells for drinking water and other household purposes. There are no data that indicate they were contaminated in the past. Recent sampling in the Kingsland area in June of 1992 indicates they are currently free of contamination, but future exposures are possible if wells become contaminated by migrating contaminants. People who use the potentially contaminated water would be exposed by ingestion, inhalation, and dermal absorption.
Contaminants of concern were detected in groundwater of the Fuel Storage Area and Building 112. Because those sites are situated near the Fire Training Area (Figure 3), groundwater flow is expected to be to the south. Therefore, those sites may be adding contaminants to the groundwater pathway in that vicinity. That pathway is discussed in the paragraph above.
Soils
The original soils at the Fire Training Area were probably Bourne, a fine sandy loam. The soil has been graded and re-worked through the years, changing the original soil structure. The surface soils now consist of fine sandy loam; the subsoil consists of friable sandy clay loam and brittle and compact fine sandy loam. Because of the soil characteristics, lateral and some limited vertical migration of contaminants may have taken place. Contaminants of concern (see Table 5) have been measured in soils at the Fire Training Area.
Installation personnel and remedial workers were and are potentially exposed to the contaminants at the Fire Training Area. Potential exposure routes include incidental ingestion, inhalation, and dermal absorption. Restricting personnel's access to the site and providing them with appropriate, personal, protective equipment during remediation would diminish the possibility of exposures.
Contaminants of concern were detected in soils sampled at the Fuel Oil Storage Area and Buildings 202, 112, and 68. Installation personnel and remedial workers were and are potentially exposed to the contaminants at those sites. Potential exposure routes include incidental ingestion, inhalation, and dermal absorption. Similar to the Fire Training Area, restricting personnel's access to the site and providing them with appropriate, personal, protective equipment during remediation would diminish the possibility of exposures.
Surface Water and Sediments
The central portion of the installation, which includes the Acid Neutralization Pits, the possible PCB Spill Area, the Open Storage Area, Area 50, and the National Guard Area, drains toward the No-Name Creek north and northeast of the National Guard Area. The No-Name Creek originates at the outfall of the storm sewer system on the installation and flows south/southeast, through the Rayon Park subdivision, until it empties into the James River about two miles from the installation. Contaminants from the storm sewer, shallow groundwater, and runoff are transported from the installation by this creek. The creek and sediments have been contaminated by the previously named sites. Metals, VOCs, and PAHs were detected in the surface water of the No-Name Creek on the installation; no contaminants were found above detection limits off site. Petroleum hydrocarbons were detected in sediment of the No-Name Creek on the installation. People who wade or swim in the No-Name Creek, which flows from the National Guard Area through the Rayon Park subdivision, may potentially be exposed to contaminants by incidental ingestion and inhalation of and dermal absorption of contaminants, if contaminants were to migrate off of DGSC. However, recent surface water and sediment sampling both on and off site in No-Name Creek were conducted in October of 1992 (Law Environmental, Inc. 1992b and Law Environmental, Inc. 1993). Although some chemicals were detected, the concentrations are not likely to cause adverse health effects.
Kingsland Creek flows along the southern border of the installation. Runoff and groundwater from the Fire Training Area, Aluminum Phosphide Residue Disposal Area, and Building 202--Reported DDT Spill Site discharge into the creek. The creek empties into the James River about 2.5 miles east of DGSC. An area about 170 feet south of the Fire Training Area receives groundwater discharge during periods of high water table conditions resulting in intermittent surface water conditions. The water drains to Kingsland Creek by way of a culvert. Two VOCs, TCE and PCE, have been detected at low concentrations in the surface water of Kingsland Creek. Anyone who fishes or plays in the creek could be exposed to the contaminants possibly by ingestion, inhalation, and dermal contact. Low levels of PCE and TCE detected thus far are not of public health concern. Recent surface water and sediment sampling both on and off site in Kingsland Creek were conducted in October of 1992 (Law Environmental, Inc. 1992b and Law Environmental, Inc. 1993). Although some chemicals were detected, the concentrations are not likely to cause adverse health effects.
Air
Prevailing winds in the DGSC area were reported in the Remedial Investigations to be southerly. Wind speeds in the area are generally moderate, except during storms. No air sampling has been conducted to determine the degree of off-post migration of contaminants as gases or particulates.
However, soil gas data indicate that total VOCs are present at the National Guard Area. Therefore, a potential exposure pathway exists for installation personnel working in this area and for nearby residents in Rayon Park. The route of exposure would be primarily by inhalation of air in buildings and surrounding grounds. Accumulation of concentrations of VOCs of public health concern is unlikely because the concentrations of total VOCs detected in soil gas are very low (concentrations ranged from 1 to 84 ppb of total VOCs). Individual VOCs at the National Guard Area were not measured because concentrations of individual contaminants were below detection limits for the equipment used. However, due to the rapid volatility of VOCs and the low levels (ranging from 1 to 84 ppb) of total VOCs detected in the soil gas, exposure levels are not expected to be of public health concern.
Soil gas data confirm the presence of VOCs at the Fire Training Area (Table 5). Installation personnel and remedial workers could be exposed to VOCs by inhalation. The residence nearest to the Fire Training Area is beyond steep inclines, approximately 0.25 miles away, and residents are not likely to be exposed to VOCs under normal climatic conditions.
Although most drums stored at the Open Storage Area contain lubricants with high flash points, some drums and containers, especially in the recoupment area, may contain products with lower flash points. During a March 1991 site visit, ATSDR staff noticed that some of the drums were popping and that some drums were unlabelled, thereby making their contents, and consequently, their flash points, unknown. Therefore, a physical hazard may exist at the Open Storage Area because weather-exposed drums could explode, or spills could result in fires. The installation is working with EPA to resolve this situation (DGSC 1992b).
C. Eliminated Exposure Pathways
Groundwater
Groundwater flow from the Acid Neutralization Pits appears to be north or east. The Remedial Investigation for the Acid Neutralization Pits indicate the shallow and deep aquifers at this site may be distinct or separate (Dames and Moore 1989a). Creeks lie to the north and east, and the pits are near the central/north central portion of the installation (Figures 1 and 3). Contaminants of the Acid Neutralization Pits are not suspected to be those detected in the private wells of the Rayon Park community nor are they likely to migrate to other homes where wells are used. The Rayon Park wells appear to be affected by contaminants from other sites (the Open Storage Area/National Guard Area/Area 50) on the installation (Dames and Moore 1989b). Therefore, no completed exposure pathways are expected to result from the groundwater contamination at the Acid Neutralization Pits.
Soils
No contaminants of concern have been detected in soil at all sites studied to date, except for the Fire Training Area, Fuel Oil Storage Area, and Buildings 202, 112, and 68. Therefore, except at those sites, no completed exposure pathways associated with ingestion and inhalation of dust particles and dermal contact with the soils are expected.
Surface Water and Sediments
Drainage from the northern portion of the installation is toward Falling Creek, which is about one mile northeast of the Acid Neutralization Pits. Runoff, drainage, and groundwater discharge are not likely to affect Falling Creek. Therefore, no completed exposure pathways associated with people swimming or wading in the creek are expected.
Parker Pond is in the southern portion of the facility, north of the Fire Training Area. The pond is reported to be used for recreational fishing, not subsistence fishing, by installation personnel (DGSC 1991a and DGSC 1992b). Parker Pond probably does not receive runoff from the sites discussed in this document. However, it does receive roadway runoff and is being investigated for possible pesticide contamination as discussed in the On-Site Contamination section of this document. Since the pond is not used for swimming (DGSC 1991a and DGSC 1992b) and data provided (DGSC 1991b) to date do not indicate the presence of contaminants in surface water or sediments, no exposures to contaminants are expected.
Air
According to interviews with installation personnel, no reactive aluminum phosphide is expected to be present at the Aluminum Phosphide Residue Disposal Area (DGSC 1992b). Therefore, no exposures by inhalation are expected. (Aluminum phosphide is not expected to be present at the area, because the material disposed of in this area was residue from reacted pellets of aluminum phosphide.)
Biota
In the summer of 1987, there was a fish kill in Parker Pond. The fish kill was believed to be the result of low oxygen concentrations in the pond because dissolved oxygen was measured at levels below those normally needed to support fish. However, a fish was analyzed for pesticides. The dead fish, stocked from another source, contained 260 ppb of DDT (DGSC 1991a, DGSC 1991b, and DGSC 1992b). In 1988 and 1991, surface water and sediment samples were collected and analyzed for pesticides. No pesticides were measured in those samples (DGSC 1991b). Findings from the surface water and sediment sampling suggest that DDT was not introduced into the fish from the pond (DGSC 1991b). Because the fish used to stock the pond are brought from an off-post facility (DGSC 1992b), the fish could have been contaminated before they were put into the pond. However, fish in the pond and fish from the hatchery should be sampled for confirmation. The facility is now stocking the pond with fish from another source.
Edible biota that may be affected by contaminants detected at DGSC include fish from Kingsland Creek and plants from small home gardens. Although no fish tissue from Kingsland Creek has been collected, the types of contaminants (Table 10) found to date in the creek are not likely to be taken up into the fish at levels of concern (ATSDR 1992b, ATSDR 1992c, Law Environmental, Inc. 1993). Therefore, eating fish from Kingsland Creek is not considered a potential exposure pathway.
To date, no vegetation samples have been collected and analyzed.
However, the types of contaminants detected in private wells that
may still be used for irrigation are not likely to be taken up by
the plants at levels of concern. Available data indicate that
plants grown near the facility are not expected to be an exposure
pathway. Future private well data may indicate a need to re-evaluate that conclusion.
In this section, ATSDR discusses health effects that could result from exposures to site contaminants. People can only be exposed to a site contaminant if they come in contact with it. People can be exposed by breathing, eating, or drinking the contaminant, or by contacting (skin) contaminated water, soil, or air.
In order to understand health effects that may be caused by a specific chemical, it is helpful to review factors related to how the human body processes the chemical after exposure. Those factors include the exposure concentration (how much), the duration of exposure (how long), the route of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, individual characteristics such as age, sex, nutritional status, health status, lifestyle, and genetics influence how the chemical is absorbed, distributed, metabolized (processed), and excreted (eliminated). Together, those factors determine health effects that exposed people may have.
To determine the possible health effects of specific chemicals, ATSDR searches scientific literature. The resulting information is compiled and published in a series of chemical-specific ATSDR documents called Toxicological Profiles. Toxicological Profiles are references that describe adverse health effects that could be associated with exposure to a specific chemical in the environment. In addition, they include health guidelines such as ATSDR's minimal risk levels (MRLs) and EPA's reference doses (RfDs), reference concentrations (RfCs), and cancer slope factors (CSFs). When RfDs, RfCs, and MRLs are not available, a no observed adverse effect level (NOAEL) or lowest observed adverse effect level (LOAEL) may be used to estimate levels at which adverse noncancerous effects are not expected.
ATSDR compares contaminant concentrations in different environmental media (soil, air, water, and food) that populations may be exposed to daily to a variety of health guidelines. This will determine whether exposure to given levels of contaminants is likely to cause an increased risk of developing cancer and/or noncancerous adverse health effects. ATSDR's MRL is an estimate of daily human exposure to a chemical likely to be without appreciable risk of deleterious effects (noncancerous) over a specified duration of exposure. MRLs are based on human and animal studies and are reported for acute (less than or equal to 14 days), intermediate (15-364 days), and chronic (greater than or equal to 365 days) exposures. If an individual's daily exposure is below the MRL, adverse health effects are not expected. A RfD is EPA's estimate for the human population, including sensitive subpopulations, of the daily exposure by the oral route likely to be without appreciable risk of deleterious noncarcinogenic effects during a lifetime (70 years). Likewise, a RfC is EPA's estimate for the human population, including sensitive subpopulations, of the daily exposure by the inhalation route likely to be without appreciable risk of deleterious noncancerous effects during a lifetime (70 years).
A NOAEL or LOAEL may be used when RfDs, RfCs, and MRLs are not available. That level is used to estimate a dose at which neither animals nor people would be expected to develop adverse noncancerous effects.
Some health guidelines such as MRLs and RfDs do not consider, however, the risk of developing cancer. To evaluate exposure to carcinogenic chemicals, EPA has established cancer slope factors (for inhalation and ingestion) that define the relationship between exposure doses and the likelihood of an increased risk of cancer compared with non-exposed controls. Usually derived from animal or occupational studies, cancer slope factors are used to calculate the exposure dose likely to result in one excess cancer case per one million persons exposed over a lifetime (70 years).
ATSDR's estimation of human exposure to contaminated media uses media-specific rates for adults and children. The rates are calculated by multiplying contaminant concentration by the ingestion rate for an adult or a child, and then dividing that number by the appropriate standard body weight (70 kg for adults, 16 kg for a child). The water ingestion rates used for adults and children are 2.0 L/day and 1.0 L/day, respectively. ATSDR uses an inhalation rate of 23 cubic meters per day (m3/day) for adults and 15 m3/day for children. Some exposures occur on an intermittent or irregular basis; in those cases, an exposure factor (EF) is calculated that averages the dose over the exposure period.
The maximum contaminant concentration detected in a particular medium is used to determine estimated exposure. Using the maximum concentration results in an evaluation that is protective of public health.
Individuals off site have been exposed to multiple chemicals by direct ingestion of water from contaminated private wells. Data are very limited, however, on the health effects of multiple chemical exposures by oral, dermal, and inhalation routes. Effects of specific contaminants detected in multiple media can be additive, antagonistic, or synergistic, i.e., adverse health effects may be increased, decreased, or one effect may be cancelled by another. Furthermore, simultaneous exposure to contaminants that are known or probable human carcinogens could increase the risk of developing cancer and/or noncancerous health effects. ATSDR's evaluation of exposures in this public health assessment is limited to individual contaminants and individual routes of exposure; multiple exposures have not been evaluated. Current research involving complex chemical mixtures eventually will add new information that will be used in future evaluations.
The private well contamination in the Rayon Park neighborhood, north and east of DGSC, is a past completed exposure pathway for residents who used the water for drinking and other household purposes (Table 9). Contaminants detected in private well water were the following VOCs: benzene, 1,2-dichloroethane, 1,1-dichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, and trichloroethylene. Contaminants from the Open Storage Area, National Guard Area, and Area 50 may be linked to the off-post migration of contaminants to private wells in the northwestern corner of the Rayon Park community.
Except for Rayon Park, residents of communities near DGSC appear to have a high rate of residential mobility. The Community Relations Plan reports that residents of Rayon Park tend to be less transient when compared to other persons in the surrounding area (Virginia Department of Waste Management 1991). Contamination was first discovered in Rayon Park wells in 1984; however, since 1987, wells with confirmed contamination have been replaced with municipal water supply. The exact duration and extent of exposure is unknown; the concentration of contaminants may have varied (i.e., higher or lower) over time. However, exposure has been confirmed for four years (1984 to 1987). The following paragraphs evaluate the potential health effects of contaminant exposure (via ingestion, inhalation, and dermal contact) to individual contaminants.
Benzene
Residents of the Rayon Park community (off-site) were exposed to benzene by ingesting benzene-contaminated water from their private wells. Exposure to benzene by both inhalation and ingestion may have taken place. Although dermal exposure was possible, dermal absorption of benzene is likely to be minimal, i.e., less than 1% of the concentration (Franz 1984, Mailbach and Anjo 1981, Susten et al 1985, ATSDR 1992a). Therefore, dermal absorption of benzene is not a significant route of exposure for residents who used that contaminated well water.
Benzene has been detected in residential wells at a maximum concentration of 1.4 ppb (parts per billion). EPA has classified benzene as a known human carcinogen by oral and inhalation routes. In industrial settings, chronic benzene exposure adversely affects the body's ability to make red and white blood cells, which may eventually lead to aplastic anemia and acute myeloblastic leukemia (ATSDR 1992a). The concentrations, and thus exposure doses, of benzene encountered in those settings are much higher than those detected in Rayon Park wells. Therefore, exposures at Rayon Park are not expected to result in an increased cancer risk because of the infrequent, low levels of benzene detected in the Rayon Park wells. The duration of exposure is unknown.
Health guidelines, such as the RfC and RfD, for benzene are undergoing review by an EPA work group. Most of the information about noncancerous health effects associated with benzene exposure in humans is from studies of workers employed by industries that make or use benzene. The concentrations, and thus exposure doses, of benzene encountered in those settings (ATSDR 1992a) are much higher (approximately 500- to 700- fold higher) than those detected in Rayon Park wells.
Assuming the estimated exposures associated with inhalation of volatilized benzene from activities such as showering and cooking are approximately equal to estimated ingestion exposures (Otto 1990 and McKone 1987), adverse noncancerous health effects are not expected from inhalation of volatilized benzene from Rayon Park wells. Although it appears that the blood and immune and central nervous systems are adversely affected by chronic benzene inhalation, the levels at which those effects have been observed are much higher than levels of benzene detected in the Rayon Park wells (1.4 ppb). For example, a study in a Texas refinery showed no changes in blood components (platelets, red blood cells, white blood cells, hemoglobin, or hematocrit) in workers who inhaled benzene at levels less than 1,000 ppb (the mean was 530 ppb) for 1-21 years (Tsai et al 1983).
Health guidelines, such as MRLs and RfDs, have not been established for noncancerous health effects in people following chronic oral exposure to benzene. However, results from animal studies suggest that chronic oral exposure to benzene adversely affects the liver, kidneys, blood and the immune and central nervous systems. However, those effects are seen at levels between 100 to 1,000 times higher than the maximum level of benzene detected in private wells in Rayon Park (ATSDR 1992a). Therefore, noncancerous health effects are unlikely.
Benzene is a VOC used in the production of plastics, detergents, pesticides, lubricants, dyes, and some types of rubber. It also is a component of gasoline, vehicle exhaust fumes, and tobacco smoke (ATSDR 1992a). The general population is exposed to benzene mainly through inhalation of contaminated air (particularly in areas of heavy traffic and around gas stations) and tobacco smoke (from both active and passive smoking). Smoking is the single most important source of benzene exposure for the estimated 40 million U.S. smokers; smoking accounts for approximately half of the total benzene exposure of the general population. Individuals employed by industries that make or use benzene or products containing benzene are probably exposed to the highest concentrations of atmospheric benzene (ATSDR 1992a). People who used their contaminated well water for drinking and other household uses may have had exposures to benzene other than from their private wells. Those persons residing in Rayon Park who were smokers or employed in occupations using benzene in the workplace may have had additional exposures to benzene.
People who used the contaminated wells in Rayon Park and may have been particularly sensitive to benzene during that time of exposure include pregnant women, their fetuses, and immunosuppressed and malnourished people (ATSDR 1992a). Whether those populations have different or enhanced responses depends on the ability of the liver and kidneys, and other target organs such as the bone marrow, to detoxify and excrete benzene. The bone marrow produces white blood cells, which as part of the immune system, help to guard against disease. For those reasons, it is expected that persons who were using contaminated wells in Rayon Park and were either elderly people with declining organ function or young children with immature and developing organs may have been more vulnerable to benzene and other toxic substances than healthy adults (ATSDR 1992a). Rayon Park area currently consists of about sixteen percent of persons 65 years of age or older and nine percent under age 10 (Table 1--1990 Census Data). Since that area is fairly stable, or less transient than other areas, it is likely that those subpopulations were also present during the years when exposures to contaminated well water were occurring.
1,2-Dichloroethane (1,2-DCA)
Residents of Rayon Park were exposed to 1,2-DCA by inhalation and ingestion of and dermal contact with 1,2-DCA-contaminated groundwater from their residential wells. People are exposed to 1,2-DCA mainly by breathing it in air or by drinking it in 1,2-DCA-contaminated water. However, if drinking water supplies contain more than 6 ppb of 1,2-DCA, exposure by ingestion is expected to be more significant than inhalation (EPA 1985). Because of the high vapor pressure of 1,2-DCA, it rapidly volatilizes thereby making dermal contact an insignificant route of exposure for residents of Rayon Park (Tsurata 1975, EPA 1985, ATSDR 1989a).
A maximum concentration of 6.2 ppb of 1,2-DCA was detected in Rayon Park well water. Little information exists about the development of cancer in people following long-term exposure to 1,2-DCA. Using animal studies, however, EPA has classified 1,2-DCA as a probable (B2) human carcinogen (NCI 1978, Van Duuren et al 1979, ATSDR 1989a) by both ingestion and inhalation routes. Those studies indicate that 1,2-DCA has caused numerous types of tumors in a variety of animals. However, exposures at Rayon Park are not expected to result in an increased cancer risk because of the infrequent, low levels of 1,2-DCA detected in the Rayon Park wells. The duration of exposure is unknown.
There are no health guidelines for noncancerous health effects in people caused by chronic exposure via ingestion or inhalation of 1,2-DCA. However, in a study of the effects of intermediate exposures, (Munson et al 1982), mice were given 1,2-DCA-contaminated water for consumption for approximately 90 days. The results showed 189,000 µg/kg/day to be the NOAEL for adverse liver effects in mice. Applying a uncertainty factor of 1000 (which would account for animal-human variability, duration variability, and human subpopulation variability), that value would correspond to 189 µg/kg/day in people. The daily estimated ingestion dose for adults and children in Rayon Park is 0.18 µg/kg/day and 0.39 µg/kg/day, respectively. Assuming the inhalation dose would be approximately equal to the ingestion dose (McKone 1987 and Otto 1990), noncancerous effects to the liver would not be expected from past exposure via ingestion and inhalation of the contaminated water due to activities such as drinking and showering and cooking, respectively.
1,2-DCA is a clear, synthetic liquid used primarily to make vinyl chloride and several solvents that remove grease, glue, and dirt. It also is added to leaded gasoline to remove lead. In the past, it was a component of some cleaning solutions and pesticides; some adhesives, such as those used to glue wallpaper or carpeting; and some paint, varnish, and finish removers (ATSDR 1989a). Automobile and heavy equipment mechanics, machinists, janitors, and registered nurses are frequently exposed to 1,2-DCA in the workplace (ATSDR 1989a). The National Occupational Exposure Survey conducted by the National Institute of Occupational Safety and Health notes that workers are exposed to 1,2-DCA when it is used as a fumigant, solvent, or diluent in open-system operations (ATSDR 1989a). People with 1,2-DCA-contaminated wells in Rayon Park may have additional exposures to 1,2-DCA, if they were employed in the occupations or industries previously discussed.
Persons who were exposed to 1,2-DCA-contaminated wells and were taking the medications disulfiram or phenobarbital, used to treat alcoholism and seizures respectively, may have been highly sensitive to the effects of 1,2-DCA (ATSDR 1989a). Those drugs may alter a person's metabolism, resulting in increased levels of the active metabolites of 1,2-DCA. Reduced hepatic glutathione (GSH) also may alter the excretion of active metabolites. GSH plays a protective role in the liver by helping the body excrete active metabolites of 1,2-DCA. Reduced nutritional intake, such as fasting, can result in lowered GSH levels, which, as shown in animal studies, may dramatically slow the excretion of 1,2-DCA (ATSDR 1989a).
1,1-Dichloroethylene (1,1-DCE)
People have been exposed to 1,1-DCE via ingestion and inhalation of, and dermal contact with 1,1-DCE-contaminated water from Rayon Park wells. All three exposure routes are believed to be equally significant with regard to absorption of 1,1-DCE based on reports in the literature (ATSDR 1989b).
A maximum concentration of 41 ppb of 1,1-DCE was detected in Rayon Park well water. Children and adults exposed to 41 ppb of 1,1-DCE would have estimated ingestion exposures of 2.56 µg/kg/day and 1.17 µg/kg/day, respectively. Reports in the literature indicate that an increased cancer risk was demonstrated in one animal study involving inhalation exposure to 1,1-DCE (ATSDR 1989b). Most studies have shown, however, that 1,1-DCE does not cause cancer in animals, and no evidence suggests that 1,1-DCE is carcinogenic to people. However, EPA has classified 1,1-DCE as a possible (Group C) human carcinogen using animal studies (ATSDR 1989b). That category applies to chemical agents for which there is limited evidence of carcinogenicity in animals and no evidence in people. Exposures at Rayon Park are not expected to result in an increased cancer risk because of the infrequent, low levels of 1,1-DCE detected in the Rayon Park wells. The duration of exposure is unknown.
Adverse noncancerous effects are not expected to result from ingestion of 1,1-DCE because the levels detected in private well water in Rayon Park would result in estimated exposure doses (of 2.56 µg/kg/day and 1.17 µg/kg/day for children and adults, respectively) which are below the minimal risk level (MRL) of 9 µg/kg/day. The MRL is the estimated level below which adverse noncancerous effects are not expected.
Assuming the estimated exposures from inhalation of volatilized 1,1-DCE from showers and cooking are approximately equal to estimated ingestion exposures (Otto 1990 and McKone 1987), no adverse noncancerous health effects are expected from inhalation of volatilized 1,1-DCE from Rayon Park wells. The estimated exposures of 2.36 µg/kg/day and 0.83 µg/kg/day in children and adults, respectively, are below the MRL of 9 µg/kg/day.
Although it is recognized that dermal contact with 1,1-DCE also is another route of exposure, (ATSDR 1989b) health guidelines such as MRLs have not been established for dermal exposure. Dermal contact can result from household activities such as showering, mopping, washing dishes, and washing cars with 1,1-DCE-contaminated water. However, assuming all three exposure routes (ingestion, inhalation, and dermal contact) are equally significant with regard to absorption of 1,1-DCE (ATSDR 1989b) and assuming the estimated exposures from ingestion of 1,1-DCE in well water would be approximately equal to estimated dermal exposures, no adverse health effects are expected from dermal contact with 1,1-DCE contaminated water. The estimated exposures of 2.36 µg/kg/day and 0.83 µg/kg/day in children and adults, respectively, are below the MRL of 9 µg/kg/day.
Also known as vinylidene chloride, 1,1-DCE is used to make various plastics, such as packaging materials (flexible films, e.g., plastic food wraps) and flame-retardant fabrics (ATSDR 1989b). A national survey conducted by NIOSH (1976) estimated that the largest numbers of workers potentially exposed to DCE in the workplace were special trade contractors or workers in the fabricated metal products or wholesale trade industries. The occupational groups with the largest numbers of exposed workers were carpenters, warehousemen (not otherwise classified), and miscellaneous machine operators (ATSDR 1989b). Residents of Rayon Park who were employed by those industries may have had exposures to 1,1-DCE besides those from their private wells.
Although information about populations that may be especially sensitive to 1,1-DCE is from animal studies, it is believed that the following groups may have been particularly susceptible to its toxic effects during the time the contaminated wells were used: infants and young children, pregnant women, consumers of alcohol, people with liver, kidney, thyroid and cardiac disease, certain central nervous system dysfunctions, and people who are fasting (ATSDR 1989b). Increased susceptibility to 1,1-DCE toxicity is largely caused by the formation of toxic intermediates during its metabolism (ATSDR 1989b).
Tetrachloroethylene (PCE)
Residents of Rayon Park were exposed to PCE when they ingested PCE-contaminated water. Although the primary route of exposure to PCE is inhalation (Hake and Stewart 1977), PCE also is absorbed following ingestion (Koppel et al 1985). Dermal absorption of PCE in people is not as significant as absorption by inhalation (ATSDR 1992b); thus, dermal contact with contaminated water from Rayon Park wells is not a significant route of exposure.
PCE was detected at a maximum concentration of 4.9 ppb in private well water of Rayon Park. People have been exposed to PCE in the past by way of ingestion and inhalation of and dermal contact with PCE-contaminated water. The EPA has classified PCE as a probable (B2) human carcinogen by oral and inhalation routes because of results from animal studies (ATSDR 1992b). However, exposures at Rayon Park are not expected to result in an increased cancer risk because of the infrequent, low levels of PCE detected in the Rayon Park wells. The duration of exposure is unknown.
For PCE, ATSDR has calculated an intermediate MRL for inhalation exposure to be 9 ppb or 1.18 µg/kg/day for children and 0.41 µg/kg/day for adults. The estimated daily ingestion exposures of Rayon Park children and adults exposed to a concentration of 4.9 ppb PCE are 0.31 µg/kg/day and 0.14 µg/kg/day, respectively. Assuming that the estimated exposures from inhalation of volatilized PCE from household activities, such as showering and cooking, are approximately equal to estimated ingestion exposures (Otto 1990 and McKone 1987), adverse noncancerous health effects --such as damage to the lungs, liver, kidneys, and central nervous system (ATSDR 1992b)-- would not be expected from inhalation of volatilized PCE from water in Rayon Park wells.
Adverse noncancerous effects from ingestion of PCE, such as damage to the central nervous system, liver, and kidneys, are not expected in Rayon Park residents, because the levels detected in their wells would result in estimated exposure doses below the oral RfD of 10 µg/kg/day (ATSDR 1992b).
There are no health guidelines for noncancerous health effects in people caused by chronic dermal contact with PCE. However, intense ocular irritation has been reported in people who have been exposed to PCE vapor at concentrations greater than 1,000 ppm (Carpenter 1937 and Rowe et al 1952). Burning or stinging sensations in the eyes occurred after exposure to greater than 280 ppm (Rowe et al 1952). Those concentrations are approximately 100-fold greater than levels expected from volatilized PCE associated with activities such as from showering and cooking. Therefore, no adverse noncarcinogenic health effects are expected from dermal contact with PCE.
PCE is a synthetic solvent used widely for dry cleaning fabrics and textiles and in metal-degreasing operations (ATSDR 1992b). General uses of PCE include carrier applications for rubber coatings, solvent soaps, printing inks, adhesives and glues, sealants, polishes, lubricants, and silicones (Chemical Products Synopsis 1985 and Mitchell 1980). Persons employed in industries using PCE, previously discussed, may be exposed to PCE in the workplace. Thus, residents of Rayon Park who were employed by those industries may have had exposures to PCE besides the exposures from their private well water. PCE can cross the placenta and has been found in breast milk, but the exposure doses in the mothers were unknown. Therefore, fetuses and nursing babies may have been at an increased risk for adverse health effects from maternal exposure, if their mothers consumed contaminated water from Rayon Park wells (ATSDR 1992b).
1,1,1-Trichloroethane (1,1,1-TCA)
Rayon Park residents were exposed to 1,1,1-TCA when they ingested and inhaled contaminated water from their private wells. Although dermal exposure is possible, dermal absorption of 1,1,1-TCA is likely to be minimal compared with inhalation (Tsurata 1975); most of it evaporates into the air (ATSDR 1990). Therefore, dermal absorption is not a significant route of exposure for Rayon Park residents.
A review of the literature found no exposure studies in animals or people that have conclusively shown 1,1,1-TCA is a carcinogen (Quast et al 1988). Therefore, at this time, 1,1,1-TCA is not considered to be carcinogenic. A maximum concentration of 500 ppb was detected in Rayon Park wells. The estimated daily exposures from ingestion of 500 ppb of 1,1,1-TCA is 31.3 µg/kg/day for children and 14.3 µg/kg/day for adults.
Health guidelines have not been established for noncancerous effects in people after chronic inhalation and ingestion of and dermal contact with 1,1,1-TCA. But, a long-term occupational study found a NOAEL for central nervous system effects that ranged from 200,000 - 900,000 ppb of 1,1,1-TCA (Maroni et al 1977). The study focused on inhalation exposures with an average duration of 6.7 years per study group. Using the lower concentration of 200,000 ppb, an estimated inhalation dose for adults would be 21,459 µg/kg/day; for children, it would be 7,521 µg/kg/day. Assuming the inhalation and ingestion doses associated with the contaminated water were approximately equal (Otto 1990 and McKone 1987) and using the NOAEL from the occupational study, adverse noncancerous effects would not be expected.
No studies were found that investigated chronic ingestion of 1,1,1-TCA by people. However, one study (Maltoni et al 1986) of systemic effects from chronic ingestion of 1,1,1-TCA by rats established a NOAEL of 500,000 µg/kg/day. Using that information and assuming the inhalation and ingestion doses would be approximately equal, adverse noncancerous effects would not be expected.
Results from animal studies indicate that nicotine enhances the lethality of 1,1,1-TCA (Priestly and Plaa 1976), suggesting that simultaneous exposure to nicotine and 1,1,1-TCA could pose an increased health risk in people. Therefore, smokers exposed to 1,1,1-TCA could have an increased risk for adverse health effects compared with nonsmokers. Low doses of ethanol (found in alcoholic beverages) also tend to enhance the lethality of 1,1,1-TCA (Woolverton and Balster 1981), suggesting that increased health risks may be associated with simultaneous exposure to those two chemicals. Because of that, alcoholics exposed to 1,1,1-TCA could also have an increased risk for adverse health effects. Phenobarbital, which is prescribed for certain cases of epilepsy, reportedly enhances the hepatotoxicity of 1,1,1-TCA in rats (Carlson 1973). Thus, an increased risk of hepatotoxicity may be associated with simultaneous exposure to that drug and 1,1,1-TCA. Moreover, people who have cardiac arrhythmias also may be more susceptible to the health effects of 1,1,1-TCA (ATSDR 1990 ). Persons belonging the groups previously described and who also were exposed to 1,1,1-TCA in Rayon Park contaminated well water may have been more susceptible to the adverse health effects from 1,1,1-TCA exposure (Byers et al 1988, Lagakos et al 1986, Mallin 1990, Vinels 1990, Hong et al 1991, Hernberg et al 1988).
1,1,1-TCA is a synthetic chemical with many industrial and household uses. It is often used as a solvent to dissolve other substances, e.g., glue and paint. In industry, it is widely used to remove oil and/or grease from manufactured metal parts. It also may be in household products such as spot cleaners, glues, and aerosol sprays (ATSDR 1990). Residents of Rayon Park who were employed by those industries may have had additional exposures to 1,1,1-TCA other than exposures from their private well water.
Trichloroethylene (TCE)
Rayon Park residents were exposed to TCE when they ingested contaminated water from their private wells. Ingestion and inhalation of and dermal contact with the contaminated water were the routes of exposure. Dermal contact seems to be more significant as a route of exposure if large amounts are applied on the skin, which might happen in an occupational setting (ATSDR 1992c ). Therefore, dermal contact is not a significant route of exposure for Rayon Park residents who used contaminated wells for household uses.
Water samples collected from private drinking water wells near DGSC contained a maximum concentration of 5.2 ppb TCE. The estimated daily exposures of Rayon Park children and adults ingesting a concentration of 5.2 ppb TCE are 0.33 µg/kg/day and 0.15 µg/kg/day, respectively. The International Agency for Research on Cancer and EPA are evaluating TCE's carcinogenicity (ATSDR 1992c) because only one animal study has found TCE to cause cancer. However, EPA has classified TCE as a probable human carcinogen by oral and inhalation routes. However, exposures at Rayon Park are not expected to result in an increased cancer risk because of the infrequent, low levels of TCE detected in the Rayon Park wells. The duration of exposure is unknown.
ATSDR has derived an intermediate MRL of 100 µg/kg/day for ingestion of TCE. The estimated ingestion doses described previously do not exceed the MRL of 100 µg/kg/day. Therefore, adverse noncancerous health effects are not expected.
There currently are no health guidelines, such as an MRL or RfC, for people who have been exposed to TCE via inhalation. Reports in the literature indicate that estimated exposures from inhalation of volatilized TCE from activities, such as showering and cooking, is approximately equal to estimated ingestion exposures (Otto 1990 and McKone 1987). Thus, adverse noncancerous health effects are not expected because the ingestion dose of 0.33 µg/kg/day for children and 0.15 µg/kg/day for adults does not exceed the ATSDR intermediate MRL of 100 µg/kg/day.
Dermal contact with the concentrations of TCE found in Rayon Park well water is not expected to result in adverse health effects. The literature reports that skin irritations, burns, and rashes have been seen in workers with occupational exposure to TCE (Bauer and Rabens 1974 and Goh and Ng 1988). The dermal effects mentioned previously are usually the consequence of direct skin contact with concentrated solutions, and those levels are much higher than (100- to 10,000-fold) those detected in Rayon Park well water. Although adverse effects have not been reported from exposure to dilute aqueous solutions (ATSDR 1992c), those levels have not been measured.
Persons particularly susceptible to TCE exposures are chronic consumers of alcohol, people with heart disease, people taking disulfiram (a medication used to treat alcoholism), and people taking the anticoagulant warfarin (ATSDR 1992c). Those medications increase the toxicity of TCE in the liver by interfering with its normal metabolism. Thus, residents using Rayon Park contaminated wells and belonging to the above groups may have been more susceptible to the health effects from TCE exposure.
According to the literature, TCE exposure usually occurs in occupational settings where the chemical is used as a solvent to remove grease from metal parts (ATSDR 1992c). Products that may contain TCE are some types of typewriter correction fluids, paints and paint removers, glue, spot removers, rug-cleaning fluids, and metal cleaners (ATSDR 1992c). Thus, residents of Rayon Park who were employed by those industries may have had additional exposures to TCE other than those exposures from using contaminated water from private wells.
Summary
Some Rayon Park residents have been exposed to six different VOCs by way of ingestion and inhalation of and dermal contact with VOC-contaminated water from their private wells. Because of infrequent exposure to low levels of VOCs in those wells, adverse health effects are not expected. The actual duration of those past exposures is unknown, and the exposures stopped when contaminated wells were replaced with municipal water in 1987. No current exposure pathways are known to exist.
C. Health Outcome Data Evaluation
Health outcome data have been evaluated because past exposure has occurred to some compounds that are potential or probable carcinogens and because the community is concerned about possible health effects associated with using contaminated groundwater. County-level health outcome data were available for review. The knowledge of the duration of exposure together with site-specific health outcome data are necessary to determine possible adverse health effects from site-related exposures.
The Riggans Mortality Tapes, a database of cancer mortality maintained by the EPA and NCI, were reviewed. The database includes virtually all cancer death records for 1950-1979. The cancer mortality rates are reported by county for each of the three decades 1950-1959, 1960-1969, and 1970-1979. In addition, the percent change from 1950-59 to 1970-79 is included in the data. The death certificates data have been obtained from the National Center for Health Statistics and the Bureau of the Census. The cause of death is coded by the International Classification of Disease (ICD) codes. The information is provided for four sex-race groups: white male, white female, nonwhite male, and nonwhite female (U.S. EPA 1987).
The Riggans Mortality Tapes were obtained for Chesterfield County, Virginia, and the United States. Cancer mortality rates are not elevated for either white or nonwhite women in Chesterfield County. However, data from the years 1950 through 1979 did indicate elevated cancer mortality rates in white and nonwhite men in Chesterfield County for several types of cancers, associated with the oral cavity and respiratory tract. For example, in white men, the death rates for cancers of the oral cavity and tongue; esophagus; and trachea bronchus and lung pleura were consistently higher than the rates for Virginia. In nonwhite men, the death rates for cancers of the oral cavity and tongue; nose, nasal cavities and middle ear sinuses; and trachea bronchus and lung pleura were consistently higher than the rates for Virginia. The same type of pattern was observed in the cancer mortality rates for the state of Virginia. Cancer mortality rates for cancers associated with the oral cavity and respiratory tract were elevated for the state, when compared to the rates of the United States.
ATSDR cannot determine if the elevated cancer mortality rates in men are related to exposure to DGSC contaminants because site-specific health outcome data are not available for communities near DGSC. Based on medical literature, development of cancers associated with the oral cavity and respiratory tract have not been linked with exposure to the contaminants (VOCs) that were detected in the water of off-site private wells.
The Surgeon General's Office has determined that the vast majority of oral cavity and respiratory tract cancer since the 1950s is attributable to increased rates of cigarette use. Chewing tobacco and snuff are also hazardous and cause cancer in the oral cavity and upper gastrointestinal tract (Surgeon General Report 1982, Hoffmann et al 1983, Amdur et al 1991). Although there are elevated cancer mortality rates in men, no data are available on smoking and occupational status for communities near DGSC, and those factors may have contributed to the development of cancers observed in Chesterfield County men.
Before 1989, the Virginia Tumor Registry has relied on voluntary reporting. Mandatory reporting began in 1989, and a report is now being generated. That report may be useful in a future investigation. At this time, however, the available information is too limited to provide an adequate analysis of the data. If new information becomes available, those data will be reviewed for public health implications.
The Virginia Congenital Anomalies Reporting and Education System (VA CARES) was established in 1985, but actually began receiving reports in 1986. VA CARES receives reports on congenital anomalies in children from birth to two years of age who were discharged from any Virginia hospital after January 1, 1987. At this time, the VA CARES reporting system has data for 1987 only, and for that reason, the available information is too limited to provide an adequate analysis of the data. When new information becomes available, those data may be reviewed for their significance to public health.
D. Community Concerns Evaluation
The primary community health concern expressed by citizens or local public health agencies was about the health of people who used past contaminated private wells for drinking and other household uses. Other concerns were related to DGSC's management of the contamination and communication about activities conducted on the installation. This section evaluates the community concerns.
The private well contamination in the Rayon Park neighborhood, north and east of DGSC, resulted in past exposures for residents who used the water for drinking and other household purposes (Figure 4). Contaminants detected in private well water that exceeded health assessment comparison values were the following VOCs: benzene, 1,2-DCA, 1,1-DCE, PCE, 1,1,1-TCA, and TCE. The exact duration of the past exposures is not known; however, exposures stopped when most of the 21 residences were connected to the public water supply in 1987. Possible health effects associated with past use of contaminated water with multiple VOCs is unknown, largely because of the lack of data published on health effects stemming from chronic exposure to multiple contaminants. However, because of infrequent exposure to low levels of VOCs in those wells, adverse health effects are not expected.
Evaluation of the health outcome data from the years 1950 through 1979 indicated elevated cancer mortality rates for white and nonwhite men in Chesterfield County, but not in women. The Surgeon General's Office has determined that the vast majority of oral and respiratory tract cancer since the 1950s is attributable to increased rates of cigarette use. Chewing tobacco and snuff are also hazardous and cause cancer in the oral cavity and upper gastrointestinal tract (Surgeon General Report 1982, Hoffmann et al 1983, Amdur et al 1991). Since data are not available on smoking and occupational status for those exposed individuals, ATSDR cannot completely evaluate if those increased rates are related to contaminant exposure. However, the medical and scientific literature have not linked exposure to VOCs with development of cancers associated with the oral cavity and respiratory tract. Exposures to individual contaminants are discussed in the Public Health Implications section.
At least three private wells in the Rayon Park area, in which contamination has not been detected are still being used for drinking water and household uses. When the wells were tested in 1987 and found to be free of contamination, those property owners elected to continue using their wells. Those three wells, and possibly other private wells in the Kingsland Creek area, are still used for drinking water and household activities and are not regularly monitored. From recent sampling conducted in June 1992, it appears that private wells in the Kingsland Creek and Rayon Park area are currently free of contamination. A well survey conducted in October 1992 indicate that out of 108 survey responses, there are 16 private wells being used for potable purposes within a quarter mile off site of DGSC. Residents using those wells may be exposed to DGSC contaminants, if contaminant plumes are determined to migrate to the north, northeast, or south. Therefore, periodic identification and monitoring should be conducted, if sampling indicates that contaminant migration could potentially occur.
Remedial Investigations now have been completed for the Acid Neutralization Pit Area, the Fire Training Area, Area 50, the Open Storage Area, and the National Guard Area (Figure 3). An expanded site investigation has been completed for the Fuel Oil Storage Area and Buildings 202, 112, and 68. That report, also containing updated sampling for the RI sites, should be available for public review in mid May of 1993. An interim plan for remediation of groundwater east of the National Guard Area is being prepared and should be available for public review in late April of 1993. Those completed documents will become part of the administrative record, and results will be placed in a repository for public review.
This public health assessment discusses and evaluates health concerns expressed by the community and state and local officials. This document has been available for a public comment period during which anyone interested in the information could review it and comment on the contents. No comments from the public were received.
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