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PUBLIC HEALTH ASSESSMENT

STRASBURG LANDFILL
NEWLIN TOWNSHIP, CHESTER COUNTY, PENNSYLVANIA


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The tables in this section list the contaminants of concern. We evaluate those contaminants in the subsequent sections of the public health assessment and determine whether exposure to them has occurred and, if so, whether those exposures are of public health significance. PADOH selects and discusses contaminants of concern based upon several factors which include: (a) concentration of chemicals on-site and off-site, (b) on-site and off-site concentrations in relation to background concentrations, (c) comparison of on-site and off-site concentrations with public health assessment comparison values for carcinogenic and non-carcinogenic endpoints, and (d) community health concerns.

In the data tables which appear in the On-Site Contamination and Off-Site Contamination sections, the listed contaminant does not mean that it will cause adverse health effects from exposure. Instead, the list indicates which contaminants will be evaluated further in the public health assessment. When selected as a contaminant of concern in one medium, the contaminant will be reported in all media sampled.

Comparison values for public health assessments are contaminant concentrations in specific media that are used to select contaminants for further evaluation. Those values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant guidelines. EMEGs are based on minimum risk levels (considering only noncarcinogenic endpoints). An EMEG is expressed as the concentration of a specific chemical substance in a specific medium. The EMEGs, by themselves, are not used as predictors of safety or adverse health effects from exposure to environmental contamination. CREGs are estimated contaminant concentrations based on a one excess cancer in a million persons exposed over a lifetime. Maximum Contaminant Levels (MCLs) represent contaminant concentrations that EPA deems protective of public health over a lifetime (70 years) at an exposure rate of 2 liters of water per day. When establishing MCLs, EPA also must consider factors other than health, such a technical capabilities to achieve a concentration if a water supply is contaminated. The MCLs are enforceable levels. Proposed Maximum Contaminant Levels (PMCLs) are being proposed by EPA.

We conducted a search of the EPA Toxic Chemical Release Inventory (TRI) for the site and local area, but TRI did not list any facilities having chemical releases.

A. On-Site Contamination

Groundwater - Monitoring Wells

EPA's contractor (E&E, Inc.) sampled 11 monitoring wells in November 1990. Previous sampling rounds in April and September of 1990 were invalidated due to laboratory error (1). Figure 4 shows the locations of the wells sampled, and Table 1 reports the contaminants and maximum concentrations. Some VOCs detected in the monitoring wells exceed our comparison values (Table 1). Because of the scarcity and wide spacing (1,000+ feet) of monitoring wells, and the locations of contaminated wells, it is not altogether clear which wells represent upgradient and downgradient conditions. This is a significant data gap relating to the hydrogeologic characterization of the site. (See Recommendations section of this document.)

Table 1. Contaminant Concentrations in On-Site Groundwater
Monitoring Wells (1)

CONTAMINANT MAXIMUM
CONCENTRATION
PPB
COMPARISON VALUE
PPB SOURCE
Tetrachloroethene 19.5 5.0 MCL
Trichloroethene 15.5 5.0 MCL
Vinyl Chloride ND* 0.2 EMEG (C)
1,2-Dichloroethene 129.0 70 MCL
Benzene 7.2 1.2 CREG
* - In-field gas chromatography analysis in April 1990 indicated a concentration of 18.2 ppb in MW-31.
EMEG (C) - Environmental Media Evaluation Guide-Child
ND - Not Detected
PPB - Parts Per Billion
MCL - Maximum Contaminant Level
CREG - Cancer Risk Evaluation Guide

Soil

The EPA contractor sampled soil at five shallow well bore locations. The shallowest interval sampled was from 0-2 feet beneath the surface. All samples were non-detect for contaminants of concern. No information is provided for the 0-3 inch depth range where people are most likely to come in contact with contaminants. Also, the soil samples were taken at monitoring well locations which are removed from those areas of the site receiving the heaviest recreational traffic. Since all soil samples were non-detect, no table has been provided.

Sediment and Surface Water

EPA's contractor collected seven on-site sediment and surface water samples between February 26 and March 6, 1990. Figure 4 shows the locations of the sampling points, and Table 2 gives the results of that sampling. Since only one sediment sample was above detection for contaminants of concern (39 ppb 1,2-dichloroethene), sediment concentrations are not tabulated.

Table 2. Contaminant Concentrations in On-Site Surface Water (1)

CONTAMINANT SURFACE WATER
CONCENTRATION
(MAX.) PPB
COMPARISON VALUE
PPB SOURCE
Tetrachloroethene NS 5.0 MCL
Trichloroethene 5.5 5.0 MCL
Vinyl Chloride 19.0 0.2 EMEG (C)
1,2-Dichloroethene 55.4 70 MCL
Benzene 5.7 1.2 CREG
NS - Not Sampled

Soil Gas

Soil gas surveys were conducted in February and October of 1990 in two distinct areas: southeast of the landfill and around the landfill's perimeter. The purpose of those surveys was to determine areas where subsurface leachate migration has occurred. The average depth of the samples was approximately 2.25 feet. Table 3 shows the maximum soil gas values along with the flux box results. Three soil gas plumes have been identified; one on the west side (1:p-22), one on the south side (1:p-8), and one beneath the southeast grid.

Table 3. Maximum Contaminant Levels from Soil Gas Surveys and
Flux Box Soil Gas Effluent, Photovac Field Analysis (1)

CONTAMINANT SOIL GAS
CONC.
PPB
FLUX BOX
CONC.
PPB
COMPARISON VALUE
PPB SOURCE
Tetrachloroethene 740 567 9.0 EMEG
Trichloroethene 3,640 84 NA NA
Vinyl Chloride 10,900 129 2.0 EMEG
1,2-Dichloroethene NS 11,000 NA NA
Benzene 4,840 150 0.12 CREG
NA - Not Available

Ambient Air

The EPA contractor collected eleven ambient air samples on April 19, 1990, on and adjacent to the landfill. Figure 4 shows the sampling locations and Table 4 lists the maximum concentrations of target compounds. In addition to ambient air samples, flux box sampling was conducted over areas of exposed PVC cap. A maximum VOC concentration of 11,000 ppb of 1,2-dichloroethene was detected on the western slope at sampling point FB-7 (Table 3). Even though elevated concentrations of target contaminants were not detected during the ambient air survey, these data may not be representative of site conditions since the sampling was performed during a wet season. VOC emissions may, therefore, have been suppressed.

Table 4. Ambient Air (1)

CONTAMINANT MAXIMUM
CONCENTRATION
PPB
COMPARISON VALUE
PPB SOURCE
Tetrachloroethene 0.09 9.0 EMEG
Trichloroethene 0.14 NA NA
Vinyl Chloride 0.48 2.0 EMEG
1,2-Dichloroethene 0.64 NA NA
Benzene 0.25 0.03 CREG

B. Off-Site Contamination

Groundwater - Residential Wells

Table 5 lists the contaminants of concern and the maximum values which have been detected off-site since 1983. Beginning in January 1990, the EPA contractor sampled 18 off-site wells. Table 5 also lists the maximum values for contaminants of concern in 1990.

Since 1983, a total of five off-site residential wells have shown at least one of the contaminants of concern at or above MCLs, as well as other health comparison values (Figure 4). They are summarized (with ranges of maximum values in parentheses) as follows: two wells with 1,2-DCE (80-413.2 ppb); one well with vinyl chloride (4 ppb); three wells with TCE (6-42 ppb); and five wells with PCE (5-46 ppb). One well contained four contaminants of concern, including vinyl chloride, and another contained three.

In 1990, five wells contained PCE, one contained TCE, and one contained vinyl chloride - all at or above the respective MCL for each compound. Contaminant concentrations were obtained from all available sampling events, including PADER samples and the in-field gas chromatography analysis.

Table 5. Off-Site Groundwater Contamination (1)

CONTAMINANT MAXIMUM
CONCENTRATION
1983-1989
PPB
MAXIMUM
CONCENTRATION
1990
COMPARISON VALUE
PPB GC PPB SOURCE
Tetrachloroethene 46.0 5.0 27.0 5.0 MCL
Trichloroethene 42.0 6.7 4.0 5.0 MCL
Vinyl Chloride 4.0 3.7 1.7 0.2 EMEG (C)
1,2-Dichloroethene* 413.0 32.0 NS 70.0 MCL
Benzene 3.4 1.4 ND 1.2 CREG
*Assumed as CIS 1,2-dichloroethene, though not always specified in site documents.

Ten private wells were sampled in the Fall of 1992. Those data were not available for review. However, EPA verbally reported to ATSDR that no wells contained contaminants above the MCL. The two wells that have consistently demonstrated the presence of contaminants contained low levels (1 to 2 ppb) VOCs before filtration and none were detected in the treated water (12).

All other off-site media were non-detect for contaminants of concern; therefore, no table has been prepared for them. However, surface water contamination is known to have occurred as early as 1980. Eyewitness accounts of PADER officials, as communicated to PADOH, describe leachate runoff to Brian Run very early in the landfill's operational history. As reported in the Background section of this report, VOCs were detected in Briar Run in 1983, but it is uncertain where the samples were collected. PADER reported (oral communication, and references 10 and 11) that both sediment and leachate repeatedly escaped the containment facilities before the landfill was closed. However, quantitative data for the leachate and sediment are not available for evaluation of those reported releases.

C. Quality Assurance and Quality Control

In preparing this public health assessment, PADOH relies on the information provided in the referenced documents and assumes that adequate quality assurance and quality control measures were followed regarding chain-of-custody, laboratory procedures, and data processing. E&E follows EPA protocols in sample handling and analysis. All sample control and chain-of-custody procedures are presented in E&E's Laboratory and Field Personnel Chain-of-Custody Documentation and Quality Assurance/Quality Control Procedures Manual, July 1987. PADER's laboratory procedures are described in Appendix F of the Remedial Investigation (1). PADOH's analyses and conclusions in this public health assessment are valid only if the information listed in the bibliography is complete and reliable.

D. Physical and Other Hazards

There are numerous physical hazards on site including poorly covered (leachate) tank openings, steep slopes, dilapidated structures perforated with shotgun pellet holes, leachate seeps, and an open sedimentation pond. In February 1993, a fence was placed around these areas that restricts access to them.


PATHWAYS ANALYSIS

To determine whether nearby residents are exposed to contaminants migrating from the site, PADOH evaluates the environmental and human components that lead to human exposure. This pathway analysis consists of five elements: a source of contamination; transport through an environmental medium; a point of exposure; a route of human exposure; and an exposed population.

PADOH categorizes an exposure pathway as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. In a completed pathway, all of the five elements exist; human exposure to a contaminant has occurred in the past, is occurring, or will occur in the future. In a potential pathway, at least one of the five elements is missing, but could exist. Potential pathways indicate that human exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present.

A. Completed Exposure Pathways

Private Well Pathway

Off-site contamination is manifested primarily in the local groundwater flow regime, and evidence of residential well contamination has existed since 1983. Contaminants of concern have moved from the landfill in the groundwater flow system to at least five exposure points (wells), where approximately 15-20 local residents have been and are currently exposed to contaminants through inhalation, ingestion, and skin contact with the water they use. Four of those wells, including the most contaminated one, lie southwest of the site in a direction believed to be the major contaminant migration pathway. Future completed pathways will occur if residents drill new wells in the contaminant plume and use the water or if current treatment systems, which are on the two wells with the highest level of contamination, fail.

At present, the two most severely contaminated private wells are fitted with carbon filtration units; therefore, users of those wells are exposed to levels of contaminants less than the MCL. The owner of one contaminated, unfiltered well reports to use the well only for irrigation and car washing. The people who use that well for car washing and irrigation are exposed to contaminants through inhalation and dermal contact, but not through ingestion. Some residents who were interviewed use bottled water for drinking, but the extent to which other area residents use treated or bottled water has not been determined.

Limited groundwater data prevent determination of wells that may be impacted in the future. Monitoring wells are spaced much too widely (500 to 2,000 feet) to define groundwater flow and contaminant migration in fractured bedrock (1). More well nests are needed southwest of the site to characterize the groundwater vertically and horizontally (1). Also, additional wells are needed at, and northeast of, "background" well MW-5S. Contaminated background wells are common at hazardous waste sites in Pennsylvania, and usually indicate unknown contaminant sources or a misunderstanding of the hydrogeologic regime. MW-5S, for example, may be located along a preferential groundwater flow path controlled by nearly vertical northeast trending fractures. At least one well nest should be installed across Briar Run from the leachate collection area (1). Such wells could define the extent of plume migration, if it exists, toward water wells on Wheatland Drive and furnish information on groundwater quality should further residential development occur east of the site. The Remedial Investigation Report, Section 7, makes similar observations and provides recommendations on expanding the monitoring well network.

Surface Water Pathway

Leachate seeps, which appear as surface water, are present on the site. People are known to use the area for recreational purposes. An EPA official reported (oral communication) of at least one individual who stated that he was spattered by surface water (leachate) while recreating on the site. EPA reports that trespassing dropped noticeably following a public meeting where the dangers of trespassing were explained to those present and the information was reported in local newspapers. Additionally, a fence was installed in February 1993 to restrict access to the site (12). No estimate of how many people trespassed on the site can be provided. Contact with the leachate occurred as a result of hiking, riding ATVs or other vehicles, and riding horseback across the site. Also, people who worked on the site prior to the closure may have been exposed to contaminated leachate. Direct contact with contaminated surface water constitutes a completed exposure pathway through the routes of skin contact, inhalation and, possibly, incidental ingestion.

Ambient Air Pathway

People living near the landfill have complained of odors coming from the landfill, especially when the facility was in operation (2); observations made during the site visit confirm that the landfill cap has been breached. Air monitoring in 1990 identified the presence of very low concentrations of organic compounds. However, the field conditions at the time of sampling may have served to suppress contaminant levels. Flux box sampling at five points where the cap was believed to be breached confirmed that expectation. All five showed elevated levels of at least one contaminant of concern. Former landfill employees and people who trespassed on the site, especially those who were involved in activities that disrupt the cap, were exposed to VOCs through the inhalation route and, perhaps to a small degree, dermal contact with airborne contaminants. No estimate of the number of people who trespassed on the site can be provided.

People who reside near the landfill are also exposed to contaminants through inhalation; however, the concentrations of those contaminants are expected to be less than those on the site because of dispersion and dilution with ambient air. Exposures to nearby residents when the facility was in operation may have been to higher levels, but data are not available to evaluate past exposures. Current exposure of nearby residents cannot be determined from existing data, either. Exposure is assumed to have occurred because odors were reported. An estimated 20 homes with approximately 60 people live adjacent to the site. Those people would be expected to be exposed to slightly higher concentrations than the remaining 190-250 people residing within one-half mile of the site.

B. Potential Exposure Pathways

Surface Water Pathway

Untreated leachate from seep areas and treated leachate from the air stripper discharge to Briar Run. Recreational users of Briar Run and Brandywine Creek could be exposed to site contaminants by dermal contact, incidental ingestion of water, inhalation of VOCs, or consumption of fish, depending upon which activity is pursued (swimming, fishing). Potential exposures to contaminants in those water systems cannot be evaluated because of these data gaps: (a) off-site surface water contamination under varying runoff conditions, (b) number of persons exposed since the landfill opened, and (c) maximum contaminant levels while the landfill operated, especially during times when permit conditions were violated.

EPA is currently working toward obtaining a design to cap the areas where the leachate is contaminating these areas. Once the design is complete and a Record of Decision is signed and implemented, the potential for exposure through this pathway will be diminished or eliminated. The process may take at least one year (12).


PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

Introduction

In this section, we will discuss the health effects in persons exposed to specific contaminants. To evaluate health effects, either a Minimum Risk Level (MRL) for contaminants developed by ATSDR or Reference Dose (RfD) developed by EPA has been used. The MRL is an estimate of daily exposure to a contaminant below which noncancerous adverse health effects are unlikely to occur. The RfD is an estimate of daily exposure to the general public (including sensitive groups) that is likely to be without an appreciable risk of harmful effects during a lifetime exposure (chronic RfD) or exposure during a limited time interval (subchronic RfD).

Trichloroethene (TCE)

Exposure to TCE has occurred and is occurring to some residents through use of their private well water. The residents are exposed to TCE through ingestion of, inhalation of, and skin contact with the contaminated water. The maximum amount of TCE detected in a private well to date is 42 µg/L. That level has been reduced for the two most contaminated wells since the installation of the carbon filtration system in the fall of 1989. At the maximum level found in the wells, neither children nor adults are expected to be exposed to levels approaching the intermediate MRL for ingestion; therefore, that level of TCE detected in the residential well is not expected to cause any acute health effects through ingestion. However, long-term exposure to this chemical may pose a slight increase in the risk of developing cancer (3).

Former employees and people who trespassed on the site were exposed to TCE in the air and, possibly, through direct contact with surface water (leachate). Those exposures cannot be evaluated for possible health effects because no information is available on the frequency individuals are exposed and the duration of those exposures.

Animal studies have shown that ingesting or breathing levels of TCE that are much higher than levels detected in private wells near Strasburg and on the site can produce nervous system changes; liver and kidney damage; effects on the blood; tumors of the liver, kidney, lung, and male sex organs; and possibly cancer of the tissues that form the white blood cells (leukemia). Results of a few studies in pregnant animals exposed to TCE in air or in food showed effects on unborn animals or on newborns. At present, information is not sufficient to determine whether cancer or the effects on the unborn seen in animals following exposure to TCE may also occur in humans (3).

Occupational studies of workers exposed to TCE have not detected TCE-induced cancer, while several animal studies have shown that TCE can produce lung and liver cancer (3). Animal studies also have shown that TCE can cause leukemia, a cancer of the tissues that form white blood cells. In reviewing the animal studies, the Department of Health and Human Services (DHHS) National Toxicology Program could not find clear evidence that TCE causes cancer in animals (3). The International Agency for Research and Cancer (IRAC), an agency which classifies chemicals for their carcinogenicity, has decided that TCE is not classifiable as to human carcinogenicity. However, EPA classifies TCE as a probable human carcinogen based upon some animal studies. Even though there is uncertainty about the carcinogenicity of TCE in humans, it is a prudent public health measure that exposure to this chemical be reduced to the lowest level possible. For that reason, TCE contamination in private well water is a public health concern (3).

Certain populations that may be especially sensitive to TCE include chronic consumers of alcohol and persons with heart disease. Persons taking disulfiram, a medication used for the treatment of alcoholism, may also be at an increased health risk due to TCE exposure (3).

Tetrachloroethene (PCE)

Exposure to PCE has occurred and is occurring to some residents through use of their private well water. The residents are exposed to PCE through ingestion of, inhalation of, and, less importantly, skin contact with the contaminated water. The maximum level of PCE that has been identified in private wells is 46 µg/L. That level has been reduced in the two most contaminated wells since the installation of the carbon filtration system in the fall of 1989. Ingestion exposure to PCE does not exceed the chronic RfD of 0.01 mg/kg/day (10 ppb) for children or adults. There are no RfD or MRL values available for inhalation and skin contact exposure (4). However, studies that are available indicate that no acute adverse health effects are expected as a result of exposure to PCE in well water at the maximum level identified (4).

Former employees and people who trespassed on the site were exposed to PCE in the air and, possibly, through direct contact with surface water (leachate). Those exposures cannot be evaluated for possible health effects because no information is available on the frequency individuals are exposed and the duration of those exposures.

Studies of occupational workers, so far, have not linked PCE to cancer in humans. However, animal studies have shown that PCE causes cancer. The level of PCE exposure that was used in those animal studies was much higher than the level detected in private well water near the site. However, EPA classifies PCE as a probable human carcinogen because of animal studies (4). People exposed to the levels of PCE identified in the private wells may have a slight increased risk of developing cancer. For that reason, PCE found in private well water is a public health concern.

Some people are more sensitive to PCE than others. PCE can cross the placenta and has been found in breast milk; therefore, fetuses and nursing babies may be at an increased risk of adverse health effects when the mother has been exposed. In addition, workers in dry-cleaning and laundry facilities have an increased chance of exposure to PCE (4).

Vinyl Chloride

Exposure to vinyl chloride has occurred and is occurring to some residents through use of their private well water. The residents are exposed to vinyl chloride through ingestion of, inhalation of, and, less importantly, skin contact with the contaminated water. The maximum level detected in private wells is 4.0 µg/L. That level has been reduced in the two most contaminated wells since the installation of the carbon filtration system in the fall of 1989. The concentration of vinyl chloride detected in the well water exceeded EPA's MCL of 2 µg/L and would result in exposure exceeding ATSDR's chronic ingestion MRL for both adults and children. Although noncarcinogenic health effects have only been documented for exposures to higher levels of vinyl chloride than the maximum level detected, the possibility of noncancerous adverse health effects cannot be ruled out for long-term exposures. Studies designed to determine if the low levels of vinyl chloride measured in outside air, drinking water, or food would cause harmful effects in humans have not been performed (5).

Former employees and people who trespassed on the site were exposed to vinyl chloride in the air and, possibly, through direct contact with surface water (leachate). Those exposures cannot be evaluated for possible health effects because no information is available on the frequency individuals are exposed and the duration of those exposures.

The International Agency for Research on Cancer reported that there is sufficient evidence for the carcinogenicity of vinyl chloride in humans (5). Also, the National Toxicology Program of the Department of Health and Human Services reported that there is sufficient evidence for carcinogenicity of vinyl chloride in humans (5). Vinyl chloride has been associated with tumors of the liver, brain, lung, and hematolymphopoietic system. A large number of epidemiological studies and case reports have substantiated the causal association between exposure to vinyl chloride and angiosarcoma of the liver (liver cancer) (5). People who are exposed to vinyl chloride through use of their drinking water have a moderate increased risk of developing cancer if exposure continues. Therefore, vinyl chloride present in private wells is of public health concern, and any exposure to the compound should be eliminated.

Men and women who work in industries where vinyl chloride is produced may be at increased risk of adverse health effects if they are also exposed through their drinking water. Pregnant women and their fetuses may also be at increased risk of adverse effects if exposed to vinyl chloride (5).

1,2-Dichloroethene

Exposure to 1,2-dichloroethene has occurred and is occurring to some residents through use of their private well water. The residents are exposed to 1,2-dichloroethene through ingestion of, inhalation of, and skin contact with the contaminated water. The maximum level detected in private wells is 413.0 µg/L. There are two forms of 1,2-dichloroethene, cis and trans. Cis-1,2-dichloroethene is considered more toxic than trans. Information generated and reviewed for evaluation in this document did not always distinguish which form was present; therefore, all 1,2-dichloroethene is considered as cis for purposes of evaluation. The maximum level of the contaminant has been reduced in the two most contaminated wells since the installation of the carbon filtration system in the fall of 1989. The maximum level of this chemical detected in the residential well exceeds EPA's MCL of 70 µg/L. However, ingestion of the maximum amount would not exceed ATSDR's intermediate MRL for children or adults. The level of this chemical detected in the residential well is not expected to cause any adverse health noncancerous effects. The health effects resulting from long-term exposure to water and air containing specific levels of 1,2-dichloroethene are not known (6). Neither birth defects nor cancer have been reported in humans or animals exposed to 1,2-dichloroethene (6). Therefore, people who are exposed to the maximum level of the contaminant detected are not expected to have any increased risk of developing cancer. The contaminant found in the private well water is not of public health concern.

Former employees and people who trespassed on the site were exposed to 1,2-dichloroethene in the air and, possibly, through direct contact with surface water (leachate). Those exposures cannot be evaluated for possible health effects because no information is available on the frequency individuals are exposed and the duration of those exposures.

No sensitive populations have been identified. Animal studies suggest that people with liver, heart, or respiratory tract disease may be more sensitive. People with kidney disorders, infants, and the elderly may also be sensitive because of their lower rate of metabolism (6).

Benzene

Exposure to benzene has occurred and is occurring to some residents through use of their private well water. The residents are exposed to benzene through ingestion of, inhalation of, and, less importantly, skin contact with the contaminated water. The maximum level detected in private wells is 3.4 µg/L. The maximum level of the contaminant in the two most contaminated wells has been reduced since the installation of the carbon filtration system in the fall of 1989. The maximum level of benzene detected in the residential well does not exceed EPA's MCL of 5 µg/L. No MRL or RfD is available for benzene. From occupational studies, adverse noncancerous health effects appear to be associated with levels much higher than those found in private wells near the site. Therefore, exposure to the maximum level of benzene found in private wells is not expected to result in adverse noncancerous health effects (7).

Former employees and people who trespassed on the site were exposed to benzene in the air and, possibly, through direct contact with surface water (leachate). Those exposures cannot be evaluated for possible health effects because no information is available on the frequency individuals are exposed and the duration of those exposures.

Human health studies have demonstrated significant excesses of leukemia, multiple myeloma, and lymphatic cancers, as well as chromosomal aberrations to be associated with exposure to benzene (7). EPA has established a factor (oral slope factor) that can be used to calculate a person's risk of developing cancer if exposed to benzene over a lifetime (7). People exposed over a lifetime to the maximum level of benzene detected in private wells may have very little or no increased risk of developing cancer over a lifetime. Since any exposure to a known carcinogen is undesirable, exposures to the compound should be eliminated.

People identified as particularly sensitive to benzene exposure include pregnant women, their fetuses, and immunosuppressed and malnourished people (7). The elderly and children with declining or immature organ function may be more vulnerable to benzene and other toxic substances than healthy adults (7).

B. Health Outcome Data Evaluation

Only five residential wells, serving an estimated 15-20 people, have been identified as containing contaminants of public health concern. Health outcome data for such a small population is difficult to interpret. Additionally, no health concerns have been expressed by the community regarding illnesses. Since only a small number of persons are impacted by contaminated groundwater and no health-related community concerns have been identified, health outcome databases are not evaluated in this document.

C. Community Health Concerns Evaluation

    We have addressed the community concerns about health as follows:

  1. Are trespassers at risk of being exposed to site contaminants?

    As indicated in the Environmental Contamination and Other Hazards and the Pathways Analysis sections, on-site ambient air is contaminated with VOCs, and exposure to this air represents a likely completed exposure pathway for trespassers. Specifically, vinyl chloride and benzene, which are human carcinogens, were present in on-site ambient air at levels of 0.48 ppb and 0.25 ppb, respectively. Those levels of exposure may pose a potential health threat for trespassers on the site. Disruption of the landfill cover by trespassers will also increase the potential for human exposure to site contaminants. Therefore, people should not be on the site unless authorized.

  2. Could exposure to levels of contaminants present in any private residential well cause adverse health effects?

    As indicated in the Environmental Contamination and Other Hazards and the Pathways Analysis sections, off-site residential well water is contaminated with VOCs, and exposure to contaminants in the water occurred, and may still be occurring, for people who use that water. Some of the contaminants are present at levels of public health concern if filtration systems fail. Other contaminants, specifically vinyl chloride and benzene, are known human carcinogens. Although only a low risk of developing cancer exists from ingesting and inhaling those compounds over a lifetime, exposure to those chemicals should be eliminated if possible.

  3. Why am I no longer being notified of my water well sampling results?

    This seems to be an isolated case. The particular individual who expressed it was not at home during a follow-up visit by PADOH. Other residents stated that they regularly receive their water sampling reports. Possibly, the frequency of sampling has been reduced to once or twice yearly due to staff reductions at PADER. This could lead some individuals to assume they were missed in a quarterly sampling round. In general, both PADER and the EPA contract sampling team (the two agencies apparently alternate) appear to maintain adequate communication with area residents. The person who is not receiving that information should contact PADER to let them know if the explanations provided do not answer the question.


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