PADOH selects and discusses contaminants of concern based upon several factors, including (a) concentrations of chemicals on site and off site; (b) comparison of on-site and off-site concentrations with health assessment comparison values for carcinogenic and noncarcinogenic end points; (c) community health concerns; and (d) quality of the field and laboratory data.
In the data tables in Appendix B under On-Site Contamination and Off-Site Contamination, the fact that a contaminant is listed does not mean that it will cause adverse health effects from exposure. Instead, the list indicates which contaminant will be evaluated further in the public health assessment. The potential for adverse health effects resulting from exposure to contaminants of concern is discussed in the Public Health Implications section of this document. 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 environmental media that are used to select contaminants for further evaluation. ATSDR and other agencies developed the values to provide guidelines for estimating the media concentrations of a contaminant that are unlikely to cause adverse health effects.
The selected contaminants of concern for the UGI site are the following: arsenic, benzene, B[a]P, ethylbenzene, naphthalene, and toluene. B[a]P is a member of a class of chemicals known as polycyclic aromatic hydrocarbons (PAHs). PAHs are a group of chemicals that are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances. They are found throughout the environment in the air, water, and soil. There are over one hundred different PAH compounds. Although the health effects of the individual PAHs are not exactly alike, several of the PAHs can cause harm to human health. Of the three PAHs found in excess of ATSDR's comparison values, B[a]P is the only one discussed in the Public Health Implications section. The other two, anthracene and pyrene, are discussed in the Eliminated Pathways section of this report.
The Toxic Chemical Release Inventory (TRI) data bases for the years 1987 through 1991 were accessed by PADOH through the National Library of Medicine's Toxicology Data Network and searched for estimated annual releases of toxic chemicals to the environment. Reports from industries within the same zip code as the UGI site (i.e., Columbia) were searched to identify possible facilities that could contribute to groundwater and other media contamination near the site.
In the 1990 and 1991 TRI data bases, one facility reported nonpoint air releases of 80,000 pounds and 81,000 pounds, respectively, of toluene. It is not felt that the reported releases have contributed to the contaminants associated with the UGI site. In the 1987 through 1989 TRI data bases, no reports of releases of contaminants of concern were found.
Waste Material in Pits
Visually identified tars were noted in the 1985 site investigation during test borings of the city gas and relief holder pits (1). The city gas holder had tars visibly identifiable between 7 and 27.2 feet below the surface. The relief holder had tars visibly identifiable between 4 and 31.5 feet below the surface. Appendix A, Figure 4, shows the location of test borings made in 1985 (1).
A sample was taken from a depth of 15 to 17 feet in the relief holder in 1985 and analyzed as a soil sample for a variety of coal tar-related compounds (1). The results of analyses of this sample shows that no contaminant of concern exceeds the comparison value for soil. In June 1993, a sample of sludge taken from the relief holder showed high levels of benzene. Appendix B, Table 1, summarizes maximum levels of contaminants found.
In 1991 and 1993, samples were taken from the demonstration wells in both holder pits and analyzed as aqueous samples. Appendix B, Table 2, shows the maximum concentrations of selected contaminants found in samples taken from the demonstration wells. The contaminants found include arsenic, benzene, B[a]P, ethylbenzene, naphthalene, and toluene. The results show that both holder pits are a source of coal tar-related compounds. The relief holder is of greater concern due to its history as both a tar separator and holding tank and the pit bottom's being essentially soil and bedrock, thus providing a direct route to fractures in the rock and, hence, groundwater. Leakage through the side walls of the holder pits is a factor in contamination of soil and groundwater. In 1985 tars were seen to be leaking through the side wall of the city gas holder pit into a test pit that had been excavated next to the exterior surface of the side wall (1).
Appendix B, Table 3, shows the maximum concentrations of contaminants found in on-site soils. Surface soil sampling was conducted, but the depths of sampling were not clearly defined. Arsenic and B[a]P are the major contaminants identified in this medium. Surface soil data (defined as 0-3 inches) are not available.
Groundwater - Monitoring Wells
Appendix B, Table 4, shows that on-site groundwater is contaminated with coal tar-related compounds, including arsenic, benzene, B[a]P, ethylbenzene, naphthalene, and toluene. All contaminants of concern exceed the comparison values used by PADOH to select contaminants for further evaluation. The concentration of benzene found in 1985, 300,000 µg/L, exceeds the comparison value of 1 µg/L by a factor of 300,000. Table 4 does not indicate the fact that the concentrations found in 1991 were about 15 times lower for benzene, toluene, and ethylbenzene than those concentrations found in 1985 (1, 4). Estimated concentrations of volatile organic compounds found in 1993 were lower than in 1991 (21). These results show that contaminants are not contained and are available for off-site migration.
Limited air sampling data exist; however, the air sampling data were obtained through the use of equipment that cannot identify specific chemicals. Therefore, no tables are provided for contaminants of concern in air.
Off-site soils have been found to be contaminated with coal tar-related compounds, in particular B[a]P. However, no data for surface soil (0-3 inches) are available. In 1985, test boring B-4, which was made across Front Street from the site (see Appendix A, Figure 4), contained measurable quantities of PAHs, indicating an area of direct tar waste disposal (1). This may be the location of the former open ditch that received tar separator overflows and might now be a source area of the tars reported to be actively migrating through the alluvial stratigraphy of the flood plain and entering river sediments. In 1991, subsurface soil samples were taken from the area across the street from the site. All three of the samples contained PAHs, with one of the samples containing significantly higher concentrations than the other two (4). Appendix B, Table 5, shows the results of analyses of these samples.
One item regarding arsenic should be noted. In one soil sample, S9, arsenic was found to be in excess of the comparison value. No depth of sampling was given, so it is not known if this sample was taken from surface soil (0-3 inches). Other metals in this sample were also higher than in other surface soil samples. Sample S9 was reportedly taken as a background sample northeast of the UGI site across the Conrail tracks (12). For that reason, this occurrence of arsenic is not considered site related.
Off-site groundwater is contaminated with benzene, ethylbenzene, naphthalene, and toluene. Appendix B, Table 6, shows the maximum groundwater contaminant concentrations found in monitoring well MW6D. These results strongly suggest the existence of a deep groundwater migration path of contaminants. Further discussion on this issue is presented in the Pathways Analyses section.
On August 16, 1988, NUS Corporation conducted a home well survey in the area and found two residences near the corner of Union and Front Street where drilled private wells were in use for domestic drinking water (19). On July 31, 1990, PP&L collected well water samples from three seasonal cottages approximately one quarter of a mile north of the site. No organic contaminants were detected in any of the samples (20).
Arsenic is found in excess of the comparison value in both MW5 and MW6S, but no coal tar-related compounds were found in these wells. Therefore, these occurrences of arsenic are not thought to be site related.
River sediments are contaminated with arsenic and B[a]P. In 1985 an area of coal tar was identified in river sediments (1). In 1987 the volume of these contaminated sediments was estimated to be 800 cubic yards. Furthermore, in 1987, the contamination found in the river was estimated to have been there for no more than 15 years. A source area of the tars was not identified. However, in 1987 tars reportedly were migrating in both the flood plain and the river (2). In 1991 the area of sediments was reported to have been covered with fill and could not be found (4). Maximum sediment contaminant concentrations are shown in Appendix B, Table 7. Appendix A, Figures 5 and 6, show the locations of sediment sampling (1, 4). The area of river affected is shown in Appendix A, Figure 4. This area of contamination may have resulted in part due to surface runoff of coal tar from the UGI site, but the exact nature of its deposition is uncertain.
Surface water runoff from the UGI site may have at one time been directed to ditches, swales, or even storm sewer pipes that no longer are apparent and that probably served as a direct surface water pathway to the Susquehanna River. When the UGI site was actively producing water gas, the surface drainage features undoubtedly served to convey tar separator overflows to the Susquehanna River.
Surface water in the Susquehanna River showed some low level contamination with benzene just downstream from the area of sediments identified as being contaminated with tars. Appendix B, Table 8, shows the maximum level of contamination found in surface water samples. Appendix A, Figures 5 and 6, show the locations of surface water sampling (1, 4).
In preparing this public health assessment, ATSDR relies on the information provided in the referenced documents. We assume that adequate quality assurance and quality control measures were followed regarding chain-of-custody, laboratory procedures, and data reporting. The analyses, conclusions, and recommendations in this public health assessment are valid only if the referenced documents are complete and reliable.
An analytical review of chemical analyses results was provided for the samples taken in 1993. All aromatic volatile compounds (benzene, toluene, ethylbenzene, and total xylenes) should be considered approximate because hold times were exceeded (21). Summaries of inorganic and organic laboratory data validation were provided for the samples taken in 1991 (4). These summaries state that no major problems were found in the analyses of contaminants of concern. However, no formal summary of quality assurance or quality control was located for the samples taken in 1985 (1).
No obvious physical or other hazards are present. Security fencing around the site effectively restricts access to the site.
To determine whether nearby residents are exposed to contaminants migrating from the site, PADOH evaluated the environmental and human components that lead to human exposure. An exposure pathway consists of five elements: (a) a source of contamination; (b) an environmental medium in which the contaminants may be present or may migrate, for example, groundwater; (c) points of human exposure, such as well water; (d) routes of exposure, such as inhalation, ingestion, or dermal absorption; and (e) a receptor population, for example, people who drink contaminated water from private wells. Tables 9, 10, 11, and 12 describe exposure pathways at the UGI site are included in Appendix B.
PADOH and ATSDR identify exposure pathways as completed, potential, or eliminated. In completed exposure pathways, the five elements exist, and so exposure has occurred, is occurring, or will occur. In potential exposure pathways, however, at least one of the five elements is missing, but could exist. Potential pathways indicate that 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.
As previously discussed, the tunnel under the railroad tracks at the site was closed to pedestrian traffic, and tars removed from the relief holder pit were placed in the tunnel. At some unspecified time prior to the 1987 recovery of the pedestrian tunnel, an employee entered the tunnel and attempted to walk atop the coal tar that was contained therein. The surface of the coal tar was encrusted from exposure to the air but was not strong enough to withstand the employee's weight, and he sank into the tars up to his knees (7). Others were not likely exposed to contaminants to this extent, but could have come into direct skin contact with contaminants when entering the tunnel or when taking part in grading activities. The 1987 remediation of the tunnel eliminated the source, thereby eliminating the exposure pathway.
Employee exposure to volatile coal tar compounds in the air on site occurred prior to the 1987 remediation. While no accurate figures are available, fewer than 50 people are estimated to have been exposed through inhaling the compounds. "Strong tar odors" coming from the tunnel were noticed by employees at the UGI site, especially during the hot summer months (6). The practice of spreading spent purifier chips around the site underscores this assumption.
Air sampling data prior to 1985 are not known to exist. Following remediation, coal tar pitch volatiles, and naphthalene were not detected in or around the tunnel (11). Limited air sampling data exist and show that, following the 1987 remediation of tars in the pedestrian tunnel, on-site contamination of air does not pose a current problem (3). However, future remediation of the holder pits, soils, and sediments may expose tars to the atmosphere and could lead to the release of coal tar-related compounds to the air. By following a USEPA approved health and safety plan, human exposure during remediation efforts is expected to be minimal.
The principal potential exposure pathways are off site. Appendix B, Table 11, shows that the pathways involve the following environmental media: groundwater, river sediments, river surface water (recreational contact), fish, and river surface water (public water supply). No data are available for surface soil (i.e., 0-3 inches). The estimated number of people that could be affected by potential exposure pathways are shown in Appendix B, Table 12.
Contaminants of concern (i.e., benzene, ethylbenzene, naphthalene, and toluene) have migrated from the UGI site through groundwater westward along the axis of the Columbia Syncline (a complex geologic feature resembling a trough or a fold in the Earth's crust) to the Susquehanna River. See Appendix A, Figure 7. At monitoring well nest 6, which is about 1,000 feet west of the UGI site next to the Susquehanna River, the deeper well (MW6D, 65 feet deep) contains site-related contaminants, but the shallow well (MW6S, 35 feet deep) does not. If the river is 10 feet deep at this point, then MW6D is screened about 47 feet below river bottom. With only a slight upward flow component (suggested by water levels at 6D and 6S), it is possible that any groundwater discharge of contaminants to the river takes place far off shore near the channel center.
This could explain why no site-related contaminants have been detected at the Lancaster City water intake approximately 100 feet from the eastern riverbank. This position is about 900 feet west-southwest of the UGI site. Mixing of contaminated groundwater with surface water and volatilization of contaminants could also explain the absence of those contaminants from the public water supply intake.
There are no known private or public water supply wells withdrawing water from the zone of groundwater contamination beneath and downgradient of the site. Hence, no known exposure to contaminated groundwater through wells is occurring. However, as previously mentioned, there are at least two uncontaminated private wells in use near the corner of Union and Front Streets (19), or about 600 feet west of MW6D. This position would place the wells about 400 feet north of the predicted position of the plume of contamination.
Because of the positions of these sources of water supplies with respect to the axis of the Columbia Syncline, the principal migration path of groundwater contaminants presents a remote or a very low potential for exposure.
Sediments in the Susquehanna River near the UGI site were found to contain coal tar in 1985 (1). This area of sediments was more fully defined in 1987 (2). The source of the coal tar is most likely the UGI site. Since 1987 the area has become less well defined, but it is still of concern as it represents a potential exposure pathway to arsenic and B[a]P and serves as a source area for contamination of surface water. The river depth at this point varies somewhat with flow, but at times it is shallow enough for people who wade in the area to come into contact with contaminated sediments. Recreational users, such as children or adults who wade in the river without hip boots, are potentially exposed to contaminated sediments.
Surface Water - Recreational
A small amount of benzene was found in surface water downstream from the area of contaminated sediments. It is possible that this is arising from the coal tar in the sediments. A remote possibility exists that recreational users of the river might ingest some of this contaminated water.
In the past, individuals who used the Susquehanna River downstream from the UGI site may have been exposed to coal tar discharges to surface waters that occurred from the tar separator (1). Historical records show that when the plant was in operation complaints were received from local fishermen whose boats were being coated with tar (2). However, no data to quantify these possible exposures have been found.
Surface Water - Public Water Supply
The nearest downstream public water supply intake is over three miles away and is not affected by site-related contamination because of the enormous dilution factor. The upstream public water supply intakes are nearer to the site and to possible discharges of contaminated groundwater into the river channel. A remote possibility exists that contaminants of concern could enter the Lancaster City water intake or the Columbia Water Company intake, which is about 3,000 feet west-northwest of the UGI site. Even if this were to occur, dilution could reduce contaminant levels to below analytical detection limits, and treatment processes for the drinking water could further reduce contaminant levels to extremely low levels.
None of the specific public water suppliers discussed above routinely analyzes the raw water for contaminants of concern. Both analyze the finished water for volatile organic compounds, and none have ever reported having detected contaminants of concern in their respective supplies (22). Because of the dilution factor and monitoring procedures that would warn the water suppliers of contamination, exposure to contaminants through use of the public water supplies at levels greater than those that can be detected are unlikely.
Fish in the river may be exposed to contaminated sediments and introduce contaminants of concern into the aquatic food chain. Naphthalene and toluene exhibit moderate tendencies to bioconcentrate in the fatty tissues of aquatic animals (17, 18). Fish in the river might conceivably be exposed to small amounts of benzene, also, but biomagnification of benzene in aquatic food chains does not appear to be important (14). No studies were found to indicate that fish were sampled and analyzed for contaminants of concern. People who consume fish from the river would be the exposed population. It is not known exactly how much fishing occurs here, but the Susquehanna River is a very popular warm water fishery.
Information on surface soil (0-3 inches) contamination both on site and off site has not been provided. This information is needed to determine if human contact with contaminated surface soil has public health implications associated with it. On-site soil contamination was found in subsurface soils but does not present a point of exposure to people on site. If future remediation efforts involve excavating contaminated subsurface soils, we anticipate that USEPA and PADER will take necessary precautions to prevent or limit exposures.
Subsurface soil contamination that may have been caused by disposing of spent purifier chips on site, spills, or overflows of the tar separator represents a source area. Contaminants may leach out of the chips and/or soil and travel in solution or otherwise into groundwater, which may then migrate off site. The recent grading of the vacant land across the street from the site shows the possibility that subsurface contaminants could be exposed to the surface; however, no data are available to evaluate that possibility. Therefore, exposure pathways involving these media are not discussed further in this report.
C. Eliminated Exposure Pathways
Aside from the exposure pathways discussed under Completed Exposure Pathways for areas on site, additional on-site potential exposure pathways have either been eliminated during past remediation or eliminated by assuming that USEPA and PADER will institute control measures to prevent one or more elements of the exposure pathway from existing in future remediation efforts.
Exposure to on-site groundwater contamination is not likely to occur because there are no on-site private wells drilled into the plume of contaminants. Although the PAH contaminants anthracene and pyrene, which were found in excess of the comparison values on site but not in off-site groundwater, are present in on-site groundwater, no drinking water or supply water wells are expected to be drilled on the site because the building formerly used as a boat business has a public water supply for use by employees and visitors.
In this section, we will discuss potential health effects that may result from exposure to environmental contaminants, available health outcome data, and community health concerns. The Toxicologic Evaluation section provides information on the noncarcinogenic and carcinogenic effects of exposure to contaminants that are above comparison values. The Health Outcome Data Evaluation section contains an evaluation of available community health information to determine whether adverse health effects have occurred. The Community Health Concerns Evaluation section contains a discussion on public health concerns voiced by the community about possible exposure to contaminants relative to documented exposures and potential health effects.
A. Toxicological Evaluation
In this section, PADOH discusses health effects that could result from exposure to site-related contaminants. To determine the possible health effects of specific chemicals, PADOH researches scientific literature. To evaluate health effects, ATSDR's minimal risk level (MRL), USEPA's reference dose (RfD), and USEPA's Cancer Slope Factor (CSF) have been used. When RfDs 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 below which no adverse health effects (noncancerous) are expected. The MRL is an estimate of daily exposure to a contaminant below which noncancerous adverse health effects are unlikely to occur. The chronic RfD is an estimate of a daily exposure (mg/kg/day) to the general public (including sensitive groups), which is likely to be without an appreciable risk of noncancerous harmful effects during a lifetime exposure (70 years). CSFs are usually derived from animal or occupational studies and are used to calculate the exposure dose likely to result in one excess cancer per million people exposed over a lifetime (70 years).
The primary public health issues of the UGI site concern the uncontrolled release of the site-related contaminants arsenic, benzene, B[a]P, ethylbenzene, naphthalene, and toluene into the groundwater and the Susquehanna River through discharge in solution in groundwater, and the presence of them in Susquehanna River sediments. Concerns of potential exposures through ingestion, dermal contact, and possibly inhalation under some circumstances (private wells or riverine recreation activities) as discussed under the Pathways Analyses section, must be considered.
There is a very low potential that exposure to arsenic has occurred, is occurring, or will occur through sediment contact by recreational users of the river in the area where tars were found in sediments. Ingestion of arsenic-contaminated sediments is the most likely route of exposure. Also, an extremely low potential exists that exposure to arsenic has occurred, is occurring, or will occur through people consuming bottom-feeding fish that have ingested contaminated sediments or other organisms that ingested arsenic. An important fact to bear in mind is that much of the arsenic present in fish and shellfish is naturally occurring in an organic form that is essentially nontoxic (13). On direct contact with small amounts of arsenic such as those in sediments, little is expected to go through the skin, so dermal contact in this case is not of health concern (13).
For noncancerous effects, ATSDR has developed a chronic oral MRL of 0.0003 mg/kg/day for arsenic (13). If a person were to ingest arsenic-contaminated sediments at the highest level detected (i.e., 10 mg/kg), noncancerous health effects are not likely to occur because an estimated exposure dose is lower than the MRL.
Arsenic is classified as a human carcinogen by USEPA and the National Toxicology Program (NTP) of the U.S. Department of Health and Human Services (13). People are not likely to ingest contaminated sediments on a regular basis. If people were to be orally exposed to arsenic at a level of 10 mg/kg, for example, for two days per week, then there would be no apparent increased risk of developing cancer.
One background soil sample, S9, contained arsenic at a level of 12.9 mg/kg. This occurrence is not considered site-related. Also, the depth of the soil sample was not given. Because surface soil (0-3 inches--depth at which people normally come into contact with soil) data are not available, an exposure assessment cannot be made.
One off-site monitoring well sample, MW5, contained an arsenic level of 16.4 µg/L. This occurrence is not considered site-related. Also, no exposure pathway exists because people do not drink or use the monitoring well water for other purposes.
There is a low potential that exposure to benzene could occur through groundwater use by residents in the cottages along Front Street. There is a low potential that exposure to benzene has occurred, is occurring, or will occur through surface water contact by recreational users of the river. Groundwater use for domestic purposes by residents who have private wells could lead to ingestion, inhalation, or dermal absorption of benzene. Surface water contact by recreational users of the river could lead to ingestion or dermal contact with benzene-contaminated surface water downstream from the area of contaminated sediments.
In humans, noncancerous health effects that may result from eating or drinking foods containing lower levels of benzene are not known (14). However, studies in animals revealed decreases in number of erythrocytes, leukocytes, and lymphocytes following exposure to benzene. For example, mice exposed to low levels of benzene in drinking water for 4 weeks had a decreased number of erythrocytes and lymphocytes (14). For noncancerous effects, ATSDR has not developed an MRL from the known animal and human toxicity studies of oral exposure to benzene because the data were insufficient. Also, USEPA has not developed an RfD; therefore, no guidance on the safe levels of oral exposure to benzene are available to evaluate low-level exposure (14).
Benzene is classified as a human carcinogen by USEPA (14), NTP, and the International Agency for Research on Cancer (IARC), and a CSF has been developed to help evaluate exposures. If recreational users of the river ingest or come into dermal contact with surface water contaminated with benzene at a level of 20 µg/L, they are not subject to a significant cancer risk.
A large data gap exists with respect to past on-site exposure of employees to benzene. The toxicologic effects of on-site airborne exposure to benzene cannot be accurately evaluated because of the lack of air sampling data. Long-term exposure to relatively high levels of benzene in the air can cause cancer of the blood. This condition is called leukemia.
A very low potential exists that exposure to B[a]P has occurred, is occurring, or will occur through sediment contact by recreational users of the river in the area where tars were found in sediments. Ingestion of B[a]P-contaminated sediments is the most likely route of exposure. Although B[a]P does not normally enter the body through the skin, small amounts could enter if contact occurs with sediment that contains high levels of B[a]P or if contact is made with heavy oils containing B[a]P (15). An extremely low potential exists that exposure to B[a]P has occurred, is occurring, or will occur through ingestion of fish that have accumulated B[a]P from sediments or from bottom-feeding organisms.
In humans, noncancerous health effects that may result from eating or drinking foods containing low levels of B[a]P are not known (15). ATSDR has not developed an MRL from the known animal and human toxicity studies of oral exposure to B[a]P because the data were insufficient. Also, USEPA has not developed an RfD (15). Therefore, no MRLs or RfDs are available to provide guidance on the safe level of oral exposure to B[a]P.
B[a]P is classified as a probable human carcinogen by USEPA, NTP, and IARC (15). If recreational users of the river ingest sediments contaminated with B[a]P at a level of 8.3 mg/kg, they are not subject to an apparent increased cancer risk if the exposure frequency is two days per week.
A large data gap exists with respect to past on-site exposure of employees to B[a]P. The toxicologic effects of on-site airborne exposure to B[a]P cannot be accurately evaluated because of the lack of air sampling data.
A very low potential exists that exposure to ethylbenzene could occur through groundwater use by residents in the cottages along Front Street. Groundwater use for drinking water by residents who have private wells could lead to ingestion, inhalation, or dermal absorption of ethylbenzene. An extremely remote possibility exists that exposure to ethylbenzene has occurred, is occurring, or will occur through surface water use by customers of the Lancaster City Water Department; dilution and treatment would probably reduce levels to below detection limits. Surface water used for drinking water by these customers could lead to ingestion, inhalation, or dermal absorption of undetectable amounts of ethylbenzene.
In humans, health effects that may result from eating or drinking foods containing lower levels of ethylbenzene are not known (16). For noncancerous effects, USEPA has developed an RfD of 0.1 mg/kg/day for ethylbenzene, based on animal studies that demonstrate changes in the livers and kidneys of animals orally exposed to ethylbenzene (16). If children were to be exposed to ethylbenzene at the highest level found in off-site groundwater, then some of those children may experience noncancerous adverse health effects because the RfD would be exceeded by a factor of about two.
A very low potential exists that exposure to naphthalene could occur through groundwater use by residents in the cottages along Front Street. Groundwater use for drinking water by residents who have private wells could lead to ingestion, inhalation, or dermal absorption of naphthalene.
In most humans, health effects that may result from eating or drinking foods containing lower levels of naphthalene are not known (17). For noncancerous effects, ATSDR has not developed an MRL from the known animal and human toxicity studies of oral exposure to naphthalene because the data were insufficient. Also, USEPA has not developed an RfD (17). Therefore, no MRLs or RfDs are available to provide guidance on the safe level of oral exposure to naphthalene.
From animal studies where an intermediate LOAEL of 133 mg/kg/day was found, noncancerous adverse health effects in humans would not be expected to occur following exposure to the highest level of naphthalene found in off-site groundwater (17). This is because the child dose would be less than the LOAEL by three orders of magnitude.
A very low potential exists that exposure to toluene could occur through groundwater use by residents in the cottages along Front Street. Groundwater use for drinking water by residents who have private wells could lead to ingestion, inhalation, or dermal absorption of toluene.
Long-term exposure to low and moderate amounts of toluene has caused slight effects on the kidneys in some people, but these people were also exposed to other solvents at the same time, and it is difficult to tell which chemical may have caused the effects (18). For noncancerous effects, USEPA has developed an RfD of 0.2 mg/kg/day for toluene based on animal studies that demonstrate changes in the weights of livers and kidneys of animals orally exposed to toluene (18). If children were to be exposed to toluene at the highest level found in off-site groundwater, then some of those children may experience noncancerous adverse health effects because the RfD would be exceeded slightly.
No community health concerns were voiced relating to the UGI site. There are several private residences in the area that use private water wells for drinking water (19). Available water quality data for these wells show that no volatile organic chemical contamination is present. The population in the area where the wells are located is most likely seasonal and the population is less than 50 people. The perceived small number of people who use the cottages, and the fact that their permanent places of residence are unknown (possibly from diverse geographic areas), made a search of vital records impractical. On-site occupational exposure to coal tar most likely occurred, but exposure data are inadequate to evaluate. No other completed exposure pathways were identified that could adversely affect public health. Therefore, no health outcome data bases were evaluated.
No organized or ad hoc groups with concerns about community health have been identified. Contact was made with USEPA, PADER, and local government officials to determine if they knew of any concerns. In all cases there were no known concerns.
The following discussion addresses the one community health concern that has been identified:
- Can exposure to coal tar vapors cause a skin rash?
Although skin irritation can occur by exposure to coal tar, this would generally be found by direct contact with the tar rather than from vapors.