PUBLIC HEALTH ASSESSMENT
AVCO LYCOMING-WILLIAMSPORT DIVISION
WILLIAMSPORT, LYCOMING COUNTY, PENNSYLVANIA
The tables in this section list the contaminants of concern; however, their listing does not imply that a health threat exists. This public health assessment evaluates these contaminants in subsequent sections and determines whether exposure to them has public health significance. PADOH selected these contaminants based upon the following factors: on and off-site concentrations; field and laboratory data quality and sample design; comparison of site-related concentrations with background concentrations; and comparison of site-related concentrations with ATSDR health comparison values for carcinogenic and noncarcinogenic endpoints.
Comparison values for the public health assessment are contaminant concentrations in specific media that are used to select contaminants for further evaluation. These values included the Environmental Media Evaluation Guides (EMEGs). 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. In addition to health factors, an MCL is required by law to reflect the technological and economic feasibility of removing the contaminant from the water supply. EPA's Reference Dose (RfD) is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse health effects.
The U.S. EPA Toxic Chemical Release Inventory data base was 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, from industries within a one-mile radius of the AVCO Lycoming site, to identify possible facilities that could contribute to the groundwater and other media contamination near the site. No significant releases which would affect the quality of the groundwater or other media near the site were reported in the 1987, 1988, and 1989 data bases.
Since 1985, when VOCs were first identified in groundwater, numerous events have been completed including Chester's investigation and the regularly scheduled sampling. Two sampling events were completed for the current investigation. The data presented in this section was collected during the recent Remedial Investigation and reported in January 1991.
The data tables include the following acronyms:
|EMEG||- ATSDR Environmental Media Evaluation Guide|
|- EPA reference dose converted to a media specific comparison value|
|J||- Estimated Quantity|
|- EPA Maximum Contaminant Level|
|- Milligram per Kilogram|
|- Milligram per Liter|
|- Not Available|
|- Not Detected|
|- Parts per Million|
|- Reference Dose|
|ug/L||- Microgram per Liter|
Soil borings were drilled on-site in two phases of the field investigation (October 1989 and August 1990) in order to collect soil samples. All samples were subsurface composite samples from various depths of 1 foot or greater. Phase 1 soil sampling consisted of 20 boreholes and 20 samples from depths of 5 feet to 18 feet. Phase 2 soil samples consisted of 12 boreholes and 40 samples from varying depths of 1 foot to 13 feet (1). Table 1 indicates the maximum concentration of on-site subsurface soil and Figure 2 in the appendices indicates all soil boring locations.
|CONTAMINANT||mg/kg (PPM)||COMPARISON VALUE|
|Vinyl Chloride||ND||1||EMEG (C)|
Groundwater - Monitoring Wells
There are two primary aquifers in the study area, the overburden and the bedrock aquifer systems. The overburden is a water table aquifer system. Groundwater sampling, as part of the RI, was done in two phases. Phase 1 groundwater sampling was conducted in November 1989 and consisted of sampling all 52 monitoring wells present in the study area (on-site and off-site). Phase 2 groundwater sampling in August 1990 consisted of groundwater sample collections from 49 monitoring wells. Phase 2 included some new bedrock aquifer wells not sampled in Phase 1 (1). Figure 3 in the appendices indicates all monitoring well locations. Table 1 in the appendices provides well construction details for all monitoring wells.
|CONTAMINANT||mg/L (PPM)||COMPARISON VALUE|
|Vinyl Chloride||0.520||0.0002||EMEG (C)|
Groundwater - Supply Wells in the WMWA Well Field
Information was obtained from PADER's investigation of Textron
Lycoming for the December 1984 to May 1985 period relating to
contaminants found in the WMWA supply wells (5). This information
was not contained in the RI and was obtained through personal
conversation. The contaminants of concern for which laboratory
test results were obtained were trichloroethylene and 1,2-dichloroethylene. The sampling dates and maximum concentrations
for the wells tested are indicated below.
These wells were not in use in 1985 or 1986 pending the investigation and planned remediation. The wells are now remediated.
No residential samples were collected even though a residential well inventory was completed. It is believed that none of the 11 residential wells are being used and none are in the contamination plume (6). The next operable unit which will deal with additional off-site groundwater sampling will also evaluate the residential wells (6). Table 2 in the appendices indicates the findings of the well inventory.
Off-site groundwater monitoring well samples were done at the same time as the on-site monitoring well sampling. Two phases (November 1989 and August 1990) of sampling from both the overburden and the bedrock aquifers were completed (see on-site groundwater monitoring wells) (see Table 3). Figure 3 in the appendices indicates all monitoring well locations.
No off-site soil sampling was done during the RI.
The surface water drainage from the plant is controlled by storm sewers. Surface water runoff from the western half of the plant is diverted to the Oliver Street sewer which discharges to Lycoming Creek. The surface water runoff from the eastern half of the plant is diverted to storm sewers which discharge to Cemetery Run. Cemetery Run, south of Third Street, discharges to an open drainage swale which then discharges to the Susquehanna River. A single sample of surface water was collected in November 1990 from the storm sewer on the eastern side of the plant prior to the point of discharge of the plant sewer to the Cemetery Run storm sewer (see Table 3) (1). Figure 4 in the appendices indicates the sample location.
Surface water samples were collected from five locations along the eastern shore of the Lycoming Creek. Two samples were collected upstream from the Oliver Street storm sewer discharge point into Lycoming Creek. These samples were collected in November 1990 (see Table 3) (1). Figure 4 in the appendices indicates the Lycoming Creek sample locations.
|Vinyl Chloride||ND||ND||ND||0.0002||EMEG (C)|
As part of the Lycoming Creek investigation in November 1990, five sediment samples were collected from the same locations as the creek surface water were collected (see Table 4). Figure 4 in the appendices indicates the sediment sample locations.
|CONTAMINANT||mg/kg (PPM)||COMPARISON VALUE|
|Vinyl Chloride||ND||1||EMEG (C)|
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 reporting. The validity of the analyses and conclusions drawn for this public health assessment is determined by the completeness and reliability of the referenced information.
There are no known physical hazards associated with the site.
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 identifies exposure pathways as completed, potential, or eliminated. Completed pathways have all five elements exist and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. Potential pathways, however, have at least one of the five elements missing, but it 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. Eliminated pathways have at least one of the five elements missing and it will never be present.
A past completed exposure pathway exists from the use of contaminated wells from the WMWA well fields. This contamination was primarily in the form of TCE and DCE. These nine wells in two well fields provide an estimated 5-8 percent of the water for Williamsport City on an annual basis (6). In the PADER testing, one of the wells was found to have contamination of 250 ug/L of TCE and 88 ug/L of 1,2-dichloroethylene as maximum contaminant concentrations. The well was not in service at this time. It is not possible to precisely evaluate past risks from this site. However, the following factors: (1) some of the wells from the reserve source had much lower levels of contamination; (2) the contaminated water was merged with a much larger uncontaminated water source; and (3) duration of use was usually short (e.g., periods of drought) minimizing the likelihood of exposures that would have been of public health concern. The remediation of the reserve public supply wells eliminated this source of contamination.
A future completed exposure pathway is possible to off-site residents. Both TCE and DCE have migrated to off-site groundwater in residential areas. Currently, all residents are hooked to the public water supply that provides safe drinking water. However, future exposure by inhalation, ingestion, and skin contact is possible under hypothetical situations as described below.
There are two primary aquifers in the site area; the overburden and the bedrock aquifer systems. Presently, there are two on-site and one off-site recovery wells in the overburden and one on-site and one off-site recovery well in the bedrock aquifer. The overburden aquifer flows primarily southward, whereas, the bedrock aquifer flows primarily southwest.
Chromium contamination is limited to the vicinity of the old WWTP with the plume in the overburden aquifer migrating southward about 500 feet.
Vinyl chloride is basically only on-site in the overburden aquifer; however, future migration off-site may be possible. However, there is no evidence that this is happening.
TCE and DCE are the primary groundwater contaminants with somewhat similar off-site plumes. In the overburden, the plume extends primarily southward to Third Street (3,000 feet). In the bedrock aquifer, the plume extends more southwesterly. The bedrock aquifer concentrations in the off-site plumes are lower values than the overburden. The plume may extend beyond Lycoming Creek.
A future completed pathway would occur if a property owner would drill a private well into the off-site area of the contamination plume.
The on-site subsurface soil is contaminated by chromium to levels that may be of a health significance, particularly to the site workers in the past. Surface soil (top 3 inches) was not sampled and, therefore, data is not sufficient to develop a health statement and this exposure pathway would then be categorized as a potential pathway. Most of the chromium-contaminated soil is now paved over as part of the ongoing remediation at the site and essentially eliminates a current pathway.
During the RI, it was noted that 11 of the 35 wells within a three-mile radius of the site were identified as domestic supply wells. These wells were not tested because none are within the defined plume boundaries and none are currently in use (3). Until these wells are made inoperable, there is a potential exposure pathway if the plume migrates to an existing private well and the owner uses that well.
The ROD for Operable Unit #2 will further address off-site
groundwater and perform more off-site monitoring well testing and
some off-site residential well testing (6). The present
understanding is that no off-site residential well that was used in
the past was contaminated from the AVCO Lycoming site.
In this section, we discuss the health effects that may occur in persons exposed to site contaminants, evaluate the relevance of state health data bases to provide information for the Avco Lycoming site, and evaluate community health concerns.
As reported in the Environmental Contamination and Other Hazards section, the contaminants of concern are VOCs and chromium.
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 non-cancer adverse health effects are unlikely to occur. The RfD is an estimate of a daily exposure in milligram per kilogram per day (mg/kg/day) to the general public (including sensitive groups) that is likely to be without an appreciable risk of deleterious, noncarcinogenic effects during a lifetime exposure (Chronic RfD) or exposure during a limited time interval (Subchronic RfD).
This discussion is theoretically based on possible future exposures to off-site groundwater at the maximum contaminant levels found since there is no data to document any past exposures or at what level of exposure may have occurred, and because no current exposures are believed to be occurring.
Occupational studies of workers exposed to TCE (levels which are much higher than the levels found in the environment) have not detected TCE-induced cancer, while some animal studies have shown that TCE can produce lung and liver cancer (7). 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. The International Agency for Research on Cancer (IARC), an agency which classifies chemicals for their carcinogenicity, has decided that TCE is not classifiable as to human carcinogenicity. EPA, which also classifies the carcinogenicity of chemicals, classified TCE as a probable human carcinogen. However, EPA is currently reviewing the carcino-genicity of TCE. There is uncertainty prevailing among the scientific community with regard to the carcinogenicity of this chemical.
The nervous system is probably the most sensitive system that will show adverse health effects from chronic exposure to TCE (7).
There was past exposure to TCE from contaminated supply wells probably at low concentrations and greatly diluted when it entered the public supply. Also, the wells were only activated in periods of decreased water supply (e.g., drought) and this reserve quantity of water was mixed with an uncontaminated source of water before reaching a receptor population. No adverse health effects are expected to occur based on past exposure.
The human health effect of trans-1,2-dichloroethylene (DCE) is central nervous system depression. DCE, at high concentrations (much higher than encountered in the environment) possesses anesthetic properties. DCE is not a known carcinogen (8).
The level of DCE detected in off-site groundwater (0.98 ppm) is above the MCL of 0.100 ppm. An MCL is the maximum permissible level of a contaminant in water that is delivered to the free flowing outlet of the ultimate user of a public water system. MCLs are deemed protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day.
As with TCE, there has been no known past long exposure to DCE that would have adversely affected human health. Even if short-term exposure had occurred at the maximum value found in a monitoring well, it is unlikely that adverse health effects would occur.
The chromium exposure that could occur is by ingestion of the contaminated off-site groundwater. Using the highest concentration detected (0.102 mg/L), the ingestion exposure for children does exceed the oral RfD of 0.05 mg/L for chromium VI. The hexavalent chromium at high doses may cause adverse health effects; however, the current concentration in the groundwater is not likely to cause any adverse health effects (9).
The AVCO Lycoming site is located within the city limits of Williamsport in Lycoming County. Twenty years of all-cause mortality and cancer mortality (total cancer and eight cancer sites) were gathered and reviewed for the years 1970-1989 for Williamsport City (10). The 1979-1989 data was analyzed using age-sex specific three-year average cancer rates (1979-1981) for Pennsylvania as the standard (11). This analysis indicated that 75.2 cancer deaths would be expected annually in Williamsport City while an average of 78 cancer deaths were observed for the 1979-1989 period, a non-significant difference. The proportions of deaths to cancer as part of total mortality was 23.6 percent for Williamsport compared to 22.4 percent for Pennsylvania for the years 1979-1989 (10).
The Cancer Registry has only been in existence in Pennsylvania for a short period. Complete years of data are currently available for only 1985-1987. The reporting of data below the county level is not as accurate as in the mortality file which has been in existence for decades. An annual report is published on cancer incidence in Pennsylvania. This only reports to the county level. Data is collected by minor civil divisions (city, borough or township); however, the accuracy of reporting is suspect. Areas where diagnosis and health care are provided, such as cities, appear to be over-reported. Only a small portion of Williamsport City is in the environs of the AVCO Lycoming site. This subset of the city is not easily identified. In summary, this data base is limited in its usefulness for evaluating health outcomes to site exposures for the following reasons: (1) inaccuracies in residence reporting; (2) data is collected for Williamsport City and the small subset living near the plant is not easily defined; and (3) data has been collected for only a short period of time creating difficulty in drawing conclusions. Therefore, residents' questions concerning morbidity or mortality outcome cannot be definitely answered by conventional analysis and surveillance.
We have addressed each of the community concerns about health as follows:
- Has there been any risk from consuming the contaminated water?
Residents of Williamsport who are serviced by the Williamsport Municipal Water Authority may have been exposed to diluted low levels of primarily TCE and DCE from contaminated reserve wells in the WMWA well fields. These wells were only used as a resource supply and comprise an estimated 5 to 8 percent of the annual water use. This infrequent exposure is not likely to produce adverse health effects and the wells are now remediated.
It is believed that no families were exposed to contamination in their private wells by the AVCO Lycoming site. The off-site groundwater characterization will be fully addressed in the OU-2 investigation and forthcoming Record of Decision.
- Has there been any epidemiological evaluation of cancer rates
in the site area?
See Health Outcome Data Evaluation above.
Also, since no residents are currently being exposed to any site-related carcinogens and there is no data to document any exposure level in the past, it probably would not be of value to do any extensive epidemiologic health study of the area around the site.
A public comment period from February 25, 1993 to April 2, 1993 brought forth no additional comments.