UNITED TECHNOLOGIES/HAMILTON STANDARD CONTROLS FACILITY
(a/k/a UNITED TECHNOLOGIES/FORMER HAMILTON STANDARD CONTROLS FACILITY)
LEXINGTON, RICHLAND COUNTY, OHIO
The Chronic and Environmental Disease Surveillance Section (Bureau of Health Surveillance, Information, and Operation Support, Ohio Department of Health) was contacted May 23, 2000 by representatives of the Ohio Environmental Protection Agency (Ohio EPA) with concerns about a perceived cancer cluster among residents living in the vicinity of the former United Technologies/Hamilton Standard Controls facility (HSC) in the village of Lexington, Richland County, Ohio. These concerns were voiced at an Ohio EPA public meeting held in Lexington May 18, 2000. Several residents linked these cancers to the presence of an extensive plume of groundwater contamination whose source has been identified by Ohio EPA as the former HSC manufacturing facility.
Chronic & Environmental Disease Surveillance (CEDS) contacted the Health Assessment Section (HAS) with regard to this site May 24, 2000, requesting 1) a description and brief history of the former facility, 2) a discussion of the toxicology of the potential cancer-causing chemicals associated with the site, and 3) an assessment of the public health threat that the site might pose to residents living in the vicinity of the former facility.
HAS staff contacted the Northwest District Office of Ohio EPA in May and discussed the site and the associated environmental contamination with the site's On-Scene Coordinator. HAS received copies of the Remedial Investigation Report prepared for the site by consultants representing the site owners (AVANT 1999A). This report, a site fact sheet (Ohio EPA 2000), and additional sampling data provided to HAS by Ohio EPA provides the basis for HAS to evaluate whether there is a public health hazard associated with contamination at the HSC facility.
The former Hamilton Standard Controls facility was built in 1954 on the edge of the flood plain of the Clear Fork of the Mohican River at the northern edge of the village of Lexington (Figure 1). It was used until 1995 for the manufacture of electrical switches and controls. As part of the manufacturing process, chlorinated solvents, primarily tetrachloroethene (PCE ) and trichloroethene (TCE) were used to degrease metal parts and then were released to the soils and groundwater underlying the site. Both of these chemicals are volatile organic compounds (VOCs) that will readily vaporize upon exposure to air, but which also can be washed from soils into the groundwater where they can be quite mobile.
The facility, at 147 Plymouth Street, is surrounded on the north, west, and south by high-density residential neighborhoods and on the east by the Clear Fork flood plain. At least 21 residential homes are located within 100 feet of the facility property line (AVANT 1999A). Several other commercial facilities are located on the flood plain directly east of the HSC facility. A public park and the village's municipal well field are located roughly 500 feet northwest of the HSC property line (Figure 2).
The Clear Fork of the Mohican River in the vicinity of the site has been determined by Ohio EPA's Division of Surface Water to be in full attainment of its Warm-Water Habitat classification (Ohio EPA 2000). The Clear Fork has been designated by the state of Ohio as a "state resource water." As such it is suitable as an agricultural and industrial water supply, and safe for full body contact as a "primary contact recreational water."
Groundwater Supplies in the Vicinity of the Site
The area in the vicinity of the site is underlain by a buried bedrock valley paralleling the current Clear Fork River and filled with unconsolidated glacial sand, gravel, and clay-rich tills from 40 to 180 feet thick that overlie sandstone and siltstone bedrock. The bedrock surface slopes from the west under the site downward to the northeast and east with the axis of the buried valley running just west of the current channel of the Clear Fork so that the glacial valley fill is thickest east of the former facility (AVANT 1999A). The ground surface is underlain by a thin veneer (5-20 feet thick) of fill and/or silty clay. This is followed by water-bearing sand and gravel up to 170 feet thick. The water table is 20 to 25 feet below the ground surface under the HSC property, but shallows upward to the east, coming to the surface and discharging to the Clear Fork of the Mohican River roughly 1,000 feet east of the HSC location (AVANT 1999A Figures 4-5).
Groundwater flow in the vicinity of the site is to the east toward the Clear Fork River. Groundwater flow in the flood plain northeast of the HSC property and in the vicinity of the village well field appears to be to the south, following the trend of the axis of the buried valley and the current course of the Clear Fork (AVANT 1999A, Figure 13). The village of Lexington (pop. 4,124) currently obtains its water supply from wells No. 5 and No. 6 that pump only intermittently. Well No. 5 is 15-inches in diameter and 96 feet in depth, screened along the interval from 71 to 96 feet below the ground surface (bgs). Well No. 6 has a 16-inch diameter and is 91 feet in depth, screened along the interval from 71-91 feet bgs. Well No. 5 typically has yields of 670 gallons per minute (gpm) and Well #6 typically pumps at an average rate of 650 gpm. Each well pumps an average of 10 hours per day across a five-day cycle. Four other wells have been operated by the village in the past. Wells No. 1 and No. 2, 140 and 90 feet in depth respectively, and located 350 feet east of the HSC facility, operated from the late 1940's until 1970 when they were taken out of service due to a loss of production. Wells No. 3 and No. 4, 137 and 90 feet in depth respectively, and located 220 feet east of the HSC facility, were main sources of water for the village system from 1970 to the early 1980's when Well No. 5 went into production. They remained in service as emergency back-up wells until they were plugged and abandoned in 1997.
The City of Mansfield operates the Brumenschenkle Farm well field situated 1,500 feet north of the former HSC property on the north side of the Clear Fork River. The well field consists of two wells, 94 and 70 feet in depth, that pump 1,387 and 1,667 gpm respectively, on a discontinuous basis from a coarse sand and gravel aquifer. Indications are that significant portions of the well field's production are from induced infiltration from surface waters of the adjacent Clear Fork River (AVANT 1999A).
In addition to municipal drinking water wells, a large number of private residential wells and several small commercial production wells were identified in areas within a 5-mile radius of the village, outside its corporation limits (ODNR well logs). Most of these wells, however, are drilled to depths in excess of 100 feet and obtain their water under confined conditions from a sandstone bedrock aquifer that is separated from the ground surface by 50+ feet of impermeable or low permeability clay. The closest identified downgradient residential or small commercial wells appear to be at least 0.5 miles east and south of the identified plume.
History of Actions at the Site
Prior to the sale of the facility in 1988, both soil sampling and a soil-vapor survey was conducted at the site. These tests indicated levels of chlorinated solvents trichloroethene (TCE) up to 68,000 parts per billion (ppb) and tetrachloroethene (PCE) up to 6,500 ppb in shallow subsurface soils on the former HSC property (ENSR 1990a). Shallow subsurface borings for proposed on-site monitoring wells in 1989 indicated PCE at 6,500 ppb, TCE at 132 ppb, and elevated levels of the metals arsenic (up to 25 parts per million [ppm]), total chromium (up to 12 ppm), copper (19 ppm), lead (up to 23 ppm), nickel (up to 17 ppm), and zinc (93 ppm) (ENSR 1990a).
Five monitoring wells installed in 1987 detected TCE up to 1,400 ppb, PCE as high as 460 ppb, and 1,2 dichloroethene (DCE) up to 87 ppb in on-site groundwater. Metals also detected in the on-site groundwater included arsenic at 130 ppb, chromium at 180 ppb, lead at 440 ppb, and nickel at 260 ppb. Ohio EPA issued orders to HSC to perform a Remedial Investigation/Feasibility Study to determine the extent of contamination and to evaluate the ability of on-site production wells to create a groundwater capture zone that would prevent groundwater contamination from migrating off-site. Additional monitoring wells were added to provide horizontal and vertical delineation of the contaminant plume. Sampling of the wells in 1995 indicated TCE levels at up to 6,700 ppb and PCE levels at up to 1,200 ppb. Two air-stripping towers were installed at the site in order to remove VOCs from groundwater pumped from the two production wells, which in 1998 were converted to extraction wells.
Additional soil sampling in 1998 indicated levels of TCE at 1,900 ppb and PCE at 8,900 ppb in on-site soils at a depth of five feet below the ground surface (bgs). At 15 feet, TCE levels were as high as 270 ppb and PCE was measured at levels as high 8,600 ppb. Groundwater beneath the facility property contains TCE at levels as high as 1,200 ppb at a depth of 30 feet bgs, up to 6,700 ppb at a depth of 35 feet bgs, and up to 2,200 ppb at a depth of 50 feet bgs. PCE levels in on-site groundwater range up to 840 ppb at a depth of 30 feet bgs and 7,200 ppb at a depth of 41 feet bgs. The highest levels of both solvents in on-site groundwater occur in the east-central portion of the property in shallow portions of the underlying sand and gravel aquifer at depths of less than 50 feet (AVANT 1999A). On-site groundwater is currently not used as a potable water source by the company or the village.
In May 1998, HSC informed Ohio EPA that their investigation of the groundwater plume indicated that the contaminant plume extended off-site. Current data (AVANT 1999A; Ohio EPA 2000) indicate that TCE and PCE at levels above the USEPA Maximum Contaminant Levels for these chemicals in public drinking water (5.0 ppb MCL) occurs in an extensive groundwater plume that is within 500 feet of the active portion of the village of Lexington well field to the northeast (Well No. 5). This plume extends over a distance in excess of 1,000 feet east of the site where it discharges into the Clear Fork of the Mohican River (Figure 2). Contaminant levels in off-site groundwater are as high as 900 ppb for TCE and 160 ppb for PCE.
While the contaminant plume currently envelopes former production wells Nos. 1,2, 3, and 4, located within 350 feet of the HSC facility, the plume has not reached the active portion of the well field (Wells No. 5 and 6) nor the City of Mansfield Brumenschlenkle Farm well field to the north. HSC has installed 30 new monitoring wells southwest of the Lexington Community Park and the village's active production wells. These monitoring wells will enable detection of northerly migration of contaminants toward the well field prior to their reaching the well field proper. The village production wells are currently being sampled monthly for contaminants and the sentinel wells are being sampled on a quarterly basis (Ohio EPA 2000).
In November 1999, Clear Fork River surface water was sampled at the point where site groundwater intersects with the river channel. TCE was detected at levels of 130 and 2 ppb at locations R-3 and R-4, respectively (AVANT 1999B). Sampling of river surface water at the same locations in December 1999 detected no TCE at sampling point R-3 and 1.2 ppb TCE at R-4 (AVANT 1999C). Follow-up sampling of the river in June 2000 detected no TCE at either sampling location (AVANT 2000).
Past efforts to contain the contaminant plume on-site by pumping the two former facility production wells have not been successful. Due to concerns expressed by the village government with regard to the safety of their water supply, HSC and Ohio EPA are currently implementing additional interim actions to reduce the source of the groundwater contamination on-site, including air sparging and soil vapor extraction (Ohio EPA 2000). These processes are intended to reduce future threats to the village water supply posed by chemicals at the site by removing these chemicals from shallow soils and groundwater at their source.
The village of Lexington has a population of 4,124 (US Census 1990). At least 21 residential homes are located within 100 feet of the facility property line (AVANT 1999A).
Residents in the vicinity of the former Hamilton Standards Control facility must come into physical contact (be exposed to) with the hazardous materials at the site or with the contaminant plume in order for these toxic chemicals to result in possible adverse health effects. In order for residents to come into contact with these chemical compounds, there must be a completed exposure pathway. Five elements must be present for a completed exposure pathway to exist: 1) a source of the toxic chemicals of concern; 2) a means for the chemical to move from its source into contact with residents (soil, air, groundwater, surface water); 3) a point where the resident comes into physical contact with the chemical (on-site, off-site); 4) how the resident comes into physical contact with the chemical (drinking it, eating it, touching it, or breathing it) and; 5) people living near the facility who are likely to come into physical contact with chemicals of concern.
Physical contact with a chemical contaminant in and by itself does not necessarily result in adverse health effects. A chemical's ability to affect a resident's health is controlled by a number of other factors, including:
- how much of the chemical a person is exposed to (the dose),
- how long a person is exposed to the chemical, and
- how often a person is exposed to the chemical.
Other factors affecting a chemical's likelihood of causing adverse health effects upon contact include the resident's:
- past chemical exposure;
- smoking, drinking alcohol, or taking certain medications;
- current health status;
- sensitivity to certain substances;
- age; and
- family medical history.
Drinking Water Pathway
The major potential exposure pathway identified in this investigation is the village drinking water supply. Although the aquifer used from which the village's drinking water is pumped is contaminated by chlorinated solvents, regular sampling of monitoring wells between the known contaminant plume has not detected any of the chemicals in question. The bulk of the contaminant plume appears to be deflected away from the village well field to the southeast by lateral flow in the sand and gravel aquifer (Figure 2).
Based on information currently available to HAS, no exposures to either TCE or PCE are occuring to residents through their drinking water supply. No residents using private wells could be located within the area impacted by the contaminant plume. Well log data obtained from ODNR indicates that private well users are obtaining their water from a deeper sandstone bedrock aquifer that is unlikely to be impacted by the known contaminant plume.
Surface Water Pathway
A second potential exposure pathway in which residents might come into contact with site-related chemicals would be through contact with TCE-contaminated surface water in the Clear Fork of the Mohican River, roughly 1,000 feet east-southeast of the HSC facility. TCE up to 130 ppb and 1,2 DCE up to 19 ppb was detected at one sample location (RW-3) along the west bank of the river in November 1999. Subsequent sampling of the river water at the same location in December 1999 had no detections of TCE or 1,2 DCE, nor were these chemicals detected in surface water samples at this location in June, 2000. Much lower levels of TCE (2.0 and 1.2 ppb, respectively) were detected in a second downstream location (RW-4) in November and December 1999. Follow-up sampling at this location in June 2000 also had no detections of TCE. Because both TCE and 1,2 DCE are volatile organic compounds, they will be removed by evaporation from the river's surface water in a short period of time. Both compounds have relatively short half-lives (several days to a week) as gases in the atmosphere (ATSDR 1997A, 1997B).
The maximum concentration of 1,2 DCE detected in Clear Fork surface waters (19 ppb) is far below Ohio EPA's Human Health water quality criteria for both drinking and non-potable water scenarios (880 ppb and 36,000 ppb respectively). The maximum concentration of TCE detected in river water adjacent to the site (130 ppb) is below Ohio EPA's Human Health non-potable water quality criteria (370 ppb), but exceeds the Human Health criteria established using a drinking water scenario (29 ppb).
Levels of TCE and 1,2 DCE detected in surface waters of the Clear Fork of the Mohican River should not pose a health hazard to area residents through incidental contact with the river water by wading, swimming, fishing, or other recreational activity. There is no evidence that anybody immediately downstream of sample locations that had detections of TCE and 1,2 DCE is using the river water as their drinking water source.
Concentrations of Chemicals of Concern
Past production activities at the former HSC facility has resulted in the contamination of shallow subsurface soils and shallow groundwater beneath the site with elevated levels of TCE and PCE. Groundwater contamination has migrated off-site, forming a broad-arcing plume that extends several hundred feet to the northeast and nearly a thousand feet to the southeast of the facility property where the plume discharges into the south-flowing Clear Fork of the Mohican River.
Concentrations of TCE and PCE in off-site groundwater range up to 900 and 160 ppb, respectively, which is several orders of magnitude above the US EPA Maximum Contaminant Limit for public drinking water supplies (5 ppb MCL for both chemicals). The edge of the contaminant plume is currently (December 1999) 450 feet from village production well No. 5 and 750 feet from production well No. 6 (AVANT 1999A). To date, there have been no detections of site-related contaminants in neither village drinking water well (Ohio EPA, personal communication, September 2000). There is no evidence that private residential wells at the edge of the village's corporate limits have been impacted by the groundwater plume. Sampling of surface water in the Clear Fork in November 1999 indicated detections of TCE up to 130 ppb at two locations on the west bank of the river, east of the HSC site. Subsequent sampling in June 2000 at the two locations indicated an absense of TCE in surface water.
Toxicology of the Contaminants of Concern
The contaminants of concern at the HSC site are the chlorinated solvents TCE and PCE that occur in the groundwater plume associated with the site. Both compounds are currently considered by US EPA to be class B2 carcinogens which are probable human cancer-causing agents. Both TCE and PCE are VOCs that readily will vaporize upon exposure to the air. However, they have a tendency to leach into groundwater as the result of the filtration (percolation) of rain water through contaminated soils. Both chemicals are normally liquids with specific gravities that are denser than water and tend to sink down through an aquifer with time and distance from the original source.
Under anaerobic conditions (oxygen-poor conditions that typically increase with depth below the ground surface), TCE and PCE eventually biodegrade to 1,2 dichloroethene (DCE) and vinyl chloride (VC) (Smith and Dragun, 1984). 1,2 DCE is currently classified as a class D carcinogen; not classifiable as a human carcinogen due to inadequate or no evidence of carcinogenicity in humans or animals. Low levels of DCE (<70 ppb) have been detected sporadically within the contaminant plume extending from the HSC site. Vinyl chloride, normally a gas, is classified by US EPA as a class A carcinogen, a known human cancer-causing agent. However, no VC has been detected within the contaminant plume (Ohio EPA personal contamination, September 2000).
Occupational studies indicate that workers breathing high concentrations of TCE (levels above 70 ppm) on a daily basis experience depression, headaches, dizziness, sleepiness, fatigue, and nausea. Chronic exposure to these levels of TCE in indoor air by workers occasionally resulted in changes in liver function that disappeared within a short time once the worker was removed from the TCE-saturated environment (NIOSH 1973). A study of a residents living on the east side of Woburn, Massachusetts, associated excessive cases of acute lymphocytic leukemia in children with exposures to elevated levels of TCE (183-267 ppb) in the public water supply over the course of five to 10 years (Lagako et al. 1984, 1986). The impacted well water contained low levels (< 50 ppb) of PCE, 1,2 dichloroethene, and chloroform as well as TCE. A similar study of residents exposed to trichloroethene and other chemicals through their drinking water supply in a New Jersey township indicated an increase in the standard mortality ratio for leukemia in females (Fagliano et al. 1990). In contrast, medical tracking of nearly 5,000 residents at 15 sites in five states that were exposed to TCE through their drinking water supply failed to indicate the development of excess cancer cases in this population over the course of a 12-year study period (ATSDR, 1999). Tracked residents were exposed to varying levels of TCE (3-24,000 ppb) for varying periods of time (7-33 years). Adverse health problems showing a statistically significant association with the TCE exposure include such non-cancer effects as speech and hearing impairments, anemia, increased incidence of strokes, increased incidence of diabetes, and increased incidence of liver disease, kidney disease, and urinary tract disorders (ATSDR 1999).
Occupational studies of workers in dry-cleaning facilities have indicated that breathing high concentrations of tetrachloroethene (PCE) at levels above 50 ppm on a daily basis has led to the development of symptoms similar to those described for TCE (NIOSH 1976, 1978). The major difference between the two solvents is the retention of PCE in the body for longer periods of time and its ability to accumulate in fatty tissues in the body (NIOSH 1976). Several studies of workers at dry-cleaning businesses have suggested associations between the development of elevated incidences of urinary tract, kidney, and cervical cancers and chronic exposure to high levels of PCE and other dry-cleaning solvents in the air at their places of work (Katz and Jowett 1981; Brown and Kaplan 1987). These studies were confounded, however, by the presence of carbon tetrachloride, trichloroethene, and several additional petroleum solvents, as well as PCE in the indoor air environments. No studies other than the Woburn study (1984, 1986) and the Toms River study (1990) have linked elevated incidence of cancers in humans through ingestion of TCE and/or PCE through the drinking water supply.
Studies of laboratory animals exposed to both TCE and PCE have associated the development of liver cancer (hepatic carcinomas) in mice exposed to these solvents through gavage. Similar studies using rats, however, failed to replicate these results (NIOSH 1975; OSHA 1988). Rats exposed to PCE through gavage developed significant increases in mononuclear cell leukemia, and male rats developed a significant increase in renal tubular cell adenomas and carcinomas (OSHA 1988). However, these results were challenged by reviews by the National Research Council of the National Academy of Sciences and US EPA's Science Advisory Board (1991).
HAS and ATSDR recognize that children are often at greater risk for environmental exposure than adults. Children's rapidly developing bodies may be more susceptible to adverse health effects resulting from exposures to toxic materials in their environment. As a result, HAS and ATSDR use public health guidelines that are specifically developed to be protective of children.
The chemicals of concern at the site, TCE and PCE, are currently classified by U.S. EPA as Class B2 -- probable human carcinogens. The carcinogenicity of these solvents, based on animal laboratory experiments with animals, is ambiguous because different species have different susceptibilities to these solvents concerning cancer incidence, type, and site. ATSDR studies of 15 other TCE sites have shown no linkage between ingestion of TCE-contaminated water and increased incidence of any cancers.
Tetrachloroethene (PCE) and trichloroethene (TCE) have not been detected in the raw water village well field production wells nor in the finished water distributed through the village water system. Village residents using the village public water supply as their drinking water source currently are not being exposed to TCE or PCE through the drinking water pathway.
TCE and 1,2 dichloroethene have been detected in areas of the Clear Fork of the Mohican River located southeast of the HSC site. However, the levels of TCE and 1,2 DCE detected should not pose an acute or long term health threat to residents coming into incidental contact with the water through recreational activities such as swimming, fishing, wading, or boating.
The contaminant plume in area groundwater near the Hamilton Standard Controls site in Lexington, Richland County, Ohio currently poses no apparent public health hazard to area residents through drinking water or incidental contact pathways.
- Ohio EPA and the village of Lexington should continue to closely monitor the village drinking water supply, both treated and untreated, for chemicals of concern.
- Ohio EPA and the Hamilton Standard Controls should continue current efforts to remediate the source of the contamination impacting the drinking water aquifer in the vicinity of the Hamilton Standard Control site.
- Additional soil gas sampling of surface soils at the site and along the facility's property line is recommended to assure that soil gas solvent levels in these areas do not pose a potential health hazard to on-site workers or adjacent off-site residents.
Robert C. Frey, Ph. D., Geologist
Irena Scott, Ph. D., Toxicologist
Beverly Henderson, Public Information Specialist
Eric Yates, Environmental Specialist
Reviewed by Ying Feng, Ph. D., Principal Investigator
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AVANT GROUP, INC. 1999A. Remedial Investigation Report for the Former Hamilton Standard Controls Facility, Lexington, Ohio, December 23, 1999.
AVANT GROUP, INC. 1999B. HSC-Lexington site: November, 1999 Confirmation sampling of monitoring wells MW-59, MW-60, MW-105, and MW-106 and surface water samples R-3 , R-4, plus trip blanks: November 1999.
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OHIO ENVIRONMENTAL PROTECTION AGENCY. 2000. Fact sheet for Hamilton Standard Controls (HSC). Lexington, Ohio: May, 2000.
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This United Technologies/Hamilton Standard Controls Facility Health Consultation was prepared by the Ohio Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.
Alan W. Yarbrough
Technical Project Officer, SPS, SSAB, DHAC, ATSDR
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.
Chief, State Program Section, SSAB, DHAC, ATSDR