PUBLIC HEALTH ASSESSMENT
OAK GROVE VILLAGE WELL
SULLIVAN, FRANKLIN COUNTY, MISSOURI
The Oak Grove Village Well site is an uncontrolled and undefined plume of trichloroethylene (TCE) contaminated groundwater in an area where groundwater movement is somewhat variable because of karst geology. Oak Grove Village is a small community with a population of 382 that is located adjacent to the northeast boundary of the city of Sullivan, Missouri. TCE contamination was originally detected in the Oak Grove Village well on June 10, 1986, by the Missouri Department of Natural Resources (MDNR) at 6 parts per billion (ppb), above the Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) of 5 ppb.
TCE is a volatile organic compound (VOC) that evaporates easily in air, but stays in soil and water without much decomposition. Since it is heavier than water it can easily pass through the soil into the groundwater. TCE is a manufactured VOC that is used mainly as a solvent to remove grease from metal parts, but can also be found in household products such as wood stains, varnishes, lubricants, adhesives, typewriter correction fluids, paint removers, and cleaners.
Following the initial detection of TCE, MDNR continued to sample the village well and various distribution points through October 1990. That sampling indicated continuing TCE contamination. Because of this ongoing contamination, MDNR issued a Notice of Violation to Oak Grove Village. The village closed its well in July 1991 and began purchasing water from Sullivan. In September 1992, Oak Grove Village disconnected from the Sullivan water supply and again began using their well, only to find that it still remained contaminated with TCE. The village again purchased their water from Sullivan. Other private wells in two separate locations in the area and a spring that drains the area also have shown TCE contamination.
Since the undefined plume(s) of TCE contaminated groundwater has affected the Oak Grove Village well, numerous private wells, a spring, and other municipal wells and because the source(s) of the contamination has not yet been determined, the site was proposed for EPA's National Priorities List (NPL) on September 13, 2001. The site was officially placed on the NPL on September 5, 2002. Since the city of Sullivan ended the contract to supply water to Oak Grove Village in December 2002, the village decided to drill a new well. Sullivan continues to supply water on a month-to-month basis as long as the village continues to show progress in providing their own water source. Due to unforeseen problems or a disagreement between the communities, the potential exists that the village may have to reactivate their old well (which contains an unknown level of TCE contamination under pumping conditions), to supply the village with water. EPA has asked what the health consequences of that action would be, so the Missouri Department of Health and Senior Services in cooperation with the Agency for Toxic Substances and Disease Registry will also assess that situation in this public health assessment.
Use of the contaminated Oak Grove Village well in the past represents a completed exposure pathway to users of the village public water system. A completed exposure pathway also existed in the past and presently exists to some private well owners in two separate areas, although presently at levels below the MCL. Because no health guidelines exist to determine the health effects from low-level long-term exposure to TCE, calculations were done to estimate the worse case risk from ingestion and inhalation exposure for non-cancerous adverse health effects as well as the risk of that exposure causing additional cancer in the population. Because no adverse non-cancerous health effects are expected and only a slight theoretical additional cancer risk exists from past exposure, the site was assigned a hazard classification of No Apparent Public Health Hazard for the past and present. The category of No Apparent Public Health Hazard is used for sites where human exposure to a contaminated media is occurring or has occurred in the past, but the exposure is below a level of health hazard.
Since it is not known if the old Oak Grove Village well will have to be reactivated, or the future levels of TCE contamination in the old well or new well, in public or private wells, or in the LaJolla Spring and its cave complex, or how many additional wells may also be affected, the site is assigned a Indeterminate Public Health Hazard for the future. The category of Indeterminate Public Health Hazard is assigned to sites for which no conclusions about the public health hazard can be made because data are lacking.
The Missouri Department of Health and Senior Services (DHSS), in cooperation with the federal Agency for Toxic Substances and Disease Registry (ATSDR), evaluated the public health impact of the Oak Grove Village Well site. This public health assessment determined if exposures at levels of health concern occurred or are likely to occur, and recommends actions to reduce or prevent possible adverse health effects. ATSDR is a federal agency within the U.S. Department of Health and Human Services and is authorized by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) to conduct public health assessments at hazardous waste sites. This document will assess past, current, and future exposure to the contaminated groundwater at the site. As requested by the Environmental Protection Agency (EPA), this public health assessment will also consider the health implications of Oak Grove Village reactivating their existing well to provide public water until a new well can be drilled and placed into operation.
The Oak Grove Village Well site is an uncontrolled and undefined plume(s) of trichloroethylene (TCE) contaminated groundwater detected in the Oak Grove Village municipal well. The source(s) of the contamination that has affected the village's well, other public and some private wells in the area, and a spring in a nearby commercial cave has yet to be determined. Oak Grove Village is a small community located adjacent to the northeast boundary of Sullivan, Missouri. See Figure 1 in Appendix A for the site location. The village has only one well that supplies the village's municipal water system of approximately 200 connections (1,2). The well was drilled to a depth of 805 feet in 1964, but has a current depth of approximately 725 feet based on a video log performed during the Phase 1 Remedial Investigation (RI). To date, only Phase 1 of the RI for the remedial investigation/feasibility study (RI/FS) has been completed for the Oak Grove Village Well site in March 2002, but further investigations are ongoing.
The Oak Grove Village well was first found to be contaminated on June 10, 1986, after water sampling by the Missouri Department of Natural Resources (MDNR) detected TCE above the EPA's Maximum Contaminant Level (MCL). TCE was detected at a level of 6 parts per billion (ppb), above its' MCL of 5 ppb. An MCL is the maximum permissible level of a contaminant in water, which is delivered to any user of a public water system. Following the initial detection of TCE, MDNR continued to sample the Oak Grove Village well and points in the distribution system on a quarterly basis through October 1990. During this period TCE continued to be detected at concentrations ranging from 2.4 to 12.0 ppb. Tetrachloroethylene (PCE) was detected in two of the sampling events in 1986 at a maximum level of 59 ppb, but has not been detected since. Because of the continued presence of TCE in the well, MDNR issued a Notice of Violation (NOV) to Oak Grove Village and the village closed the well in July 1991 and began purchasing water from Sullivan (1,2).
In September 1992, Oak Grove Village disconnected from Sullivan's water supply and reopened their well. MDNR reinstated sampling on a quarterly basis once Oak Grove Village reopened the well. During all four quarters, TCE exceeded the MCL with concentrations ranging from 10 to 25 ppb. Due to the continuing detection of TCE above the MCL, MDNR issued a second NOV, and in February 1994 Oak Grove Village closed the well and again began purchasing water from the city of Sullivan (2,3). The Oak Grove Village well remains functional and is capable of being returned to service (2). In the hope of reducing the concentration of TCE in the well, the well was pumped to waste (not used for drinking) between May 16, 1997 and June 9, 1997. Concentrations did not decrease and remained between 10 and 13 ppb. On September 11, 1997, the Oak Grove Village well was sampled as part of an MDNR Additional Site Assessment. After being purged for 20 minutes, TCE contamination had increased to 42.3 ppb from the last known concentration of 13 ppb in June of 1997 (2). Because the undefined plume(s) of contaminated groundwater have affected the Oak Grove Village well and numerous private wells and because the source(s) of the contamination has not yet been determined, the site was proposed for EPA's National Priorities List (NPL) on September 13, 2001, and officially placed on the NPL on September 5, 2002 (4,5).
Recent sampling of the Oak Grove Village well for the Phase 1 RI (by MDNR) during September, October, and December 2001, as well as the most recent by MDNR in June 2002, has found TCE at a level of less than 1 ppb. All of these samples were taken without the well in an active pumping condition. In the June 2002 sample, MDNR used a packer system to isolate and sample a low volume of water from the Oak Grove Village well at different depths. Of the depths sampled, only one revealed detectable levels of TCE at 0.9 ppb. MDNR plans to do further sampling under actual pumping conditions to determine the level that would be present under actual usage (1,6).
On May 23, 2002, the city of Sullivan notified Oak Grove Village by letter that the water agreement with the village would expire on December 31, 2002, and the city did not plan to extend the agreement except on a month-to-month basis (7). Options for the village's future public water supply were discussed in a June 13, 2002, meeting between representatives of Oak Grove Village, MDNR, EPA, and DHSS. The decision was made to proceed with plans to drill a new well, and if needed, add a treatment system to provide a safe source of public water. EPA requested a health consultation to determine what health effects might be expected to occur to the village's water users if the village finds it necessary to reactivate their old well (8). This public health assessment will also address that issue. During a phone conversation with a representative of Oak Grove Village, DHSS learned that a new well will probably be ready by the spring of 2003, and it was confirmed that as long as the village can show progress toward getting their own public water supply, the city of Sullivan will continue to supply the village with water until the new well is operational (telephone conversation with Denise Revelle, clerk of Oak Grove Village, 2002 August 5). Oak Grove Village has drilled their new well and analysis of preliminary sampling results collected over a 48-hour period (April 12-13, 2003) indicated that the level of TCE varied from 5.8 ppb to 70.8 ppb (9). To provide the village with a safe public water supply, the village has plans to add an air stripper to eliminate the TCE before it is supplied to the public water system (telephone conversation with MDNR site project officer, 2003 May 5).
Because of the area's TCE groundwater contamination, other wells and an area spring have also been affected. To determine the extent of the contamination, Phase 1 of a RI sampled over 90 private wells in June and July 2001. Of these private wells only one had TCE levels above the MCL at 12 ppb (1). Previous sampling by MDNR in July 2000 found this well and a neighbor's well to be contaminated at 16.4 and 12.8 ppb TCE respectively. Although the wells remain contaminated, the two residences have been provided whole-house filtration systems by EPA as part of a short-term Removal Action to eliminate exposure. Unlike the Oak Grove Village well where exposure to users of the system was discontinued for a period of time while being connected to the Sullivan water supply, these private well users may have been exposed to TCE contaminated groundwater for a longer period of time. Assuming that TCE was present in these private wells around the time that sampling was first done on the Oak Grove Village well in 1986 until whole house filtration systems were installed in 2000, the residents would have been exposed to an expected increasing level of TCE contamination up to the 16.4 ppb over a 14 year period of time. TCE levels are expected to have gradually increased over time because nearby private wells that were sampled in 1992 by DHSS and again sampled by MDNR in 2002 have shown a gradual increase. For exposure calculation purposes the highest TCE level detected (16.4 ppb) will be used for the expected 14 years of exposure to develop a worse case exposure scenario.
Seven other private wells sampled during the RI had detectable TCE levels, but all were below the MCL and clustered in two separate areas. Levels ranged from 0.37 to 2.9 ppb in the RI sampling event, however levels in all the wells have varied during other sampling events. The well with elevated TCE (12 ppb) and four other wells are located northeast of the Oak Grove Village well and are clustered around the western side of the old Sullivan Landfill, a possible source of TCE and other contaminants. The remaining three private wells where TCE was detected are located approximately three miles northwest of the Oak Grove Village well in an area along Highway AF (See Figure 2 in Appendix A). Contamination of the private wells along Highway AF is possibly from a different contamination source than the private wells northeast of the Oak Grove Village well (1).
The RI also sampled 11 springs in the area, with only the LaJolla Spring having detectable levels of TCE at 5.7 ppb. Resampling by MDNR in June 2002 detected TCE at 2.3 ppb in the LaJolla spring water. The spring is located northeast of the Oak Grove Village well near the Meramec River. Dye tracing injected into points west and west-southwest, including points in Sullivan, confirms that LaJolla Spring drains the area to its west (1). LaJolla Spring flows through a cave complex before it drains into the Meramec River (See Figure 2). The cave complex is a large commercial cavern that is visited by approximately 150,000 people a year. The air in the caverns was sampled for TCE by EPA in 1995. TCE was not detected (10). MDNR and EPA sampled the cave air and spring water in October 2002 to determine if contamination was present. During this sampling event, it was reported that in the area of the cave visited by the public and employees, TCE was detected in the spring water at a maximum of 7.9 ppb at the end of the normal trail (11) and in the air of the ballroom at 19 parts per billion by volume (ppbv) or 19 ppb (12). Additional air and water samples were collected in the upper portions of the cave where the public doesn't have access and employees seldom go. In these samples, TCE levels ranged in the air from non-detectable to 82 ppb and in the spring water from 2.0 to 12.6 ppb (11, 12). A second round of sampling was completed in May 2003. Air sampling results taken at three locations in the cave used by visitors indicated that TCE air levels have increased. These results indicated that TCE was at a level of 190 ppb in the ballroom. The highest TCE level detected in the cave air was at the far end of the tour route at 260 ppb (13). Additional sampling of the cave air has taken place since the release of the public comment version of the public health assessment (PHA) of August 7, 2003. In August 2003, air samples were taken but results were unusable because of equipment failure. In October 2003, another round of air and water sampling confirmed the elevated levels of TCE air contamination taken in May 2003. The maximum level of TCE detected in air was 310 ppb at the far end of the tour route (14). A water sample from the stream (at the same location) found TCE at a maximum of 12.3 ppb (14). The discussion under the Inhalation Exposure at the LaJolla Spring Cave Complex heading and the Cancer heading has not been changed because results are relatively similar. The public health implications would need to be reassessed if contaminant levels continue to increase. Chloroform was detected below health guidelines levels (14) at one of the six (plus background) sampling locations during the October 2003 sampling event and will not be considered in this PHA.
Because TCE contamination has affected the area's groundwater, some of the adjoining city of Sullivan municipal wells have also been affected. Of the current ten operational city of Sullivan wells, four have shown levels of contamination, with two of those having TCE contamination above the MCL. One of the wells is active with an air stripper and the other has a filtration system that did not perform as expected and is presently inactive (Written comments from MDNR site project officer, 2002 October 24). Sampling data since 1986 indicate that the level of TCE contamination has varied over time and the possibility exists that the level of contamination could increase or affect other city of Sullivan wells.
To determine the source(s) of the contamination in and around the communities, numerous investigations have been completed. The latest was the Phase 1 RI done for MDNR that determined there are several potential source areas of the TCE contamination (1). They are, but are not limited to the:
Of the above listed sites, only the Former TRW Facility in Sullivan has been thoroughly
investigated with remediation having been conducted at the site (See Figure 1 for location). The
responsible party performed these actions under the Resource Conservation and Recovery Act.
This remediation has included sludge 
and TCE contaminated soil removal and a groundwater
investigation that determined the groundwater below the TRW site was contaminated with high
levels of TCE and other volatile organic compounds (VOCs). To remediate the contaminated
groundwater, TRW has in place a groundwater monitoring system, a drinking water contingency
plan, and a groundwater pump and treatment system to remove and treat the highest
concentrations of VOCs in shallow groundwater. Also, TRW in conjunction with the city of
Sullivan has installed treatment systems on certain contaminated city wells (15).
The Phase 1 RI concluded that contamination of the Ozark Aquifer in the area is becoming widespread and contaminated groundwater has been detected in the Oak Grove Village well, several nearby city of Sullivan wells, private wells west of the old Sullivan landfill, a group of private wells near AF Highway, and in the LaJolla Spring. The RI also concluded that it is possible that there may be overlapping contaminant plumes from more than one source impacting area wells. Recommendations from the RI included further site-specific investigations to better understand the hydrogeology of the area, identify sources of contamination, and propose potential remedial actions. Following the recommendations of the RI, MDNR continues to monitor and expand sampling of the area.
Land Use, Natural Resources, and Geology
The Oak Grove Village Well site is located on village property in the building occupied by the city hall. Land use around the Oak Grove Village Well Site is mostly residential in the village. Outside of the city limits, to the north through the southeast, are larger, usually wooded residential properties with their own private wells. The city of Sullivan abuts the village to the west and south. Other areas not used for residential property outside of the village are wooded rolling hills. The closed, old Sullivan landfill is located approximately one mile northeast of the village and has a small subdivision clustered around its western side (See Figure 2).
Natural resources in the area consist mostly of the Meramec River and the Meramec State Park located east of the Oak Grove Village Well site. LaJolla springs flows into and through an associated cave complex to its outlet into the Meramec River. The cave complex is a large commercial cavern that is visited by approximately 150,000 people a year.
The Oak Grove Village well draws groundwater solely from the Ozark Aquifer. All but one of the ten city of Sullivan wells also draw water from the Ozark Aquifer. The exception is one well that was drilled through a confining layer beneath the Ozark Aquifer; however, the majority of its water is believed to be coming from the Ozark Aquifer. Groundwater flow in the Ozark Aquifer, on a regional basis, is unconfined and is influenced by major topography (1). Hydrogeologic assessments indicate that the recharge area for the Oak Grove Village well is to the southwest of the site. However, major faults occurring in close proximity to the site and in all directions from the site, in addition to karst features in the groundwater aquifer make groundwater movement difficult to predict (1,2).
According to 2000 census data, Oak Grove Village has a population of 382. The population of the village is 97.9% white, 0.3% American Indian or Alaska Native, 0.5% Asian. In addition, 5 individuals (1.3%) identified themselves as being of two or more races. In 2000, there were 35 children under the age of 5 years old and 45 individuals over 65 living in Oak Grove Village. The median household income for 1999 was $35,357. In 1999, ten families were listed as being below the poverty level. Of the 138 households in the village (2000 Census), 43 received Social Security incomes, 24 received retirement income and three received public assistance income (16). In general, the community represents a white, working-class community in a semi-rural area of Franklin County.
This section addresses the pathways by which residents of the area may have been exposed to the TCE contaminated groundwater. When a chemical is released into the environment, the release does not always lead to exposure. Exposure only occurs when a chemical comes into contact with and enters the body. To determine whether the residents of Oak Grove Village and surrounding areas were exposed to contaminants at this site, DHSS conducted an analysis of exposure pathways. For a chemical to pose a health risk, a completed exposure pathway must exist. An exposure pathway consists of five elements including a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population. Completed exposure pathways require that all five of the elements of exposure exist. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present. Potential exposure pathways, however, have at least one of the five elements missing or uncertain, but could exist. Completed and potential exposure pathways could have occurred in the past, could be occurring presently, or could occur in the future (17).
Completed Exposure Pathways
Past:
The five elements of a completed exposure pathway at the Oak Grove Village Well site are explained below:
Table 1 in Appendix B illustrates the different exposure pathways present at the Oak Grove Village Well site.
People at the Oak Grove Village site can be exposed to TCE through ingestion, inhalation, or dermal contact. Ingestion exposure would occur by drinking water or eating food prepared with contaminated water. People can also be exposed to TCE through inhalation and dermal contact while showering, bathing, and washing clothes and dishes as well as other household activities. Exposure by inhalation can also occur in areas where TCE volatilizes from contaminated water into air that has limited circulation.
Completed exposure pathways to TCE contaminated water above its' MCL are known to have existed for the users of the Oak Grove Village public water supply from the time of first discovery in June 1986 and ended when the village closed the well in July 1991. During this 5-year period public water supply users were likely exposed to TCE at levels ranging from 2.4 to 12 ppb. The village then connected to the Sullivan public water supply. Completed exposure pathways again existed after the village reopened their well from September 1992 to February 1994. Residents were exposed to a maximum level of 25 ppb of TCE during this approximately 1.5-year period before again reconnecting to the Sullivan public water system. PCE contamination was detected in only two sampling events in 1986 (at 59 and 16 ppb) and has not been detected since. No further samples have shown PCE contamination; therefore PCE will not be discussed further as a contaminant in this public health assessment.
Completed exposure pathways to levels of TCE contamination above EPA's MCL existed to residents using private wells outside of the Oak Grove Village public water system until they were supplied with a whole-house water treatment system.
Present:
Presently no completed exposure pathways to TCE contaminated groundwater above its' MCL are known to exist. Completed exposure pathways to TCE contaminated groundwater below the MCL are presently occurring to a limited number of private well owners, but no adverse health effects are expected unless the level of TCE dramatically increases.
Workers at, and possibly visitors, to the cave complex associated with the LaJolla Spring are exposed to levels of TCE contaminated air. Long-term exposure (years) could potentially have adverse health effects.
Future Potential Exposure Pathways
Potential exposure pathways exist because the TCE contamination remains in the groundwater at the Oak Grove Village Well site and the surrounding area.
Because the Oak Grove Village's contract with the city of Sullivan to supply public drinking water expired on December 31, 2002 (Sullivan continues to supply water on a month to month basis), the potential exists that the village will have to reactivate their existing well to supply the village's water needs until a new well can be drilled and placed into service. Although the levels of contamination in the well under actual pumping conditions are not presently known, levels of TCE could be at least as high as or even higher than the last time the well was known to be actively pumped (42.3 ppb). Early testing of the new village well has shown that it is also affected by the contamination.
Potential exposure pathways exist to residents outside of the Oak Grove Village public water supply area. The levels of TCE in presently contaminated private wells below the MCL could increase to levels above the MCL and the plume could migrate and impact additional wells. Users of new wells drilled into the TCE contamination plume also have the potential to be exposed to contaminated groundwater.
Workers at, and possibly visitors to the cave complex associated with the LaJolla Spring have the potential to continue to be exposed to levels of TCE contaminated air that could cause adverse health effects after years of exposure. Visitors will be exposed for only a short period of time during the tour (approximately 1.5 hours), while workers may be exposed for their expected period of employment (years). There is also the potential that the city of Sullivan public wells could be further impacted by the contamination.
Introduction
This section will discuss the health effects of exposure to specific contaminants. A discussion of non-cancerous health effects and the possibility that TCE exposure might cause cancer is evaluated in this section. To evaluate non-cancerous health effects, ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily human exposure. Exposure to a contaminant level below the MRL is not expected to cause adverse non-cancer health effects. Levels above an MRL do not mean that health effects will definitely occur; rather, it calls for more investigation into whether health effects may or may not occur. MRLs are developed for each route of exposure, such as ingestion and inhalation, and for the length of exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greater than 365 days) (18). This toxicological evaluation section will discuss the possible adverse health effects that water users might expect from long-term exposure to low levels of TCE contamination in their drinking water. An MRL has not been developed for long-term low-level exposure to TCE, so exposures above EPA's MCL will be further evaluated. The possibility of TCE causing cancer and the theoretical risk of exposure to TCE causing additional cancers is discussed under the cancer section.
TCE is the major contaminant that was detected at the Oak Grove Village Well site. TCE has also been detected in various private wells in two separate areas around the Oak Grove Village Well site, but only above the MCL in two private wells near the landfill (presently on whole-house filtration systems). The other private wells have TCE at less than the MCL and are presently not considered a health concern. Considering that new research (16 studies) has been completed and are published in the Environmental Health Perspectives (19) on the toxicity of TCE and the cancer slope factor has been lowered accordingly (cancer slope factor now is available as a range), long-term low-level exposure to TCE below the present MCL may become more of a health concern.
Trichloroethylene
TCE is a volatile organic compound that evaporates easily in air, but stays in soil and water without much decomposition. Since it is heavier than water it can pass easily through the soil into the groundwater. It is used mainly as a solvent to remove grease from metal parts, but can also be found in household products such as wood stains, varnishes, lubricants, adhesives, typewriter correction fluids, paint removers, and cleaners. Most people can begin to smell TCE in air at around 100,000 ppb. Once it enters the body it is changed to other chemicals that have been shown to be toxic to animals and are probably toxic to humans (18).
The major target of TCE is the nervous system where exposure to large amounts may cause dizziness, sleepiness, headaches and even unconsciousness (TCE was once used as an anesthetic for surgery at around 1,000,000 ppb). At higher levels and possibly long-term low-level exposure, liver and kidney damage and changes in heartbeat can occur (18).
When TCE is inhaled, approximately half of the amount breathed in is exhaled and the other half enters the bloodstream. When TCE contaminated water is ingested, most of the TCE will be absorbed into the bloodstream. Much of the TCE that enters the bloodstream will also be exhaled. Once in the blood, the liver breaks down TCE into other chemicals (dichloroacetic acid, trichloroacetic acid, chloral hydrate, and 2-chloroacetaldehyde). The majority of these chemicals will be excreted in urine within a day (18).
Exposure (non-cancerous)
People can be exposed through ingestion by drinking contaminated water or eating food prepared with contaminated water. People can also be exposed to air borne TCE through inhalation. Household activities using TCE contaminated water such as showering, bathing, and washing clothes and dishes, and other similar activities can increase TCE levels in the air. Exposure through dermal contact can take place during showering, bathing, or other activities that put the skin in contact with TCE-contaminated water. A more detailed explanation of the exposure pathways at the Oak Grove Village site can be found in Table 1 in Appendix B.
Dermal Exposure:
Dermal effects of exposure to TCE are usually the consequence of direct skin contact with concentrated solutions in occupational settings. Exposures to these concentrated solutions usually result in desiccation (drying) of the skin due to the defatting action of the solvent that may lead to dermatitis. Dermal contact with TCE at the levels present in the village well and in private wells are magnitudes lower (ppb versus the possibility of pure product used in occupational settings), do not pose a health concern through this route of exposure.
Ingestion Exposure:
Ingestion exposures were calculated using the worst-case exposure scenario for past and potential future exposures if the Oak Grove Village well was reactivated. Based on the discovery of TCE contamination in the Oak Grove Village well in 1986, exposure to TCE was estimated to have occurred in the past to users of the Oak Grove Village public water system at a maximum level of 25 ppb, in two separate periods of time totaling approximately 6.5 years. Residents were not exposed to this level for the full 6.5 years. However, this period of time and the maximum TCE level were used to calculate a worst-case exposure scenario. To calculate a dose, we assumed that adults, on average, drink 2 liters (66 ounces) of tap water each day and weigh 70 kilograms (Kg) or 154 pounds. For children (one to six years of age), we assume that they drink 1 liter (33 ounces) of tap water each day and weigh 10 Kg (22 pounds) (17). The calculated exposure dose from using the public water system in the past was 0.0007 mg/Kg/day for adults and 0.0025 mg/Kg/day for children. Exposure was also calculated for the potential exposure that could occur if the Oak Grove Village well was reactivated and public water users were exposed to 42 ppb TCE for a 2-year period until a new well and possibly a treatment system could be put into service. The calculated exposure dose was 0.0012 mg/Kg/day for adults and 0.0042 mg/Kg/day for children. The exposure that could have occurred to users of TCE contaminated private wells was also calculated and used the maximum detected TCE level (16.4 ppb) for an expected maximum length of time (14 years). The calculated exposure dose was 0.00047 mg/Kg/day for adults and 0.00164 mg/Kg/day for children. All of these theoretical calculations make very conservative (protective) assumptions and may over estimate the exposure that occurred or may occur. The calculations can be found in Appendix C.
Inhalation Exposure and Total Residential Exposure:
Because TCE inhalation levels in residences are not known, total exposure through ingestion and inhalation was estimated by doubling (x 2) the ingestion exposure level assumed to have occurred at the maximum levels and time periods. The calculations can be found in Appendix C. The worst case calculated total doses (ingestion and inhalation) for the Oak Grove Village Well site from past exposures were 0.0014 mg/Kg/day for adults and 0.0050 mg/Kg/day for children. For potential future exposure, given the Oak Grove Village well is reactivated, the total doses were calculated to be 0.0024 mg/Kg/day for adults and 0.0084 mg/Kg/day for children. The total doses were also calculated for the private well users at 0.00094 mg/Kg/day for adults and 0.0033 mg/Kg/day for children.
Total exposures (ingestion and inhalation) were found to be below ATSDR's MRL for acute ingestion exposure (0.2 mg/Kg/day). Because of insufficient data, ATSDR does not have intermediate or chronic ingestion guidelines for TCE (18). Because no MRL has been developed for intermediate or chronic ingestion exposure for TCE, more investigation was needed to determine if health effects are likely to occur from ingestion exposure. The worst-case doses were compared to and found to be below the No Observed Adverse Health Effects Level (NOAEL) of studies involving chronic exposures to TCE in animals. Using an additional safety factor of 10 for humans, the calculated exposures still did not exceed the NOAEL (18).
In studies of humans who were exposed to TCE contaminated drinking water, varying conclusions have been reached. ATSDR has maintained a TCE Subregistry Baseline data file on approximately 5,000 persons with documented environmental exposure to TCE (along with other chemicals) through private wells. For the report, ATSDR compared health conditions reported by the TCE Subregistry registrants with health conditions reported in a nation-wide survey of the general population. Certain age groups reported some health conditions more frequently, while some had higher rates for only men or only women. This study did not confirm the health conditions (they were self-reported) and the study did not completely identify the exposure level. Persons in the study were exposed from 6.5 to 18 years to concentrations varying from less than 1 ppb to 19,380 ppb (determined from limited sampling data, usually one to two sampling events) (20, 21). Findings of the latest follow-up of the study indicate that subregistry participants had a reporting rate above the national norms in various age groups for speech impairment and hearing impairment for children under 10 years of age (only on the baseline study), anemia and other blood disorders, stroke, urinary tract disorders, liver problems, kidney problems, diabetes rates, and skin rashes. Although the findings of ATSDR TCE Subregistry report do not identify a cause and effect relationship between TCE exposure and adverse health effects, they do reinforce the need to continue ongoing follow-up of the participants (21).
Of the reported health problems listed above, only the rate of strokes was reported to increase with increasing concentration of TCE. For the other health problems, their occurrence did not increase with higher exposure levels. If the health problems were related with the exposure to TCE, we would expect the number of people with a specific health problem to increase with higher levels. Therefore, it is unlikely that the reported health problems (anemia and other blood disorders, urinary tract disorders, liver problems, kidney problems, diabetes rates, and skin rashes) are associated with the exposure to TCE in private wells. Of those reporting strokes, a good portion also reported having other health problems including hypertension, diabetes, and being smokers, all of which contribute to the incidence of stroke (20).
Considering the concentrations and period of time that residents at the Oak Grove Village site were exposed to TCE contaminated drinking water and air, no adverse non-cancer health effects are expected from past exposure. If the village reconnected to the existing well, future exposure and health effects cannot be determined because of unknown TCE levels and the period of time that exposure would continue.
Inhalation Exposure at the LaJolla Spring Cave Complex:
Exposure at the cave complex associated with the LaJolla Spring consists only of inhalation of low levels of TCE contamination in the air of the cave. Spring water was also found to be contaminated, but is not used for drinking or body contact recreation and no exposure pathway is expected. Even though air concentrations of TCE were below detectable limits in sampling completed by EPA in 1995, sampling in October 2002 detected TCE at 19 ppb in the cave air of the area used by visitors and employees. In the May 2003 sampling, those levels had increased to a maximum of 260 ppb. Exposure is expected to occur to the visitor to the cave for the length of the tour (approximately 1.5 hours) and to the workers for their workday. ATSDR has developed an MRL for the inhalation of TCE for acute exposure time periods (less than 14 days) of 2,000 ppb (18). Considering that the concentration of TCE detected in the cave air is below the MRL and the expected exposure time is short, the visitor exposure to the contaminated air in the cave complex is not expected to pose any adverse health risk.
Workers, on the other hand, are expected to spend an extensive amount of time in the cave complex when compared to visitors; thus, resulting in increased exposure to the TCE contaminated air. To determine if worker's exposure to the May 2003 maximum detected level of 260 ppb TCE would pose any non-cancerous health consequences, we compared the detected level to ATSDR's intermediate MRL (14 to 364 days) of 100 ppb. The elevated level of 260 ppb has since been confirmed by an October 2003 measurement of 310 ppb, both of which exceeds the intermediate MRL screening value. It is worth mentioning, that MRL screening values were derived from rat studies that determined a lowest observed adverse effect level (LOAEL) of 50,000 ppb. At this level, the following health effects were observed in rats: decreased wakefulness during exposure, decreased post exposure heart rate, and slow wave sleeping (18). However, one must keep in mind the MRL screening values usually have a safety factor for humans when data is taken from animal studies and the health effects implicated in animal studies with TCE do not apparently exist in humans. Therefore, given the built in safety factor, we do not expect any adverse health effects to the workers during an intermediate period of exposure (14 to 364 days).
Information on humans exposed to TCE for chronic periods of time (greater than 1 year) by the inhalation route consist mostly of studies of workers exposed to much higher levels than those detected or expected in the cave complex. These studies indicate that the nervous system may be the most sensitive target, such as in a study of 50 workers employed for various lengths of time (1 month to 15 years) in different industrial cleaning and degreasing operations using TCE. Complaints due to chronic exposure included decreased appetite, sleep disturbances, ataxia, vertigo, headaches, short-term memory loss, and fewer word associations. A greater frequency of symptoms was noted in workers exposed to higher (85,000 ppb) than lower (14,000 ppb) mean TCE concentrations (22). Other studies of workers occupationally exposed for chronic periods of time indicate that the liver and kidney are targets of TCE (18).
For long-term exposure (equal to or greater than 365 days), ATSDR has not been able to develop a chronic MRL because of the lack of adequate measurements of exposure levels in some studies and/or lack of health effects that could be specifically related to the exposures (18).
Because of the insufficient data from health studies and the likelihood that contaminant levels will change over time, it is not known what non-cancerous health effects long-term low-level inhalation exposure may have to workers who spend years working in the cave complex.
Cancer
The American Cancer Society estimates that in the United States, slightly less than half of all men and slightly more than one-third of all women will develop some form of cancer in their lifetime (23). To determine the theoretical cancer risk for adults exposed to hazardous chemicals, EPA has developed cancer unit risk factors (Oral Slope Factor). Cancer risks are calculated over a lifetime, estimated to be 70 years. DHSS calculated the cancer risk for the Oak Grove Village Well site and the different exposure pathways associated with the site using the worse case scenario (using the highest level of the cancer slope factor range, the maximum level detected, and the maximum expected exposure time). Because of the conservative nature of these calculations, this approach provides a theoretical estimated risk of cancer. In actuality, the true or actual risk is unknown and could be as low as zero. The cancer calculations can be found in Appendix C.
The ability of TCE to cause cancer from ingestion and inhalation exposure is presently under review by the EPA. TCE is classified by the International Agency for Research on Cancer as probably carcinogenic to humans (limited human evidence; sufficient evidence in animals). ATSDR has developed a Cancer Risk Evaluation Guide (CREG) for a number of chemicals. CREGs are comparison values set by ATSDR to determine if a chemical is above a level that should be further evaluated. CREG is a level that if exposed for a lifetime (70 years) could cause one additional cancer in a population of one million (1x10-6). Because TCE is under review, no CREG value is available for the different exposure pathways (24).
Since the Oak Grove Village public water users were likely exposed to TCE contaminated groundwater for approximately 6.5 years, the theoretical cancer risk was calculated for this maximum exposure period with the maximum known value of TCE contamination (25 ppb). Calculations for additional risks of cancer for past total exposure (ingestion and inhalation) to users of the public water system at the Oak Grove Village Well site for adults are 5.2 x 10-5 (or 52 additional cancers in a million people) and for children is 1.75 x 10-4 (or 175 additional cancers in a million people). Theoretical cancer risks were also calculated for private well users assuming the maximum TCE level detected (16.4 ppb) for the expected maximum period of time (14 years) those residents could have been exposed. Additional cancer risks for adults were 7.52 x 10-5 (or 75.2 additional cancers in a million people) and for children 1.56 x 10-4 (or 156 additional cancers in a million people). It is not expected that residents were exposed to the maximum level of contamination for the calculated period of time, thus the actual cancer risk for this population may be much lower and could be as low as zero.
Theoretical cancer risks were calculated for potential future exposure that would occur if the old village's well were reactivated. Calculations were made using the maximum known TCE level (42 ppb) for the estimated period of time (2 years) to get a new well operational. Additional cancer risks for adults were 2.74 x 10-5 (or 27.4 additional cancers in a million people) and for children is 9.6 x 10-5 (or 96 additional cancers in a million people), assuming the TCE concentration would remain constant. See Appendix C for calculations.
EPA presently has a draft document that draws information from 16 new state-of-the-science papers on the health effects of exposure to TCE. The slope factor for cancer calculations for ingestion uses these updated values to be more health protective. The EPA cancer slope factor for TCE ranges from 0.02 to 0.4 (mg/Kg/day)-1(21). For the above cancer calculations we used the maximum slope factor of 0.4 along with the maximum levels of contamination and the maximum period of exposure time to develop the worse case exposure scenario.
Workers in the cave complex were expected to have been exposed in the past and are presently being exposed to elevated levels of TCE contaminated air (maximum level of 260 ppb). While the detected levels of TCE are not above the Occupational Safety and Health Administration (OSHA) permissible exposure limit of 100 ppm (or 100,000 ppb) for the time weighted average (TWA) for an 8 hour workday or above the guidelines set by the American Conference of Governmental Industrial Hygienists (ACGIH) TWA of 50 ppm (or 50,000 ppb)(18), there is still reason for concern. While the OSHA and ACGIH levels do not consider the cancer potential, TCE may be carcinogenic (under review) and considering that a worker may spend eight hours a day, five days a week, 50 weeks a year in the cave complex, for their expected period of employment (25 years), there is a theoretical elevated risk of cancer among workers if the level of TCE air contamination remains elevated.
These worst case theoretical cancer calculations show a slight increased risk of cancer from past and potential future exposure, but in reality, humans exposed to TCE for chronic periods via the inhalation and dermal route in the workplace apparently do not experience an increased incidence of cancer, as indicated by numerous epidemiological studies. Ingestion exposure to TCE and cancer in humans from long-term low-level exposure is inconclusive, with a number of studies indicating an association and a number of studies not indicating an association (18). After evaluation of these 16 new studies on TCE health risks are complete, some of the uncertainties may be cleared up or further studies may need to be done.
Children and Other Sensitive Populations
A sensitive population may exhibit a different or enhanced response to hazardous chemicals than will most persons exposed to the same level of hazardous chemicals in the environment. Reasons for sensitivity might include genetic makeup, age, gender, health and nutritional status, and exposure to other toxic substances. In general the elderly, with declining organ function, and the young, with immature and developing organs, are more vulnerable to toxic substances than healthy adults.
A number of studies have suggested or shown associations between TCE exposure and children's health effects, but these studies had limitations that question their validity. Developing fetuses are susceptible to the toxic effects of chemicals that can cross the placental barrier. Also, premature and newborn infants will be more vulnerable to TCE exposure than the general population because of their immature and developing organs. In general, several studies suggest, but do not conclude, that exposure to TCE may cause birth defects (heart defects, respiratory system defects, eye defects, neural tube defects, and oral cleft defects) or childhood leukemia in children who were exposed in utero (as a fetus). In some studies, other chemicals were present besides TCE. Children listed in ATSDR's National Exposure Registry for TCE were reported as having higher rates of hearing and speech impairment, but there are still questions regarding these reports (18). Because it is difficult to predict the amount of exposure that a developing fetus may be exposed to at this site, it is also difficult to predict what birth defects or disease, if any, may result from exposure at this site. However, considering the maximum concentration of TCE (25 ppb) that Oak Grove Village water supply users may have been exposed to for a short period of time, it is not expected that developing fetuses and/or children would be affected. Women, who believe they were exposed to TCE during pregnancy and are concerned about possible health impacts to their unborn child, should consult their personal physicians.
Other sensitive populations including those that consume alcohol or who are treated with disulfiram (a drug used to treat alcohol dependency) may be at greater risk of TCE poisoning. This occurs because ethanol and disulfiram can both inhibit the metabolism of TCE and cause it to accumulate in the bloodstream, increasing its effects on the nervous system. Also, those with compromised liver and kidney function may be at a higher risk from exposure to TCE or its metabolites. The liver serves as the primary site of TCE metabolism and the kidney as the major excretory organ for TCE metabolites. People who smoke may also increase their risk of toxic effects from TCE (18).
During the site visits, meetings, and water sampling events, residents raised no health concerns. On private well sampling events that DHSS sampled or participated in, some technical questions were asked about the chemical and detected levels. DHSS discussed their private well sampling results and provided health information to those residents.
On September 9, 2003, DHSS held a public availability session to present the public comment version of the Oak Grove Village Well Public Health Assessment to the public and to gather and discuss any health concerns the public might have. No health concerns were presented in person at the meeting or received in the mail. Some technical comments were received during the public comment period that was extended an additional 30 days and are discussed in Appendix D.
This Public Health Action Plan (PHAP) for the Oak Grove Village Well site contains a description of actions to be taken by the Missouri Department of Health and Senior Services (DHSS), the Agency for Toxic Substances and Disease Registry (ATSDR) and other stakeholders. The purpose of the PHAP is to ensure that this public health assessment not only identifies public health hazards, but provides an action plan to mitigate and prevent adverse human health effects resulting from past, present, and future exposures to hazardous substances at or near the site. Below is a list of commitments of public health actions to be implemented by DHSS, ATSDR, or other stakeholders at the site:
PREPARER:
Arthur Busch
Environmental Specialist
Section for Environmental Public Health
Missouri Department of Health and Senior Services
REVIEWERS:
Rachelle Kuster
Environmental Specialist
Section for Environmental Public Health
Missouri Department of Health and Senior ServicesCherri Baysinger
Environmental Specialist
Section for Environmental Public Health
Missouri Department of Health and Senior ServicesGale Carlson
Chief, Assessment Group
Section for Environmental Public Health
Missouri Department of Health and Senior Services
ATSDR Technical Project Officer:
LCDR Alan Parham
Environmental Health Scientist
Division of Health Assessment and ConsultationRoberta Erlwein
Section Chief
Environmental Health Scientist
Division of Health Assessment and Consultation
ATSDR Regional Representative:
Denise Jordan-Izaguirre
Senior Regional Representative
EPA Region VII
. 1994
September.. Federal Registry Notice: 2002 September 5.. Last updated 2002 May 15.The Oak Grove Village Well Public Health Assessment was prepared by the Missouri Department of Health and Senior Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with the approved methodology and procedures existing at the time the public health assessment was initiated.
Alan Parham
Technical Project Officer, SPS, SSAB, DHAC
The Superfund Site Assessment Branch of the Division of Health Assessment and Consultation, ATSDR, has reviewed this public health assessment and concurs with its findings.
Roberta Erlwein
Section Chief, SPS, SSAB, DHAC, ATSDR
Figure 1. Oak Grove Village Well Site Location Map
Figure 2. Oak Grove Village and Other Areas with TCE Contaminated Water
TABLE 1: Oak Grove Village Well Site Exposure Pathways
| Pathways Name |
Exposure Pathways Elements |
Time |
Type of Pathway | ||||
| Source | Environmental Media | Point of Exposure | Route Of Exposure | Receptor Population | |||
| Groundwater | TCE Contaminated Groundwater | Groundwater | Residents connected to Oak Grove Village Water | Ingestion Inhalation Dermal Contact |
Oak Grove Village Public Water Users | Past | Completed |
| Groundwater | TCE Contaminated Groundwater | Groundwater | Private Well Owners below MCL | Ingestion Inhalation Dermal Contact |
Private Well Users | Past, Present, Future |
Completed, Potential |
| Groundwater | TCE Contaminated Groundwater | Groundwater | Private Well Owners above MCL | Ingestion Inhalation Dermal Contact |
Private Well Users | Past | Completed |
| Groundwater | TCE Contaminated Groundwater | Groundwater | Private Well Owners above MCL | Ingestion Inhalation Dermal Contact |
Private Well Users | Future | Potential |
| Groundwater | TCE Contaminated Groundwater | Groundwater | Residents Connected to Oak Grove Village Water | Ingestion Inhalation Dermal Contact |
Oak Grove Village Public Water Users | Future | Potential |
| Groundwater | TCE Contaminated Groundwater | Groundwater | Residents Connected to Sullivan Public Water | Ingestion Inhalation Dermal Contact |
Sullivan Public Water Users | Future | Potential |
| Air in Cave | TCE Contaminated Groundwater | Cave Air | Cave Interior | Inhalation | Cave Employees and Visitors | Present, Future |
Completed |
APPENDIX C: EXPOSURE CALCULATIONS
Click here to view Appendix C in PDF format (PDF, 39KB)
APPENDIX D: SUMMARY OF COMMENTS RECEIVED ON THE PUBLIC COMMENT VERSION OF THE OAK GROVE VILLAGE PUBLIC HEALTH ASSESSMENT
Comments:
Agreed. However, considering that TCE was detected at only six parts per billion in 1986 and gradually increased from that point, we believe that using the worst case exposure scenario for the known years of exposure covers any additional exposure that may have occurred.
Air sampling data is presented as parts per billion volume (ppbv) while health and regulatory levels are presented in parts per billion (ppb), which in reality are the same units. The text has been revised so that all concentrations are reported in ppb to avoid any confusion.
The public health assessment uses the ATSDR Public Health Assessment Guidance Manual for its methodology and is not intended to be a quantitative document, but instead, to explain to the public what their expected exposure may have been in the past, present, and future and the possible health effects from that exposure. The public health assessment uses the worse case scenario, which would include using the upper range number for cancer risk as per the guidance manual when actual exposure is not known. A reference to the ATSDR PHA Guidance Manual has been added to the text.
Agreed. The text has been changed to state that it will be difficult to predict groundwater movement in the karst geology, even though four of the five dye trace studies from the Sullivan and Oak Grove Village areas have appeared in LaJolla Springs. Also, the PHA recommends that more sampling be done to determine the nature and extent of the TCE contamination that should aid in creating a more complete understanding of groundwater movement.
The PHA simply reports information from the Remedial Investigation and the levels of contamination detected during recent sampling events. The main purpose of the PHA is to determine how humans can be exposed to those contaminants and the possible adverse health effects from that exposure. Determination of the source(s) and levels of the TCE contamination in the groundwater, air, and spring water are part of the Remedial Investigation that is now in phase II.
OSHA standards assume that workers are exposed to hazardous chemicals used in or generated as a result of routine work activities and that workers are trained to control or prevent exceedances of its exposure standards (including the use of personal protective clothing, medical monitoring, and gear to help prevent excessive exposures. Because TCE is not used or generated at the LaJolla cave complex and accordingly these programs are not in place, DHSS has taken a more protective approach to the assessment of the health of workers and visitors. Even with this more protective approach, DHSS feels that visitors to the cave complex do not face any additional risk because their exposure does not exceed ATSDR's MRL for acute exposure to TCE.
The site is listed in EPA's National Priority List (NPL) as the Oak Grove Village Well Site, which is where in 1986 the original discovery of TCE contaminated groundwater occurred. Besides the Oak Grove Village well, other areas in the vicinity of the well have also been affected by the TCE contaminated groundwater, including some Sullivan city wells, a number of private wells, and LaJolla Spring and its associated cavern complex.
The focus of the PHA is to determine if exposure to the public has, is, or will occur and to recommend ways to eliminate that exposure and to determine what adverse health effects that exposure may cause. Even if an area of contamination was found not to be associated with the Oak Grove Village Well site, but was still affecting or could affect the health of the public it would still be our obligation along with the regulatory agencies to investigate the site and eliminate that exposure to the public.
APPENDIX E: GLOSSARY OF TERMS AND ACRONYMS USED IN THE OAK GROVE VILLAGE WELL PUBLIC HEALTH ASSESSMENT
ATSDR defines an exposure pathway as having 5 parts:
When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.
