PETITIONED PUBLIC HEALTH ASSESSMENT
CONNECTICUT CORRECTIONAL INSTITUTION
(a/k/a SOMERS CORRECTIONAL FACILITY)
SOMERS, NEW HAVEN COUNTY, CONNECTICUT
The tables in Appendix B list contaminants in each medium. These contaminants are evaluated in subsequent sections of the public health assessment to determine whether exposure to them has public health significance. ATSDR selects and discusses contaminants based upon several factors. They include concentrations on and off-site, the quality of the field and laboratory data, sample design, comparison of on-and off-site concentrations to public health assessment comparison values for noncarcinogenic and carcinogenic endpoints, and community health concerns.
The listing of a contaminant in the tables does not mean that it will cause adverse health effects, if exposure occurs at the specified concentrations. Contaminants included in the tables are further evaluated in this public health assessment. The potential for adverse health effects resulting from exposure to contaminants of health concern is discussed in the Public Health Implications section.
Comparison values for ATSDR public health assessments are contaminant concentrations in specific media that are used to select contaminants for further evaluation. ATSDR and other agencies developed these values to provide guidelines for estimating the media concentrations of a contaminant that are unlikely to cause adverse health effects, given a standard daily ingestion rate and standard body weight (see Appendix C for a description of the comparison values used in the public health assessment).
In 1993, Fuss and O'Neill sampled surface water from Woods Stream and its tributary as part of the source investigation. A total of nine surface water samples were collected and analyzed for the presence of PCE and trichloroethylene (TCE). PCE was detected in the tributary near the south prison fence, near the sand filter beds, and at the confluence of the tributary and Woods Stream. The maximum level detected (292 ppb) was detected in the area of the small stream it runs by the sand filter beds. In August 1994, Fuss and O'Neill resampled surface water in the same locations. The maximum level detected in 1994 was 146 ppb, from a water sample taken near the sand filter beds (Table 1, Appendix B).
Further surface water sampling was conducted by Fuss and O'Neill in January 1995 (Fuss & O'Neill, Additional Environmental Investigations, Osborn CCI, January 1996). and PCE levels detected were below ATSDR Comparison Values.
Soil and sediment
In 1993, Fuss and O'Neill sampled sediments in Woods Stream and its tributary in conjunction with the surface water sampling. Levels of TCE and PCE were detected in sediments in the same area where PCE was detected in surface water. The maximum levels of PCE and TCE were 499 ppb and 221 ppb, respectively (Table 2, Appendix B). Additional subsurface soil sampling was conducted by Fuss and O'NEILL in 1995 in the area of the former wastewater treatment plant on-site. The levels of PCE were below comparison values (Fuss & O'Neill, Additional Environmental Investigations, Osborn CCI, January 1996).
On-site subsurface soil testing was conducted in the area of the laundry facility as a follow-up to results of soil gas testing. Subsurface soil levels (0-7 feet) had PCE concentrations ranging from 9 to 71 ppm in the area of the laundry facility. These elevated levels, are above the comparison value for PCE in soil (70 ppm). During soil sampling in October 1983, TCE was also detected in subsurface soils in the area of the laundry facility at a maximum concentration of 66 ppm. This value is above ATSDR's comparison value of 60 ppm. The distribution of PCE and TCE contamination indicated a pattern of contamination consistent with a surface spill or related surface release. Whether this continues downward to bedrock was not determined.
In December 1993, approximately 150 cubic yards of the PCE-contaminated soil were removed from this area. Sampling at the limits of the area of excavation confirmed the removal of soils above the 0.1 ppm action level, where possible.
In 1986, the state began detecting PCE in supply wells S2 and S3. The maximum level detected was 27 ppb. Drinking water for the inmates and workers was obtained by blending water from the wells. Between 1986 and 1990, Osborn CCI mixed water from wells S1, S2, S3, and S4. Water quality was monitored on a quarterly basis. Levels ranged from 1.3 to 11 ppb, with an average level of 6.8 ppb. In April 1990, CDPHAS lowered the action level for PCE from 20 ppb to 5 ppb. At this time, Osborn CCI discontinued use of well S2 and began using the prison supply well in Enfield (Table 3, Appendix B).
In 1991, the state contracted with Fuss and O'Neill to investigate the source of PCE contamination in the supply wells. In 1993, Fuss and O'Neill sampled on-site monitoring wells for PCE and other volatile organic compounds (VOC). The maximum level of PCE detected was 4970 ppb. TCE was also detected above comparison values. Further groundwater samples were taken and analyzed in January 1995, and the levels of PCE and TCE detected were below comparison values (Fuss & O'Neill, Additional Environmental Investigations, Osborn CCI, January 1996).
In 1993, Fuss and O'Neill sampled soil gas in areas suspected to be sources of PCE groundwater contamination. These areas were: the former sand filter beds, the former sludge drying beds, the former floor drain outfall area, the boiler plant tanks, and the laundry area. Samples were analyzed in the field using direct injection into a SRI Model 8610 gas chromatograph equipped with photo ionization and electrolytic conductivity detectors. The gas chromatograph was calibrated for benzene, toluene, xylene, TCE, and PCE. The minimum detection limit was 1 to 5 ppb.
The maximum PCE level detected was near the former laundry facility and was 4829 ppb. PCE levels were not detectable 20 feet from this area. Levels of PCE below 30 ppb were also detected near the boiler house area. PCE was not detected 80 feet from the boiler house. No VOCs were detected in any of the other areas (Table 4, Appendix B).
In March 1993, the Sanitarian for the Town of Somers took random samples from private wells throughout the town. Wells were sampled for VOCs. Two wells from the Rye Hill Circle area were found to have elevated levels of PCE.
The following month, the state conducted an investigation of all the private wells in the Rye Hill Circle area. Wells were sampled for VOCs. Thirty-five of the 74 wells had PCE levels over 5 ppb. The maximum level detected was 500 ppb (Table 5, Appendix B)
Surface Water and Sediment
In May 1993, and August 1994, Fuss and O'Neill took surface water samples from Woods Stream at the property line and 100 feet north of George Wood Road. These samples were analyzed for VOCs, but none were detected. No sediment samples were taken at these locations.
In February 1994, residents hired a contractor to conduct surface water sampling of Woods Stream off-site. PCE was detected at 2.7 ppb on the north side of George Wood Road, about a half mile south of Osborn CCI, and at 2.3 ppb just south of the property line (Lawsuit 1993) (Table 6, Appendix B).
Toxic Chemical Release Inventory
ATSDR searched the EPA Toxic Chemical Release Inventory (TRI) for the site and local area. TRI is an EPA maintained database containing a summary of toxic chemical releases reported by industries as required by Section 313 of the Emergency Planning and Community Right-To-Know Act of 1986. No toxic releases were reported by the facility named (Osborn CCI), city, or zip code (06071).
In preparing this public health assessment, ATSDR relies on the information provided in the reference documents. We assume that adequate quality assurance and quality control measures were followed regarding chain of custody, laboratory procedures, and data reporting, unless stated.
No physical hazards were noted during the site visit. Access to the site is restricted with typical maximum security prison fences and guards.
To determine whether people were exposed to contaminants originating from the Osborn CCI site, ATSDR evaluated the environmental and human components that lead to human exposure. This pathways analysis consists of five elements:
- 1) source of contamination
2) environmental medium in which the contaminants may be present or may migrate
3) points of human exposure
4) routes of human exposure such as ingestion, inhalation, or dermal exposure
5) receptor population.
ATSDR identifies exposure pathways as completed or potential. A completed exposure pathway exists in the past, present, or future if all five elements of an exposure pathway link the contaminant source to a receptor population. Potential pathways, however, are defined as situations in which at least one of the five elements is missing, but could exist. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. All completed and potential exposure pathways for this public health assessment are presented in Table 7, Appendix B.
On-site Supply Wells
Workers and inmates at the Osborn CCI consumed water with PCE levels above 5 ppb for at least ten years. The PCE contamination was first detected in supply well S2 at 27 ppb and S3 at 12 ppb. Less than a month later, Osborn CCI mixed water from wells S1 and S4 to lower the PCE levels below 20 ppb (the action level at that time). Between 1986 and 1990, the average PCE level was about 7 ppb (based on quarterly monitoring). In 1990 (when the action level for PCE was lowered to 5 ppb), Osborn CCI discontinued use of well S2, and began using a supply well on the Enfield prison property. Since that time, PCE concentrations have been below 5 ppb.
In 1986, the state first detected PCE at 27 ppb on-site in two of the Osborn CCI supply wells. Subsequent investigation in the early 1990's found that the sand filter bed from the on-site waste water treatment facility was the primary source of PCE contamination in groundwater. The boiler plant (still operational) may be an additional source of PCE. The waste water treatment facility operated from 1963 until 1984, when Osborn CCI was connected to the Enfield Sewer System.
The on-site supply wells are the only source of potable water for the prison facility. Exposures routes include ingestion and inhalation (while showering) by inmates and workers. The duration of exposure to approximately 7 ppb PCE is about 10 years. Since monitoring data are not available before 1986, the duration and extent of exposures are not known. However the prison was not fully operational before 1963.
Private well water
Residents down-gradient of Osborn CCI used private well water contaminated with PCE. Exposure routes include ingestion and inhalation (while showering). Residents on Rye Hill Circle whose property borders the prison's had the highest levels of PCE (500 ppb). Exposures ceased in 1993 with the installation of granulated activated carbon filters.
Environmental investigations indicate that the on-site sand-filter beds and possibly the boiler plant are sources of PCE contamination in off-site private wells. Fuss and O'Neill have identified a plume of PCE contamination in the bedrock aquifer, which extends from the site into the Rye Hill Circle Area.
The majority of the homes in the Rye Hill Circle area were built between 1976 through 1980, indicating the exposure to PCE may have been up to 18 years. However, reports indicate that private wells are at the "leading edge" of the plume. It is unlikely that exposures were worse or even constant over the last 18 years (Figure 4, Appendix A).
Surface water and sediments
PCE was detected in Woods Stream both on and off-site. The maximum level detected was approximately 400 ppb. Residents report that children play in this stream, and may be exposed to PCE through contact with the stream, or incidental ingestion of stream water. However, the levels of PCE do not exceed comparison values for this type of intermittent and short-term exposure. Therefore, this pathway has been eliminated from further analysis.
Soil gas measurements were taken to help determine potential sources of PCE contamination. Results of the sampling indicate limited areas of elevated PCE concentrations in soil gas on-site. However, there is no indication that PCE-contaminated soil gas has migrated off-site. The soil gas pathway was considered because of the possibility for PCE-contaminated soil gas to collect in residences off-site, and cause further exposure via inhalation of PCE in homes.
However, there is no evidence that PCE-contaminated soil gas has migrated off-site via groundwater or subsurface soil. Therefore, this pathway has been eliminated from further analysis.
On-site subsurface soil
The maximum level of PCE detected in on-site subsurface soil was 71 ppm, which is slightly above a comparison value of 70 ppm. This PCE-contaminated soil could have been another possible source of groundwater contamination; so it was removed in 1994. However, direct contact with this soil would not pose a health threat. Therefore, this pathway has been eliminated from further analysis.
In this section, ATSDR discusses the health effects that could plausibly result from exposures to site contaminants. While the relative toxicity of a chemical is important, the response of the human body to a chemical exposure is actually determined by several additional factors, including the magnitude of exposure (how much), the duration of exposure (how long), and the route of exposure (i.e., breathing, eating, drinking or skin contact). Lifestyle factors (i.e., occupation and personal habits) have a major impact on the likelihood, magnitude, and duration of exposure. In addition, individual characteristics such as age, sex, nutritional status, overall health, and genetic constitution affect how a contaminant is absorbed, distributed, metabolized, and eliminated from the body. In short, the probability that exposure-related adverse health outcomes will actually occur does not depend solely on concentrations in environmental media.
Based on the available scientific data, much of which the agency has collected in its Toxicological Profiles, ATSDR has determined concentrations of chemicals that can reasonably (and conservatively) be regarded as harmless, assuming default conditions of exposure. The resulting comparison values and health guidelines, generally include ample safety factors to ensure protection of sensitive populations. They are used to screen contaminant concentrations at a site and to select so-called "chemicals of concern" that warrant closer scrutiny by agency health assessors and toxicologists. A "chemical of concern" is defined as any chemical that is detected in air, water, or soil at concentrations that exceed one or more of ATSDR's comparison values. (See Appendix C for a more complete description of ATSDR's comparison values, health guidelines and other values ATSDR uses to screen site contaminants.)
It cannot be emphasized strongly enough, however, that comparison values are not thresholds of toxicity. While concentrations at or below the relevant comparison value may reasonably be considered safe, it does not necessarily follow that any concentration that exceeds a comparison value would be expected to produce adverse health effects. Indeed, the whole purpose behind highly conservative, health-based standards and guidelines is to enable health professionals to recognize and resolve potential public health problems before that potential is realized.
Chemicals of Concern at Somers
The only contaminants of concern detected so far at Somers are PCE and TCE in groundwater. With regard to these contaminants, ATSDR considers that the level and duration of exposure experienced by Somers residents was insufficient to produce any adverse health effects. These two chemicals are further discussed below. More toxicological background material is provided for PCE than for TCE because the maximum concentration of the former was much greater, and has engendered more community health concern. Technical discussions of PCE and TCE carcinogenicity may be found in Appendices F and G, respectively.
Trichloroethylene (TCE) is a fat solvent used primarily for degreasing metals, but exposure is probably more widespread in the dry cleaning industry (EPA, 1993; ATSDR, 1993). Since it does not adsorb strongly to soils, surface spills can leach into the groundwater (EPA, 1993). Central nervous system depression is the most prominent effect of excessive inhalation exposure in occupational settings. The current Occupational Threshold Limit Value (TLV) is 50 ppm or 259 mg/m3. The oral toxicity of TCE is rather low.
In 1993, TCE was detected at a maximum level of 8.6 ppb in one of the private wells at Somers (Fuss and O'NEILL, Inc). The duration of exposure is limited to a maximum of 13-18 years, since the homes in this area were built between 1976 and 1980, and steps were taken in 1993 to eliminate the exposure (i.e., by making available filtered water, and connection to public water). However, since these homes are now on the leading edge of the PCE plume, levels of exposure were probably much lower in the past. The actual duration of past exposure may have been much less than 13-18 years. The maximum level of TCE detected in groundwater at Somers (8.6 ppb) only marginally exceeded EPA's MCL of 5 ppb (ATSDR, 1993), and was very much lower than ATSDR's intermediate EMEGs of 20,000 ppb for adults and 7,000 ppb for children. No chronic EMEG for TCE in drinking water is available. (Note: ATSDR's EMEGs for TCE are so much higher than the MCL because the former are based only on non-cancer effects, while the latter takes into account the contaminant concentration in drinking water that EPA deems protective of public health, considering the availability and economics of water treatment technology).
Based on these comparison values for non-cancer effects, the maximum estimated exposure to TCE at Somers would not be considered to be toxicologically significant.
Tetrachloroethylene (also known as perchloroethylene or PCE) is a chlorinated hydrocarbon used primarily as a dry-cleaning solvent, and less often, as a degreasing and drying agent for metals (ATSDR, 1993b). Not known to occur naturally, PCE enters the environment from sources such as vaporization losses from dry cleaning, metal degreasing industries, and leachate from vinyl liners in asbestos-cement water pipelines used for water distribution (EPA, 1993). The general population will be exposed to PCE through inhalation of contaminated ambient air and ingestion of contaminated drinking water, especially from polluted groundwater sources. In humans, only limited metabolism of PCE takes place and most absorbed PCE is eliminated unchanged in expired breath (Ellenhorn & Barceloux, 1988; Patty 1981). PCE's long half-life (65 hours) in human breath reflects its tendency to partition into fat.
Carcinogenic Effects. PCE is a nongenotoxic animal carcinogen. The induction of cancers in rodents requires extremely high doses and involves elements of rodent biology not shared by humans. (See Appendix F, "PCE and Cancer".) A number of epidemiological studies of men and women exposed occupationally by inhalation to PCE have not identified an increased risk of cancer (ATSDR, 1993b). (It should be noted that occupational exposures are typically much higher than residential exposures.) Therefore, the relevance of the animal data is now being questioned by many scientists and government agencies. Considering the dubious carcinogenicity of PCE at low doses in humans, and the limited level and duration of exposure at Somers, ATSDR has based the current toxicological evaluation for Somers on the potential for noncancer effects, rather than on cancer-specific comparison values such as ATSDR's CREG.
Non-Carcinogenic Effects - Oral. PCE is only slightly to moderately toxic in laboratory animals. In mice and rats, the oral LD50 (the orally-administered dose that will kill half of all treated animals) is 8,850 and 2,600 mg/kg, respectively (EPA, 1993; Patty, 1981). By comparison, the acute LD50 of ethyl alcohol in rats is about 10,000 mg/kg (Klassen & Eaton, 1991). The liver is the primary target of PCE administered orally to animals (Andrews & Snyder, 1991). In humans, however, ingestion of a small amount of undiluted PCE is unlikely to cause permanent injury.
In humans, PCE was formerly used as a remedy for intestinal worms in oral doses of 2.8-4.0 ml or about 4.5-6.5 grams (NRC, 1980).
Inebriation was the only troublesome side effect noted in 46,000 patients. In one poisoning case, a 6-year-old boy went into a coma after ingesting 12 to 16 grams of PCE (HSDB, 1992; Koppel et al, 1985). The clinical condition of the patient improved considerably with hyperventilation therapy. Jaundice was reported in an infant fed breast milk containing 3,000 to 10,000 ppb PCE (Bagnell & Ellenberger, 1977). The infant recovered after breast-feeding was discontinued.
Ingestion Exposure at Somers. According to available information, 35 wells have been found to be above the State of Connecticut drinking water standard of 5 ppb. Fifteen (15) of these wells have concentrations between 120-500 ppb (Petition letter).
Similar to TCE discussed above, the duration of PCE exposure is limited to a maximum of 13-18 years, but was probably much less since the homes are only now on the "leading edge" of the PCE plume. For the same reason, levels of some residents' exposure in the past were probably much lower than the current maximum. Prison inmates and staff were exposed to an average level of about 7 ppb for approximately 4 years. The latter level of PCE only marginally exceeds the MCL of 5 ppb, and is not likely to have been toxicologically significant over the limited duration of exposure. Based solely on health guidelines for noncancerous effects, the larger (maximal) residential exposure is also unlikely to be associated with any acute or chronic adverse health effects, past, present, or future. This conclusion is based on comparisons with EPA's oral reference dose and drinking water standards for PCE.
The Drinking Water Equivalent Level (DWEL) is a lifetime exposure level specific for drinking water (assuming that all exposure is from that medium) at which adverse noncarcinogenic health effects would not be expected to occur. The DWEL for PCE is 500 µg/L (IRIS, 1994), which coincidentally is equal to the highest recorded level of PCE in Somers well water. The DWEL value includes an uncertainty factor of 1,000, which means that this DWEL is 1,000 times lower than the no effect level observed in animal studies.
Assuming (conservatively) 10 years of exposure to 500 µg/L PCE in drinking water (before bottled water and, later, in-house treatments were provided) and 60 years of exposure to 3.0 µg/L (the median PCE concentration in the finished groundwater of 36 U.S. cities), the average lifetime exposure would be 0.006 mg/Kg/day, which is below the EPA's reference dose (RfD) of 0.01 mg/kg/day (IRIS, 1994). The RfD is an estimate of a daily exposure to the human population that is likely to be without an appreciable risk of deleterious effects during a lifetime. Since the residents of Somers have actually been exposed to PCE for much less than the 70-yr lifetime on which both the DWEL and the RfD are based, the margin of safety is even greater.
EPA's Longer-Term Health Advisory for PCE, a PCE level in drinking water that should not be associated with any deleterious health effects over a period of up to 7 years, is 1,400 µg/L for children and 5,000 µg/L for adults (i.e., 3-10 times higher than the maximum level found in Somers well water), and includes a built-in "safety factor" of 100 to allow for interspecies and intrahuman variability (IRIS, 1994).
Thus, at the levels of PCE reported in the wells of Somers, Connecticut, the 10 or more years of exposure that may have been experienced by some Somers residents are unlikely to produce any long-term adverse human health effects.
Nor would any acute toxic effects have been expected to result from a daily exposure of 1 mg/day (equivalent to consuming two liters of water per day with 500 µg of PCE per liter of water). It must be emphasized that most residents experienced exposures significantly lower than the maximum level on which this analysis was based.
Non-Carcinogenic Effects - Inhalation. The following health effects of PCE have been reported in people occupationally exposed to high concentrations, i.e. higher than the current TLV of 25 ppm PCE in air (ACGIH, 1995). In excess of 100 ppm, PCE is irritating to mucous membranes and the respiratory tract (EPA, 1993; Ellenhorn & Baeceloux, 1988) and may produce largely reversible effects in the liver (HSDB). The major response to higher concentrations (e.g., 200 to 500 ppm) is depression of the central nervous system, the symptoms of which may include dizziness, headache, vertigo, inebriation and unconsciousness (EPA, 1993; Patty, 1981).
In one study, there was no response in men or women repeatedly exposed to 100 ppm for 7 hours per day (ACGIH, 1986). In another study, electroencephalograph scores suggested cerebral cortical depression in 4 male subjects exposed by inhalation to 100 ppm PCE for 7.5 hours/day for 5 days (Hake & Stewart, 1977). However, no neurological effects were identified by a battery of behavioral and neurological tests. Massive exposures sufficient to cause unconsciousness have also resulted in proteinuria, hematuria, and pulmonary edema (HSDB, 1992).
Inhalation Exposure at Somers: Residents' inhalation exposures at Somers would not, in the judgement of ATSDR, have been sufficient to cause any of the effects mentioned in the previous section. Although there are no indoor air data on PCE at Somers, it is reasonable to expect that PCE levels in residential air at Somers will be orders of magnitude lower than those shown to be without adverse health effects in occupational settings (i.e., enclosed spaces). Nevertheless, concentrations of PCE may become locally elevated in residential indoor air as a result of volatilization from contaminated water, especially that used in bathing or showering.
ATSDR has calculated what it believes to be "a worst case scenario" for inhalation exposure to PCE associated with showering or bathing in PCE-contaminated groundwater at Somers. In this worst case scenario, estimates of the resulting concentration of PCE in air are still below ATSDR's acute Environmental Media Evaluation Guideline (EMEG) of 0.6 ppm, and 200 times lower than the level considered by OSHA safe to work in for 8 hours per day, 40 hours per week (i.e., the TLV of 25 ppm). Thus, ATSDR considers that no adverse health effects would be expected as a result of bathing in water containing 500 µg PCE/L. (This level is the bathing standard for PCE in the State of Connecticut.)
Concerns regarding Health Histories and Medical Records
Seventy-five health histories were provided to ATSDR staff, along with several medical records. All of these health concerns were documented in the HEALTH OUTCOME DATA AND COMMUNITY HEALTH CONCERNS Section.
In most cases of low-level chronic exposure to a chemical such as PCE, it is not possible to conclusively establish a causal link between the reported health effects in residents and the estimated exposures. However, the plausibility of such a link may be tested by comparing site-specific health outcome data with the known consequences of higher level exposures in workers, poisoning cases, and laboratory animals. Based on such a comparison, it is the opinion of ATSDR that the exposures to PCE experienced by the persons at Somers are unlikely to have caused any adverse health effects in the past and are not expected to cause any in the future.
When a health problem correlates with exposure, it is certainly natural to assume that the exposure may have actually caused the health problem. In the case of the PCE exposure at Rye Hill Circle, reports of health effects that ceased after filters were installed were considered, along with what is known about PCE exposure generally. However, ATSDR could not reconcile the reported correlation between exposure and symptoms since adverse health effects have not been seen at doses significantly higher than those that may have been experienced by Rye Hill Circle residents. Thus, while it was reasonable to consider PCE exposure as a possible cause of these health effects, ATSDR believes that alternative explanations should now be considered.
Based on what is known about the PCE exposure, it is unlikely that the past PCE exposure could have caused an increased rate in these illnesses in the Rye Hill Circle population.
Given the non-specific nature of the reported symptoms and the low levels of apparent exposure to PCE, it would be virtually impossible to establish a causal relationship between the two, even if one existed. The likelihood that the dose of PCE received by Rye Hill Circle area residents could have caused health effects, is remote based on information about effects in animals and workers that have been exposed to higher levels of PCE. Therefore, ATSDR does not believe that the levels of PCE-exposure experienced by area residents would have adversely affected their health.
Concerns regarding groundwater contamination
Residents of the Rye Hill Circle area also had health concerns related to the stress of coping with the discovery of PCE in their water supply. Several residents reported that the stress has negatively impacted their health and quality of life. Lingering unanswered concerns continue to aggravate stress levels.
ATSDR conducted an exposure investigation of the groundwater pathway (APPENDIX H). This investigation was able to more accurately estimate the extent and duration of PCE-contamination in the Rye Hill Circle area water supply. ATSDR will revise any previous public health decisions if warranted. Information generated during the exposure investigation may also be used to assure that public health will be protected in the future. Meanwhile, ATSDR considers that the answers and information provided in the current public health assessment should help to reduce stress and anxiety among affected residents.
The only information available is that residents had PCE in their water supplies in 1993, with a maximum level of 500 ppb. The exposure could have been up to 18 years (when the homes were built). However, because homes are only now on the leading edge of the plume, the actual duration of past exposures is likely to be much less than 18 years. See the Public Health Action Plan for more information regarding this exposure investigation.
Protecting public health in the future should be a primary concern when considering remedial alternatives at Osborn CCI. ATSDR will use information gathered as part of this public health assessment and the exposure investigation to provide input into remedial decision making as needed. It should be noted, however, that the toxicological evaluation of this site revealed no threat to human health and that exposures via drinking water have already been eliminated.