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PUBLIC HEALTH ASSESSMENT

SMITHTOWN GROUNDWATER CONTAMINATION
(a/k/a SMITHTOWN GROUND WATER CONTAMINATION)
SMITHTOWN, SUFFOLK COUNTY, NEW YORK


SUMMARY

The Smithtown Groundwater Contamination site is in the Town of Smithtown, encompassed by the Villages of Nissequogue and Head of the Harbor and the Hamlet of St. James in Suffolk County, New York. Groundwater in the area is contaminated with volatile organic compounds (VOCs), primarily tetrachloroethene (also known as perchloroethylene, perc, or PCE). Many residents in the area use private wells for their potable water supply. Residents with contaminated private wells were exposed to VOCs in their water for an undetermined amount of time, possibly up to thirty years.

Samples collected from private wells between 1996 and 1998 showed that 38 wells were contaminated with PCE above the United States Environmental Protection Agency (US EPA) maximum contaminant level (MCL) and the New York State Department of Health (NYS DOH) drinking water standard of 5 micrograms per liter (µg/L), which is about the same as parts per billion or ppb for water. Six of the 38 wells had concentrations of PCE that also exceeded the US EPA's Removal Action Level of 70 µg/L. One additional well sampled in 1996 was contaminated with 1,2-dichloropropane in excess of the US EPA MCL and NYS DOH drinking water standard of 5 µg/L.

For some compounds, the US EPA MCL and the NYS DOH drinking water standards differ. In 1998, nine wells were contaminated with 1,1,1-trichloroethane and one well was contaminated with cis-1,2-dichloroethene at levels which exceeded the NYS drinking water standard of 5 µg/L; these wells did not exceed the US EPA's MCL for these compounds of 200 µg/L for 1,1,1-trichloroethane and 70 µg/L for cis-1,2-dichloroethene.

Beginning in April 1998, the US EPA initiated a removal action to reduce exposures to water contaminated with VOCs above the US EPA MCLs. As of April 1999, all 38 homes that had PCE concentrations in excess of the US EPA and the NYS DOH drinking water standard had been provided with a treatment system or an alternative water supply. Those 38 homes included the well with cis-1,2-dichloroethene and two with 1,1,1-trichloroethane. Seven wells with 1,1,1-trichloroethane and the well with 1,2-dichloropropane remain without treatment systems.

Because people were exposed to VOCs in drinking water at levels above New York State drinking water standards at the Smithtown Groundwater Contamination site, public health actions were needed to interrupt or minimize exposures (primarily to PCE). These exposures may have increased or continued had these measures not been taken. Human exposures to these contaminants occurred via ingestion, inhalation, and dermal contact. Exposures to VOCs in drinking water may have occurred for as long as 30 years. Studies of workers exposed to PCE and other chemicals suggest, but do not prove, that PCE causes cancer in humans. Somewhat weaker evidence that comes from other studies show that people living in communities with drinking water supplies contaminated with mixtures of chemicals including PCE have higher risks of certain types of cancer than do people living in communities with uncontaminated drinking water. Because there is evidence from studies in animals and humans that exposure to elevated levels of PCE can increase the risk of adverse cancer and noncancer health effects in humans, we evaluated the potential health risk for exposure to these chemicals at the Smithtown Groundwater site.

Available data indicate that people drinking water from the six wells contaminated with PCE at the highest contaminant levels detected (82 µg/L to 200 µg/L) are estimated to have a moderate increased risk of developing cancer. Those exposed to 1,2 dichloropropane at the highest contaminant levels detected (14 µg/L) are estimated to have a low increased risk of developing cancer. The risks of non-carcinogenic effects - primarily to the liver, kidneys and nervous system - from exposure to site-related contaminants are estimated to be low to minimal. Some studies suggest, but do not prove, that the developing fetus may have increased sensitivity to the effects of PCE. The possibility that children may have increased sensitivity to PCE was taken into account when evaluating the potential health risks associated with the site.

Since 1996 and before treatment systems were installed, the Suffolk County Department of Health Services (SCDHS) issued health advisories to residents exposed to contaminants in their private drinking water supplies. In addition, the US EPA and Village officials held several community meetings to respond to residents' concerns. Residents expressed concerns about the possible sources of contamination and remediation of the problem. The NYS DOH continues to work with federal, county, and other state officials to address the remaining contamination and to ensure that the selected remedies are protective of public health.

The site currently presents no apparent public health hazard at the 38 residences which have been connected to public water supplies or where treatment systems have been installed to reduce levels of PCE contamination to below drinking water standards. In eight homes, residents may currently be exposed to levels of other site-related VOCs in excess of NYS DOH drinking water standards; however, the levels detected and the duration of exposure to date are not expected to result in adverse health effects. Future exposures could occur if groundwater is not remediated and contaminants migrate to additional wells, if new wells are installed in the contaminated plume(s), or if treatment systems are not maintained. Recommendations to reduce the threat of future or existing exposures include: maintaining the installed treatment systems and monitoring the quality of the treated water, installing additional treatment systems when VOC levels exceed the NYS DOH drinking water standards, providing public water where feasible, and pursuing a more permanent, long-term groundwater remedy.

This site is being considered for inclusion in the NYS VOC Exposure Registry. If this site is selected in the future, residents of households who were exposed in the past to VOCs from private well drinking water supplies will be asked by the NYS DOH to participate. The exposure registry allows long-term follow-up on the health status of persons with documented exposures to VOCs. An exposure registry such as this one is a resource for research that may help us learn whether exposures to VOCs are related to health effects. Future analysis, based on VOC Exposure Registry information, may increase understanding of potential health effects from exposures similar to those experienced by residents in the area affected by the Smithtown Groundwater Contamination site. People who are enrolled in the Registry will be kept informed of any research results that come from the Registry data.

The NYS DOH and ATSDR will continue to coordinate with the US EPA, SCDHS, and the NYS DEC to implement the recommendations in this public health assessment and explore options for providing uncontaminated water supplies for those residents who continue to use wells that have contaminated water. Residents who were exposed in the past to VOCs in drinking water will be considered for inclusion in the NYS DOH VOC Exposure Registry.


PURPOSE AND HEALTH ISSUES

The purpose of this public health assessment (PHA) is to evaluate the public health implication of the human exposure pathways from contaminants at the site. Moreover, this PHA fulfills the congressional mandate for a public health assessment for each site being proposed to the National Priorities List (NPL). This public health assessment will focus primarily on exposure to VOCs in private drinking water supplies, the only documented exposure pathway at the site. Exposures to VOCs from contamination at potential source areas, such as those associated with contaminated soils or vapors, can not be evaluated at the present time because appropriate information is not available. The actions taken to date to identify those potentially exposed and to provide an alternate source of drinking water for the homeowners with wells contaminated above the NYS DOH drinking water standard will be discussed in this document.


BACKGROUND

A. Site Description and History

The Smithtown Groundwater Contamination study area (site) is an area of contaminated groundwater in the Town of Smithtown, Suffolk County, New York and includes the Villages of Nissoquogue and Head of the Harbor, and the Hamlet of St. James. The area is approximately 2.5 square miles and is south of Stony Brook Harbor and east of the Nissequogue River (Figure 1). The study area is primarily residential with some light commercial industry to the east of the Village of St. James and to the south of Smithtown. Approximately 1,500 people live within the study area. Many residents in the study area rely on private wells as their sole source of potable water. Residential wells in the area are contaminated with volatile organic compounds (VOCs), primarily tetrachloroethene (also known as perchloroethylene, perc, or PCE).

Between 1996 and 1998, the Suffolk County Department of Health Services (SCDHS) collected approximately 150 water samples from homes with private wells throughout the area. The results indicated widespread VOC contamination. PCE was the predominant contaminant of concern and was the basis for the additional investigations conducted by the SCDHS and the United States Environmental Protection Agency (US EPA). The initial investigation found twenty-three wells contaminated with PCE at concentrations exceeding the US EPA Maximum Contaminant Levels (MCL) and the New York State Department of Health (NYS DOH) drinking water standard of 5 micrograms per liter (µg/L). The MCL is the maximum permissible level of a contaminant in water delivered to the free-flowing outlet of the ultimate user of a public water system (ATSDR, 1993). Four of the 23 homes had PCE concentrations exceeding the US EPA's Removal Action Level (RAL) of 70 µg/L.

As a follow up to the sampling conducted by the SCDHS, the US EPA collected approximately 350 well water samples from 300 homes to determine the extent of VOC contamination. The sampling was part of an Integrated Assessment to evaluate the site for both Superfund Removal Action and National Priorities List (NPL) eligibility. Analytical results indicated a total of 38 residential wells contaminated with PCE at concentrations above the US EPA MCL and the NYS DOH drinking water standard of 5 µg/L. Six of these wells were found to have levels of PCE exceeding the US EPA's RAL of 70 µg/L.

In addition to the PCE contamination, eleven of the residential wells sampled by the SCDHS and the US EPA were contaminated with other VOCs in excess of NYS DOH drinking water standards. While the US EPA MCL and NYS DOH drinking water standard are the same for PCE (5 µg/L), for some other VOCs, the NYS DOH drinking water standard is lower than the US EPA MCL. Nine wells had concentrations of 1,1,1-trichloroethane (1,1,1-TCA) at concentrations above the NYS DOH drinking water standard of 5 µg/L but below the US EPA MCL of 200 µg/L. Another well contained cis-1,2-dichloroethene above the NYS DOH drinking water standard of 5 ug/L but below the US EPA MCL of 70 µg/L. In one other well that was sampled only in 1996, the concentration of 1,2-dichloropropane exceeded the NYS DOH drinking water standard and the US EPA MCL of 5 µg/L.

The New York State Department of Environmental Conservation (NYS DEC) submitted a request to the US EPA in October 1997 for assistance in funding alternative water supplies for affected residents. The NYS DEC was not able to undertake actions because a source had not been identified. The site was proposed for the NPL on September 29, 1998. The site was listed on the NPL on January 19, 1999. The site was listed by the NYS DEC on its Registry of Inactive Hazardous Waste Disposal Sites in January, 2000.

To address the immediate health concern from exposure to PCE in drinking water, the US EPA initiated a removal action in April 1998. The US EPA supplied bottled water to four of the six residences with wells contaminated with PCE above the federal RAL. The other two residences with PCE concentrations above the RAL had granulated activated carbon (GAC) treatment systems installed at their own expense. In June 1998, the US EPA expanded the delivery of bottled water to homes where the State and federal drinking water standard for PCE was exceeded. These actions were undertaken until a more permanent solution could be implemented.

In July 1998, the US EPA initiated a removal action to provide a permanent water supply for residents. At residences where the US EPA MCL was exceeded and where water mains were available, the US EPA provided service connections to the public water supply. At residences where US EPA MCL was exceeded and water mains were not available, the US EPA installed GAC treatment systems or upgraded existing treatment systems. The US EPA continued bottled water delivery to homes where US EPA MCL was exceeded until final connections to water supply mains were made or alternative treatment systems were installed or upgraded.

Thirty-eight private residential wells had concentrations of PCE in excess of the US EPA's MCL and the NYS DOH drinking water standard. As a result of the US EPA's removal actions, all of these homes have alternative water supplies. A total of 29 homes were provided with connections to public water supplies. Household GAC water treatment systems were installed at seven homes; existing treatment systems were upgraded in two homes.

Three of the eleven wells that were contaminated with VOCs other than PCE at concentrations above NYS DOH drinking water standards were among the 38 wells where PCE concentrations exceeded the US EPA MCL. One of these was the well contaminated with cis-1,2-DCE above the NYS DOH drinking water standard. The other two had 1,1,1-TCA concentrations above the NYS DOH drinking water standard. These three residences were among those connected to the public water supply by the US EPA's removal action.

The US EPA's removal action addressed homes where VOC concentrations in private water supplies exceeded US EPA MCLs. However, for some VOCs, including 1,1,1-TCA, the NYS DOH drinking water standard is lower than the US EPA MCL. The US EPA cannot provide connections or treatment for wells where contaminant concentrations do not exceed Federal MCLs. Thus, seven wells where concentrations of 1,1,1-TCA exceeded the NYS DOH drinking water standard were not addressed by the US EPA's removal action. The removal action also did not address the residential well that exceeded the NYS DOH drinking water standard and US EPA MCL for 1,2-dichloropropane in 1996 because this isolated occurrence did not appear to be related to the other contamination in the area.

The US EPA is conducting a remedial investigation to determine the extent of the groundwater contamination and to identify potential source areas. The SCDHS has also investigated several former and current commercial/industrial facilities south and east of the site to identify potential sources of the contaminated groundwater plume or plumes. Potential responsible parties investigated thus far include seven dry cleaning facilities, five auto repair shops, a cesspool facility, a gas station and a bus maintenance facility. Waste disposal systems were contaminated with VOCs including PCE at twelve of the fifteen potential sources investigated by the SCDHS. At the direction of the SCDHS, these facilities removed the contaminated materials from their waste disposal systems and disposed of them properly. The SCDHS collected samples that confirmed the satisfactory remediation of these potential source areas.

B. Actions Implemented During the Public Health Assessment Process

Public water mains continue to be extended into affected areas. Additional homes are connected to the public water system as the water mains are extended. The SCDHS continued its water sampling program in the affected area and continued to investigate potential sources of the contamination.

C. Site Visit and Physical Hazards

NYS DOH staff met with SCDHS staff on May 12, 1999 and visited the affected area. The purpose of the site visit was to observe area characteristics and to inspect the locations of suspected sources. The site visit included a walking inspection of an area at the southern end of Stony Brook Harbor where spring water from an artesian well, Dunton Spring, is allegedly collected and a drive through the town and residential areas. Staff observed public water supply lines being installed at several locations within the site area. In the area of the spring, staff observed spring water flowing from a hose, which could be used for dispensing/collecting spring water. No physical hazards were identified at the site.

D. Demographics

The affected area was defined as the approximate 2.5 square mile region where well water is being tested for contamination. The NYS DOH estimated from the 1990 Census (US Bureau of the Census, 1991) that 1,500 people live within the area. This population is 98.4% white. The percent of persons of Hispanic origin is 2.9%. Based on the 1990 census, 4.8% of the population is under 6 years of age, 19.4% is 6-19 years of age, 69.3% is 20-64 years of age, and 6.5% is 65 years or older. In 1990 there were 321 females of reproductive age (ages 15-44) in the area. The area lies mostly within block groups 1349.04/9, 1350.04/1, and 1350.04/2. The median household income for this area is $90,500 in 1989, with 1.3% of the population living below the poverty level. There are no schools or nursing homes in the area. The following chart compares these demographics with statewide averages.

 

New York State

Area of Site
Age Distribution
     <6 8.3% 4.8%
     6-19 18.4% 19.4%
     20-64 60.2% 69.3%
     >64 13.1% 6.5%
Race Distribution
     White 74.4% 98.4%
     Black 15.9% 0.3%
     Asian 3.9% 1.4%
     Other 5.8% 0.0%
Ethnicity Distribution
     Percent Hispanic 12.3% 2.9%
1989 Mean Household Income $32,965 $90,509
% Below Poverty Level 13.0% 1.3%


COMMUNITY HEALTH CONCERNS

The US EPA and Village officials held a public meeting in Smithtown on July 22, 1998 to discuss the groundwater contamination investigation and the selected remedial action. Residents expressed concerns about the possible source(s) of the contamination, remediation of the problem and responsibility for costs associated with the supply of an uncontaminated drinking water source. The removal action initially selected by the US EPA included installation of household GAC treatment systems at most affected residences. However, the majority of residents preferred connection to the public water supply over installation of treatment systems. The US EPA was informed that privately-funded water mains were planned or proposed for much of the affected area. Based on this finding, the US EPA revised the removal action to include providing public water main connections to affected residents where available. The US EPA did not provide water main connections or treatment systems to eight homes where VOC contamination exceeded NYS drinking water standards. These included the seven with 1,1,1-TCA concentrations between the NYS DOH and US EPA MCLs and the one with 1,2-dichloropropane in excess of the NYS DOH and US EPA MCLs.

Before treatments systems were installed, or before connections to public water supplies were provided, Suffolk County health officials provided written statements to affected residents advising them of potential health effects from exposure to VOCs and recommended ways to reduce their exposures to VOCs in household water.


ENVIRONMENTAL CONTAMINATION

This section includes a discussion of sampling data for environmental media. The environmental data presented in this section were gathered during investigations by the SCDHS and the US EPA. The following sections summarize the results of the investigations of groundwater contamination in and around the study area.

Groundwater

Groundwater in the area is known to be contaminated. The contamination includes an area of two to three square miles. Private wells in the area which use groundwater as a source of potable water are between 70 and 200 feet deep. In some cases, individual water supplies showed no contamination in areas where neighbors had high levels of contamination. Such differences may be due to differences in depth and construction of individual wells.

Between 1996 and 1998, approximately 500 private well samples were collected by the SCDHS and the US EPA (multiple samples were collected from some residences). The volatile organic compounds PCE, 1,1,1-trichloroethane (TCA), cis-1,2-dichloroethene and 1,2-dichloropropane were detected at concentrations greater than the NYS DOH drinking water standards (Table 1 in Appendix B). Two of these contaminants, PCE and 1,2-dichloropropane, exceeded applicable US EPA MCL. Lesser concentrations of other VOC compounds, including breakdown products of PCE, were detected at levels which did not exceed applicable drinking water standards (Table 2 in Appendix B). Two samples contained tetrachloroterephthalic acid (TCPA), a breakdown product of the pesticide dacthal, though not at levels which exceeded the NYS DOH drinking water standard.

TCA was detected more frequently than PCE, but at lower concentrations. TCA was present in approximately two-thirds (264/405) of the samples collected; PCE was detected in approximately one-third (161/481) of the samples collected. Samples containing cis-1,2-dichloroethene (up to 6 µg/L) and 1,2-dichloropropane (up to 14 µg/L) were less frequent.

One household well was contaminated with PCE at 200 µg/L, the highest level detected. This level is approximately 40 times the US EPA and NYS DOH drinking water standard. In all, six wells were contaminated with PCE above the US EPA's RAL of 70 µg/L; another 32 were contaminated at levels ranging between 5 and 70 µg/L. Approximately 68 private wells were contaminated with PCE at levels below the current US EPA MCL and NYS DOH drinking water standard of 5 µg/L.

The highest level of TCA detected was 38 µg/L. Nine wells were contaminated with TCA at levels above the NYS DOH drinking water standard; however, the majority (approximately 85) of wells contaminated with TCA are at levels below the NYS DOH drinking water standard of 5 µg/L. One well was contaminated with cis-1,2-dichloroethene (6 µg/L) at levels slightly above the NYS DOH drinking water standard of 5 µg/L. These private wells did not exceed the US EPA's MCL of 200 µg/L for TCA and 70 µg/L for cis-1,2-dichloroethene. 1,2-Dichloropropane was detected at one residence at a level of 14 µg/L, which exceeds federal and state drinking water standards of 5 µg/L for the compound.

Analytical data from existing groundwater monitoring wells near suspected source areas did not indicate significant VOC contamination. The US EPA is planning to install additional groundwater monitoring wells in the study area to define the extent of the groundwater contamination.

Samples collected from the artesian well, Dunton Spring, contained up to 2 µg/L of PCE. The US EPA is planning to resample Dunton Spring and other "seep" areas where groundwater is discharged to the surface.

Surface Water

Groundwater in the area is thought to flow in a north-northwest direction, with strong influences in flow direction towards the Nissoquoque River and Stony Brook Harbor (C.D.M. 2000). This will be confirmed during the remedial investigation of the site. The contamination appears to be moving in a northwest direction toward Stony Brook Harbor and the Nissoquoque River. Several residential wells directly adjacent to Stony Brook Harbor have been contaminated with PCE and 1,1,1-TCA; two of these wells have been contaminated above the RAL. There are no analytical data for surface water from Stony Brook Harbor or the Nissoquoque River.

Sediment, Sludge and Liquids at Potential Source Areas

The SCDHS has been investigating potential sources of the contamination by sampling the septic tanks, cesspools/leaching pools and/or other on-site waste disposal systems of several businesses south and east of the site. The SCDHS investigated fifteen facilities that could be responsible for the groundwater contamination. Samples collected from the waste disposal systems of twelve of these fifteen facilities contained high concentrations of VOCs, including PCE. The other three potential sources either did not use VOCs or their disposal systems did not contain chlorinated solvents. Samples from the twelve potential sources contained concentrations of PCE and its breakdown products up to 67,900,000 µg/L (6.6% by weight) in liquid and up to 160,000 µg/kg in sludge. To date, all of the identified waste disposal systems have been satisfactorily remediated through excavation or pumping and require no further action. The US EPA and SCDHS will continue the search for potential sources of the area's groundwater contamination.

Air/Soil Vapor

No outdoor or indoor air samples have been collected. The VOC contamination associated with the site is believed to be related to subsurface sources not directly vented to the atmosphere. No soil vapor samples have been collected. Soil vapor migration is not likely in the study area because the VOC contamination appears to be limited to the groundwater and levels of contamination are low, the groundwater is deep, and the depth of the contaminants in the groundwater are still deeper. As more detailed investigations of potential source areas are conducted, soil vapor or air samples may be collected at these locations


PATHWAYS ANALYSIS

This section of the public health assessment (PHA) identifies completed exposure pathways associated with the site in the past, during the present and potentially in the future. An exposure pathway is the process by which an individual may be exposed to contaminants originating from a site. An exposure pathway is comprised of five elements including: (1) a contaminant source, (2) environmental media and transport mechanisms, (3) a point of exposure, (4) a route of exposure, and (5) a receptor population.

The source of contamination is the origin of the release of the contaminant to the environment (any waste disposal area or point of discharge); if the original source is unknown, it is the environmental media (soil, air, biota, water) which are contaminated at the point of exposure. Environmental media and transport mechanisms "carry" contaminants from the source to points where human exposure may occur. The exposure point is a location where actual or potential human contact with a contaminated medium may occur. The route of exposure is the manner in which a contaminant actually enters or contacts the body (i.e., ingestion, inhalation, dermal adsorption). The receptors are people who are exposed or may be exposed to contaminants at a point of exposure.

For the Smithtown Groundwater Contamination site, there is one completed exposure pathway - exposure to VOCs in private drinking water. Exposure to contaminants in drinking water supplies can occur via ingestion, dermal contact and absorption during showering, bathing or other household uses, and via inhalation of aerosols and vapors from water used in the household. For an undetermined period of time, well owners have been exposed to VOCs in their drinking water supply. Prior to 1996, we do not know how long or at what concentrations people were exposed to these contaminants. If a worst case exposure scenario is assumed, the maximum exposure duration could be as long as 30 years, the approximate time since the affected homes were constructed and the potential source facilities were operational. Exposures have been eliminated or significantly reduced at residences where PCE contamination exceeded the US EPA MCL through the implementation of water treatment systems or provision of alternate water supplies (see Table 2 in Appendix B). However, if treatment systems fail or if wells are used in the future (e.g., household or irrigation purposes), then exposures could recur. Exposure to VOCs at levels below current US EPA MCL may still be occurring at some households. Homes with private wells that contain site-related contamination above the NYS drinking water standard, but below the US EPA's MCL and thus not addressed by the US EPA's previous removal action, are being considered as candidates for an alternate water supply under a separate action contemplated by the NYS DEC.

Exposure to VOCs through ingestion of contaminated spring water (Dunton Spring) remains a potential pathway if the spring water is collected for drinking. The SCDHS maintains a database of the historic monitoring results from the spring. The US EPA sampled the spring as recently as 1998. A review of the data indicates that VOC contaminants have not been detected at concentrations exceeding US EPA or NYS drinking water standards. While there are no current or were no known past exposures to VOCs from the spring above the drinking water standard, migration of the contaminant plume(s) into the area of the spring could result in exposures at higher levels. The US EPA is planning to resample Dunton Spring and sample several potential seep points along the shores of Stony Brook Harbor to characterize the nature and extent of groundwater contamination in these areas.

Past potential pathways of exposure may have existed around potential source area facilities. Subsurface sediments and soils in and around the septic systems of some of these areas were heavily contaminated with VOCs. To date, all of the identified waste disposal systems have been satisfactorily remediated. Employees of the suspected facilities and other individuals could have been exposed in the past to residual VOC vapors in indoor air. The vapors could have originated in heavily contaminated subsurface soils and sediments and migrated into overlying buildings and structures via soil vapor migration. This exposure pathway may have been completed in the past but does not exist in the present due to the corrective remedial measures undertaken at the suspected facilities. There are no analytical data on indoor air quality from any of the identified potential source areas; therefore, we do not know the public health implications of the past potential exposures.

Soil vapor migration is unlikely in the study area because the VOC contamination appears to be limited to the groundwater. The levels of contamination are relatively low and the groundwater is deep.


PUBLIC HEALTH IMPLICATIONS: ADULT AND CHILDREN'S HEALTH ISSUES

An analysis of the toxicological and epidemiological implications of the human exposure pathways of concern is presented below. To evaluate the potential health risks from contaminants of concern associated with the Smithtown Groundwater site, the NYS DOH assessed the risks for cancer and noncancer health effects. The risks of health effects depend primarily on contaminant concentration, exposure route, exposure frequency and duration. Additional information on the NYS DOH assessment for this site is presented in Appendix C.

A. Toxicological and Epidemiological Evaluation

Exposure to contaminants in drinking water supplies can occur via ingestion, dermal contact and inhalation from water uses such as showering, bathing or other household uses. Although exposure varies depending on an individual's lifestyle, each of these exposure routes contributes to the overall daily intake of contaminants and, thus, can increase the risk for chronic health effects.

For an undetermined period of time, possibly for up to approximately 30 years, some private water supply wells in the Smithtown community have been contaminated with chlorinated volatile organic compounds (VOCs). The highest levels of cis-1,2-dichloroethene (6 µg/L), 1,2-dichloropropane (14 µg/L), PCE (200 µg/L) and TCA (38 µg/L) measured in private wells exceed NYS public drinking water standards and/or public health assessment comparison values (see Table 3 in Appendix B). Therefore, these chemicals have been selected for further evaluation.

Studies of workers exposed to PCE and other chemicals show an association between exposure to high levels of these chemicals and increased risks of certain forms of cancer, including cervical, esophageal and non-Hodgkin's lymphoma (ATSDR, 1997). These associations are unlikely to be due to chance; however, the role of other factors in causing these cancers, including exposures to other potential cancer-causing chemicals, is not fully known. Thus, these data suggest, but do not prove, that PCE causes cancer in humans. Other studies show that people living in communities with drinking water supplies contaminated by mixtures of chemicals including PCE have higher risks of certain types of cancer (e.g., non-Hodgkin's lymphoma) than do people living in communities with uncontaminated drinking water. These studies are weaker than those of workers largely because we do not know for certain whether the people who got cancer actually drank the contaminated water for long periods of time before they got cancer. PCE and 1,2-dichloropropane cause cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1989, 1997). Chemicals that cause cancer in laboratory animals may cause cancer in humans who are exposed to lower levels over long periods of time. Whether 1,2-dichloropropane causes cancer in humans is not known. The highest detected level of PCE in well water people drank was 200 µg/L, and six samples from untreated wells had levels between 82 and 200 µg/L. Based on the results of animal studies, studies in humans and limited sampling of private residential water supply wells, people drinking water over a period of up to 30 years containing PCE at levels from 82 µg/L up to 200 µg/L are estimated to have a moderate increased risk of developing cancer. People drinking water with PCE levels from 5 µg/L to 82 µg/L for 30 years have a low risk of developing cancer. For people drinking treated water with an occasional breakthrough concentration of PCE in excess of the drinking water standard (such as the 11 µg/L concentration observed in one home), the risk is estimated to be very low. People exposed to 14 µg/L 1,2-dichloropropane are also estimated to have a low increased cancer risk. Toxicological data are inadequate to assess the carcinogenic potential of cis-1,2-dichloroethene and 1,1,1-trichloroethane (ATSDR, 1995, 1996).

The chlorinated contaminants detected in some of the private drinking water supplies in the Smithtown community also produce a variety of noncarcinogenic effects, primarily to the liver, kidneys and nervous system. Although the risks of noncarcinogenic effects from past exposures to the highest levels of these chlorinated VOCs in private drinking water supply wells are not completely understood, the existing data suggest that they would be low for PCE levels from 175 µg/L to 200 µg/L, minimal for PCE concentrations up to 175 µg/L and minimal for cis-1,2-dichloroethene (6 µg/L), 1,2-dichloropropane (14 µg/L) and TCA (38 µg/L). Following treatment, the risk for PCE would be minimal.

B. ATSDR Child Health Initiative

The ATSDR Child Health Initiative emphasizes examining child health issues in all of the Agency activities, including evaluating child-focused concerns through its mandated public health assessment activities. The ATSDR and NYS DOH consider children when evaluating exposure pathways and potential health effects from environmental contaminants. We recognize that children are of special concern because of their greater potential for exposure from play and other behavior patterns. Children sometimes differ from adults in their susceptibility to hazardous chemicals, but whether there is a difference depends on the chemical. Children may be more or less susceptible than adults to health effects from a chemical and the relationship may change with developmental age.

The possibility that children or the developing fetus may have increased sensitivity to PCE (the primary contaminant at the Smithtown Groundwater Contamination site) was taken into account when evaluating the potential health risks associated with the site. Human studies suggest that exposure to mixtures of chlorinated solvents (including PCE) in drinking water during pregnancy may increase the risk of birth defects (e.g., neural tube defects, oral cleft defects, and congenital heart defects) and/or childhood leukemia (ATSDR, 1997). In each of these studies, however, there are uncertainties about how much contaminated water the women drank during pregnancy and about how much PCE was in the water the women drank during pregnancy. Moreover, the role of other factors in causing these effects is not fully known. The most important of the factors was the potential exposure during pregnancy to other chemicals in drinking water. These studies suggest, but do not prove, that the developing fetus may have increased sensitivity to the effects of PCE.

When pregnant animals are exposed by ingestion or inhalation to large amounts of PCE (i.e., amounts that caused adverse health effects in the adult animal), adverse effects on the normal development of the offspring are observed. In addition, a study in young mice suggests effects on the central nervous system after transient exposure to PCE by ingestion 10 to 16 days after birth (Fredriksson et al., 1993). The estimated levels of exposure to PCE at the Smithtown Groundwater Contamination site were more than 400 times lower than the levels of exposure in the animal studies in which adverse health effects were observed. Thus, the possibility that children may have increased sensitivity to PCE was taken into account when evaluating the potential health risks associated with the site.


HEALTH OUTCOME DATA

This site is being considered for inclusion in the NYS VOC Exposure Registry. If this site is selected in the future, residents of households who were exposed in the past to VOCs from private well drinking water supplies will be asked by the NYS DOH to participate. The exposure registry allows long-term follow-up on the health status of persons with documented exposures to VOCs. An exposure registry such as this one is a resource for research that may help us learn whether exposures to VOCs are related to health effects. Future analysis, based on VOC Exposure Registry information, may increase understanding of potential health effects from exposures similar to those experienced by residents in the area affected by the Smithtown Groundwater Contamination site. People who are enrolled in the Registry will be kept informed of any research results that come from the Registry data.


CONCLUSIONS

Because people were exposed to VOCs in drinking water at levels above New York State drinking water standards at the Smithtown Groundwater Contamination site, public health actions were needed to interrupt or minimize exposures (primarily to PCE). These exposures may have increased or continued had these measures not been taken. Human exposures to these contaminants occurred via ingestion, inhalation, and dermal contact. Exposures to VOCs in drinking water may have occurred for as long as 30 years. Studies of workers exposed to PCE and other chemicals suggest, but do not prove, that PCE causes cancer in humans. Somewhat weaker evidence that comes from other studies show that people living in communities with drinking water supplies contaminated with mixtures of chemicals including PCE have higher risks of certain types of cancer than do people living in communities with uncontaminated drinking water. Because there is evidence from studies in animals and humans that exposure to elevated levels of PCE can increase the risk of adverse cancer and noncancer health effects in humans, we evaluated the potential health risk for exposure to these chemicals at the Smithtown Groundwater site.

Available data indicate that people drinking water from the six wells contaminated with PCE at the highest contaminant levels detected (82 µg/L to 200 µg/L) are estimated to have a moderate (See Appendix C) increased risk of developing cancer. Those exposed to 1,2 dichloropropane at the highest contaminant levels detected (14 µg/L) are estimated to have a low increased risk of developing cancer. Toxicological data are inadequate to assess the carcinogenic potential of cis-1,2-dichloroethene and 1,1,1-trichloroethane. The risks of non-carcinogenic effects - primarily to the liver, kidneys and nervous system - from exposure to all site-related contaminants are estimated to be low to minimal. Residents who were exposed are being considered for inclusion in the NYS VOC Exposure Registry.

Exposures to PCE in drinking water at concentrations above its drinking water standard have been eliminated or significantly reduced in thirty-eight homes. Therefore, the site currently poses no apparent public health hazard for individual households supplied with a treatment system or public drinking water. However, future exposures could occur for residents not connected to public water supplies if groundwater is not remediated and the contaminants migrate to additional wells, if new wells are installed in the contaminated plume, or if treatment systems are not maintained. Occasional failures in the treatment system could result in temporary exposure to contaminants at concentrations above the drinking water standard. The increased cancer risk associated with the occasional breakthrough is estimated to be very low. Proper maintenance of these systems is encouraged.

Residents using seven wells may currently be exposed to 1,1,1-TCA and residents using one well to 1,2-dichloropropane at levels which exceed current NYS DOH drinking water standards. Although people exposed to these contaminants at the highest levels detected are estimated to have a low to minimal increased risk of developing cancer and noncancer effects, respectively, the NYS DOH, in accordance with prudent public health practice, recommends that measures be taken to minimize the potential for human consumption of drinking water containing elevated concentrations of VOCs.

Exposure pathways other than via drinking water are not considered to be significant. A single source of the contamination has not been found, and there may be or may have been multiple sources. Historic groundwater flow data indicate that the contamination is moving in a northwest direction. Investigations currently underway for the Smithtown Groundwater site will provide the details necessary to track the movement of groundwater contamination more thoroughly.


RECOMMENDATIONS

  1. Actions should continue to be taken to reduce exposures to people from drinking water that exceeds drinking water standards.
  2. Installed treatment systems must be maintained and the quality of the treated water should be monitored until contamination stops or an alternative water supply is provided.
  3. Monitoring of potentially affected private wells in the area should continue, with alternative water supplies provided to additional homes identified as having contaminant levels which exceed the NYS drinking water standard.
  4. Potential sources of contamination, if any, should continue to be identified and remediated as necessary. Potential exposures from these areas should also be evaluated.
  5. The natural spring in the study area should be sampled and appropriate control measures should be implemented, if necessary.
  6. A permanent, long-term remedy for groundwater users should be sought.

PUBLIC HEALTH ACTION PLAN

The Public Health Action Plan (PHAP) for the Smithtown Groundwater Contamination site contains a description of actions to be taken by ATSDR and/or the NYS DOH following completion of this health assessment. For those actions already taken at the site, please refer to the Background section of this public health assessment. The purpose of the PHAP is to ensure that this public health assessment identifies public health hazards and provides a plan of action designed to mitigate and prevent adverse human health effects resulting from the past, present and/or future exposures to hazardous substances at or near the site. Included is a commitment on the part of ATSDR and/or the NYS DOH to follow up on this plan to ensure that it is implemented. The public health actions to be implemented by ATSDR and/or the NYS DOH are as follows:

  1. The NYS DOH and SCDHS will work with the NYS DEC and US EPA to explore options for providing alternative water sources to residents who continue to use wells that are contaminated with 1,1,1-TCA and 1,2-dichloropropane above NYS drinking water standards.
  2. The NYS DOH will coordinate with the appropriate environmental agencies to develop a plan to implement the recommendations contained in this public health assessment.
  3. ATSDR will provide follow-up to this PHAP, as needed, outlining the actions completed and those in progress. This report will be placed in repositories that contain copies of this public health assessment and will be provided to people who request it.
  4. Residents who were exposed in the past to VOCs in drinking water will be considered for inclusion in the NYS DOH registry of VOC exposures in drinking water.
  5. The NYS DOH, in conjunction with the SCDHS, will continue community health education activities to people whose drinking water supplies are contaminated with PCE in the Smithtown Groundwater Contamination study area. These activities will include meeting with the public and providing information on ways to reduce exposures to VOCs in drinking water.

ATSDR will reevaluate and expand the PHAP when needed. New environmental, toxicological, or health outcome data, or the results of implementing the above proposed actions, may determine the need for additional actions at this site.


REFERENCES

Agency for Toxic Substances and Disease Registry (ATSDR). 1989. Toxicological Profile for 1,2-Dichloropropane. U.S. Department of Health and Human Services. Atlanta, Georgia: U.S. Public Health Service.

Agency for Toxic Substances and Disease Registry (ATSDR). 1992. ATSDR Public Health Assessment Guidance Manual.

Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Toxicological Profile for 1,1,1-Trichloroethane. Update Draft. U.S. Department of Health and Human Services. Atlanta, Georgia: U.S. Public Health Service.

Agency for Toxic Substances and Disease Registry (ATSDR). 1996. Toxicological Profile for 1,2-Dichloroethene. Update Draft. U.S. Department of Health and Human Services. Atlanta, Georgia: U.S. Public Health Service.

Agency for Toxic Substances and Disease Registry (ATSDR). 1997. Toxicological Profile for Tetrachloroethylene. Update Draft. U.S. Department of Health and Human Services. Atlanta, Georgia: U.S. Public Health Service.

CDM Federal Programs Corporation, 2000. Smithtown Groundwater Contamination Site Phase 1 Remedial Investigation, Final Workplan. Volume I.

Fredriksson, A.,B.R.G. Danielsson and P. Eriksson. 1993. Altered Behavior in Adult Mice Orally Exposed to Tri-and Tetrachloroethylene as Neonates. Toxicol. Lett. 66: 13-19.

New York State Department of Environmental Conservation (NYSDEC). 1997. Letter from Michael J. O'Toole to Richard Caspe, Re: Groundwater Contamination, Town of Smithtown, Suffolk County, NY.

Suffolk County Department of Health Services (SCDHS). 1999. Memorandum from Walter T. Petrule to Distribution, Re: St. James Survey Relating to the Private Well Contaminations in Nissequogue and Head of the Harbor.

Suffolk County Department of Health Services (SCDHS) Office of Water Resources. 1997. Village of Head of the Harbor 1996 Private Well Sampling Survey, Prepared by Thomas Nanos, R.S.

US Bureau of the Census. 1991. 1990 Census of Population and Housing Summary Tape File 1B. US Department of Commerce.

US Bureau of the Census. 1992. 1990 Census of Population and Housing Summary Tape File 3A CD-ROM. US Department of Commerce.

US Environmental Protection Agency (US EPA). 1998-1999. Region II. Removal Action Branch Pollution Report.

US Environmental Protection Agency (US EPA). 1998. Memorandum from Eric J. Wilson to Richard L. Caspe, Re: Change in Scope of Response and Ceiling Increase at the Smithtown Groundwater Site, Smithtown, Suffolk County, New York.


PREPARERS OF REPORT

New York State Department of Health

Rebecca Mitchell
Assistant Sanitary Engineer
Bureau of Environmental Exposure Investigation

Teresa Foster
Public Health Specialist
Bureau of Environmental Exposure Investigation

William Gilday, P.E.
Senior Sanitary Engineer
Bureau of Environmental Exposure Investigations

Sharlin Liu
Assistant Research Scientist
Bureau of Toxic Substance Assessment

Thomas Johnson, Ph.D.
Research Scientist
Bureau of Toxic Substance Assessment


Agency for Toxic Substances and Disease Registry

Regional Representative
Arthur Block
Regional Operations
Office of the Assistant Administrator

Technical Project Officer
Greg Ulirsch
Technical Project Officer
Division of Health Assessment and Consultation
Superfund Site Assessment Branch


CERTIFICATION

This Public Health Assessment was prepared by the New York State 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 public health assessment was initiated.

Gregory V. Ulirsch
Technical Project Officer, SPS, SSAB, DHAC


The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this public health assessment, and concurs with its findings.

Richard Gillig
Chief, SPS, SSAB, DHAC, ATSDR


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