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PUBLIC HEALTH ASSESSMENT

ISLIP MUNICIPAL SANITARY LANDFILL
(a/k/a BLYDENBURGH ROAD LANDFILL)
HAUPPAUGE, SUFFOLK COUNTY, NEW YORK

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

To evaluate if a site poses an existing or potential hazard to the exposed or potentially exposed population(s), the site conditions are characterized. This site characterization involves a review of sampling data for environmental media (e.g., soil, surface water, groundwater, air) both on- and off-site and an evaluation of the physical conditions of the contaminant sources or physical hazards near the site which may pose an additional health risk to the community or receptor population(s).

Contaminants selected for further evaluation are identified based upon consideration of the following factors:

  1. Concentrations of contaminant(s) in environmental media both on- and off-site;

  2. Field data quality, laboratory data quality, and sample design;

  3. Comparison of on-site and off-site contaminant concentrations in environmental media with typical background levels;

  4. Comparison of contaminant concentrations in environmental media both on- and off-site with public health assessment comparison values for (1) noncarcinogenic endpoints, and (2) carcinogenic endpoints. These comparison values include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), drinking water standards and other relevant guidelines. Contaminant concentrations which exceed a comparison value do not necessarily pose a health threat; and

  5. Community health concerns.

The selected contaminant(s) is evaluated in the Public Health Implications section (Toxicological Evaluation) of the Public Health Assessment (PHA) to determine whether exposure to these chemicals is of public health significance.

The On-Site Contamination and the Off-site Contamination subsections include discussions of sampling data for environmental media; summary tables of sampling data are presented in Appendix B. If a chemical is selected for further evaluation in one medium (e.g., soil, sediment, surface water, groundwater, air), that contaminant will also be reported in all other media, if detected. A listed contaminant does not necessarily mean that it will cause adverse health effects from exposure.

For the purpose of evaluating environmental sampling data and site conditions in this PHA "on-site" refers to the area within the property boundary as indicated on Figure 2 (Appendix A) of this PHA and "off-site" refers to all areas outside of this property boundary.

A. On-site Contamination

The most recent environmental data for the Islip Landfill were collected as part of the remedial investigation/feasibility study (RI/FS) by the environmental engineering firms Geraghty and Miller, Inc. and Malcolm Pirnie under contract with the Town of Islip.

Air

On-site ambient air was not sampled at the Islip Landfill. As part of the RI in 1991, the Industrial Source Complex (ISC) model was used to evaluate the potential on-site and off-site exposures to site-related contaminants in air. Using the concentration of contaminant measured or estimated at the pollutant source, the ISC model considers meteorological and topographical conditions to predict an annual average concentration of contaminant potentially present at an on-site or off-site receptor location. The sources of volatile organic air contaminants at this site include combustion products emitted from the on-site facility which generates electricity from collected landfill gas, the uncombusted gases released directly to the atmosphere from the actively vented gas collection wells, the uncombusted gases emitted from the two flares at the northern end of the landfill, and the potential migration of uncollected landfill gas. The associated health risk can then be calculated using the modeled level of exposure. The health risks associated with exposure to site-related air contaminants are discussed in the Public Health Implications section of this document.

Many of the pollutant sources used in the ISC model have since been controlled by connecting the uncontrolled gas vents to a flare system and constructing a cap on the landfill which includes a gas collection/control system.

Soil Gas

In 1990, soil gas was surveyed at 11 locations on the west central border of the landfill, inside the landfill gas collection/control system. Elevated concentrations of VOCs and combustible gases were found (Appendix B, Table 2). VOCs in soil gas samples taken from a single cluster well (No. 10 gas well) outside the landfill gas collection system were also elevated (Appendix B, Table 3). However, the No. 10 gas well was sampled while the landfill gas collection system was not operating. In order to evaluate the effectiveness of the landfill gas collection/control systems, the Town of Islip has placed permanent soil gas monitoring well clusters on the perimeter of the landfill, outside the collection loop. Recent sampling of the perimeter soil gas monitoring wells did not detect combustible gases in the perimeter soil gas monitoring wells. This sampling was conducted when the gas collection systems were functional.

In the past, landfill gas collected along the eastern perimeter of the landfill was vented directly into the air. During the RI landfill gas samples taken from the collection fans along the eastern perimeter of the site had elevated levels of chlorinated compounds, including vinyl chloride (Appendix B, Table 4). To reduce the release of untreated landfill gas, the Town is flaring the gas collected from the eastern perimeter of the site. However, the collection/flare system for the eastern perimeter gas wells usually operates for less than one hour per day due to low level of methane gas.

Soil

On-site surface and subsurface soil samples were not taken from the section of the landfill where the alleged disposal of solvent wastes occurred, since the area of alleged hazardous waste disposal is unknown and would be buried under a large volume of municipal waste (Appendix A, Figure 3).

Groundwater (monitoring wells)

Monitoring well clusters (Appendix A, Figure 4) were developed to evaluate on-site groundwater quality in the Upper Glacial and Magothy aquifers. Elevated levels of VOCs and inorganic compounds were detected in several of the on-site groundwater monitoring wells in the east/southeast area of the landfill.

The organic contaminants in on-site groundwater include trichloroethene at 71 mcg/L, tetrachloroethene at 23 mcg/L and 1,1,1-trichloroethane at 170 mcg/L (Appendix B, Table 5). Many of the breakdown products of these VOCs were also detected in on-site monitoring wells. The Upper-Glacial aquifer has been contaminated with chlorinated solvents originating from the landfill. Using a colormetric test, total phenols were detected in one on-site monitoring well at a concentration of 20 mcg/L. Phenols are commonly found at municipal landfills and may be produced by the bacterial decomposition of organic matter.

Although lead, zinc, thallium and iron were detected in on-site monitoring wells at elevated concentrations, comparable levels of these metals were also detected in upgradient monitoring wells 3, 5 and 9.

PCBs and pesticides were not detected in any of the groundwater samples.

B. Off-site Contamination

Air

In late 1979 and during the early part of 1980, the Town's consultant determined that gas generated in the landfill was migrating through the soil into the basements of some homes bordering the landfill. Explosive levels of methane gas were detected in the basements of two homes about 50 and 100 feet from the eastern border of the landfill. These homes were abandoned and then purchased by the Town in 1979. In the spring of 1980, the NYS DOH detected vinyl chloride at a concentration of 0.0036 mg/m3 in air samples taken in the basement of the home about 50 feet from the border of the landfill. This home was never reoccupied and was later demolished.

As discussed previously in the On-Site Contamination section, the ISC dispersion model was used to evaluate potential on-site and off-site migration of site-related air contaminants. In addition, three rounds of ambient air samples were collected near the landfill and were analyzed for VOCs. Sampling points included the Whippoorwill School, a neighboring horse farm, the Townhouses and Woods Edge Court (Appendix A, Figure 5). Due to extensive trip and instrumental blank contamination and the lack of upwind/background samples, these ambient air sampling results are inconclusive.

Soil Gas

A single off-site soil gas sample location (Appendix A, Figure 5) was chosen near the Whippoorwill School. Soil gas samples were taken on three occasions during the off-site ambient air sample collection. Although soil gas samples had low levels of some VOCs (Appendix B, Table 6), these results are suspicious due to trip and instrument blank contamination.

Groundwater (monitoring wells)

Monitoring well clusters were developed to evaluate off-site groundwater quality in the Upper Glacial and Magothy aquifers (Appendix B, Table 7). VOCs including vinyl chloride (21 mcg/L), 1,1-dichloroethane (97 mcg/L), 1,2-dichloroethene (130 mcg/L), 1,1,1-trichloroethane (43 mcg/L), trichloroethene (50 mcg/L), and tetrachloroethene (39 mcg/L) were detected on at least one occasion during the three rounds of groundwater sampling between April and October of 1990. The contamination was detected primarily in the off-site groundwater monitoring wells in the area south/southeast of the landfill. The upgradient wells were not contaminated. The Upper Glacial and Magothy aquifers are contaminated with organic solvents migrating from the site.

Phenols were detected in five downgradient monitoring wells at a maximum concentration of 40 mcg/L. This semi-volatile organic contaminant is commonly found at municipal landfills and may be present as a result of the bacterial decomposition of organic matter.

Bis(2-ethylhexyl)phthalate, was detected in one downgradient off-site well at a concentration of 53 mcg/L and in upgradient well #3 at a concentration of 110 mcg/L. This compound is a plasticizer commonly found at municipal landfills. The presence of bis(2-ethylhexyl)phthalate may be due to improper sample collection and/or sample extraction prior to analysis.

Lead was detected at elevated concentrations in non-filtered samples taken from on-site and off-site Upper Glacial and Magothy monitoring wells. However, lead concentrations in filtered samples taken from all but one monitoring well were below the public drinking water standard set by the NYS DOH. Chromium was detected at elevated concentrations in the Upper Glacial aquifer only. Many of the other metals in downgradient monitoring wells were in upgradient wells in comparable concentrations.

Groundwater (private supply wells)

Fifty private wells near the landfill were sampled by the Town's consultant (H2M), the SC DHS, NYS DOH and the US EPA during 1978-80 (Appendix B, Table 1). Eighteen of the 50 wells were contaminated with chlorinated solvents. Based on this information, the Town supplied public water to all homes and businesses close to the landfill in 1981. In October of 1991, the NYS DOH and the SC DHS found a three-family home within the groundwater contaminant plume that was not connected to public water. A sample taken from this residential well contained chlorinated organic solvents, including tetrachloroethene, chloroform and dichlorodifluoromethane, at concentrations of 18, 1 and 8 mcg/L, respectively. This home was connected to public water in May of 1992.

Groundwater (public supply wells)

Potable water in the area surrounding the landfill is supplied through public water. Three public water supply wells are within 1.5 miles of the landfill and serve a total of about 4,000 people. The Nichols Road, Liberty Street and Oval Drive public water supply wells are southeast, east and southwest, respectively, from the site. The Nichols Road wells are the only public water supply wells in the path of the groundwater contaminant plume migrating from the landfill.

Trace levels of 1,1,1-trichloroethane were detected in samples taken from the Nichols Road and Liberty Street wells. Although the levels of solvent detected in these wells did not exceed NYS DOH standards for public water supplies, they were taken out of service in January of 1989 by the Suffolk County Water Authority (SCWA) as a precautionary measure. The trace levels of contamination in these wells is not believed to have originated from the landfill. After continued monitoring showed that the contaminant levels were not increasing, the Nichols Road and Liberty Street wells were returned to service in June of 1990.

The Oval Drive wells southwest of the landfill were taken out of service in 1977 due to solvent contamination believed to have originated at the Jancyn Cesspool Cleaner manufacturers. Tetrachloroethene, trichloroethene and 1,1,1-trichloroethane were detected in samples taken from this public well field at maximum concentration of 10, 61 and 900 mcg/L, respectively. Jancyn is suspected of discharging solvents into subsurface leaching pits. Only the three shallow wells in the well field were contaminated. Carbon filters were installed on the shallow wells, and all the wells, except one, went back on line in September of 1990. Recent samples taken prior to filtration from the Oval Drive well field contained 1,1,2-trichloro-1,2,2-trifluoroethane at 8 mcg/L.

C. Quality Assurance and Quality Control

The analytical data used by the NYS DOH to prepare this PHA are found in the referenced documents. Laboratory data are evaluated with respect to specific quality assurance (QA) and quality control (QC) measures. Data which do not meet certain QA/QC criteria, for reasons such as excessive blank contamination or non-reproducible results, were not used in the PHA or were qualified in the document as questionable results.

D. Physical and Other Hazards

One hazard associated with the site involves the presence of methane in landfill gas. Methane can migrate through porous media as soil gas and enter confined building spaces (basements) through crawl spaces, plumbing holes, other floor holes (e.g., sumps) and foundation cracks. The potential for methane to collect in a confined space is of concern as this condition may result in a flammable/explosive atmosphere and, hence, be a safety problem. In order to reduce the potential for off-site migration of landfill gas, the Town has constructed a landfill cap which includes an active gas collection/control system.

E. Toxic Chemical Release Inventory (TRI)

To identify facilities that could contribute to groundwater, soil, or air contamination in the area around the Islip Landfill site, the NYS DOH searched the Toxic Chemical Release Inventory (TRI) data for 1989. TRI is developed by the US EPA from the chemical release (air, water, soil) information provided by certain industries.

A search of the 1989 TRI identified one industrial facility (Ragen Data Systems) within a 2.5 mile radius of the Islip Landfill site. This facility reported 1989 air emissions for the chemical 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113), totaling 4,600 pounds per year. Based on these TRI data and air emissions modeling, results of the screening evaluation indicate that emissions from this facility would not affect ambient air near the Islip Landfill site at levels exceeding a screening criterion of 0.001 mg/m3. Consequently, this TRI facility would not be expected to pose an additional health risk to the population near the site. This facility did not report any discharges to water or soil.

PATHWAY ANALYSES

This section of the PHA identifies potential and completed exposure pathways associated with past, present and future use of the site. 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 source of contaminant release 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 receptor population is the person or people who are exposed or may be exposed to contaminants at a point of exposure.

Two types of exposure pathways are evaluated in the PHA; a completed exposure pathway exists when the criteria for all five elements of an exposure pathway are documented; a potential exposure pathway exists when the criteria for any one of the five elements comprising an exposure pathway is not met. A suspected exposure pathway is considered to be eliminated when any one of the five elements comprising an exposure pathway has not existed in the past, does not exist in the present and will never exist in the future.

A. Completed Exposure Pathways

Indoor Air Pathway

VOCs have been detected in the perimeter landfill gas collection systems and in on-site soil gas probe holes. Site contaminants could migrate through porous media as soil gas and enter confined building spaces (basements) through crawl spaces, plumbing holes, other floor holes (e.g., sumps) and foundation cracks, and contaminate indoor air.

In late 1979, explosive levels of methane gas were detected in the basements of two homes 50 and 100 feet from the eastern landfill border. In addition to methane, the NYS DOH detected vinyl chloride in the basement of the home 50 feet from the landfill border at a concentration of 0.0036 mg/m3. These homes were abandoned and then purchased by the Town of Islip in 1979. The home where vinyl chloride was detected was never reoccupied and was later demolished. Due to the migration of landfill-generated soil gas, the indoor air pathway of human exposure was completed in the past. The NYS DOH estimates that about five people were exposed to site-related contaminants in indoor air. To reduce the potential of soil gas migration, active perimeter soil gas collection/treatment systems were constructed at the landfill in 1983. Based on investigations done by the Town of Islip, soil gas is not detectable in the permanent soil gas monitoring wells when the gas collection/control systems are functional. Exposure to soil gas may occur when the systems are not functional.

Groundwater Exposure Pathways

Exposure to chemicals in drinking water supplies is possible by ingestion, dermal adsorption or inhalation from water uses, such as showering, bathing and cooking. Although exposures vary depending on individual lifestyles, each of these exposure routes contributes to the overall daily uptake of contaminants and thus increases the potential for chronic health effects.

The groundwater pathway of human exposure was completed in the past. The NYS DOH estimates that 45 people were exposed to site-related contaminants in drinking water. However, due to the provision of alternate water supplies by the Town of Islip, current and future exposure to site-related contaminants via this pathway are not expected.

Based on findings of the remedial investigation, the Upper Glacial (shallow) and Magothy (deep) aquifers are contaminated with VOCs originating from the site. Although the groundwater pathway of exposure was thought to have been eliminated in 1981 with the extension of public water, a three-family residence with a private well downgradient from the landfill was identified in 1991. This well contained chloroform (1 mcg/L), tetrachloroethene (18 mcg/L) and dichlorodifluoro-methane (8 mcg/L). Chloroform and tetrachloroethane were detected in groundwater monitoring wells at the site. This home was connected to a public water supply. Some of the shallow wells in the Oval Drive public water supply well field were contaminated with organic solvents. The contamination in this well field in 1977 is believed to have originated from the Jancyn Cesspool Cleaner Manufacturers Company. At that time, the contaminated supply wells were taken out of service. Carbon filtration systems were installed on the contaminated wells which went back into service in September of 1990. Recent sampling of this well field, prior to filtration, found Freon 113 (1,1,2-trichloro-1,2,2-trifluorethane) at 8 mcg/L.

B. Potential Exposure Pathways

Ambient Air Pathway

Past, current and future exposure pathways are possible from contamination of the on-site and off-site ambient air. Populations at risk of exposure to contaminated ambient air via inhalation include on-site workers, children attending the Whippoorwill Day Care facility and residents near the site. The population potentially exposed to site-related contaminants in air would include the approximate 6,200 people living within one mile of the landfill. Although ambient air sampling was conducted during the RI, due to extensive quality control sample contamination and the lack of upwind/background samples the ambient air sampling results are insufficient to evaluate this environmental pathway of exposure.

The ISC model was used to evaluate on-site and off-site exposures to site-related contaminants in air. Many of the pollutant sources used in the ISC model have since been controlled by connecting the uncontrolled gas vents to a flare system and constructing a cap on the landfill which includes a gas collection/control system.

VOCs have been detected in the perimeter landfill gas collection systems and in on-site soil gas probe holes. Site contaminants could migrate through porous media as soil gas and enter confined building spaces (basements) through crawl spaces, plumbing holes, other floor holes (e.g., sumps) and foundation cracks, and contaminate indoor air.

Based on investigations done by the Town of Islip, soil gas is not detectable in the permanent soil gas monitoring wells when the perimeter soil gas collection/control systems are functional. Exposure to soil gas may occur when the systems are not functional.

C. Eliminated Exposure Pathways

Surface Water

This human exposure pathway has been eliminated from further discussion in this PHA since there are no surface waters adjacent to the site.

Soil Exposure Pathways

Since soil contaminated by the alleged disposal of hazardous waste is buried in the unlined portion of the landfill under a large volume of municipal waste (Appendix A, Figure 3), exposure to contaminated soil is not a pathway of concern.

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

An analysis of the toxicological implications of the human exposure pathways of concern is presented below. To evaluate the potential health risks from contaminants of concern associated with the Islip Landfill site, the NYS DOH has assessed the risks for cancer and noncancer health effects. The health effects are related to contaminant concentration, exposure pathway, exposure frequency and duration. For additional information on how the NYS DOH determined and qualified health risks applicable to this health assessment, refer to Appendix C.

  1. Past ingestion, dermal and inhalation exposure to VOCs in private water supply wells.

    For an undetermined period of time (less than 18 years), 18 private water supply wells downgradient from the Islip Landfill site were contaminated with chlorinated volatile organic solvents (Appendix B, Table 1). These wells were sampled between 1978-1980. Contaminant levels in drinking water prior to this sampling are not known. Due to this contamination, the Town of Islip connected homes near the landfill to public water in 1981. Levels of tetra-chloroethene (124 mcg/L), 1,1,1-trichloroethane (8 mcg/L), trichloroethene (7 mcg/L) and vinyl chloride (77 mcg/L) exceed New York State public drinking water standards for each of these VOCs (Appendix B, Table 8).

    Vinyl chloride is a known human carcinogen (ATSDR, 1991j). Past exposure to the highest level of vinyl chloride found in private wells could pose a high increased cancer risk. Tetrachloroethene and trichloroethene (ATSDR, 1991h,i) have caused cancer in laboratory animals exposed to high levels over their lifetimes. Chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans who are exposed to lower levels over long periods of time. Whether or not these two VOCs cause cancer in humans is not known. Based on the results of animal studies and limited sampling of private water supply wells, it is estimated that persons exposed to drinking water contaminated with tetrachloroethene and trichloroethene could have a low increased risk of developing cancer. Toxicological data are inadequate to assess the carcinogenic potential of 1,1,1-trichloroethane (ATSDR, 1990h).

    1,1,1-Trichloroethane can damage the nervous system, liver and cardiovascular system at exposure concentrations several orders of magnitude greater than those measured in these private water supply wells (ATSDR, 1990h). Tetrachloro-ethene, trichloroethene and vinyl chloride (ATSDR, 1991h,i,j) also produce a variety of noncarcinogenic toxicities (primarily nervous system, liver and kidney effects) at exposures several orders of magnitude greater than exposure from these private water supply wells. Chemicals that cause effects in humans and/or animals after high levels of exposure may also pose a risk to humans who are exposed to lower levels over long periods of time. Although the risks of noncarcinogenic effects from past exposures to these VOCs in private drinking water supplies are not completely understood, the existing data suggest that they are low for vinyl chloride and minimal for the other VOCs.

    In October 1991, a water sample was taken from a residential well of a home in the path of the groundwater contaminant plume. The well water contained tetrachloroethene (18 mcg/L) and dichlorodifluoromethane (8 mcg/L) at levels that exceed New York State public drinking water standards. The home was connected to public water in May 1992. The toxicological properties of tetrachloroethene have already been discussed. Toxicological data are inadequate to assess the carcinogenic potential of dichlorodifluoromethane. Chronic exposure to the levels of tetrachloroethene found in this home's private supply well would pose a low increased cancer risk. In addition, this chlorinated solvent produces noncarcinogenic effects at exposures several orders of magnitude greater than exposure from the private drinking water supply well. Although the risks of noncarcinogenic effects are not completely understood, the existing data suggest that they would be minimal. Dichlorodifluoromethane can damage the heart, liver, central nervous and respiratory systems at exposure concentrations several orders of magnitude greater than that measured in this private well (US EPA, 1991a). Although the risk of noncarcinogenic effects from this exposure is not completely understood, the existing data suggest that it is minimal.


  2. Past ingestion, dermal and inhalation exposure to VOCs in public drinking water supplies.

    For an undetermined period of time, about 4,000 residents in the area surrounding the Islip site were exposed to VOCs in drinking water. Levels of 1,1,1-trichloroethane (900 mcg/L) and trichloroethene (61 mcg/L) were detected in water from the Oval Drive wellfield prior to its being taken out of service in 1977. This solvent contamination does not appear to be site-related and probably originated from a nearby industrial facility (Jancyn Cesspool Cleaner Manufacturers). Contaminant levels in drinking water prior to this sampling are not known nor is it known to what extent mixing with other well water lowered the levels of contaminants reaching household taps. New York State drinking water standards for each of these VOCs is 5 mcg/L. The health risks from exposure to these two VOCs have already been discussed. Past exposure to the level of trichloroethene found in this public wellfield could pose a low increased cancer risk. In addition, trichloroethene and 1,1,1-trichloroethane produce noncarcinogenic effects at exposures several orders of magnitude greater than exposure from drinking water from this public well. Although the risks of noncarcinogenic effects are not completely understood, the existing data suggest that they are minimal.


  3. Past inhalation exposure to VOCs in indoor air.

    In 1979, explosive levels of methane were detected in the basement of two homes near the eastern border of the landfill. In addition to methane, vinyl chloride was detected in the basement of one of the homes at a concentration of 0.0036 mg/m3. Both homes were abandoned in 1979. The home where vinyl chloride was detected was never reoccupied and was later demolished. Since these residences were constructed in 1973, the maximum duration of exposure to methane, vinyl chloride and possible other VOCs was six years.

    Methane is an asphyxiant which displaces oxygen. Individuals who breathe high levels of methane may become dizzy, experience difficulty in breathing or lose consciousness due to the lack of oxygen (Sax, 1979). Another public health threat from methane generation is the potential for explosive levels of methane to accumulate in closed buildings and hence be a safety problem.

    As discussed previously, vinyl chloride is a known human carcinogen. Past inhalation exposure to vinyl chloride at a concentration of 0.0036 mg/m3 for six years would pose a low increased cancer risk. In 1983 the Town constructed the first phase of the landfill gas collection/control system. This system has been continuously updated as needed.

    Construction of the active gas collection/control system at the perimeter of the landfill and a landfill cap which includes a gas collection/control system significantly reduces or eliminates the potential for off-site migration of landfill gas.


  4. Potential ingestion, dermal and inhalation exposure to contaminants in drinking water as a result of contaminant plume migration.

    As indicated in Table 5 and 7, on-site and off-site groundwater is contaminated with organic chemicals and metals at concentrations that exceed New York State groundwater and/or drinking water standards or guidelines. Residences surrounding the Islip Landfill site are supplied with public water and there are no known private water supplies near the site that are currently being used for drinking. One public water supply wellfield is hydraulically downgradient from the landfill. In the absence of planned groundwater remediation, this public water supply wellfield could become contaminated with site-related compounds in groundwater.

    Organic Compounds

    Vinyl chloride and benzene are known human carcinogens (ATSDR, 1991a,j). Chronic (lifetime) exposure to the highest level of vinyl chloride found in on-site or off-site monitoring wells could pose a moderate increased cancer risk; for benzene the increased cancer risk could be low. Methylene chloride, 1,1-dichloroethene, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethene, tetrachloroethene and bis(2-ethylhexyl)phthalate (ATSDR, 1989b,c; 1990d; 1991e,g,h,i) cause cancer in laboratory animals exposed to high levels over their lifetimes. Chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans who are exposed to lower levels over a long period of time. Based on the results of animal studies, chronic (lifetime) exposure to the highest levels of 1,1-dichloroethane and 1,2-dichloroethane found in on-site and off-site groundwater could pose a moderate increased cancer risk; methylene chloride, tetrachloroethene, trichloroethene and bis(2-ethylhexyl)phthalate could each pose a low increased cancer risk; and exposure to 1,1-dichloroethene could pose a high increased cancer risk. Toxicological data are inadequate to assess the carcinogenic potential of acetone, 2-butanone, dichlorodifluoromethane, total 1,2-dichloroethene, trichlorofluoromethane, 1,1,1-trichloro-ethane and toluene (ATSDR, 1989f; 1990a,e,h; US EPA, 1991b).

    The chlorinated contaminants, as well as toluene, acetone and 2-butanone, produce a variety of noncarcinogenic toxicities (primarily liver, kidney and nervous system effects) at exposures several orders of magnitude greater than potential exposure from on-site groundwater. Bis(2-ethylhexyl)phthalate can adversely affect the male reproductive system (ATSDR, 1991e). Trichlorofluoromethane can damage the heart, liver, central nervous and respiratory systems (US EPA, 1991a). Exposure to benzene has been associated with damage to the blood cell-forming tissues and the immune system (ATSDR, 1991a). These chemicals, in addition to all the others that were detected, produce their noncarcinogenic effects at exposures several orders of magnitude greater than potential exposures from on-site and off-site groundwater. Although the risks of noncarcinogenic effects from potential exposure to these organic contaminants in drinking water are not completely understood, the existing data suggest that they would be low.

    Metal Contaminants

    Metal contaminants of potential concern in on-site and off-site groundwater include lead, chromium, cadmium, manganese, iron and sodium. Chronic exposure to lead is predominantly associated with neurological and hematological effects (ATSDR, 1991f). The developing fetus and young children are particularly sensitive to lead-induced neurological effects. The primary toxicities associated with ingestion of large amounts of chromium have been kidney damage, birth defects and adverse effects on the reproductive system (ATSDR, 1991d). Lead causes cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1991f). Chronic (long-term) exposure to cadmium can lead to kidney damage and may cause adverse effects on bone, the gastrointestinal tract, liver, blood and reproduction (ATSDR, 1991d). The highest levels of iron and manganese in groundwater monitoring wells are over 65 and 600 times the levels, respectively, at which the aesthetic quality (e.g., taste) of drinking water begins to be affected (WHO, 1984). Ingestion of large amounts of iron can lead to accumulation in the body and tissue damage, whereas elevated intake levels of manganese can cause nervous system effects (ATSDR, 1990f). However, due to the effects of these metals on the aesthetic qualities of drinking water, it is unlikely that water which contained iron and manganese at toxic levels would be ingested. The main concern about high sodium levels in drinking water is possible adverse effects on individuals with high blood pressure and possibly heart disease. Exposure to drinking water contaminated with these metals, in particular lead at the highest concentrations found in groundwater monitoring wells, could pose a high increased risk of adverse health effects. Some of the metals found in on-site and off-site groundwater may be associated with the geological conditions of the area.


  5. Potential inhalation exposure to VOCs of individuals working on-site and nearby residents from migration of on-site and off-site vapors in air and soil gas.

    The ISC dispersion model was used to evaluate potential exposures to airborne contaminants migrating from the landfill. Based on the ISC modeled data, the excess lifetime cancer risk associated with exposure to air contaminants was low for employees (on-site workers) and the residents living at the maximally impacted off-site location. However, the ISC modelling of cancer risks was conducted before the Town connected the uncontrolled landfill gas vents along Blydenburgh Road to a flare system and constructed a cap on the landfill which includes a landfill gas collection/control system. These control measures will reduce the possibility of soil gas migration and exposure to site-related contaminants in air.

    Although modelling was used to estimate excess cancer risks, the ambient air data are not adequate to assess definitively the toxicological implications of this exposure pathway. However, some limited data suggest that benzene, carbon disulfide, chlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane, 1,1-dichloroethene, ethylbenzene, tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, vinyl chloride, and xylenes found either in on-site or off-site soil gas could pose a public health threat, if the gas collection/control system which includes flaring of the collected gas is not operating (Tables 2,3,4 and 6).

    The toxicological properties of 1,1-dichloroethane, 1,2-dichloroethane, 1,1-dichloroethene, ethylbenzene, tetrachloroethene, 1,1,1-trichloroethane, trichloroethene and vinyl chloride have already been discussed. Benzene is a known human carcinogen (ATSDR, 1991a) and carbon tetrachloride and chloromethane are known to cause cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1989a; 1990c,g). Toxicological data are inadequate to assess the carcinogenic potential of carbon disulfide, chlorobenzene, ethylbenzene and xylene. The chlorinated organic contaminants can also produce a variety of noncarcinogenic toxicities (primarily liver, kidney and nervous system effects). Benzene can damage blood-cell forming tissues and the immune system. Styrene can damage red blood cells and the liver and carbon disulfide has been associated with adverse effects on reproduction and fetal development (ATSDR, 1990g; 1991a; US EPA, 1991).

B. Health Outcome Data Evaluation

NYS DOH has not evaluated health outcome data specifically for the Islip Landfill site. Breast cancer incidence rates have been examined for small geographic areas of Nassau and Suffolk Counties for the years 1978-1987. No association was found between breast cancer incidence patterns and contaminated drinking water wells or hazardous waste sites.

The NYS DOH is conducting a study of cancer incidence near a number of landfills in New York State which are known to be generating landfill gases, including the Islip Landfill.

The cancer and non-cancer health risks associated with drinking contaminated groundwater are high. The ability of the health outcome data bases to detect an increase in disease is, however, limited due to the small size of the population affected. Therefore, health outcome databases will not be searched at this time. The people exposed to contaminated drinking water from the Blydenburgh Landfill site and the Oval Drive public drinking water supply wells will be considered for addition to the NYS DOH registry being developed for VOC exposures from drinking water. Enrollees in the VOC registry will be asked to complete a questionnaire that collects demographic information and information on water usage, health status and other factors (e.g., smoking, occupation). Registrants will be re-contacted every two years to obtain updated information. The registry will be a source of information about drinking water and health and may be used to examine whether particular chemicals in drinking water are related to specific health outcomes. In addition, if the registry provides evidence of health effects related to VOC exposures, NYS DOH will be able to share this information with participants.

NYS DOH is currently reviewing private well sampling results from around the state to select households for inclusion in the registry. Interviews with persons selected for the registry are expected to begin in late 1995 or early 1996.

C. Community Health Concerns Evaluation

We have addressed each of the community concerns about health as follows:

  1. Have the contaminants migrating from the landfill in air contaminated the air inside of the Whippoorwill School?

    In May of 1980, indoor air samples taken at the Whippoorwill School by H2M were reported to contain vinyl chloride at 0.26 mg/m3. The results of this initial study are questionable and were never confirmed by sampling conducted in the school by the NYS DOH and the US EPA. Based on this information, vinyl chloride was probably not present in the school at detectable concentrations.


  2. What is the potential for landfill gas migration to residential areas?

    In 1983, the Town installed the first phase of a landfill gas control system. This system has been continuously updated as needed to prevent the off-site migration of landfill gas. Based on samples taken from soil gas monitoring wells on the site border in 1989, landfill gas is not migrating off-site. The recently constructed landfill cap includes an active gas collection/control system which further reduces the possibility of soil gas migration and release of site-related contaminants to the air.


  3. What is the potential for exposure to contaminated drinking water?

    Based on current information, all homes in the area of the groundwater contaminant plume are connected to public water. However, if homes with private wells are threatened or contaminated by site-related contamiants in the future, connection to public water will be provided. Therefore, the potential for exposure to site-related contaminants in drinking water is minimal.

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