PUBLIC HEALTH ASSESSMENT
PORT WASHINGTON LANDFILL
NORTH HEMPSTEAD, NASSAU COUNTY, NEW YORK
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:
- Concentrations of contaminant(s) in environmental media both on- and off-site;
- Field data quality, laboratory data quality, and sample design;
- Comparison of on-site and off-site contaminant concentrations in environmental media with typical background levels;
- Comparison of contaminant concentrations in environmental media both on-site 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
- Community health concerns.
The selected contaminant(s) are 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.
Environmental data contained in this section have been collected principally as part of the RI/FS completed for the L4 section of the Port Washington Landfill. Hydrogen sulfide data are from on-going perimeter and off-site monitoring at the L5 Field 3 section of the landfill and should not be attributed to the L4 section.
The most recent data from the RI indicate that contamination is present in groundwater, leachate and soil gas on site (Tables 1-3). These data were collected during 1988 and 1989. Soil gas results are from landfill surface flux boxes (Table 1). These are bell-shaped devices that collect emissions from the landfill surface, without the influence and dilution of the ambient air. Data from flux boxes give the flow rate of gaseous emissions from the landfill surface to the ambient air. The resulting flux data can be used in modeling ambient air exposures. Leachate samples were collected from the leachate collection system manhole located on the L4 section (Table 2). Organic chemical contamination of groundwater is centered on the northwestern and western edge of the L4 section in both the shallow and deep aquifers (Table 3).
On-site soil samples (0-6 inches) were collected from the surface of the L4 cell. The only organic compounds detected were two phthalates and several polycyclic aromatic hydrocarbons (PAHs). Almost all of the highest concentrations of PAHs in the soil samples were from samples collected on or near landfill roadways. All of the organic and inorganic parameters analyzed for were below public health assessment comparison values for soils. Available data do not indicate a significant source of contaminants in surface soil.
Deeper on-site soil samples were collected during the soil boring/monitoring well installation activities of the RI/FS. These soils are contaminated with low levels of volatile organic compounds (VOCs) and PAHs. Since these soils are relatively deep, 20 to 100 feet, human contact with contaminants in this medium would not be expected to occur. Therefore, this pathway has been eliminated.
Off-site contamination of groundwater and soil gas has been demonstrated by the data collected during the RI/FS. Ambient air was contaminated off-site (Table 4); however, the data may reflect contamination derived from sources other than the Port Washington Landfill and limited off-site ambient air sampling conducted since 1989 has essentially shown no volatile organic contaminants above typical background levels.
Soil gas monitoring well data indicated that the soil gas on the western edge of the L4 section is highly contaminated with VOCs (Table 5). Soil gas contamination extended to the west of the site perimeter into the golf course and the residential areas. VOCs were found relatively deep in the soils and probably reflect residual contamination from past gas migration out of the landfill or from migration during periods when the gas collection system has not operated.
Groundwater monitoring wells to the west and northwest of the L4 perimeter were found to be contaminated with VOCs during the RI/FS (Table 6).
The Port Washington Water District's Southport well contained 1,1,1-trichloroethane at 5 mcg/L and tetrachloroethene at 2 mcg/L as sampled in September 1980. The well was taken out of service in June 1981 after vinyl chloride was detected at 38 and 47 mcg/L from consecutive analyses. The results from the 1981 analyses are questionable due to improper instrumentation being used in the analyses. The Southport well remained out of service as a result of confirmed VOC levels at or approaching state drinking water standards. Although the Southport well is hydraulically upgradient from the site, the PWWD's pumping tests indicate that the cone of influence created when the Southport well was pumping reached eastward toward the landfill and intercepted groundwater from beneath the site. Based on the PWWD's study, it is likely that the 1,1,1-trichloroethane and tetrachloroethene contamination was from the landfill.
Regional groundwater flow is to the east toward Hempstead Harbor. To date, no surface water, sediment, or biota in Hempstead Harbor have been sampled for contamination. However, the groundwater can be monitored to evaluate whether contaminants from the landfill could be migrating toward the harbor. Groundwater monitoring wells are present between the landfill and Hempstead Harbor and are sampled every three months since 1992. The sampling data for 1992 through 1994 showed that trace levels of VOCs were detected in one monitoring well on one occasion in 1993. These compounds were not detected in subsequent samples. Cadmium was detected at one time in one monitoring well at a level of 24.0 mcg/L which is above the NYS DOH public drinking water standard of 5 mcg/L. Elevated levels of iron and chloride were also detected in some of the downgradient monitoring well samples. Iron was also detected at elevated concentration in an upgradient monitoring well. The NYS DOH public drinking water standards for iron and chloride are based on aesthetic considerations such as taste, odor and plumbing fixture staining. Based on the downgradient monitoring well data and due to significant dilution, the levels or types of contamination detected in downgradient groundwater would not result in a measurable effect on the water quality of Hempstead Harbor. Long term monitoring of groundwater will continue as part of the landfill closure.
Surface water from rainfall is contained on-site either from percolation into sandy soils or is retained by the leachate collection system. On-site surface water does not discharge off-site except for collected leachate which discharges to the local wastewater treatment facility.
From December 1989 to January 1991, poor operational practices resulted in the generation and release of excessive amounts of hydrogen sulfide from cell L5 Field 3 to the ambient air off site. During December 1990 and January 1991 hydrogen sulfide levels at the fence line exceeded 1,000 ppb with daily maximum levels exceeding 3,000 ppb. Relatively high hydrogen sulfide concentrations have been documented off-site (Table 4). In response to odor complaints by residents and businesses in the area, the NC DOH began monitoring for hydrogen sulfide in the community near the landfill in January 1991. Monitoring for hydrogen sulfide was performed daily with additional monitoring for volatile organic compounds periodically. As specified in an Order on Consent between the NYS DEC and the Town of North Hempstead, the hydrogen sulfide monitoring was to be performed daily at specified fixed points as well as at specified upwind and downwind points. The hydrogen sulfide monitoring program tracks the downwind plume emanating from the landfill. In March 1991, the monitoring program was turned over to the Town's consultant and daily monitoring was continued using protocols established by the NC DOH. Since February 1991, the levels of hydrogen sulfide off-site have primarily been consistent with background indicating that control measures now in place are working.
The RI was done in accordance with US EPA Quality Assurance and Quality Control (QA/QC) guidelines. Investigations conducted before the RI may not have met these guidelines. Samples collected by the NC DOH and analyzed by approved laboratories were subject to NC DOH procedures in effect at the time of sampling. In preparing this public health assessment, the NYS DOH relies on information provided in the referenced documents.
Analyses of Southport Well samples taken in May and June 1981 found vinyl chloride at levels up to 43 mcg/L; however, subsequent analyses of additional samples did not detect vinyl chloride. The initial results were attributed to the use of an incorrect analytical method. Because of this, the analytical reports were retracted by the reporting laboratory.
No other QA/QC problems were identified which would alter the interpretations of the data in this public health assessment.
There are no known physical hazards to the general public at this site. Access is controlled by a guard patrolled gate and site fence. Consultants and employees of the Town of North Hempstead are involved in remedial construction activities at the site and may be subject to physical hazards from these activities. Fire and explosion hazards as a result of methane migration to off-site structures are being controlled by the landfill perimeter gas collection system.
To identify facilities that could contribute to groundwater, soil, or air contamination in the area around the Port Washington Landfill site and/or create health risks unrelated to the 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 Toxic Chemical Release Inventory (TRI) identified one industrial facility (Pall Corp.) located within a 2.5 mile radius of the Port Washington Landfill site. Based on TRI data and air emissions modeling, results of the screening evaluation indicate that emissions of methylene chloride and isopropyl alcohol from this facility should not affect ambient air near the Port Washington Landfill site at levels exceeding a screening criterion of 1 micrograms per cubic meter (mcg/m3). Consequently, this TRI facility would not be expected to pose an additional health risk of concern to the population near the site. This facility did not report any discharges to water or soil.
To determine whether nearby residents and persons on-site are exposed to contaminants migrating from the site, an evaluation was made of the environmental and human components that lead to human exposure. The pathways analysis consists of five elements: a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population.
An exposure pathway is categorized as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. A completed exposure pathway occurs when the five elements of an exposure pathway link the contaminated source to a receptor population. Should a completed exposure pathway exist in the past, present, or future, the population is considered exposed. A potential exposure pathway exists when one or more of the five elements is missing, or if modeling is performed to replace real sampling data. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present. The discussion that follows incorporates only those pathways that are important and relevant to the site.
Soil Gas Pathway
A completed exposure pathway exists for the migration of landfill gases to people off-site. This exposure has been documented in the past and may be occurring intermittently whenever the active landfill gas collection system is inoperative. Large quantities of methane gas are being generated by organic decomposition of municipal wastes within the landfill mass. This methane acts as a carrier medium for VOCs that were disposed of in the landfill, transporting the VOCs through the unsaturated soils. Prior to the installation of landfill gas controls, the generated gases were migrating through the unsaturated soils off-site. Contaminated subsurface soil gas has the potential to migrate into building foundations, presenting an inhalation exposure to residents and non-residents. During winter months, when surface soils are generally frozen, preferential migration routes brought the landfill gases containing VOCs into homes and structures where soils were unfrozen and more porous. The VOCs include vinyl chloride, 1,1,1-trichloroethane, toluene, 1,1,2-trichloroethane, benzene and methane.
The existing landfill gas vent system at the L4 section of the landfill should operate continuously. However, at times the operation of the system has been interrupted resulting in some subsurface landfill gas migrating to the west of the site. VOCs are being carried by the landfill gas, both through the unsaturated zone and through releases to ambient air at the landfill surface. Data indicate that 1,1-dichloroethene, 1,1-dichloroethane, trans-1,2,-dichloroethene, 1,1,1-trichloroethane, 1,2-dichloroethane, 1,2-dichloropropane, trichloroethene and tetrachloroethene are present in off-site gas wells (Table 5).
Furnace puff-backs, indicating explosive levels of methane, occurred in homes to the west of L4 and document past exposures. Inhalation exposures (both indoor and outdoors) could be occurring in the residential areas west of the site (Wakefield Ave.) and in non-residential areas south and southwest of the site. Studies of the gas migration problem identified VOCs and combustible levels of methane in the landfill gases. Prior to the extension of the landfill gas collection system, studies by the Town of North Hempstead found elevated methane levels (greater than 2.5%) in buildings located in the Seaview Industrial Park.
Ambient Air Pathway
Exposures to VOCs and hydrogen sulfide in ambient air from landfill gas emissions may have occurred in the past, which identifies this medium as a past completed exposure pathway. Although a gas collection and venting system is in place, it has been operating intermittently and as a result exposures may be occurring presently; however, limited off-site ambient air sampling done since 1989 has shown no VOCs above typical background levels. Hydrogen sulfide air levels measured off-site exceeded 1 ppm on several occasions in the summer and fall of 1990. The hydrogen sulfide air levels were significantly reduced by February 1991 after the town installed the gas collection system. Exposures to VOCs and hydrogen sulfide may occur in the future, if the gas venting system is not operating over a long period of time. Exposures may occur to on-site employees and contractors and to off-site adjacent residents and workers.
Exposures to low levels of VOCs below the NYS DOH drinking water standards for organic contaminants in the Southport Public Supply Well may have occurred in the past. Exposure to contaminants in groundwater probably occurred through ingestion, inhalation or dermal contact. Exposures are not occurring presently because the Southport public supply well has been taken out of service.
A potential route of exposure that may have occurred in the past as well as in the future is the use of contaminated groundwater. Leachate from the landfill has been contributing to groundwater contamination beneath and adjacent to the landfill. The lack of an impermeable cap on the landfill is resulting in large quantities of precipitation infiltrating the waste mass and producing leachate. Areas of the landfill that have an intact liner collect the leachate for treatment and disposal off-site to a sewage treatment plant. Unlined areas of the landfill, or areas where the liner is not intact, produce leachate that migrates directly into the groundwater below the site.
Groundwater is contaminated in the area of the Port Washington Landfill by the landfill mass. The uppermost aquifer named the Upper Glacial, is contaminated with VOCs west of the site. A groundwater plume containing landfill leachate components such as metals is northeast of the site. Both inorganic and organic compounds exceed state and federal drinking water standards (Table 3). The Port Washington Water District's (PWWD) Southport Well has been inactivated, due to VOC contamination in the groundwater. This well is west of the site and is about 330 feet deep drawing from the deeper Magothy aquifer. Without remediation, both the organic and inorganic leachate plumes will migrate to the northeast following regional groundwater flow and potentially contaminate the Magothy Aquifer which is currently being used as a source of drinking water. The PWWD has several water supply wells to the west and southwest of the site. Contaminants from the landfill have affected the aquifers used by these wells. Exposure from the use of contaminated groundwater could occur if the Southport well was brought back into service because the pumping influence may draw contaminated groundwater from the landfill; however, due to State regulation of all public water supplies, exposure to levels of contaminants greater than drinking water standards are not expected. The PWWD serves about 35,000 people.
Groundwater contaminants detected both on-site and off-site exceed the current NYS DOH drinking water standards for organic contaminants (Tables 3 and 6). However, public water supply and irrigation wells currently in use are not being affected by contaminated groundwater associated with the landfill.
Soil and Leachate Pathway
Based on past and current on-site conditions and controls, neither soil nor leachate are available for direct contact and these human exposure pathways have been eliminated from further discussion in this public health assessment. Exposure to site-related contaminants in the surface soil is not expected to occur since the upper fill dirt is "clean" fill brought in from off-site.
Exposure to contaminated subsurface soils will not occur unless subsequent on-site excavation of soils is conducted. Future remedial activities will include minimal, if any, disturbance of subsurface soils. Future excavation of on-site soils could expose workers to contaminants via several routes including ingestion, inhalation and skin contact. Future exposure to site workers would be minimized if site workers follow appropriate health and safety guidelines.
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 Port Washington 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 exposure duration. For additional information on how the NYS DOH determined and qualified health risks applicable to this health assessment, refer to Appendix C.
- Inhalation exposure to VOCs in ambient air by nearby residents and workers.
VOCs have been emitted as co-contaminant gases with methane and other gases produced by the decomposition of wastes within the landfill for an undetermined period of time. Exposures could have been occurring for a period of less than 15 years, that is from sometime after the landfill opened in 1974 until 1989 (Table 4). Very limited off-site ambient air sampling conducted during the 1988-1989 RI detected vinyl chloride as a contaminant of concern in ambient air (Table 4). Exposures could have been occurring for a period of less than 15 years; however, no data are available prior to 1988. Limited off-site ambient air sampling conducted since 1989 has shown no volatile organic contaminants above typical background levels.
Vinyl chloride is a known human carcinogen (ATSDR, 1993). Based on the limited sampling data available since 1989, past exposure to vinyl chloride in off-site ambient air could pose a low increased cancer risk. Vinyl chloride is also known to produce noncarcinogenic toxic effects (primarily to the liver, kidneys and nervous system). Although the risks of noncarcinogenic effects from past exposures to vinyl chloride found in off-site ambient air aren't completely understood, the existing data suggest that they were minimal.
Although a gas collection and venting system is in place at the L4 section of the landfill, it has been operating intermittently. Due to deterioration which resulted in decreased effectiveness, the system may at times be failing to capture all subsurface landfill gas. Therefore, the potential still exists for low level exposures both on-site and off-site through inhalation. Limited off-site ambient air sampling conducted since 1989, however, has essentially shown no detectable release of VOCs above typical background levels. The potential for VOCs to be released in the future is not likely, as the proposed landfill closure will include rehabilitation and extension of the existing gas collection system, as stated in the ROD.
- Inhalation exposure to hydrogen sulfide in off-site ambient air.
During the fall of 1990, operational problems at the L5 section of the Port Washington Landfill led to the production of large amounts of hydrogen sulfide gas which migrated off-site. The NC DOH has been compiling reported illness complaints from residents living near the landfill. These complaints have included nausea, headache, eye irritation and burning, breathing problems, throat irritation and cough (Table 8). Hydrogen sulfide smells like rotten-eggs and some people can smell it at very low levels, as low as 0.5 ppb in air. During December 1990 and January 1991, off-site maximum levels exceeded 3,000 ppb (Table 4).
Short-term (i.e., acute) exposure to hydrogen sulfide in amounts of 1,000 ppb or greater can produce eye, nose and throat irritation, nausea, headache and loss of appetite and sleep (NYS DOH, 1991). People exposed chronically (i.e., long-term) to hydrogen sulfide are likely to have similar health effects as they do from acute exposures, except that the effects may occur at lower exposure levels and the symptoms may be more persistent. Studies have not been conducted to determine if exposure for long periods of time has caused any lasting effects on sensitive organ systems such as the respiratory tract or nervous system.
Remedial measures performed by the Town of North Hempstead in February and March of 1991 have reduced this exposure to hydrogen sulfide to less than 50 ppb in downwind samples which has resulted in a considerable decrease in the number of illness complaints (Table 8). However, the source of the generation and release of hydrogen sulfide, which is the landfill's most recently used cell (L5 Field 3), still exists. Therefore, any interruption in the gas control system to collect hydrogen sulfide could result in the release of high levels of this gas and health complaints.
- Past inhalation exposure to volatile organic compounds in indoor air.
For an undetermined period of time of less than 8 years (after the landfill opened in 1974 until 1981-1982 when gas venting systems were installed) the indoor air of homes west of the Port Washington Landfill was contaminated with volatile organic compounds. No data are available prior to 1981. Indoor air measurements carried out in 1981 detected methane, vinyl chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, and benzene at levels requiring further evaluation (Table 7). Monitoring for methane indicated that levels of this gas were at the lower explosive limits (50,000 ppm) in several homes. Installation and operation of an active soil vapor venting system has considerably reduced or eliminated this exposure in these homes. Commercial buildings to the south of the landfill have also had elevated methane levels greater than 2.5% (25,000 ppm). The landfill gas collection system has been extended to intercept the migrating gas entering these commercial buildings.
During the winters of 1979, 1980 and 1981, small furnace area explosions occurred in homes to the west of the landfill, suggesting that high levels of methane were present. Vinyl chloride and other volatile organic chemicals appear to be carried with methane. Therefore, exposure to the highest levels of methane and volatile organic chemicals may have occurred for about three to four winter months per year for the years 1979 through 1981.
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 the highest indoor level of vinyl chloride detected (240 ppb) could pose a moderate increased cancer risk. Benzene is also a known human carcinogen (ATSDR, 1991a). Past exposure to the highest level of benzene (30 ppb) could pose a low increased risk of developing cancer. 1,1,2-Trichloroethane is known to cause cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1989j). Chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans exposed to lower levels over long periods of time. Whether 1,1,2-trichloroethane causes cancer in humans is unknown, but based on the results of animal studies, past exposure to this chemical at the highest concentrations found in indoor air could pose a low increased risk of developing cancer. Toxicological data are inadequate to assess the carcinogenic potential of 1,1,1-trichloroethane (ATSDR, 1990e).
Vinyl chloride produces noncarcinogenic toxic effects (primarily to the liver, kidneys and the nervous system) in humans and laboratory animals. Benzene damages the blood-cell forming tissues and the immune system. 1,1,1-Trichloroethane damages the nervous system, liver and cardiovascular system. However, the toxicological data are not sufficient to quantify the risks of these effects from past inhalation exposures.
- Past ingestion, dermal and inhalation exposure to organic contaminants in a public water supply well.
For a time period of less than one year, the Port Washington Water District's Southport Well was contaminated with volatile organic chemicals. Tetrachloroethene was detected in this public water supply well in 1981 at a level of 2 mcg/L. This level exceeded the public health assessment cancer comparison value for this chemical (see Table 3). From 1977 to 1980, tetrachloroethene levels were below detection limits. Prior to 1977 the contaminant levels in this well are not known. The well, which was constructed in 1954, was utilized for public water supplies until June 1981.
Chronic exposure to contaminants in drinking water can occur by ingestion, dermal contact and absorption during showering, bathing or other household uses and inhalation of aerosols and vapors from water used in the household. Although exposure varies depending on an individual's lifestyle, each of these exposure routes contributes to the overall daily uptake of contaminants and thus increases the potential for chronic health effects.
Tetrachloroethene causes cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1991g). 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 chemicals cause cancer in humans is not known. Based on the results of animal studies and limited sampling of this public water supply, it is estimated that persons who were exposed to drinking water contaminated with tetrachloroethene could have a very low increased risk of developing cancer.
- Potential inhalation exposure to volatile organic compounds by migration of on-site and off-site soil vapors into nearby homes and commercial buildings.
Adequate air monitoring data are not available to assess the toxicological implications of this exposure pathway. However, data suggest that benzene, vinyl chloride, chloroform, methylene chloride, acetone, 1,1-dichloroethene, 1,1-dichloroethane, 1,2-dichloroethane, 2-butanone (methyl ethyl ketone), 1,1,2,2-tetrachloroethane, tetrachloroethene, trichloroethene, toluene and xylene found in on-site soil gas and carbon tetrachloride, chloroform, 1,1-dichloroethene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, tetrachloroethene and trichloroethene found in off-site soil gas could pose a public health threat (Tables 1 and 5).
Among these volatile organic contaminants, benzene and vinyl chloride are known human carcinogens (ATSDR, 1991a; 1993) and carbon tetrachloride, chloroform, methylene chloride, 1,1-di-chloroethene, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, tetrachloroethene and trichloroethene are known to cause cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1989a,e,f,h,i; 1991b,c,f,g,h). Whether these chemicals cause cancer in humans is unknown, but chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans exposed to lower levels over long periods of time. Toxicological data are inadequate to assess the carcinogenic potential of 2-butanone, acetone, toluene and xylene (ATSDR, 1989i; 1990a,f; 1992). These organic contaminants are also known to produce noncarcinogenic toxic effects (primarily to the liver, the kidneys, and the nervous and cardiovascular systems) and benzene is known to damage blood-cell forming tissues and the immune system.
- Potential ingestion, dermal and inhalation exposure to contaminants in public water supply wells as a result of on-site and off-site contaminated plume migration.
Volatile Organic Compounds
As indicated in Tables 3 and 6, groundwater both on and off-site is contaminated with volatile organic compounds at concentrations that exceed New York State drinking water standards or guidelines. Drinking water supply wells could become contaminated as a result of on-site and off-site groundwater migration.
The toxicological properties of volatile organic compounds found in on-site and off-site groundwater have already been discussed (see #4 above). Chronic (lifetime) exposure to the highest levels of vinyl chloride, 1,1-dichloroethene and tetrachloroethene (see Tables 3 and 6) found in on-site and off-site groundwater could pose a high increased cancer risk. In addition, although the combined noncarcinogenic risks from potential exposures to the volatile organic compounds (listed in Tables 3 and 6), found in on- and off-site groundwater aren't completely understood, the existing data suggest that they could be low.
Metal contaminants at levels exceeding New York State drinking water standards have also been detected in on-site groundwater.
Sampling results for metal contaminants in groundwater are shown in Table 3. Chronic exposure to elevated lead levels is predominantly associated with neurological and hematological effects (ATSDR, 1991e). The developing fetus and young children are particularly sensitive to lead-induced neurological effects (ATSDR, 1991e). Exposure to lead in drinking water at the highest levels found in on-site groundwater would pose a high risk of adverse health effects to children and the developing fetus. Lead causes cancer in laboratory animals exposed to high levels over their lifetimes (ATSDR, 1991e). 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). Exposure to chromium in drinking water at the highest levels found in on-site groundwater could pose a moderate risk of adverse health effects. There is no evidence that chromium is carcinogenic by ingestion exposure.
The most sensitive effect from chronic exposure to cadmium is kidney damage (ATSDR, 1991b). Exposure to cadmium in drinking water at the highest levels found in on-site groundwater could pose a low risk of adverse effects on the kidneys. There is no evidence that cadmium is carcinogenic by ingestion exposure. Exposure to high manganese concentrations increases the risk of nervous system effects (ATSDR, 1990d). However, the level of manganese in on-site groundwater is over 80 times the level at which the aesthetic quality of drinking water begins to be affected (WHO, 1984) and it is unlikely that such water would be ingested for any extended period of time. Gastrointestinal effects, liver and kidney damage have been associated with the consumption of large amounts of copper (ATSDR, 1989d). The risk of these effects would be low at levels found in on-site groundwater. Toxicological data are inadequate to assess the carcinogenic potential of manganese and copper. Finally, the level of iron in on-site groundwater is over 330 times the level at which the aesthetic quality of drinking water begins to be affected (WHO, 1984). Although iron is an essential nutrient, ingestion of large amounts can lead to iron toxicity characterized primarily by gastrointestinal disorders (Henretig and Temple, 1984). However, it is unlikely that such exposures could occur due to iron's effects on the aesthetic quality of water.
If site-related contaminants migrate to the active, downgradient public drinking water supply wells, the public health implications summarized above would be minimized because the routine monitoring mandated by New York State will provide for early detection and implementation of controls to minimize human exposures.
In April 1987, the NYS DOH completed a study of cancer incidence in census tracts 3010p and 3014 in Port Washington for cancers diagnosed during the years 1978-1984. These census tracts are to the north and west of the landfill. A significant excess of brain cancer was found among males, and a significant excess of leukemia was found among females.
Case interviews were later conducted for the brain cancers and leukemia cases. One of the leukemia cases was diagnosed prior to moving the Port Washington area, while another of the cases never lived in the study area for more than one week a year. The incidence of leukemia was found to be significantly elevated, if these two cases are excluded from the original study. Brain cancer among males remained significantly elevated within the original study area. All were long-time residents of the area and no additional information was obtained from the interviews that indicated non-landfill related exposures that may be related to brain cancer. The brain cancer cases were in a small portion of the study area, about one mile from the landfill.
A follow-up study was completed in January 1988 in which the investigation time frame and geographic area looked at were increased. The follow-up study results for the broader geographic area indicated that the incidence of brain cancer and the incidence of leukemia were within expected limits. Neither cancer was significantly elevated for the period 1973-1977.
Community concerns have been raised over possible health effects caused by landfill gas emissions. In response to these concerns, the NYS DOH and the NC DOH conducted public health education programs and health studies. In addition, these agencies worked with the ATSDR, US EPA, NYS DEC, and the Town of North Hempstead to reduce the exposures of concern. Public health education has been done through public meetings, personal contact, and telephone contact. In addition, this public health assessment will be provided to interested members of the community. The NYS DOH conducted a cancer incidence study in census tracts adjacent to the landfill in 1987 in response to concerns expressed by the community.
The NC DOH has been compiling reported health conditions from residents living near the landfill (Table 8). The number of illness complaints received by the NC DOH has decreased from those levels reported in early 1991 to less than 10 a month in April and May, 1991.
Hydrogen sulfide levels detected off site, attributed to the L5 landfill, have decreased dramatically since the gas control system was installed in February 1991. This is evident in Figure 2 which shows the weekly average hydrogen sulfide levels for concentric zones around the landfill between January 6, 1991 and April 7, 1991. Other measures which have been taken to reduce exposures are detailed elsewhere in this public health assessment.