PUBLIC HEALTH ASSESSMENT
DUPAGE COUNTY LANDFILL (BLACKWELL FOREST PRESERVE)
WARRENVILLE, DUPAGE COUNTY, ILLINOIS
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in this document list the contaminants of concern. These contaminants will be further evaluated in the remaining sections of this health assessment to determine if they pose a threat to public health. The listing of a contaminant on the following tables does not necessarily mean it poses a threat to public health. The selection of these contaminants is based on the following factors:
Comparison values for a public health assessment are levels used to select contaminants for further evaluation. These values, prioritized below, include Environmental Media Evaluation Guides (EMEGs), Cancer Risk Evaluation Guides (CREGs), Reference Dose Media Evaluation Guides (RMEGs), Lifetime Health Advisories (LTHAs), and Maximum Contaminant Levels (MCLs). If a site-related contaminant is found at levels above any of these comparison values or if no comparison value exists for the chemical in that medium (air, water, or soil), it will be evaluated further in the remaining sections of this document to determine if it poses a significant threat to public health. Known or suspected human carcinogens with no carcinogenic comparison value will also be listed as a contaminant of concern and will be evaluated in the remaining sections of this public health assessment.
EMEGs are comparison values developed for chemicals that are relatively toxic, frequently encountered at NPL sites, and present a potential for human exposure. They are derived to protect the most sensitive members of the population (e.g., children) and are not cut-off levels, but are comparison values. They do not consider carcinogenic effects, chemical interactions, multiple route exposure, or other media-specific routes of exposure, and are very conservative concentration values designed to protect the public.
CREGs are estimated contaminant concentrations based on one excess cancer in a million persons exposed to a chemical over a lifetime (70 years). These are also very conservative values designed to protect sensitive members of the population.
RMEGs are estimates of a daily oral exposure to a particular chemical that is unlikely to produce any noncarcinogenic adverse health effects over a lifetime. They are based on USEPA reference doses (RfDs) and are conservative values designed to protect sensitive members of the population.
RfCs are estimated air concentrations an individual can breathe for a lifetime (70 years) without experiencing adverse health effects. They are developed by the USEPA.
LTHAs are estimated water concentrations an individual can drink for 70 years without experiencing noncarcinogenic health effects. These numbers contain a margin of safety to protect sensitive members of the population. These values are established by the USEPA and are considered only if no EMEG, CREG, or RMEG is available for the chemical.
MCLs have been established by the USEPA for public water supplies to reduce the chances of adverse health effects from use of contaminated drinking water. These standards are generally well below levels associated with health effects and take into account the financial and technical feasibility of achieving specific contaminant levels. These are enforceable limits that public water supplies must meet. These values are considered only if no EMEG, CREG, RMEG, or LTHA is available for the chemical. USEPA has also established MCLGs, maximum contaminant level goals. These are not enforceable, but are used as comparison values in preference to MCLs.
In the laboratory analyses of the on-site media sampling (indicated below), there was no indication as to the type of chromium (hexavalent or trivalent) detected; therefore, the chromium detected will be considered the hexavalent type (type more likely to cause adverse health effects).
No volatile organic compounds were detected in two upwind (on landfill) ambient air samples or one taken downwind of the DuPage County Landfill (Figure 5; Warzyn Engineering, Inc., 1992). However, odors have been noted within 10 to 30 feet of some gas vents, including several along a paved path to the summit and one near the top of the hill. This suggests the local presence of contaminants.
Many volatile compounds were found in landfill gas collected from leachate vents (Figure 5; Table 1). No comparison values exist for landfill gas.
Many organic compounds were found in leachate from the landfill (Figure 5; Table 2), and the volatile chemicals were similar to those found in landfill gas. No pesticides, polycyclic aromatic hydrocarbons (PAHs), or polychlorinated biphenyls (PCBs) were found in leachate; however, many inorganic chemicals including ammonia, arsenic, cadmium, chromium, lead, manganese, mercury, nickel, thallium, vanadium, and zinc were detected (Table 3). No comparison values exist for leachate.
In shallow monitoring wells (Figure 6), fewer contaminants were found and their concentrations were generally lower than in leachate. In shallow groundwater, benzene, chloroethane, 1,1-dichloroethane, 1,2-dichloroethene, tetrachloroethene, trichloroethene, vinyl chloride, di-n-octylphthalate, ammonia, arsenic, and manganese were the chemicals of concern (Table 4). Contaminants were restricted to within about 200 yards of the landfill.
In deep monitoring wells (Figure 7), fewer contaminants were found, and the concentrations were generally lower than in shallow groundwater. Benzene, 1,2-dichloroethane, di-n-octylphthalate, and manganese were the chemicals of concern (Table 5). Again, contaminants were restricted to within 200 yards of the landfill.
Soil sampling locations are shown in Figure 8. Table 6 lists the contaminants detected in background samples, on-site surface soil samples (0 to 6 inches in depth), and on-site subsurface soil samples (6 to 12 inches in depth) at levels above their comparison values. Although some PAHs were detected in the background soil samples, none was detected in the on-site soils. No PCBs were found in the background soil samples; however, the PCB (Aroclor 1254) was found in on-site surface soil samples, but was not found in the subsurface soil samples.
Of all the inorganic chemicals detected in the soil samples, only the cadmium concentration found in the background soil sample exceeded (slightly) the normal range of background levels found in Illinois (Table 6). Inorganic elements in soil which are not above state or regional background concentrations will not be discussed further.
Sediment sampling locations are shown in Figures 8 and 9. Table 7 lists the concentrations of chemicals in on- and off-site (background) sediments. None of the sediment samples was found to contain inorganic chemicals at levels which exceeded their range of normal background concentrations found in Illinois or regional soils (Table 7); therefore, the inorganic chemicals will not be discussed further. PAHs were detected in background sediment samples taken from Herrick Lake, about 1.5 miles to the east, and from the side of Silver Lake opposite the landfill. Benzo(a)pyrene was found in background sediments from both lakes, but exceeded its comparison value only in the Herrick Lake sediment samples.
The concentrations of PAHs in the sediment samples taken from the side of Silver Lake near the landfill were similar to the concentrations found in the Herrick Lake background sediments. PAHs were also found in both upstream (background) and downstream sediments of Spring Brook.
Surface water sampling locations are shown in Figures 8 and 9. Background sampling locations included Herrick Lake and the side of Silver Lake opposite the landfill. No volatile organic compounds, semi-volatile organic compounds, pesticides, or PCBs were detected. Background chemicals exceeding comparison values included arsenic and manganese (Herrick Lake only; Table 8).
In the part of Silver Lake by the landfill, arsenic and manganese were found at levels exceeding their comparison values (Table 8). Manganese was the only chemical in Sand Pond and arsenic was the only substance in Pine Lake that exceeded their comparison values. In the past, people swam in Sand Pond; however, sampling at that time did not find contamination (Booth and Vagt, 1986).
Spring Brook had very high levels of nitrate, plus nitrites in surface water upstream (background) and downstream of the landfill (Table 8), indicating contamination from an upstream source. The likely sources are malfunctioning septic systems, fertilizer runoff, and the Wheaton sewage plant. Downstream of the landfill, the arsenic concentration exceeded its comparison value.
In general, the concentrations of chemicals in background samples and surface water potentially affected by the landfill were similar (Table 8).
A search of USEPA's Toxic Release Inventory (TRI) database indicated that there were no industries in the Warrenville (zip code 60555) area reporting chemical releases to the air, water, or land.
The concentrations of chemicals in off-site air are unknown. Because volatile organic compounds (VOCs) were not detected in the on-site ambient air upwind and downwind of the landfill, their airborne concentrations are probably not elevated off-site (at least not because of landfill emissions).
The locations of private wells around the site are shown in Figures 3a and 3b. During the RI, low levels of VOCs were detected in 15 of the 51 downgradient private wells. Arsenic was above comparison values in some background wells (Table 9). Benzene, 1,1-dichloroethene, dieldrin, antimony, arsenic, and manganese were chemicals exceeding their screening comparison values in some downgradient private wells. A high level of lead was found in one private well which is northwest and not downgradient of the site. ATSDR advised these residents of the lead contamination and the possible hazards associated with drinking the contaminated well water.
The concentrations of chemicals in off-site soil are unknown.
Aside from Herrick Lake (background), the concentrations of chemicals in off-site sediments are unknown.
Aside from Herrick Lake (background), the concentrations of compounds in off-site surface water are unknown.
C. Quality Assurance and Quality Control
Warzyn, Inc. (1994) mostly followed acceptable quality assurance/quality control (QA/QC) procedures for chain of custody, blanks, and laboratory procedures. However, results for insecticides in off-site groundwater were dismissed as laboratory errors although they were not found in any of the blanks. According to USEPA, these rejections were not warranted, and the data are considered valid.
Warzyn, Inc. (1994) used only one upgradient monitoring well for the glacial till. This is inadequate to characterize background groundwater because of natural variability in the glacial till and, hence, the chemicals in groundwater. Consequently, it is difficult to tell if variations between chemicals found both in upgradient and downgradient wells were caused by contamination or natural variability. Additional upgradient shallow monitoring wells are needed to adequately characterize the groundwater. Warzyn, Inc. (1994) also notes that the bedrock aquifer upgradient of the landfill is overlain by impermeable clay, while that downgradient of the landfill is overlain with sand and gravel; therefore, the water which recharges the aquifer upgradient of the landfill has a different chemistry than that present downgradient of the landfill.
In Warzyn Engineering, Inc. (1992), there were no upgradient shallow monitoring wells, so comparison to background concentrations cannot be made. However, the glacial aquifer begins under the landfill, making it impossible to have upgradient shallow monitoring wells.
The presence of contaminants in background surface soil and Herrick Lake background sediment samples suggests they may not be representative of background concentrations in the area.
For other documents, IDPH relied on the information in them. IDPH assumed that adequate QA/QC measures were followed regarding chain-of-custody, laboratory procedures, and data reporting. The analyses, conclusions, and recommendations in this health assessment are valid only if the referenced documents are complete and reliable.
Aside from the possibility of someone drowning in one of the on-site surface water bodies or falling on the steep northern, southern, or western slopes of the landfill, there are no on-site physical hazards. Gas flares are caged to prevent contact.
A hazardous chemical can affect people only if they contact it through an exposure pathway at a sufficient concentration to cause a toxic effect. This requires a source of exposure, an environmental transport medium, a route of exposure, and an exposed population (point of exposure). A pathway is complete if all of its components are present and people were exposed in the past, are currently being exposed, or will be exposed in the future. If (1) parts of a pathway are absent, (2) data are insufficient to determine if it is complete, or (3) exposure may occur at some time (past, present, future), then it is a potential pathway. If a part of a pathway is not present and will never exist, the pathway is incomplete and can be eliminated from further consideration. The exposure pathways at this site are summarized in Table 10.
A. Completed Exposure Pathways
Volatile organic compounds from the wastes can dissolve in groundwater or move through soil gas. Soil gas can migrate to the surface or laterally through the soil. Warzyn Engineering, Inc. (1992) said that soil gas probably moves out through the leachate vents rather than laterally through the soil because it is likely to follow the path of least resistance. However, the concentrations of chemicals in soil gas around the landfill have not been measured to verify this hypothesis.
On- and off-site workers, nearby residents, and park users may be exposed to airborne chemicals via inhalation, dermal contact, and ingestion (dust). Volatile organic compounds are emitted into the air through leachate vents and probably also through the landfill cap, where they are diluted by the ambient air. Because the gas vents are caged, direct exposure to undiluted landfill gas will not occur. Limited air sampling has not found volatile organic compounds upwind or downwind of the landfill. However, odors have been noted within 10 to 30 feet of some gas vents, including several along a paved path to the summit and one near the top of the hill. This suggests the local presence of contaminants and human exposure. The odors are not pleasant and would not encourage extended stays. Exposure is likely occasional and of brief duration. Because of limited exposure duration and ambient air dilution, the inhalation of volatile compounds on- or off-site is probably negligible and will not be discussed further.
Since the site is well-vegetated, the production of contaminated dust should be minimal. Also, there are no buildings on the landfill where landfill gas could accumulate. If, in the future, buildings are constructed on the landfill, then landfill gas infiltration and accumulation may be a concern.
Surface soil of the landfill can be contaminated by leachate or direct contact with wastes. Then, contaminated surface soil could be eroded from the landfill. Surface runoff tends to flow radially away from the center of the landfill hill and discharge into the surrounding surface water bodies (Figure 10). This could contaminate sediments of the surrounding on-site lakes and streams. Chemicals in leachate could move through groundwater to the on-site surface water bodies, most likely Sand Pond, Pine Lake, and Spring Brook (at times of low flow only). This could also contaminate their sediments. Groundwater flow will be discussed under potential pathways. There is some evidence that contamination of Sand Pond sediments has occurred.
On-site workers may be exposed to chemicals in on-site sediments through dermal contact or incidental ingestion (past, present, future). About 80 people work part- or full-time on-site. Although on-site workers practice rescue diving, this is done only a few days each year (95 percent of the time it is less than 2 days per year; Warzyn Inc., 1994). Swimming is no longer permitted in Sand Pond. In the past, people swam in Sand Pond; however, sampling at that time did not find contamination (Booth and Vagt, 1986). Consequently, swimmers were evidently not exposed to contaminants in sediments. While dermal contact with and ingestion of sediments by park users may occur, this is probably infrequent. Therefore, for the past and present, the exposure to contaminants in sediments is probably negligible and will not be discussed further.
As previously described for sediments, surface water may become contaminated by runoff from the landfill or polluted groundwater. On-site workers may be exposed to chemicals in on-site surface water through dermal contact or incidental ingestion (past, present, future). Few people would deliberately drink on-site surface water. Incidental ingestion by on-site workers may occur and dermal contact will occur during practice or actual rescue diving. This practice is done infrequently (95 percent of the time it is less than 2 days per year; Warzyn Inc., 1994), and swimming is no longer permitted in any of the on-site lakes. Consequently, the ingestion of surface water by on-site workers is probably negligible. In the past, people swam in Sand Pond; however, sampling at that time did not find contamination (Booth and Vagt, 1986). Consequently, swimmers were evidently not exposed to contaminants in surface water. While dermal contact with and ingestion of surface water by park users may occur, this is probably infrequent. Therefore, for the past and present, the exposure to contaminants in surface water is probably negligible and will not be discussed further.
Water from precipitation can infiltrate through the cap of the landfill, and this movement is enhanced by sand and gravel, but inhibited by clay. The steep sides of the landfill promote runoff and decrease infiltration. If infiltrating water contacts wastes in the landfill, it can dissolve contaminants and become leachate. Similarly, if groundwater flows into the landfill and contacts waste, it can become contaminated. The flow of leachate into the surrounding groundwater and the flow of groundwater are controlled by the geology of the site. Plumes of contaminated groundwater usually extend no more than about 3,300 feet from a landfill (Christensen et al., 1994).
Some chemicals are transported more easily by groundwater than others. In groundwater, the heavy metals cadmium, copper, lead, nickel, and zinc exhibit little mobility because they do not dissolve easily in water and are strongly adsorbed to geologic material or tend to form precipitates. Consequently, high concentrations of heavy metals generally occur close to landfills. Attenuation of organic compounds by subsurface geologic materials is generally small in aquifers with low organic carbon content (Christensen et al., 1994). Organic compounds which dissolve the most easily in water are generally the most mobile in groundwater. Organic compounds can also be broken down into other chemicals (Christensen et al., 1994), which may be more or less toxic.
The on-site geology has been well-characterized and consists of glacial deposits about 50 to 60 feet thick overlying dolomite bedrock (Figures 11a to 11f). The Yorkville, Malden, and Tiskilwa tills are mostly silt and clay, with some interbedded seams of sand and gravel, especially in the Malden. Clay in these tills would inhibit the downward movement of contaminants; however, sand and gravel seams in these layers would tend to promote the lateral movement of pollutants. Under the western side of the landfill and to the west, the Yorkville and Malden tills are absent. In this area, the Tiskilwa layer thins from 8 to 3 feet in thickness, and it may be absent in some locations. In this area, the highly permeable glacial outwash (sand and gravel) of the Henry Formation overlies the Tiskilwa till and forms a shallow aquifer. Under the layers of till is dolomite bedrock, and about the upper 25 to 50 feet of this formation is fractured and comprises the shallow bedrock aquifer.
The on-site groundwater system has been well-characterized. It is controlled by the three-dimensional geometry of the till units and the on-site surface water bodies. The general flow of groundwater in the till is west and southwest (Figures 12a to 12d). Silver Lake discharges into the glacial till, and this water also moves west and southwest. In the glacial deposits immediately around the landfill, the direction of groundwater movement is radially away from the leachate mound. This mound formed as the water level in the landfill rose about 5 feet per year between 1968 and 1970. It then rose around 1 foot per year until 1980, when its elevation stabilized at about 760 feet. Opinions differ as to whether the mounding is caused by capillary action and the increased absorptive ability of refuse compared to soil or by infiltration of precipitation. Some of this water may not be hydraulically connected with that of the deeper glacial till, but separated from it by impervious clay layers.
The movement of groundwater in the till is also affected by Spring Brook, which discharges water into the Henry Formation. The degree of discharge varies seasonally as the water table fluctuates. In spring, when the water table is high, discharge occurs in at least the southern half of Spring Brook shown in Figure 12a. Later in the year, when the groundwater surface is low (Figure 12b), discharge occurs along its entire on-site length. The USEPA Remedial Investigation (RI) was performed during an unusually dry year, and Spring Brook discharged into the groundwater along its entire on-site length during that period (Figures 12c and 12d). This discharge causes local groundwater mounding, slowing the westward flow of leachate in the glacial till and redirecting it southward. This mounding, however, does not completely stop the westward flow of groundwater. Silver Lake also discharges into the glacial till, and this water moves west and around the leachate mound.
In the shallow bedrock aquifer, groundwater flow is generally west (Figure 13a and 13b). This aquifer supplies about 68 percent of the groundwater used in DuPage County, while around 30 percent of it comes from deeper rock formations, and only 2 percent of it is taken from the glacial till. Private and municipal wells in the vicinity use the shallow dolomite aquifer.
Hydrogeological measurements indicate that water is seeping downward from the glacial till into the bedrock aquifer. Most of this transfer is occurring in the western part of the site, where sand and gravel of the Henry Formation overlies the thin, leaky aquitard (a geologic material of low permeability that slows the movement of groundwater) of the Tiskilwa till. Thus, in at least this part of the site, the glacial till and shallow bedrock aquifers are hydraulically connected. Deeper bedrock aquifers (i.e., below the shallow bedrock aquifer) are protected from contamination by thick layers of unfractured dolomite and shale (Warzyn, Inc., 1994; Warzyn Engineering, Inc., 1992; Booth and Vagt, 1986). In the Chicago area, including DuPage County, water in the shallow dolomite aquifer is being used more rapidly than it is being recharged.
Contamination of nearby private and municipal wells to the west, southwest, and south is a concern. However, there is no evidence of an advancing contaminant plume, and pollutants have generally been restricted to within 100 to 200 yards of the landfill. Further downgradient, contaminants are evidently diluted by unpolluted water, including that from the Henry Formation.
Several chemicals found in private wells apparently did not originate from the landfill. Arsenic was found at levels greater than comparison values, but not greater than levels found naturally in some parts of Illinois. Slightly elevated levels of arsenic in area groundwater may be a natural phenomenon and not site related. Endrin aldehyde is an impurity in the insecticide, endrin, and it is also produced as a decay product. Endrin and dieldrin are no longer used, but are very persistent insecticides. The detected dieldrin and endrin aldehyde may have been from past agricultural use in the area.
It is unclear whether three contaminants found in some downgradient private wells (benzene, 1,1-dichloroethane, and cis-1,2-dichloroethene) originated from the landfill. Historically, these three compounds have been found in monitoring wells within 100 to 200 yards of the landfill; however, with one exception, they have not been found in monitoring wells farther west and south (downgradient). On one sampling date, low concentrations of benzene, 1,2-dichloroethene, and trichloroethene were found in one of these more distant deep monitoring wells (G-138 Figure 7), but not in four others (two deep {G-139 and G-133D} and two shallow {G-133S and G-122; Figure 6}). If contaminants detected in 15 of 51 downgradient private wells came from the landfill, then (1) the intervening monitoring wells more than 200 yards from the landfill should more consistently have VOCs, (2) these compounds should be in more than one of the more distant monitoring wells, and (3) their concentrations should be higher in the more distant monitoring wells than in the private wells. In addition, the off-site hydrogeology has not been investigated. Consequently, the source of the VOCs in off-site residential wells remains uncertain. 1,1-Dichloroethane found in private wells may have been produced by chlorination during servicing. Benzene (a component of gasoline and other petroleum compounds) was found in only one well, and a possible source other than the landfill is unknown.
Future (or further) contamination of surrounding wells may occur if erosion or other disturbance of the cap (e.g., construction) increases infiltration and, hence, leachate production. This may increase the concentrations of chemicals and the extent of contamination in downgradient groundwater. The geology and hydrogeology around the site have not been investigated, so the likelihood of contamination of downgradient private and municipal wells is unknown. If these wells become contaminated, people can be exposed to pollutants through dermal contact, inhalation of volatile organic compounds during showering and other water use activities, and ingestion. About 11,390 people will be exposed if the Warrenville municipal water supply becomes contaminated. If 4 people consume water from each of the approximately 120 private wells that are within 4,000 feet west, southwest, or south of the site, then about 480 people will be exposed if these wells become polluted.
B. Potential Exposure Pathways
Surface soil could be contaminated by leachate or direct contact with wastes. Park users and on-site workers could be exposed to this soil through dermal contact, inhalation (dust), or ingestion. Because the site is well-vegetated, contact with surface soil and dust production is probably minimal. In addition, daily exposure of a pica child (a child who is prone to eating dirt) on-site is unlikely. Consequently, exposure via this pathway is probably negligible and will not be discussed further.
The environmental pathways for the contamination of soil, sediments, or surface water have been previously described. With the exception of cadmium and PCBs, the chemicals found on-site should not accumulate in plants or animals. If an organism absorbs a chemical faster than it is eliminated from its body, it will accumulate the chemical in a process called bioaccumulation. In the food chain, animals eat large quantities of their prey (or plants), and with compounds that bioaccumulate, this can cause higher concentrations in organisms at successive levels of the food chain. For example, zooplankton which eat phytoplankton have higher concentrations of bioaccumulating chemicals than their food. The fish which eat zooplankton have higher levels, and the large fish which eat smaller ones have even higher concentrations. This phenomenon is called biomagnification. Because they are soluble in fat, relatively insoluble in water, and are not easily broken down by the body, PCBs exhibit bioaccumulation and biomagnification. PCBs were found in surface soil at only one location, and not in on-site surface water bodies (sediments or surface water). Spring Brook is too small to be fished, and Sand Pond is closed to the public. If PCBs should reach Silver or Pine Lakes (used for fishing), people could be exposed to contaminants by eating contaminated fish.
Regular consumption of on-site plants by the public is unlikely. Consequently, even if vegetation became contaminated, exposure by consumption of the plants would probably be negligible.
To evaluate potential health effects, the estimated exposure doses to site-related compounds were compared with health effects information in the literature, primarily ATSDR Toxicological Profiles. ATSDR and USEPA have developed chemical-specific guidelines for evaluating the potential for adverse health effects of chemicals in air, water, and soil. ATSDR has developed Minimum Risk Levels (MRLs) to evaluate non-cancerous health effects. An MRL is an estimate of the daily human exposure to a contaminant below which non-cancerous adverse health effects are unlikely to occur. The exposure is expressed as milligrams of chemical per kilogram of body weight per day (mg/kg/d) for oral exposure. MRLs are developed for both the oral and inhalation routes of exposure. They are also developed for different lengths of exposure, such as acute (14 days or less), intermediate (15 to 364 days), and chronic (365 days or more). If an estimated exposure dose exceeds an MRL, it can be compared to the Lowest Observed Adverse Effect Level (LOAEL) for a specific health effect in animals or humans. A USEPA Reference Dose (RfD) is an estimate of the daily exposure (mg/kg/d) to the general public that is likely to be without an appreciable risk of deleterious noncancerous effects during a lifetime. The USEPA has also developed health advisories for exposure to drinking water for periods of one-day, ten-day, longer-term, and lifetime exposures to non-carcinogens.
USEPA also evaluates the potential of a chemical to cause carcinogenic (cancer) effects over a lifetime. To do this, they have estimated cancer slope factors for certain chemicals with sufficient toxicological information on cancerous effects. These cancer slope factors are estimates of the potency of a chemical to cause cancer and are used to estimate the cancer risk of specific doses. These risk estimates, however, are extremely conservative and are meant to protect susceptible members of the public. There is a 95 percent probability the actual risk is no higher, it is probably lower, and it may be zero. Furthermore, cancer risk estimates are extrapolated to low doses from high dose animal or human (usually occupational exposure) studies. This approach is somewhat controversial. Some researchers believe body repair mechanisms can handle low doses, and that higher ones are needed to cause cancer. Some people also question the validity of high to low dose extrapolation. Until more information on carcinogenesis becomes available, USEPA takes the conservative approach that there is no threshold and any exposure to a carcinogen carries a finite risk.
USEPA has established a weight-of-evidence classification system for carcinogens based on the adequacy and consistency of the available human and animal data. Group A compounds are known human carcinogens (usually occupational exposure). Group B1 chemicals are probable human carcinogens based on limited human data. Group B2 compounds are probable human carcinogens based on sufficient evidence in animals, but inadequate or no evidence in people. Group C chemicals are possible human carcinogens based on limited data. Group D compounds are not classifiable as to human carcinogenicity because of inadequate or no data. For group E chemicals, there is evidence they do not cause cancer.
In the exposure estimate calculations, for drinking water, consumption was 1 liter per day for children and 2 liters per day for adults. Soil ingestion rates were 5,000 milligrams per day for pica children and 100 milligrams per day for adults. Body weights were 10 kilograms for children and 70 kilograms for adults. For residents, daily exposure was assumed.
Benzene was detected in leachate and was a chemical of concern in on-site shallow groundwater, on-site deep groundwater, and one downgradient private well. Benzene can be absorbed after inhalation, ingestion, or dermal contact. Most of the reported health effects have been observed after inhalation exposure, and, unfortunately, little information is available after exposure through other routes (ATSDR, 1995a).
Oral exposure to on- or off-site levels of benzene in groundwater would not be expected to cause noncancerous health effects. There is sufficient evidence that benzene can cause leukemia in people after inhalation, but it is uncertain whether it can cause cancer after oral or dermal exposure (ATSDR, 1995a). While leukemia has been seen in rats after oral gavage exposure, the type of leukemia is different from the one observed in humans. The kind of leukemia observed in humans is rare in rodents (ATSDR, 1995a). USEPA has classified benzene as a known human carcinogen (Group A). Using the animal data, USEPA derived a cancer slope factor which can be used for estimating the cancer risk of specific doses. Drinking water from on-site shallow or deep groundwater, on-site monitoring wells, and the downgradient private well would cause no apparent increased cancer risk.
Chloroethane was found only in on-site shallow groundwater. It can be absorbed after inhalation, ingestion, or dermal contact (ATSDR, 1989b). In one animal study, high doses in air caused increased liver and uterine cancer in female mice, and also possibly lung cancer in male mice. In rats, chloroethane slightly increased the incidence of tumors. USEPA has not classified it as a carcinogen, but limited animal data suggest it may be able to cause cancer in humans (ATSDR, 1989b). There is little information on the effects of long-term exposure to chloroethane. Only one study was performed, and no health effects were observed in rabbits given higher doses than found on-site. Because of limitations of this study, the No Observable Adverse Effect Level (NOAEL) could not be determined (ATSDR, 1989b). Exposure to contaminated on-site groundwater is not occurring and is unlikely to occur in the future. It is unknown whether chloroethane may reach off-site downgradient private or municipal wells.
1,1-Dichloroethane was found in leachate, on-site shallow groundwater, background private wells, and downgradient private wells. It can be absorbed after inhalation or ingestion, and probably also after dermal contact (ATSDR, 1989c). There is very little toxicological information on chronic, low-level exposure to this compound. No changes were noted in the liver, kidneys, or lungs of male mice which drank levels of 1,1-dichloroethane in water about 14,000, 300,000, and 25,000,000 times higher than the maximum concentration in leachate, on-site shallow groundwater, and downgradient private wells, respectively. Exposure to leachate and contaminated on-site groundwater is not occurring and is unlikely. One study suggested 1,1-dichloroethane may cause cancer in animals, while another experiment came up with the opposite conclusion (ATSDR, 1989c). Consequently, it is uncertain whether it may cause cancer. USEPA has classified 1,1-dichloroethane as Group C, possibly carcinogenic in humans based on limited animal data and no human studies.
1,2-Dichloroethane was a chemical of concern in on-site deep groundwater. It can enter the body after ingestion, inhalation, or dermal contact (ATSDR, 1992). In mice, immune system suppression occurred after oral administration of 1,2-dichloroethane at a dose about 16,000 times greater than that of a child drinking on-site deep groundwater; however, in another study, mice that received a dose in drinking water that was 630,000 times higher than that of a child drinking on-site deep groundwater, exhibited no such effects. In one study, people exposed to 1,2-dichloroethane in drinking water exhibited increased rates of colon and rectal cancer; however, other chemicals were likely present and may have contributed to the observed effects. In rats and mice, oral exposure to this compound can cause cancer of the adrenal gland, liver, pancreas, skin, and spleen. Consequently, it may be able to cause cancer in people (ATSDR, 1992). USEPA has classified 1,2-dichloroethane in Group B2, as a probable human carcinogen, based on adequate animal evidence and insufficient human data. Using the USEPA cancer slope factor, lifetime consumption of the highest 1,2-dichloroethane level found in on-site deep groundwater would result in no apparent increased cancer risk. Exposure to on-site deep groundwater is not currently occurring and is not likely to occur in the future. It is unknown whether it may reach off-site private wells at levels of concern in the future.
1,2-Dichloroethene was a chemical of concern in on-site shallow groundwater. It can be absorbed after ingestion, inhalation, or dermal contact (ATSDR, 1994a). Consumption of water with the highest 1,2-dichloroethene concentration found in shallow on-site groundwater would not exceed the chronic oral RfD. If it should reach nearby private or municipal wells, its concentrations would be even lower, so adverse noncancerous health effects are not expected from this route of exposure. The effects of long-term exposure to 1,2-dichloroethene are unknown (ATSDR, 1994a).
Tetrachloroethene was found in leachate and was a chemical of concern in on-site shallow groundwater. It can be absorbed after ingestion or inhalation (ATSDR, 1995b). Drinking shallow on-site groundwater with the highest concentration of tetrachloroethene would not exceed the chronic oral RfD for children or adults. In humans, the health effects from drinking water with low levels of tetrachloroethene are essentially unknown. In animals, health effects after ingestion (ATSDR, 1995b) have been observed only at higher levels than are present in leachate or on-site groundwater. In mice, increased liver weight has been observed in mice that were administered tetrachloroethene at doses more than 4,500 times higher than possible from drinking leachate. No one is drinking leachate or shallow-on-site groundwater, and the diluted levels which may potentially reach nearby private or municipal wells should not cause any non-cancerous health effects.
In animals, tetrachloroethene can cause kidney and liver cancer after inhalation and liver cancer after ingestion, but these cancers have not been reported in people exposed to tetrachloroethene (ATSDR, 1995b). Based on animal evidence, USEPA has classified it as a Group B2 carcinogen. Using the USEPA cancer slope factor, the consumption of on-site shallow groundwater would result in an estimated no apparent increased cancer risk.
Trichloroethene was detected in leachate and was a chemical of concern in on-site shallow groundwater. It can be absorbed after inhalation or ingestion, but skin absorption is unlikely at on-site levels. In one study, people served by a water supply contaminated with organic solvents, including 267 parts per billion (ppb) of trichloroethene and 21 ppb of tetrachloroethene (at the wells), exhibited increased respiratory disorders (asthma, bronchitis, and pneumonia in children), as well as constipation, decreased blink reflex, diarrhea, immunologic abnormalities, leukemia, nausea, and skin lesions. However, because of uncertainties in the actual levels of exposure at the tap, the length of exposure, and exposure to other chemicals, it is uncertain whether trichloroethene caused any of these effects (ATSDR, 1995c). Consumption of leachate or on-site shallow groundwater with the highest level of trichloroethene would not exceed the MRL for children or adults, so noncancerous health effects are not expected. In animals, trichloroethene can cause liver cancer, but this effect has not been reported in humans (ATSDR, 1995c). Based on animal evidence, USEPA has classified it as a Group B2 carcinogen, although the evidence is being reevaluated. Using the USEPA cancer slope factor, the consumption of on-site shallow groundwater with the maximum level of this compound would cause an estimated no apparent increased cancer risk. Consumption of leachate or contaminated on-site groundwater is not likely to occur.
Vinyl chloride was found in leachate and it was a chemical of concern in on-site shallow groundwater. Vinyl chloride can enter the body after inhalation or ingestion. After absorption, most of it is eliminated from the body within 1 day. However, some of it is converted into other chemicals, which are often more toxic and are eliminated more slowly (ATSDR, 1991e). Consumption of water with the maximum concentration of vinyl chloride found in leachate or shallow on-site groundwater would exceed the chronic MRL for children (by 110 to 150 times) and adults (by 30 to 43 times). However, no one is likely to be exposed to leachate or on-site shallow groundwater. It is not known whether vinyl chloride may reach nearby private or municipal wells at levels of concern. In animals, chronic oral exposure to vinyl chloride can cause liver damage and liver cancer. It can cause cancer in people after inhalation (Group A carcinogen), but there have not been any human studies after ingestion (ATSDR, 1991e). The available data are insufficient to estimate the possible cancer risk of vinyl chloride at specific doses.
The insecticide, dieldrin, was a chemical of concern only in downgradient private wells. It can be absorbed after dermal contact, inhalation, or ingestion. It accumulates in fat and is eliminated from the body very slowly (ATSDR, 1991a). Ingestion of groundwater with the highest concentration of dieldrin would not exceed the chronic MRL for children or adults, so noncancerous health effects are not expected. In mice, dieldrin can cause liver cancer (ATSDR, 1991a) and USEPA has classified it as a Group B2 carcinogen. USEPA has developed a cancer slope factor for dieldrin, which can be used to estimate the risk of specific doses. Lifetime ingestion of groundwater with the highest detected concentration in private wells would result in an estimated no increased risk of cancer.
This compound was detected in on-site shallow and deep groundwater. No information is available regarding human health effects of di-n-octylphthalate exposure (ATSDR 1994b). USEPA has recently determined that there is not enough evidence to say that it definitely causes harmful effects in humans or on the environment. In animal studies, di-n-octylphthalate has caused mildly harmful effects in the livers of some rats and mice given very high doses by mouth for short or intermediate durations of time. Brief oral exposures to lower doses of di-n-octylphthalate generally caused no harmful effects (ATSDR 1994b). Exposure is not currently occurring to this compound because no one is drinking on-site groundwater.
Endrin aldehyde, a decay product of and an impurity in the insecticide, endrin, was found only in downgradient private wells. It can be absorbed after dermal contact, inhalation, or ingestion (ATSDR, 1994c). Dietary exposure of rats to endrin aldehyde at levels about 17 million times higher than possible from ingestion of the water from the contaminated downgradient private wells caused slight increases in the activities of some liver enzymes (ATSDR, 1994c). ATSDR (1994c) could not find any other studies on health effects in humans or animals after oral exposure to endrin aldehyde.
Ammonia was detected in leachate and was a chemical of concern in on-site shallow groundwater. It can be absorbed after inhalation or ingestion, and a small amount may be absorbed if liquid ammonia is spilled on the skin (ATSDR, 1989a). Ingestion of on-site shallow groundwater with the highest concentration of ammonia would exceed the intermediate MRL by about a factor of 9 for children and 3 for adults. In rabbits, oral exposure to ammonia caused enlarged adrenal glands at intakes 36 times that possible from drinking on-site shallow groundwater. In rats, it caused increased water intake and reduced food intake in weanlings, and decreased body weight in adults which drank water with about 27 times the amount of ammonia in shallow on-site groundwater (ATSDR, 1989a). No one is drinking on-site shallow groundwater, so exposure to ammonia is not presently occurring. There have been no studies of cancer in humans following oral ammonia exposure. Studies in mice have not shown a link between ammonia consumption and cancer. Colorectal cancer incidence, however, may be influenced by ammonia concentrations in the gut. Cancer and polyp incidences are highest in areas of the colon having the highest ammonia concentrations (ATSDR, 1989a).
Antimony was a chemical of concern only in downgradient private wells. It can enter the body after ingestion or inhalation (ATSDR, 1990a). Ingestion of water with the maximum level in private wells would exceed the chronic RfD for children, but not adults. Chronic antimony exposure may irritate the eyes, lungs, and skin, as well as cause diarrhea, heart problems, and vomiting (ATSDR, 1990a). However, these symptoms occurred at higher doses than possible from drinking water from downgradient private wells. While animals have contracted lung cancer after breathing antimony dust, there are no animal or human cancer studies after chronic ingestion of antimony (ATSDR, 1990a). Because antimony was not detected on-site at elevated concentrations, the landfill is evidently not the source of the concentrations found in downgradient private wells.
Arsenic was found in leachate and was a chemical of concern in on-site shallow groundwater, and in background and downgradient private wells. Arsenic can be absorbed after inhalation or ingestion. While large amounts are harmful, small quantities of arsenic may be beneficial. Inhalation of arsenic increases the risk of lung cancer (ATSDR, 1991b). Because the site is well-vegetated, airborne levels of arsenic in dust should be low. Oral exposure to arsenic has been linked to increased incidence of skin cancer in people (ATSDR, 1991b), and USEPA has classified it as a known human carcinogen (Group A). Ingestion of arsenic can cause areas of skin pigmentation (ATSDR, 1991b). In the body, arsenic is converted into methyl arsenic or dimethyl arsenic by enzymes, and these latter compounds are less toxic and more easily excreted. It is uncertain what intake of arsenic can be detoxified by this process, but limited data indicate the enzymes may begin to be saturated (i.e., cannot convert at a faster rate) at doses of 0.003 to 0.015 milligrams per kilogram per day. Consequently, doses below 0.001 milligrams per kilogram per day (about three times the MRL) are likely to pose little risk of noncancerous health effects (ATSDR, 1991b). Ingestion of water from on-site shallow groundwater and downgradient private wells with the highest arsenic concentrations would exceed this level for children. However, low levels of arsenic may be beneficial in the diet. USEPA has established an MCL of 50 ppb for arsenic in public drinking water supplies. None of the private wells sampled exceeded the MCL, and no adverse health effects have been reported in people from areas where naturally occurring levels of arsenic that approach the MCL are in drinking water. Therefore, adverse health effects from arsenic exposure would not be expected.
Cadmium was detected in the leachate and was a chemical of concern in background soil. Cadmium is readily absorbed after inhalation or ingestion, but little enters the body after dermal contact. Once absorbed, it accumulates in the body, particularly in the kidney and liver. It can also bioaccumulate in fish, livestock, and plants (ATSDR, 1991c). Ingestion of background soils with the maximum cadmium concentration by a pica child, but not an adult, would exceed the chronic oral MRL. Chronic exposure to low levels of cadmium can result in enough accumulation to cause toxic effects, including kidney damage, and possibly also anemia, endocrine alterations, high blood pressure, immunosuppression, and loss of smell. Cadmium exposure in pregnant women may result in lower birth weights, but birth defects have not been observed in humans (ATSDR, 1991c). It is unlikely that exposure to cadmium would take place at levels of health concern.
High concentrations of lead were found in leachate and one private well, which was not downgradient. Lead can be absorbed after inhalation or ingestion. After inhalation, nearly all of the lead deposited in the lower respiratory tract is absorbed, regardless of the chemical form. After ingestion, absorption in children is about 50 percent, while only 8 to 15 percent of ingested lead is absorbed by adults. In adults, the absorption of lead after fasting can be up to 45 percent. Lead uptake is higher in people with inadequate calcium, iron, selenium, and zinc intakes, and it is also increased by fatty foods. In children, about 30 percent of the ingested lead in soil is absorbed. In the body, lead is mostly deposited in bone, with a half-life of 27 years. The half-life of a chemical in the body is the time for half of it to be eliminated. In adults, 95 percent of the lead body burden is in bone, while about 73 percent of the lead body burden in children is in bone. Lead in bones is liberated during pregnancy and lactation. It can readily pass the placenta, and because of its persistence in bone, fetal uptake can occur long after maternal exposure has ended (ATSDR, 1991d). In one case, a lead-poisoned child was born to a mother who herself had been lead-poisoned at the age of two, more than 30 years before. No other significant source of lead exposure could be established (Silbergeld, 1991). Infants and children up to 2 years old retain 34 percent of the absorbed lead, while adults retain only 1 percent of it (ATSDR, 1991d).
The most serious effect of lead is neurological impairment, and children are the most susceptible. In children, prenatal exposure, as well as postnatal blood lead levels of 10 to 15 micrograms per deciliter, have been associated with numerous disabilities, including cognitive deficit (decreased IQ), decreased growth, reduced birth weight, and reduced hearing. There seems to be no threshold below which lead does not affect IQ or hearing (ATSDR, 1991d), and the neurological effects of lead seem to be permanent (Needleman et al., 1990).
In children, lead can cause kidney damage at blood lead levels of 30 micrograms per deciliter, as well as vitamin D deficiency and symptoms of rickets above about 30 micrograms per deciliter (ATSDR, 1991d). Because of their greater uptake, slower elimination, and greater sensitivity to lead, children 6 years old or less are the most susceptible. Because of frequent hand-to-mouth activity, 18 months to 2.5 years of age is the most critical time.
Given their lower absorption of and decreased sensitivity to lead, it is unlikely that adults would absorb enough lead from groundwater to cause observable symptoms. However, lead absorbed by pregnant females or women who may be pregnant in the future may be transferred to fetuses in cord blood and infants in breast milk, potentially causing health problems in the children.
While some studies of workers exposed to lead suggest increased cancer rates, the exposure levels are unknown, exposure to other chemicals such as arsenic occurred, and smoking rates were not examined. Therefore, no link between lead exposure and cancer in humans could be established. In animals, oral exposure to lead can cause kidney tumors (ATSDR, 1991d). Based on animal evidence, USEPA has classified lead as a Group B2 carcinogen.
Manganese was detected in leachate and was a chemical of concern in on-site shallow and deep groundwater, as well as downgradient private wells. Manganese can be absorbed after ingestion or inhalation. Only about 3 to 5 percent of ingested manganese is absorbed, but the amount absorbed after inhalation is unknown. It is believed the small amounts consumed by people in a typical diet are important to their health, but high concentrations are harmful (ATSDR, 1990b). Consumption of on-site shallow or deep groundwater with the highest manganese concentration would exceed the chronic oral RfD for children and adults; however, daily ingestion of on-site groundwater is unlikely. There is controversial evidence that elevated manganese levels similar to those found on-site may be able to cause brain damage, with symptoms such as weakness, stiff muscles, and trembling of the hands. However, other chemicals may have been involved, and it is uncertain whether manganese was the cause (ATSDR, 1990b).
B. Health Outcome Data Evaluation
There have not been any health studies of people around the DuPage County Landfill. It is uncertain whether site contaminants have reached downgradient private wells. The contaminant concentrations found in them were very low. Elevated lead levels found in one private well were likely caused by lead solder or piping in the plumbing, as it was not downgradient of the site and intervening monitoring and private wells were not contaminated. Limited air sampling has not detected volatile organic compounds upwind or downwind of the landfill. The site is well-vegetated, which should minimize contact with soil and dust production. Because exposure of surrounding residents and park users has probably been negligible, no health effects are expected from on- or off-site exposure, and no health studies are warranted at this time. In the future, if new data show that exposure of people is occurring at levels of health concern, the need for health studies will be re-evaluated.
C. Community Health Concerns Evaluation
People near the site are concerned about the possible contamination of their private wells or municipal water supply. There is no evidence of an advancing contaminant plume, and historically, contaminants in groundwater have generally been restricted to within 100 to 200 yards of the landfill. It is uncertain whether site contaminants have reached downgradient private wells. In the future, if erosion or other disturbance of the cap (e.g., construction) increases the infiltration of precipitation, this may increase leachate production. This may increase the concentrations of chemicals and the extent of contamination around the landfill, possibly affecting downgradient private and municipal wells (west, southwest, and south of the landfill).
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