PUBLIC HEALTH ASSESSMENT
IONIA CITY LANDFILL
IONIA, IONIA COUNTY, MICHIGAN
The endangerment assessment portion of the Remedial Investigation (RI) for the ICL site identified eleven indicator chemicals as chemicals of concern: butyl benzyl phthalate, cadmium, chromium, 1,1-dichloroethane, trans-1,2-dichloroethylene, manganese, methylene chloride, selenium, silver, 1,1,1-trichloroethane, and vinyl chloride (10). Chemicals detected in samples associated with the site that did not meet the contractor's criteria for indicator chemicals were acetone, copper, ethylbenzene, lead, mercury, methyl ethyl ketone, styrene, toluene, trichloroethylene, and xylene. The soil, sediment, and groundwater concentrations of copper and the soil and sediment concentrations of silver and manganese found on the site are similar to background levels. The 1,1-dichloroethane and xylene concentrations found on the site appear to be well within ranges commonly accepted to pose no significant health risk.
Contaminants of concern for this assessment were selected from those chemicals for which the concentration in at least one environmental medium exceeded a health-based comparison value. Lifetime exposure to chemical concentrations at or below the appropriate comparison values for a chemical should not result in more than 1 case of cancer in 1 million people exposed or any increase in non-cancer health effects. Comparison values used in this assessment include:
- ATSDR Environmental Media Evaluation Guides (EMEGs)
ATSDR Cancer Risk Evaluation Guides (CREGs)
Reference Dose Media Evaluation Guides (RMEGs)
U.S. EPA Drinking Water Health Advisories (Lifetime)
U.S. EPA Safe Drinking Water Act Maximum Contaminant Levels
If no comparison values for a chemical in a medium exist, or there is no CREG available for a carcinogen, the chemical is retained as a contaminant of concern.
To identify facilities that could contribute to the groundwater, surface water, soil, and air contamination near the Ionia City Landfill site, the MDPH searched the 1987, 1988, and 1989 Toxic Chemical Release Inventory (TRI) database. The TRI is developed by the U.S. EPA from the chemical release information provided by certain industries. Although the TRI indicated a number of airborne releases of chemicals within the site's zip-code area, these releases are unlikely to have impacted contaminant levels in on-site or nearby off-site areas.
Contaminants of concern for this assessment are listed in Table 1.
Unless otherwise identified, all environmental data cited in this section were taken from the RI report (1).
A. On-Site Contamination
In July 1981, the MDNR constructed 3 observation wells in Area A of the site. From the depths reported, these wells were all screened in the shallow aquifer. Two of these wells, the third had been damaged and was unusable, were sampled in August 1981. The concentrations found of contaminants of concern are listed in Table 2 (12). In 1987 and 1988, the RI contractors constructed 5 monitoring wells on the site. Four of these wells were screened in the shallow, water-table aquifer, the other in the intermediate-depth aquifer. No monitoring wells have been drilled into the bedrock aquifers on the site. The maximum concentrations in parts per billion (ppb) of contaminants found in on-site monitoring wells were: cadmium, 22; chromium, 186; 1,1-dichloroethane, 26; trans-1,2-dichloroethylene, 28; selenium, 12; silver, 13; and vinyl chloride, 69 (Table 2). None of the organic chemicals of concern were detected in the intermediate-depth aquifer.
As part of the design for the remediation of the site, U.S. EPA contractors installed five monitoring wells into the shallow aquifer around the drum area on the site. These wells and selected of the previously installed monitoring wells near the site perimeter were sampled in August 1992 and November 1993. The concentrations of several organic contaminants were considerably higher in the November sampling than in the earlier one (also in Table 2) (13). This increase has been attributed to spillage during the December 1992 removal of liquid wastes from the drums.
There were no surface soil samples collected in the RI. The shallowest subsurface soil samples collected were from 1.0 to 1.5 feet below the surface. ATSDR prefers data on the top 3 inches of soil to base an evaluation of health hazards from dermal contact, incidental ingestion, or fugitive dust.
On-site subsurface soil samples, taken from depths of 1.0 to 1.5 feet during the RI, showed little contamination (Table 3). The samples were collected near the perimeter of the site. Cadmium levels were slightly higher in on-site soil samples (1,700-3,000 vs. 1,200-2,000 ppb). All the concentrations were above the background range for cadmium in soil, as cited in the RI report.
A series of trenching operations to characterize the waste during the RI produced samples of wastes, drum contents, and soil surrounding drums (Table 4, Table 5). The samples were taken from depths of 4 to 18 feet. Samples from Area B showed fewer organic chemicals and at much lower levels than those from Area A. However the maximum concentration of cadmium was found in Area B.
Deeper soil samples taken during the installation of monitoring wells did not show a pattern of chemical composition consistent with site-related contamination (Table 6).
Sediment and surface water sampling in 1982 of the east tributary within the site boundaries found low concentrations of volatile organic chemicals (VOCs), especially 1,1-dichloroethane, 1-2-dichloroethylene (isomer not specified) and vinyl chloride, chromium, manganese and selenium (Table 7, Table 8). Sampling in the same area during the RI/FS did not detect contaminants at levels significantly above the concentrations found upstream of the site.
The RI contractors monitored the air around the worksite for VOCs during the trenching operations, for worker safety. They used photoionization detectors (PID) and flame ionization detectors (FID), which do not identify specific chemicals and which are only semi-quantitative. To quote from Reference 1, p. 3-22: "[S]everal intact drums containing liquids were excavated towards the western limits of the trench. At this area, the PID/FID measurements of the ambient air were elevated; the elevated measurements were sustained throughout the excavation operations." A technical memorandum for this work (Reference 14) reported FID readings above 1,000 ppm and PID readings of 1,740 ppm in one trench. The workers reported odors of nitrobenzene and chlorinated benzenes.
Air testing in 1988 showed low concentrations of 1,1,1-trichloroethane downwind of the site and not upwind (Table 9). Neighboring residents complained about odors from the landfill when it was in operation, however, the local authorities have not heard any such complaints since 1983. At the request of the MDPH, staff from the Ionia County Health Department contacted some nearby residents in January 1992 and asked if they had noticed any unusual odors in their basements that may be related to vapors from the landfill. The residents, some of whom had lived there for many years, said that they had not noticed any unusual odors (15).
As with on-site samples, no surface soil samples were collected from off-site locations during the RI. In 1988, off-site subsurface (1-1.5 feet deep) soil samples showed no site-related contamination (Table 10, Table 11).
During the RI, the contractors constructed 11 wells near the site, 3 to the north (upgradient), the rest to the southwest (downgradient). Eight of these wells were screened in the shallow aquifer, the other three in the intermediate-depth aquifer. Analyses of groundwater sampled from these wells shows a plume of VOC and metal contamination in the shallow aquifer extending at least 600 feet southwest of the site. Water from off-site monitoring wells contained up to 10 ppb cadmium, 14 ppb chromium, 26 ppb 1,1-dichloroethane, 23 ppb trans-1,2-dichloroethylene, 12 ppb silver, and 86 ppb vinyl chloride (Table 12). Several of these wells were also sampled in August 1992 and November 1993 (also in Table 12) (13).
Residential wells near the site were sampled during the RI in March 1987. The only chemicals of concern detected were manganese, tetrachloroethylene, and zinc, with only tetrachloroethylene equalling or exceeding comparison values (Table 13). Tetrachloroethylene was only found in one residential well, northeast (upgradient) from the site. That well was sampled again by the Ionia County Health Department in March 1988, and no tetrachloroethylene was detected (detection limit 1 ppb) (16). The source for the presence of this chemical in that well is not known, though it is probably not related to the Ionia City Landfill site. The wells tested, those closest to the site, were located either upgradient from the site or beyond the Grand River, the presumed discharge point of the shallow aquifers. There are no producing wells that tap any of the aquifers between the site and the Grand River.
The only contaminant found in Grand River water downstream of the site at levels significantly higher than upstream was cadmium at 9 to 10 ppb (Table 14). Cadmium was not detected (detection limit 5 ppb) upstream. Grand River sediments showed no site-related contamination (Table 15).
C. Quality Assurance and Quality Control
In preparing this Health Assessment, MDPH has relied on the analytical data provided in the referenced documents and has assumed that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analysis and conclusions drawn for this Health Assessment are determined by the reliability of the referenced information.
The soil samples in the RI were taken at depths of 1.0 to 1.5 feet below the surface. True surface samples, not more than 6 inches deep and preferably 3 inches deep, are preferred to allow an accurate assessment of health risks from contact, incidental ingestion, or fugitive dust.
Methylene chloride, methyl ethyl ketone (MEK), and styrene were commonly found in laboratory quality control blank samples, as noted in the Tables. The first two are common laboratory reagents, and their presence in the blank samples cast doubts on whether the chemicals are actually present in the site samples. The RI Report marked some of the MEK concentrations in sediment samples as having blank contamination, but other sediment samples with the same concentrations or lower were not so qualified.
Based on observations made during MDPH's latest site visit, access to the northern third of the site (Area A) is restricted by a fence, with a locked gate. However, the eastern sections of the fence have fallen or been knocked down, permitting relatively free public access. The rest of the site is unfenced, although there are remnants of an older fence on the western perimeter of the site.
The physical hazards present include local irregularities and slopes in the terrain and a few trenches or holes. While the baseball diamond was in use, between 1969 and 1981, players risked running into rubbish hidden by the grass (17).
To determine whether nearby residents are exposed to contaminants migrating from the site, ATSDR evaluates the environmental and human components that lead to human exposure. An exposure pathway contains five major 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 considered a completed pathway if there is evidence that all five of these elements exist or are likely to exist at some point in time or have in the past been present. A pathway is considered a potential pathway if one or more of these elements is not known to be or have been present, but could be or have been. An exposure pathway can be eliminated from consideration if one of the elements is not present and could never be present. The following sections discuss the most important exposure pathways at this site.
There is evidence of traffic by hunters, anglers, and recreational vehicle users on Area B of the site. Area A has only been fenced since 1984, and in the 1970s there was a baseball diamond on that part of the site. By 1989, the fence around Area A was down along much of the eastern perimeter, allowing easy access to the restricted area. With access to the site, direct contact with contaminated soil, ingestion of contaminated soil,(1) and inhalation of volatile chemicals released when the soil is disturbed become pathways for human exposure. Shallow subsurface soil samples from Area B showed much lower levels of indicator and other chemicals than did samples from Area A. Results of surface soil (0-3 inch) sampling and analysis are not available. The most contaminated sections of Area A have been capped with clay, mitigating the chance of exposure upon access. The clay cap was only intended as a temporary measure, however, and MDPH personnel observed on a site visit that the cap has already eroded in places. They also observed discolored areas of soil in Area A, indicating contaminated surface soil.
There is a history of complaints from neighboring residents about odors emanating from the ICL site, though none have been recorded since 1983. Air testing in 1988 showed a small amount of 1,1,1-trichloroethane downwind of the site and not upwind (See Table 9). The concentration detected is approximately one-millionth of the Threshold Limit Value (TLV) recommended by the American Council of Government Industrial Hygienists, and approximately five-millionths of the workplace standard set by the Occupational Safety and Health Administration. Air monitoring for worker protection during the 1987-88 RI work found elevated concentrations of VOCs present during excavation and trenching around the buried drums. This indicates that proper safety equipment should be used by workers during future site remediation and that the perimeter of site should be monitored to detect movement of airborne chemicals as well as soil gas off the site.
One of six nearby residential wells tested in 1987 contained tetrachloroethylene at a concentration at or above the comparison value. This well was upgradient (northeast) of the site, and was the most distant of the wells tested from the site. Tetrachloroethylene was not detected in on-site groundwater. The tetrachloroethylene in the residential well is probably not related to the ICL site. The chemical was not detected when the well was sampled again the following year, however, the detection limit in the second sampling was higher than the concentration found in the first. Residents using the well for household purposes could be exposed to the chemical by ingestion, dermal contact, or inhalation secondary to household use.
Four wells (37-60 feet deep) located north (upgradient) of the site, and the two closest wells on the other side of the Grand River (94 and 350 feet) were tested in 1987. No other wells in the vicinity are known to draw on the shallow aquifer. The deepest well taps one of a series of aquifers in the bedrock beneath the site. Ionia city water comes from wells that also tap bedrock aquifers a mile north, and upgradient, of the site.
Only the shallowest aquifer shows evidence of contamination. The pressure in the next deeper aquifer is higher than that in the shallow one, which may help to confine the contaminants to the shallow aquifer. The contamination plume extends southwest from the site, passing under Cleveland Street toward the river. The property under which the plume flows is currently used for agriculture. The crops are not irrigated. There are currently no producing wells drawing on the contaminated aquifer downgradient of the site and north of the Grand River. The aquifer discharges into the river and presumably terminates at this point.
Much of the off-site property above the contaminant plume is in the Grand River floodplain, which limits the options for future development of the property and makes well-drilling into the contaminant plume unlikely. Currently, this area is zoned for agricultural purposes (the area was planted with corn at the time of the MDPH site visits) and long range planning has it zoned for industrial use. The intermediate-depth aquifer is only twenty to thirty feet below, and its pressure is somewhat higher than that in the shallower one. The pressure difference reduces the likelihood that contaminants will spread into the deeper aquifers.
Although the groundwater pathway poses a potential hazard to human health, the contaminated aquifer downgradient of the site is not being used. However, should the aquifer be found to extend beneath the Grand River, other water supplies may be threatened.
Surface Water and Sediment
The Grand River forms the south boundary of the site, and an intermittent tributary to the river forms the eastern boundary. A depression in the northeast corner of the site fills with water in wet seasons. At the time of the MDPH site visit, water in the river and its tributaries was high, and this depression had been flooded by the tributary. The entire site lies within the hundred-year flood plain of the Grand River. There are steep banks down to the water on the east and south sides of the site, and on the west side of Cleveland Street down to the agricultural land. Signs of erosion exist on these banks, and some exposed trash is visible in Area B. Contaminants from the site could reach the river through soil erosion during storm run-off or flooding, or by discharge of leachate. Recreational use of the river may therefore provide a pathway for human exposure through dermal contact with water or sediments, incidental ingestion of river water, or ingestion of contaminated fish or other biota. There is no recorded use of the river water for household and potable uses. Sampling of water in the river and the east tributary has only shown low levels of site-related contamination. The 1,1-dichloroethane and vinyl chloride concentrations detected in a 1982 sampling of water from the tributary (Table 8) are high enough to be of concern, but the chemicals were only detected in one sample and were not detected again in the water during the RI. VOCs also tend to volatilize readily from water. The cadmium found in water from the Grand River downstream of the site might not be connected to the site, since none of the other metals among the contaminants of concern on the site were detected in the water.
Except for mercury, the chemicals of concern at the site do not tend to bioaccumulate significantly in fish and other aquatic biota. Mercury has not been documented at elevated levels in river or tributary water or sediments at the site. There is no record of sampling of fish from the river near the site, though the chance of contaminated fish is considered to be minimal for the reasons stated above.
Plants may accumulate some metals, such as cadmium, chromium, lead, and selenium, if they are grown in soil containing high levels of these elements or if the water they are irrigated with contains these elements at high levels. Plants growing on the site are not likely to be consumed by humans, though consumption of game animals that have fed on the site may be a pathway for exposure. In the shallow subsurface soil samples, the cadmium content appears elevated in all samples, including the background sample. One off-site sample showed a high selenium content (1,800 ppb). All other samples had levels of these elements within typical background ranges. Groundwater from the contaminated aquifer is not currently used for irrigation.
Contaminants contained in the river water and sediments may be deposited in soil during floods, and could potentially accumulate in plants grown in the soil after the water recedes. However, at the documented levels of contamination of the river and tributary, the accumulation of the chemicals of concern in plant tissue would not be considered a significant pathway for human exposure.
Run-off from the remainder of the site might have collected in the depression in the northeast corner long enough for sediment to settle out. None of the soil studies in the RI investigated the depression.
Transport of contaminated surface soil by the wind as fugitive dust is a potential pathway for contaminants to leave the site. However, dense vegetation on the site should reduce the generation and movement of fugitive dust from contaminated surface areas. The absence of surface soil data limits our ability to fully evaluate this potential exposure pathway.
Several volatile organic chemicals have been found in the waste in the landfill. Decomposition of organic materials can generate organic gases, such as methane, especially under anaerobic conditions. Volatilized chemicals and liberated gases can migrate laterally through porous soils and collect in nearby structures, especially basements, potentially to toxic or explosive levels. The available information is not sufficient to determine the risk to residences near the landfill from migration of gases and vapors from the landfill.
There appear to be several factors present that could reduce the risk from soil gas migration. The porous cover over most of the landfill should permit volatile chemicals and gases to escape to the atmosphere. Anaerobic conditions are also unlikely to persist under the porous cover. Snow and ice would reduce the cover's porosity during winters. Lateral migration is unlikely through the clay subsoil in the site area. However, there is a porous sand layer under the surficial layer, and the water table is as deep as 3 feet beneath the bottom of the clay. Volatile chemicals may migrate laterally through the porous section of the unsaturated zone. The bottom of the landfill is clay, of some unknown thickness, though the RI investigators found water in the wastes, probably groundwater coming through or around the clay. Volatile chemicals dissolved in water seeping through the wastes might be carried into the aquifer, where they could vaporize into the interstitial air above the water table. Few buildings in the area are built with basements, due to the shallow water table. On their site visit in January 1992, MDPH staff noted several houses immediately north and west of the site which appeared to have basements. At the request of MDPH, staff from the Ionia County Health Department contacted the residents in some of these homes and asked if they had noticed any unusual odors in their basements that may be related to vapors from the landfill. The residents, some of whom had lived there for many years, said that they had not noticed any unusual odors (15).
Subsurface Soil and Buried Wastes
With future erosion of the site, buried wastes may become exposed and human exposure may occur through direct contact, ingestion, or inhalation of volatile chemicals. A trespasser on the site who accidentally or deliberately broaches a drum containing liquid wastes might become exposed to the chemicals within via dermal contact, incidental ingestion, or inhalation of volatile components. All known drums containing liquid wastes have been either removed from the site or their contents drained for off-site disposal. There is no information indicating that significant exposure has occurred to date by this route.
As noted in the Environmental Contamination and Other Hazards and Pathways Analyses Sections above, human exposure to metals and organic chemicals from the Ionia City Landfill site may be occurring and may have occurred in the past via direct contact with contaminated soils, inhalation of fugitive dusts, or inhalation of volatile organic compounds. People using a residential well near the site were exposed to tetrachloroethylene, which was probably not related to the ICL site.
There is not enough data available to evaluate the public health implications of the potential pathways for groundwater, surface water and sediment, biota, fugitive dust, soil gas, and sub-surface soil. The only completed exposure pathways at the site are those involving exposure of trespassers to contaminated surface soil and transport of volatile chemicals via the air. The indications that these pathways are complete are qualitative, discolored soil, odors, and non-specific organic vapor detectors, and do not identify the contaminants for health effects evaluation.
Exposure doses for this site were computed using standard values for body weight, water consumption, and incidental soil ingestion (18). The exposure to VOCs through inhalation secondary to household use was estimated by assuming one shower a day, lasting 10 minutes, with air concentration computed from Line A in Figure 5 from Reference 19. The risk of non-cancer adverse health effects was evaluated by comparison with ATSDR-derived Minimal Risk Levels (MRLs) and U.S. EPA-derived Reference Doses (RfDs) and Reference Concentrations (RfCs). MRLs, RfDs, and RfCs are exposure levels below which it is generally accepted that non-cancer adverse health effects are unlikely to occur. These levels may not be protective for extra-sensitive populations, such as the very young, the very old, those whose immune systems are under stress, and those who have a particular sensitivity to the chemical. The increased risk of contracting cancer was considered significant if, based on U.S. EPA slope factors, it was estimated that one additional case of cancer would be expected to occur in a population of one million experiencing the exposure.
Tetrachloroethylene (also known as perchloroethylene or PCE) was found in two samples, a water sample from an upgradient residential well and a soil sample from the bottom of a trench in Area A of the landfill. No one is likely to ingest enough PCE from either source to incur any adverse non-cancer health effects. Exposure to PCE has been linked to liver and kidney cancer in experimental animals. PCE was formerly classified as a probable human carcinogen (U.S. EPA Class B2), however, the U.S. EPA has withdrawn the classification pending further review (20). Exposure to the PCE in the contaminated soil should not pose any significantly increased cancer risk. Lifetime consumption of water containing the concentration of PCE found in the residential well near the site could result in an increased risk of cancer slightly above the level of significance. The daily dose of PCE inhaled by a person whose shower uses this water is not likely to result in a significantly increased risk of contracting cancer.
This section discusses, in general terms, the potential health effects associated with exposure to chemicals that have been documented to be related to the site. It is impossible to identify all chemicals that might be at the site. The landfill was an open, largely unregulated dump during much of its operating period. There are few records of what materials were dumped in the landfill. Chemical reactions in the landfill can generate other compounds, as well. The sampling of the site that has been done was unavoidably selective, and cannot be said to completely characterize the landfill contents.
Exposure to chlorinated hydrocarbons, such as 1,1-dichloroethane, trans-1,2-dichloroethylene, methylene chloride, 1,1,1-trichloroethane, trichloroethylene, and vinyl chloride, can cause central nervous system depression, liver damage, and kidney damage. Such damage has mainly been observed at high exposure levels, hundreds of parts per million in the air. FID/PID organic vapor measurements during a trenching operation during the RI exceeded 1,000 ppm, though the specific chemicals detected were not identified. People in the vicinity of further excavation into the wastes without proper protective equipment might be exposed to the chemicals. Exposure to these chemicals has been linked to cancer, primarily of the liver, in experimental animals and workers in plants producing or using them. Vinyl chloride has been classified by the U.S. EPA as a proven human carcinogen (U.S. EPA Class A). 1,1-Dichloroethane and methylene chloride are classified as probable human carcinogens (U.S. EPA Class B2). Trichloroethylene was formerly classified as a probable human carcinogen (U.S. EPA Class B2), however, the U.S. EPA has withdrawn the classification pending further review (21, 22, 23, 24, 25, 26).
A child subject to pica behavior who plays in soil containing the concentrations of cadmium recorded at and near the site could ingest enough of the metal to exceed the MRL for chronic exposure by ingestion. He or she would not be likely to ingest enough of the metal to attain the doses at which adverse non-cancer health effects have been observed in studies of humans exposed to the metal (LOAELs), though the dose might exceed those at which no adverse non-cancer health effects were observed (NOAELs). However, the cadmium concentrations at which the NOAELs might be exceeded were only found in sub-surface soil in the landfill, where children of the age subject to pica behavior are not likely to play. A child whose primary drinking water supply contains the concentration of cadmium found in the Grand River near the site might ingest enough of the metal to exceed the MRL. Based on the observed cadmium concentrations, non-cancer adverse health effects from exposure to the metal at the site are unlikely. Long-term exposure to cadmium can cause kidney and lung damage. Cadmium can accumulate in the body. For inhalation exposures only, cadmium is classified as a probable (U.S. EPA Class B1) carcinogen. There is not enough information available to classify the carcinogenicity of the element by other routes of exposure or to evaluate the risk of contracting cancer from any exposure to cadmium (27).
Chromium-containing compounds usually contain the metal in one of two valence states, trivalent or hexavalent. Compounds containing hexavalent chromium are generally much more toxic than those containing trivalent chromium, causing skin irritation and liver damage. For inhalation exposures only, hexavalent chromium compounds are classified as proven (U.S. EPA Class A) carcinogens. There is not enough information available to classify the carcinogenicity of this chemical species by other routes or to estimate a cancer risk from ingestion exposure. There is insufficient evidence to classify trivalent chromium compounds with respect to their carcinogenicity. Trivalent chromium is a necessary trace element, though it can be toxic at high levels of exposure. Hexavalent chromium tends to be reduced to the trivalent species in the environment (28). The valence state of the chromium found at and near the site has not been identified. A child of the age subject to pica behavior who plays in soil containing the maximum concentration of chromium found in the drummed wastes on the site might ingest enough chromium to exceed the RfD, regardless of the valence state of the metal. This ingested dose would not exceed the LOAELs for trivalent chromium, though it might exceed the LOAELs for hexavalent chromium. Any child playing in this soil might incidentally ingest enough chromium to exceed the RfD, though not the LOAELs, for hexavalent chromium. No adult is likely to incidentally ingest enough chromium from the soil on the site to exceed the RfD for either valence state. The waste is currently either buried or removed from the site, and children are not likely to be exposed to it.
Lead is classified as a probable human carcinogen (U.S. EPA Class B2). The metal is also a cumulative poison, affecting the nervous system. Because of the metal's cumulative effects, the potential health effects from exposure are dependent upon the individual's history of prior exposure. It is impossible to make any definitive statement of health risks relating to an environmental concentration. The State of Michigan has established a target level for environmental clean-up of 400 ppm lead in soils. Some researchers have suggested that there may be no level of exposure that is safe, particularly with regard to developmental effects (29).
The concentrations of butyl benzyl phthalate, chromium, lead, methylene chloride, styrene, toluene, 1,1,1-trichloroethane, and trichloroethylene found in the buried drums and the soil around them are of concern if further erosion of the temporary cap should expose the waste, increasing volatilization and off-site movement. As long as the site remains accessible, recreational use or unauthorized dumping will probably continue and contact with the waste might occur.
Further erosion of the site could eventually wash significant quantities of contaminants into the east tributary and the Grand River, contaminating the water and sediments of both these streams.
The contaminants found on the site include ketones, such as acetone (found on the site but at concentrations below comparison values) and methyl ethyl ketone, and chlorinated hydrocarbons, such as 1,1-dichloroethane, 1,2-dichloroethylene, 1,1,1-trichloroethane, trichloroethylene, and vinyl chloride. Researchers have reported on animal experiments that indicate that exposure to ketones may increase the potential for liver damage from a later human exposure to chlorinated hydrocarbons (30-34). However, the levels of the chemicals are low in readily accessible media and blank contamination (laboratory quality control measures) indicates that the reported concentrations of the ketones may be inflated. Future exposure to higher levels of these chemicals would be possible if buried wastes are exposed.
Based on the evaluations performed as part of this health assessment, there are no indications that humans had significant exposure to site-related contaminants. In addition, there were no community health concerns identified during this evaluation. Therefore, health outcome data were not evaluated in conducting this health assessment.
There have not been many expressions of community health concern regarding the ICL site. While the landfill was operating, the neighbors occasionally complained of odors and reported fires and explosions associated with landfill operations. After the landfill was closed, local residents used the site for recreation, with little apparent concern. There are signs of continued unauthorized dumping, hunting, fishing, and off-road vehicle use on the accessible portions of the site.
A draft of this public health assessment was released for public comment on March 8, 1991. The public comment period lasted until April 8, 1991. Although the official comment period has ended, further information and comments will be considered during future assessments of, or consultations on, the site.
The MDPH released a second draft of this Public Health Assessment for public comment on December 14, 1994. The comment period lasted until January 13, 1995. The MDPH received no additional comments in this period.