SOUTH MACOMB DISPOSAL AUTHORITY #9, 9A
ST. CLAIR SHORES, OAKLAND COUNTY, MICHIGAN
An environmental pathways analysis is conducted in order to determine the implications of contamination at and around the site. Such an assessment consists of determining the nature and extent of contamination, evaluating whether complete environmental pathways exist, and assessing the implications of those pathways. A complete environmental pathway consists of five elements: (1) a source of contamination, (2) an intra or intermedia migration route, (3) a point at which a human can become exposed, (4) routes of exposure, and (5) a receptor population. The public health implications of contamination existing at a point where a population may become exposed is dependent on the existence of an exposure route (a mechanism by which individuals become exposed to contaminants e.g., ingestion, inhalation, and dermal contact) and the magnitude and frequency of the exposures which may occur.
The first step in performing this analysis is to identify contaminants of concern that will be further evaluated in subsequent sections of this public health assessment to determine the public health significance of exposure to them. Inclusion of a contaminant in tables and discussion here does not imply that exposure would result in adverse health effects. When selected as a contaminant of concern in one medium, that contaminant is recorded in all media tables.
ATSDR selects contaminants of concern based upon one or more of the following factors:
Data tables include the following abbreviations:
| = Michigan Department of Natural Resources = Cancer Risk Evaluation Guide = Environmental Media Evaluation Guide = Environmental Protection Agency = Michigan Toxic Substance Control Commission = Reference Dose Media Evaluation Guide = Lifetime Health Advisory for drinking water (EPA) = parts per billion = parts per million = Below Detection Limit = Not Detected = Maximum Contaminant Level |
ATSDR uses several types of medium-specific comparison values to assist in selecting the
contaminants that will be evaluated later for public health significance. For this assessment the
specific comparison values include Environmental Media Evaluation Guides (EMEGs), Cancer
Risk Evaluation Guides (CREGs), and Reference Dose Media Evaluation Guides (RMEGs).
EMEGs are estimated comparison concentrations that are based on the Minimal Risk Levels
(MRLs) presented in the ATSDR Toxicological Profiles for specific chemicals. At this time,
MRLs consider only non-carcinogenic toxic effects of a chemical substance. CREGs are
estimated contaminant concentrations that are based on one excess cancer for a million persons
exposed over a lifetime and are calculated from EPA's cancer slope factors. RMEGs are
calculated from EPA's Reference Doses and are based on their estimates of the daily exposure to
a contaminant that is unlikely to cause adverse health effects.
Most of the environmental data used in this report to assess the nature and extent of contamination is taken from the EPA Remedial Investigation Report (RI) dated August 23, 1990. Previous investigations at the site were conducted by the MDNR, MDPH, MTSCC, and the consulting firm of Neyer, Tiseo, and Hindo, LTD. Data collected during some of these investigations is included in the RI along with data gathered during EPA's remedial investigation.
During the various environmental investigations groundwater samples were collected from both on-site and off-site locations. Air, soil gas, surface soil, subsurface soil, and leachate samples were collected on the site. In addition, sediment and surface water samples were collected from McBride Drain, which lies adjacent to the site.
Analyses of the samples during the EPA Remedial Investigation were performed at laboratories participating in the EPA's Contract Laboratory Program (CLP). CLP analyses conducted on subsurface soil, surface soil, sediment, surface water, and groundwater samples include tests for Target Compound List (TCL) volatiles, TCL semi-volatiles, pesticides & PCBs, oil & grease, unfiltered metals, and cyanide. In addition, filtered metals analysis was performed on groundwater and surface water (1). Air samples were analyzed for the presence of eight organic compounds. Soil gas samples were analyzed for total organic vapors.
Environmental investigations at this site have indicated that leachate and groundwater have consistently contained elevated levels of organic and inorganic contaminants. Contaminants detected at elevated levels include: ammonia, antimony, arsenic, barium, benzene, cadmium, chromium, 1,2 dichloroethane, lead, manganese, methylene chloride, methyl ethyl ketone, nickel, nitrates, selenium, tetrachloroethylene (PCE), trichloroethylene (TCE), vanadium, vinyl chloride, and zinc. Between 1984-1987 several organic contaminants were detected in residences during indoor air sampling. These contaminants may be related to building materials and household products. The available data did not indicate significant surface soil, surface water, subsurface soil, or sediment contamination.
The following chemicals were detected in on-site leachate samples at elevated concentrations between the years 1982-1988: methylene chloride, benzene, PCE, TCE, vinyl chloride, cadmium, lead, nickel, zinc, arsenic, chromium, selenium, and manganese. Refer to Table 1 for maximum concentrations.
Leachate samples collected in 1988 were drawn directly from the sumps of the leachate collection system. One sample was collected at the northeastern corner of Site 9 and the other was collected from the central portion of the southern property line of Site 9a. EPA officials consider these locations representative of both sites. Potential chemicals of concern detected in these samples are: methylene chloride, nickel, zinc, and manganese. Maximum concentrations for chemicals detected were found in the samples from Site 9a.
Leachate: Samples collected between 1983-1988
| Contaminant | Maximum Concentration (ppb) |
Source, Year | Comparison Value |
| methylene chloride | 13,000 | MDNR 1983 | 5.0 CREG |
| lead | 680 | MDNR 1983 | NONE |
| benzene | 40 | MTSCC 1983 | 1.0 CREG |
| PCE | 110 | MTSCC 1983 | 0.7 CREG |
| TCE | 130 | MTSCC 1983 | 3.0 CREG |
| vinyl chloride | 30 | MTSCC 1983 | 0.2 EMEG |
| zinc | 87,000 | MTSCC 1983 | 3000 RMEG |
| arsenic | 120,000 | MTSCC 1983 | 0.02 CREG |
| chromium | 260,000 | MTSCC 1983 | 50 RMEG |
| cadmium | 146,000 | local resident | 7.0 EMEG |
| selenium | 6,988,000 | local resident | 30 EMEG |
| nickel | 940,000 | EPA 1988 | 200 RMEG |
| manganese | 33,300 | EPA 1988 | 50 RMEG |
Leachate samples from earlier investigations in 1982 and 1983 contained high levels of benzene, methylene chloride, TCE, vinyl chloride, PCE, nickel, chromium, arsenic, and selenium. Some of the leachate samples were collected from the leachate collection system at Site 9a as part of a survey conducted by the MDNR in September 1983. Other samples were collected from a manhole near the southern border of Site 9a by the MTSCC in July 1983, and from an unidentified location by a nearby resident in 1982. Limited off-site leachate data was available for review by ATSDR; thus a thorough assessment of the implications of historical offsite leachate contamination of residential yards and basements cannot be conducted. In 1991, MDPH provided ATSDR with results from water sampled in the sump pit of a residential basement and sediment and standing water in a residential yard. These results will be discussed in the residential sampling section.
The EPA collected groundwater samples during three sampling events: January 1989, July 1989, and November 1989. The MDNR, the MDPH, the MTSCC, and the consulting firm of Neyer, Tiseo, and Hindo, Ltd, collected groundwater samples during varying times between 1983 and 1991. The groundwater sample results will be separated into two major categories: on- and off- site monitoring results and residential well results. The former category is subdivided by specific aquifer. The residential well information cannot be discussed by specific aquifer because available well construction information is not sufficient to allow classification of them by aquifer (1).
ON- AND OFF-SITE MONITORING WELLS
The local aquifer system is composed of three interdependent aquifers: the shallow, the intermediate, and the deep. Discontinuous clay layers allow flow paths from the three aquifers to merge.
Chemicals detected above comparison values are as follows: benzene, vinyl chloride, methylene
chloride, zinc, lead, cadmium, nickel, arsenic, chromium, antimony, barium, manganese, and
vanadium. In on-site monitoring wells, the maximum contaminant levels were detected in either
the shallow or the intermediate aquifer. Chemicals having maximum concentrations within the
shallow aquifer include: benzene, methylene chloride, lead, cadmium, antimony, and
manganese. Vinyl chloride, zinc, nickel, arsenic, chromium, barium, and vanadium had
maximum concentrations within the intermediate aquifer. Refer to Table 2 for concentration levels.
The following chemicals were detected in off-site monitoring wells at levels exceeding comparison values: zinc, lead, cadmium, nickel, arsenic, chromium, antimony, barium, and manganese. Six out of ten maximum concentrations were detected within the intermediate aquifer. The remaining maximums were detected within the deep aquifer. It is important to note that Michigan has some extensive geographic areas with elevated levels of arsenic in groundwater known to be naturally occurring. Refer to Table 3 for concentration levels.
On-site Monitoring Wells: Data collected between 1983-89, Maximum Concentration in ppb
| Contaminant | Shallow Aquifer | Intermediate Aquifer |
Deep Aquifer | Comparison Value | Source |
| benzene | 36 | 6-22 | ND | 1.0 | CREG |
| methylene chloride | 1700 | 19 | 19 | 5.0 | CREG |
| vinyl chloride | 25 | 33 * | ND | 0.2 | EMEG |
| antimony | ND-837 | 23-256 | 44-95 | 4.0 | RMEG |
| arsenic | 78 † | 1-219 | 2-36 | 0.02 | CREG |
| barium | ND | 14-3660 | 57-2190 | 700 | RMEG |
| cadmium | 5-491 | 3-26 | 4-31 | 2 | EMEG |
| chromium | 6-136 | 6-692 | 7-619 | 50 | RMEG |
| lead | 2-1260 | 7-445 | 850 * | NONE | |
| manganese | 77-13000 | 31-12300 | 42-12800 | 50 | RMEG |
| nickel | 36-443 | 19-927 | 7-608 | 100 | LTHA |
| vanadium | 3-273 | 5-871 | 6-568 | 30 | EMEG |
| zinc | NC | 26-30800 | 36-10900 | 3000 | RMEG |
ND: not detected
NC: not detected at a level of concern
* : MDNR investigation, 1983
† : NTH investigation, 1987
Unless otherwise noted data results are from the 1989 EPA investigation.
Off-site Monitoring Wells: Data collected between 1983-89, Maximum Concentration in ppb
| Contaminant | Shallow Aquifer | Intermediate Aquifer | Deep Aquifer | Comparison Value | Source |
| antimony | ND | 66-231 | ND | 4.0 | RMEG |
| arsenic | NC | 7-66 | NC | 0.02 | CREG |
| barium | 122-1330 | 122-1330 | 303-1330 | 700 | RMEG |
| cadmium | ND | 9-31 | ND-8.4 | 7 | EMEG |
| chromium | 13-204 | 13-240 | 42-308 | 50 | RMEG |
| lead | 31-39 | 6-481 | 920 † | NONE | |
| manganese | 1070-2010 | 124-8380 | 618-1470 | 50 | RMEG |
| nickel | 24-137 | 10-384 | 50-201 | 200 | RMEG |
| zinc | 234-2770 | 44-11900 | 337-31500 | 3000 | LTHA |
ND: not detected
NC: not detected at a level of concern
* : MDNR investigation, 1983
† : NTH investigation, 1987
Unless otherwise noted data results are from the 1989 EPA investigation.
Though the presence of contaminants at levels of potential concern in residential wells were not noted by the latter EPA investigation, earlier investigations (1983 and 1984) conducted by state and local agencies initially concluded that residential wells were contaminated with VOCs. The MDPH has established a policy for replacement of private water supplies where synthetic organic chemicals are found at detectable levels. This policy has been partially based upon the inability for private wells to be regularly monitored to detect the encroachment of higher contaminant levels at a later date. Thus, once impacted wells were identified near the SMDA site, residents were instructed not to use their water. Most residential wells are no longer in use. Refer to Table 4 for contaminant concentration levels in residential wells.
Residential Wells: Data collected by MDNR/MDPH between 1983-90, Concentration Range or Maximum in ppb
| Contaminant | Concentration Range | Comparison Value | Source |
| ammonia | ND-82000* | 3000 | MRL |
| arsenic | ND-40* | 0.02 | CREG |
| benzene | ND-17 | 1.0 | CREG |
| cadmium | ND-13.6* | 7 | EMEG |
| 1,2 dichloroethane | ND-9 | 0.4 | CREG |
| lead | ND-225 | None | |
| methylene chloride | ND-54 | 5.0 | CREG |
| methyl ethyl ketone | ND-1827 | 200 | LTHA |
* Reference 5a
Data collected during MDPH residential well sampling rounds indicate sporadic low levels of
organic contaminants such as styrene, trichloroethylene, and chloroform. Contaminants such as
benzene, methyl ethyl ketone, methylene chloride and ammonia were detected more frequently
and at higher levels. There were no consistently elevated levels of heavy metals. In many wells
elevated concentrations were detected only once. One example of this is a well where lead was
detected at 225 ppb in 1988. In addition, the presence of ether and freon type compounds was
observed frequently. ATSDR, however, does not have any concentration data for these
compounds. It should also be noted that methane was detected in the water of two residential
wells in 1986 using a gas water separation technique. The majority of affected wells were
located at residences along 24 Mile Road between the years 1983 and 1988.
Benzene was detected in McBride Drain at a concentration of 39 ppb during the MDNR survey conducted in 1983. This concentration is nearly eight times greater than EPA's maximum contaminant level for benzene in drinking water. The laboratory that analyzed the surface water sample, however, indicated the possibility that contamination of the sample within the laboratory during analysis may have affected the accuracy of the analytical results. The sample location is reportedly downstream of McBride Drain just below the SMDA site, parallel to the southern edge of the landfill. Several leachate outbreaks have occurred along this stretch of the Drain, which is also thought to be a surface discharge point of the intermediate aquifer.
Groundwater, soil gas, indoor air, standing water, sediment, and sump water samples were collected at several residences near the SMDA site from 1983 to 1991. Residential well sampling results are discussed in the Groundwater Section. Residential soil gas sampling results are discussed in the Soil Gas Section. The analytical results of samples from the remaining media will be discussed in this section.
In 1982, following a complaint by a resident that red "ooze" from the landfill had seeped into a basement, analysis on sump water and a sludge like material was conducted. Although traces of some volatile organic compounds (VOCs) (toluene, 1,2-dichloroethene, and 1,1-dichloroethane -- under 10 ppb) were detected in sump water in the residential basement, an evaluation by a researcher at Wayne State University attributed the red slime to the high iron content of the shallow groundwater and iron-loving bacterial growths (e.g. Gallionella ferrugina). The same kind of reddish growths were found in McBride Drain upstream from the landfill (3).
Between 1984 and 1987 MDPH conducted indoor air sampling at three residences near the SMDA site. Toluene, fluorotrichloromethane, 1,1 dichloroethane, 1,2 dichloroethane, xylene, and 1,2-dichloropropane were detected in one or more of the residences. These chemicals may not be related to the landfill. Methane levels were not tested. The production of methane gas from the breakdown of wastes is often associated with landfills.
In May of 1991, officials of the MDPH and MDNR conducted sediment and standing water sampling on residential property adjacent to the site. The bulk of the chemicals detected were metals. Iron, manganese and lead in the water samples were above background and within the range of on-site ground water concentrations. Lead was the only chemical detected above background levels in the sediment samples (7).
Very few organic chemicals were detected in the samples. Those detected in sediments were at concentrations greater than background levels and within the range of concentrations detected in on-site soil samples collected by EPA. The concentrations of organics found in the water samples were inconsistent with EPA groundwater sample results. Several concentrations of contaminants detected at the residence either were below background or below concentrations detected on-site. In addition, some of the contaminants had not been detected on-site. Toluene, 1,4-dichlorobenzene, and 1,2,4-trichlorobenzene were detected at concentrations within the range of those detected on-site by EPA (7).
MDNR concluded that most of the chemicals detected in the samples were related to the SMDA site and identified the contamination as a result of a leachate outbreak. Although most of the chemicals detected were at background levels, MDNR recommended that the soils and water from this area not be used (7).
In August of 1991, MDPH conducted sampling of sump water from the basement of a residence. Several organics were tentatively identified during analysis. However, due to premature termination of the analytical test a more conclusive identification of the contaminants was not possible (6).
A total of 105 soil gas samples were collected during two surveys. The samples were collected at points surrounding the perimeters of the landfill areas (Sites 9 and 9a, excluding the western side), from within the cap material, from residential and adjacent properties north of 24 Mile Road, and at background surface soil sample points. Sample values were presented as total volatile organics. Soil gas samples collected during the surveys were analyzed by two different methods: organic vapor analyses and photoionization detection. Organic vapor analyses showed positive deflections which indicated probable concentrations of methane gas (1).
Crop foliage was tested in 1982 for polychlorinated biphenyls, TCE, and various pesticides.
None of these contaminants were detected. Green peppers and green tomatoes were tested by
the Michigan Department of Agriculture in 1983. Traces of inorganics (not specified) were
found. The same year the Michigan State Cooperative Extension Service reported that observed
tomato stunting and leaf silvering may be due to high soluble salt and nitrate levels in the soil.
Residential soil sampling in 1991 did detect contaminants thought to be related to the SMDA
site. It is not clear whether biota in the area was affected by the contamination.
Quality assurance and quality control (QA/QC) methods were utilized on data obtained for the RI. EPA reports that during the laboratory analyses, some parameters were determined to be outside the quality control limits. These deviations are clearly indicated in the remedial investigation report and do not significantly impact use of data (9). QA/QC documentation was only partially available for data from previous investigations and information submitted to ATSDR by state and local agencies. The ATSDR recognizes that many limitations on the quality of that data may exist. Because of the history of this site, we deemed it desirable to examine data collected prior to EPA involvement.
The composition of waste materials deposited in landfills may allow for the production of methane, a highly explosive gas. Both on- and off-site monitoring have indicated the possible presence of methane. During winter periods when topsoil is frozen, lateral movement of methane gas can result in potentially explosive conditions in the basement of homes and other confined spaces under circumstances where venting is not provided. Although the EPA investigation reported no trends between sample points and no "significant" concentrations above background, additional information is needed before an assessment can be made of the potential for explosion due to the existence of methane and other landfill gases around this site.
Both groundwater and surface water contamination have been documented by past investigations conducted on and around the site. The environmental pathway of greatest concern at this site is groundwater. The associated human exposure routes include ingestion and dermal contact with contaminated groundwater and inhalation of volatiles emanating from contaminated groundwater. Exposure is believed to have occurred in the past, may presently be occurring, and may occur in the future.
Although the surface water pathway is complete, it is not presently of concern. The potential for McBride Drain to become contaminated does exist, however, as of the most recent investigation the drain was not found to be contaminated. The drain is not normally used for recreational purposes but it does flows through a golf course and golfers undoubtedly retrieve their stray balls from the surface water body. Thus, if McBride Drain were to become contaminated due to a leachate outbreak a small risk of exposure due to direct contact with the water in the Drain would be possible.
Other potential environmental pathways at this site include the surface soil, and biota pathways. These pathways would be due to contamination of surface soil and surface water resulting from leachate outbreaks. Although there has been one confirmed leachate outbreak in recent years the risk of exposure through this pathway is small. In addition, exposure via inhalation of entrained soil particles and ingestion of crops which have bioaccumulated contaminants is highly unlikely.
Movement of Contaminants from Soil/Waste Layers to Groundwater
Similar contaminants were detected both in onsite monitoring wells and residential wells used for drinking water. Because individuals were at risk for exposure in the past and may currently be at risk for exposure, the groundwater pathway is complete.
An important migration mechanism at this site is infiltration. Infiltration is the process by which precipitation moves through soil layers to replenish moisture, recharge aquifers, and support streamflows. The rate at which contaminants in soils and buried wastes migrate along with infiltrating water is dependent upon several factors. Three major factors are the climate, the physical characteristics of the soil, and the physical and chemical characteristics of the contaminants.
Macomb County has an average yearly precipitation of 28.07 inches (9). The soil at the site is best described as a mixture of sandy loams, fine sands, and clay loam. EPA determined that the permeability of the cap material at Site 9 was higher than that at Site 9a (9). This indicates that infiltration through the cap layer would occur at a faster rate on Site 9 as compared to Site 9a.
Chemicals released from landfill materials during infiltration episodes are transported in a plume of leachate which percolates through soil and waste layers and into groundwater. The plume disperses both downward and laterally. As discussed in the on-site contamination section, the presence of discontinuous clay layers allows for contaminant movement between the three aquifers. Contaminants may enter the shallow aquifer, move downward into the intermediate and deep aquifers, and then move laterally off the site.
Organic contaminants with high organic carbon partition coefficients (Koc) tend to adsorb to organic matter in waste and soils; while organic chemicals having low Koc's (<100) such as benzene (Koc:83) and methylene chloride (Koc:8.8) tend to migrate more freely into groundwater. Both of these chemicals were detected in the leachate and in the groundwater at the site. The extent to which inorganic contaminants will be mobile in leachate is more complicated and is dependent on several factors including pH, oxidation-reduction potential, and the presence of other anions or cations. The leachate at this site contained several inorganic contaminants which were also detected in the groundwater samples. It is important to note that this area of Michigan is known to have naturally occurring high inorganic metal content in soil. Two elements in particular that are found in high concentrations are iron and arsenic.
The distribution of organic and inorganic contaminants within the three aquifers is both spatially and temporally erratic. This pattern is consistent for landfills. Due to the nature of a landfilling operation, source areas are often not discrete but may exist at random locations throughout the site. Contaminant migration from these sources is also not expected to occur at a continuous rate. It is more realistic to expect slugs of contamination to move away from sources at various times and at varying rates. These rates depend on the characteristics of the chemicals contained within those areas and the environmental conditions which may influence or inhibit migration. The range of contaminant concentrations detected during the many sampling events is evidence of this.
During the EPA investigation the maximum contaminants in leachate were found in samples taken from Site 9a, despite the greater permeability noted earlier in the surface soils covering Site 9. This seems to suggest that either 1) wastes buried in Site 9a may collectively act as a greater potential source of contamination that can potentially migrate to the shallow aquifer and beyond, or that 2) wastes disposed of at Site 9a may be more contaminated than those at Site 9 (9).
The EPA has identified two contaminant plumes; one in the intermediate aquifer and the other in the shallow aquifer. Neither of the plumes are well defined but, of the two, the shallow is the least defined due to the low number of samples collected during the remedial investigation (9). A plume has not been identified in the lower aquifer. The sampling data in Table 2 show less contamination in this aquifer than in the upper aquifers.
Groundwater beneath the site exhibits multi-directional flow patterns as a result of mounding effects. The primary flow pattern or route of off-site migration for groundwater has been identified as being through the intermediate aquifer. The leachate plume first enters the shallow aquifer. Flow to the north is restricted by the slurry wall and flow towards the east, west, and south is expected to quickly enter the intermediate aquifer. Once in the intermediate aquifer, contaminants have greater potential to move laterally off the site toward residential wells.
ATSDR has been informed that one of the leachate collection systems does not capture the entire leachate plume (8). Some of the leachate not collected by the system at Site 9 is believed to be captured by the system at 9A. If leachate not collected by either system migrates through the shallow aquifer in the southeasterly direction, area crock wells may be affected.
Exposure to contaminated groundwater from use of residential wells is believed to have occurred in the past. There is a small risk that it may currently be occurring and that it may occur in the future. The exposure routes of concern associated with this medium are ingestion, inhalation, and dermal exposure. Several remedial actions have taken place since the contamination of residential wells was first detected. Most residences near the site are now connected to municipal water, approximately nine are not connected. Although monitoring through February 1995 has not indicated the presence of contamination, the potential for future exposure to contaminated groundwater does exist, but is highly unlikely (8a).
Movement of Contaminants from Groundwater to Surface Water
At Site 9a, leachate entering the shallow aquifer is primarily captured by the leachate collection system. It may be possible that a small amount of leachate is not captured by this system. Leachate not captured by the leachate collection system can possibly migrate into the intermediate aquifer. Because McBride Drain is thought to be the surface discharge point for the intermediate aquifer, contaminants may reach McBride Drain. The current sampling results indicate that McBride Drain is not contaminated. Although contamination was documented in the past, this pathway is currently incomplete because: 1) contamination of the McBride Drain does not currently exist and 2) is not likely to occur in the future due to proposed remediation of the site.
If this pathway becomes complete due to migration via leachate seeps or discharge of the groundwater plume to McBride Drain, there may be a small risk for human exposure via direct contact. Additional pathways which could be indirectly affected are air and biota. The air pathway may be affected because as contaminated groundwater surfaces at McBride Drain, VOCs will volatilize into the atmosphere. The biota pathway may be affected because water from the creek is used downstream for irrigation of crops and at the golf course for irrigation of the greens. Uptake of contaminants by terrestrial biota may occur. There are reportedly no sport fish in McBride Drain, so aquatic biota that might be consumed by humans is not likely to be a concern. Exposure resulting from these pathways would likely be minimal due to the infrequent nature of contamination of the Drain and dilution effects of the contamination which may enter the drain area.
Overflow of Leachate onto Adjacent Properties during Flooding
Local residents have raised complaints regarding leachate flooded fields. During periods of extreme stress on the leachate collection system (periods of increased infiltration beyond the storage capacity of the system), it may be possible for leachate to overflow. However, this is highly unlikely since the leachate is removed from the collection systems at regular intervals.
The MDNR and EPA have responded to citizens complaints of leachate outbreaks and flooding on several occasions. Testing of the liquid samples taken during those times rarely substantiate leachate outbreaks. There was, however, a confirmed off-site leachate outbreak in 1991 due to bubbling up of the leachate plume. This pathway is complete, but the risk of future occurrence is considered small due to the infrequent nature of confirmed incidents and the duration which an individual may be exposed to contaminants.
Leachate outbreaks may occur easier in areas of the landfill affected by erosion, the southern perimeter and barren areas. Because these areas do not support vegetation well, they are at higher risk for natural and leachate induced erosion. Two consequences of leachate induced erosion are: 1) contamination of McBride Drain directly by leachate and/or migration of contaminated soil particles contaminated by leachate and 2) entrainment of contaminated soil particles into the air. The pathways associated with surface water contamination have already been discussed. Risk of inhalation of contaminated entrained particles is considered minor due to the infrequent nature of confirmed leachate outbreaks.
The overall risk of exposure to contaminants through the surface soil pathway due to leachate contamination is very small due to the infrequent nature of confirmed outbreaks. In addition, there reportedly is an on-site engineer who is responsible for maintaining the cap surface in order to prevent leachate outbreak occurrences. If conditions change, this pathway should be further evaluated since recreational and residential areas surround the site.
Leachate Overflow and Uptake from Soil
Residents have raised concerns about the impact of leachate outbreaks both indirectly and directly affecting their crops. Testing of foliage and vegetables in 1982 and 1983 by the Michigan Department of Agriculture and the Michigan State Cooperative Extension Service could not substantiate these claims. Soil sampling on private property in 1991 did confirm the occurrence of a leachate outbreak. The area in which contamination was found was adjacent used for growing crops. The residents were told not to use soils and water from the affected area. If residents do not use this area there is no risk of exposure.
MDNR has received reports that leachate is released to area manholes instead of being taken to a treatment center three times a week. If leachate is being disposed of in this manner, workers could be exposed dermally, as well as via inhalation and incidental ingestion (due to splashes) while pumping the leachate into the manholes. In addition, workers who may need to enter manholes may be exposed via inhalation of vapors (confined space) and dermal contact.
The contaminants of concern disposed (released) into the environment at SMDA have the potential to cause adverse health effects. However, for adverse health effects to occur the pathway for exposure must be completed. A release does not always result in exposure. A person can only be exposed to a chemical if they come in contact with the chemical. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a substance containing the contaminant.
Several factors determine the type and severity of health effects that occur from an exposure to a contaminant. Such factors include the exposure concentration (how much), the frequency and/or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together those factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant.
ATSDR considers the above physical and biological characteristics when developing health assessment guidelines. Toxicological profiles prepared by ATSDR summarize chemical specific toxicological and adverse health effects information. Health assessment guidelines such as ATSDR's MRL and EPA's Reference Dose (RfD) and Cancer Slope Factor (CSF) are included in the toxicological profiles. Those health assessment guidelines are used by ATSDR health professionals in determining the potential for developing adverse noncarcinogenic health effects and/or cancer from exposure to a hazardous substance.
A Minimal Risk Level (MRL) provides a basis for comparison with concentrations of contaminants in different environmental medium (soil, air, water, and food) to which people might be exposed. If daily exposure occurs at an amount below the MRL, harmful noncancerous health effects are not expected to occur. The method for deriving MRLs does not include information about cancer, therefore, an MRL does not imply anything about the presence, absence, or level of cancer risk.
An EPA Reference Dose is an estimate of the daily exposure for the human population, including sensitive subpopulations, that is likely to be without appreciable risk of adverse noncarcinogenic health effects during a lifetime (70 years). The RfD is a health guideline for the oral route of exposure. For carcinogenic substances, EPA has established the Cancer Slope Factor (CSF) as a health guideline. The CSF is used to determine the number of excess cancers expected from exposure to a contaminant.
To link the site's human exposure potential with health effects that may occur under site-specific conditions, ATSDR estimates human exposure to the site contaminant from ingestion and/or inhalation of different environmental media. The following relationship is used to determine the estimated exposure to the site contaminant:
ATSDR uses standard intake rates for ingestion of water. The intake rate for drinking water is 2 L/day for adults and 1 L/day for children. Standard body weights for adults and children are 70 kg and 10 kg, respectively. The maximum contaminant concentration detected at a site for a specific medium is used to determine the estimated exposure. Use of the maximum concentration detected in a specific medium will result in the most protective evaluation for human health. In addition, some exposures occur on an intermittent or irregular basis. For those exposures, an exposure factor (EF) is calculated that averages the dose over the exposure period. Since the exposure period is not known at SMDA, 70 years was used for a conservative estimate.
The contaminants of concern at this site are benzene, methylene chloride, arsenic, ammonia, 1,2-dichloroethane, lead, methyl ethyl ketone, nitrates, and cadmium. These contaminants were detected in residential wells during the years 1983-1990 at levels which exceed ATSDR comparison values. Exposure to contaminated groundwater is believed to have occurred through the ingestion, dermal contact, and inhalation routes due to past use of contaminated private wells. An MDPH/MCHD survey has indicated that nine residential wells near the site may still be in use. Monitoring through 1991 has indicated that these wells are not contaminated. The potential for future exposure exists but can be eliminated once residences connect to municipal water and completely refrain from using water for non-potable purposes.
The above chemicals may potentially impact on public health because chronic exposure to levels associated with adverse health effects may have occurred and future exposure may occur unless all private wells are abandoned. Toxicological implications resulting from exposure to the above chemicals are discussed below. However, more detailed information regarding exposure frequency and duration is necessary to make a more accurate site specific assessment.
For additional information on each chemical, please see Appendix B.
BENZENE
Benzene was detected in five residential wells at concentrations up to 17 ppb. At the time of detection residents were already being provided alternate drinking and bathing water.
Exposure to benzene may have occurred in the past via ingestion, inhalation, or dermal contact with benzene contaminated water. The lowest concentrations of benzene that may cause chronic, non-cancerous adverse effects via ingestion are largely unknown, and health guidelines identifying a safe level have not been established (11). Thus, ATSDR cannot predict what non-cancerous adverse health effects, if any, may result from exposures at levels detected in wells near SMDA.
Based on calculations for a lifetime of oral exposure to the benzene detected, there is no apparent increased risk of developing cancer.
The most common exposure to benzene comes from breathing air containing it because benzene evaporates very quickly (11). Levels of benzene in the air at which noncancerous adverse health effects have been observed are one hundred-fold higher than those expected from private wells in the SMDA area. Thus, noncancerous adverse health effects are not expected to result from inhalation exposure to benzene contaminated water.
There has not been any air monitoring done at the SMDA site. Based on the groundwater concentrations, inhalation of benzene would result in an increased risk of cancer. Benzene is considered to be a human carcinogen via inhalation by the EPA, the Occupational Safety and health Administration, the World Health Organization, and the International Agency for Research on Cancer (11). A review of several studies by Aksoy (1985) showed sufficient data demonstrating benzene as a potent carcinogen causing leukemia, malignant lymphoma, multiple myeloma, and lung cancer (11). Leukemia has occurred in some workers chronically exposed to benzene (levels of exposure were not reported). Benzene-induced leukemia has a latency period of 5 to 15 years and, in some instances, is proceeded by aplastic anemia (11). Aplastic anemia is a condition caused by bone marrow failure. However, the idea that exposure to low levels of benzene may be carcinogenic is not universally accepted (11).
Benzene can enter your body through the skin. However, studies regarding human dermal exposure to benzene were not reported (11). Adverse dermal effects have been observed in laboratory animals following skin contact with undiluted benzene. Dermal contact with benzene similar to the concentrations detected in private wells should not be of public health concern.
Several factors may predispose an individual's sensitivity to the adverse health effects of benzene exposure. Young people are vulnerable with nutrition, genetics, and immunoresponse playing a role. Pregnant women and their fetuses are at risk since benzene can cross the placenta. Also, drug and alcohol consumption contribute to an individual's sensitivity to benzene.
METHYLENE CHLORIDE
Methylene chloride was detected in one residential well at 54 ppb. The estimated oral exposure dose is ten-fold below the RfD. Also, there is no increased cancer risk from methylene chloride exposure at the concentrations detected. Thus, cancerous and non-cancerous adverse health effects are not expected to result from oral exposure to methylene chloride in private wells.
Human and animal studies demonstrate that the liver and kidneys are primary targets of methylene chloride toxicity following inhalation (14). Animal studies suggest that chronic or recurring exposures to methylene chloride may cause cell changes in the liver and kidney. However, based on these animal studies and those of workers occupationally exposed to high but unknown levels of methylene chloride, it seems unlikely that serious liver or kidney damage in humans will occur unless exposure levels are extremely high (14). Therefore, the methylene chloride levels detected at this site are unlikely to cause adverse liver or kidney damage via inhalation.
Several populations may be especially sensitive to the adverse health effects of methylene chloride. Methylene chloride is often metabolized to carbon monoxide in the liver, thus raising the carbon monoxide level in the blood. Persons with cardiovascular disease and respiratory dysfunction may experience adverse effects at lower levels than others (14). Smokers already have increased carbon monoxide levels in their blood, thus they are sensitive to methylene chloride.
Carbon monoxide may have adverse consequences on fetal development. Animal studies show that methylene chloride readily crosses the placenta and can enter breast milk. Therefore, pregnant women should take extra precaution to avoid methylene chloride exposure. In addition, methylene chloride may be mildly irritating to skin on repeated contact and has been reported to cause dermatitis in some cases, therefore children playing around leachate areas may be at risk (14).
ARSENIC
The maximum arsenic concentration detected is 40 ppb. The estimated exposure dose is 1.14 µg/kg/day. Non-cancerous adverse health effects have not been observed after exposure at similar doses. Human studies indicate that oral doses in the range of 20-60 µg/kg/day may produce signs of arsenic toxicity. These signs include digestive tract irritation, anemia, abnormal heart function, and liver and/or kidney injury (15). The severity of these symptoms tend to increase as exposure time increases (15).
An increased cancer risk may result from oral exposure to arsenic at the concentrations detected. Arsenic is classified by the EPA as a human carcinogen via oral exposure. Arsenic ingestion may increase the risk of liver, bladder, kidney, and lung cancer (15). There is substantial evidence that chronic oral exposure to elevated levels of arsenic increases the risk of skin cancer. The largest study of this relationship was conducted by Tseng, et al., in 1968. Over 40,000 people with well water arsenic levels ranging from 1-1820 ppb were examined. The incidence of skin cancer was correlated with arsenic levels in the water, and a strong relationship between skin cancer and other symptoms of arsenic toxicity was noted. Therefore, arsenic levels associated with SMDA Sites 9 and 9A could, upon ingestion, increase the probable risk of cancer of the skin, liver, bladder, kidney, and lungs.
Some people may be at an increased risk to the toxic effects of arsenic. Individuals with protein-poor diets or choline deficiency, deficiency in a B-complex vitamin essential to liver function, may be especially sensitive to arsenic exposure. Also, individual genetic variability involving the liver's ability to detoxify arsenic may predispose one to the adverse effects of arsenic.
AMMONIA
Ammonia was detected in residential wells at a maximum concentration of 82,000 ppb during the years 1983-1990. The estimated exposure dose exceeds the MRL of 0.3 mg/kg/day. Past exposure to ammonia likely occurred through inhalation and ingestion of and dermal contact with groundwater contaminated with ammonia. Exposure may still be occurring through the use of private wells.
Ammonia is a colorless gas with a very sharp odor. The odor is familiar to most people, because ammonia is used in household cleaners, window cleaning products, and smelling salts. You can smell ammonia when it is in the air at a level higher than 50,000 ppb. Adverse health effects have not been reported at levels below 50,000 ppb. Therefore, you will probably smell ammonia before you are exposed to a concentration in air that may harm you (18).
The health effects resulting from short- or long-term human exposure to water containing specific concentrations of ammonia via ingestion are not known. Information available for people exposed to ammonia through ingestion usually involve case reports of people who swallowed household ammonia. Thus, the information is from acute exposure to high, but unknown, concentrations. Because of this, it cannot be determined if any non-cancerous adverse health effects would result, or resulted in the past, from ingestion of ammonia associated with SMDA.
Dermal exposure to ammonia has produced adverse respiratory, cardiovascular, gastrointestinal, renal, and dermal/ocular effects in humans (18). However, these effects resulted after exposure to massive amounts of ammonia vapor or highly concentrated ammonia, the exact concentration is unknown. Thus, the concentrations of ammonia that may result in certain adverse health effects are largely unknown.
Carcinogenic potential of ammonia has not been established in humans exposed by the inhalation, ingestion, or dermal routes of exposure.
There were not any populations identified that might be especially sensitive to the effects of ammonia exposure. However, farmers can be exposed to ammonia when applying fertilizer or decaying manure.
1,2-DICHLOROETHANE
A maximum concentration of 9 ppb of 1,2-DCA was detected in residential wells. The estimated exposures from ingestion are below the levels that would be anticipated to cause acute (short-term) effects. However, little is known about the effects on health of long-term, low-level exposure [27]. In addition, exposures through inhalation and dermal absorption have not been considered in that estimate and reports in the literature suggest that exposure through inhalation during bathing is at least equal to exposure from ingestion. Because the levels at which 1,2-DCA could cause particular adverse health effects in humans are largely unknown, ATSDR cannot determine if chronic (70 years) exposure to 1,2-DCA in groundwater at SMDA could result in adverse, noncancerous effects.
Estimated exposure to 1,2-DCA through ingestion and inhalation of the groundwater would not result in an increased risk of cancer. Therefore, exposure to 1,2-DCA is not a public health concern regarding cancer.
There were not any populations identified that might be especially sensitive to the effects of 1,2-DCA exposure.
LEAD
Lead was detected at a maximum concentration of 225 ppb in residential wells. Ingestion is the primary route of exposure to lead. Dermal and inhalation exposure are not very significant because little lead passes through the skin and it does not volatilize from water. The biologic effects are the same regardless of how lead enters the body (20). At the present time, no studies have established what concentrations of lead present in various environmental media may result in blood lead levels associated with adverse health affects. Because of this, ATSDR cannot determine if exposures to lead associated with SMDA would result in blood lead levels associated with adverse health effects. Small exposures to lead can result in chronic toxicity because the body accumulates it over a lifetime and releases it slowly (20). The bones and teeth contain more than 95% of total lead in the body.
Lead primarily affects the peripheral and central nervous systems, reproduction, development, blood cells, and the metabolism of vitamin D (20). Exposure to lead resulting in high blood lead levels (blood lead concentrations exceeding 80 ug/dL) can severely damage the brain and kidneys of adults and children and may affect the male reproductive system after short- and long-term exposure. Long-term exposure resulting in blood lead levels between 15-30 ug/dL has been reported to cause decreased growth and Intelligence Quotient (IQ) in young children and increased blood pressure in middle-aged males. Both short- and long-term exposure resulting in blood lead levels between 10-15 ug/dL in pregnant women can result in pre-term birth, decreased birth weight, and reduced mental ability of their offspring (20).
The nervous system is the most sensitive target of lead toxicity. Lead is a serious threat to the central nervous system (CNS) of infants and children. One study showed that CNS damage in two-year-olds caused by lead exposure resulted in continued deficits in neurological development. Cognitive deficits and lower IQ scores were observed in these children at age five (20). Children with increased teeth lead levels have exhibited decreased attention spans and classroom performance, concentration problems, deficits in speech and language processing, and negative social behavior (20). In addition, hearing acuity has been shown to decrease with increasing blood lead levels (20). Hearing loss may contribute to the poor concentration and learning disabilities experienced by children with increased lead levels. Neurological symptoms including impaired concentration, subtle behavioral changes, and fatigue have been seen in adults with blood lead levels as low as 40 ug/dL (20).
Lead has produced profound adverse effects on human reproduction when exposure levels were high. A study by Wildt et al. (1983) found that men who had blood lead levels greater than 50 ug/dL resulting from occupational exposure exhibited adverse testicular effects. Effects seen included decreased prostate/seminal vesicle function, lowered semen volumes, and lower functional maturity of sperm (20). In pregnant women, occupational exposure to lead has been associated with an increased likelihood of miscarriage. In addition, Nordstrom et al. (1978) discovered an increased frequency of miscarriages in women living near a lead smelter.
Lead absorbed by pregnant women can transfer to the fetus via the placenta. Developmental consequences of pre-natal exposure to lead include premature birth, decreased birth weight, and neurobehavioral deficits (21). Lead can also be transferred through maternal milk to the nursing infant. Evidence of an association between prenatal lead exposure and congenital malformations has not been found.
Exposure to lead may result in adverse effects on blood cells. Lead inhibits the body's ability to manufacture hemoglobin, the oxygen carrying component of red blood cells. Exposure to lead may result in anemia. Anemia is evident only when the blood lead level is significantly elevated (>75 ug/dL) (20). However, in children, lead poisoning rarely results in anemia (20).
Occupational, clinical, and general population studies imply that lead exposure may result in adverse cardiovascular effects. Two large-scale studies provide evidence of a small but statistically significant link between blood lead levels and blood pressure in men (21). In these studies, men with blood lead levels higher than 37 ug/dL had a higher proportion of hypertension than other men. This effect appears to occur more in middle-aged men.
Lead appears to affect vitamin D metabolism in the kidney. Lead causes a reduction in the circulation of the vitamin D hormone and a disturbance in calcium metabolism. These effects can lead to impaired bone and tooth development (21).
Case reports have implicated lead as a potential renal carcinogen in humans. However, the EPA has concluded that human data is inadequate to determine the potential carcinogenicity of lead exposure. Exposure to lead salts has caused kidney tumors in laboratory animals. Therefore, the EPA classifies lead as a probable human carcinogen based on animal studies.
Several populations may be sensitive to the adverse health effects caused by lead. Pregnant women, fetuses, and children are particularly affected by lead exposure. Children with glucose 6-phosphate dehydrogenase deficiency have greater blood lead levels than non-deficient children with similar exposure. Persons with sickle-cell anemia may be especially sensitive to the neurological effects of lead exposure. Middle-aged men are at a risk for increased blood pressure resulting from lead exposure. In addition, those with dietary deficiencies in calcium, iron, and zinc may be susceptible to the adverse effects of lead.
METHYL ETHYL KETONE (MEK)
MEK was detected in private wells at a maximum concentration of 1827 ppb. The estimated oral exposure dose is ten-fold below the RfD. Thus, non-cancerous adverse health effects are not expected to result from oral exposure to MEK in private wells.
MEK is readily absorbed by all routes of exposure. Volunteers exposed to 25,000 ppb MEK in air for five minutes were not affected. They experienced mild irritation of the nose and throat upon exposure to 100,000 ppb (22). Workers chronically exposed to 300,000-500,00 ppb MEK in air experienced headache, irritation, and nausea. Because air concentrations associated with SMDA are expected to be far below those experimental levels, no adverse health effects resulting from inhalation of MEK is expected.
No information regarding dermal exposure to diluted or low concentrations of MEK was found in the literature.
The data on possible carcinogenicity of MEK is inadequate to determine if it is a human carcinogen.
CADMIUM
Cadmium was detected in residential wells at a maximum concentration of 13.6 ppb. For adults, the estimated exposure dose does not exceed the RfD, however, the estimated dose for children does exceed the RfD. Exposure to cadmium via ingestion and/or inhalation can cause adverse effects on the kidneys, skeletal system, and the lungs. However, cadmium volatilization is low from water, therefore exposure from inhalation at this site is expected to be negligible. Little cadmium is absorbed through the skin, thus dermal exposure is not of great concern.
The kidney is the most sensitive tissue to long-term cadmium exposure. Kidney damage may be caused by cadmium via oral exposure or inhalation. However, the lowest dose thought to produce kidney damage (0.01 mg/kg/day) is well above the dose expected to result from ingestion of 13 ppb cadmium (3.89 X 10-4 mg/kg/day).
It is not known if cadmium exposure causes cancer in humans. There is not any human or animal evidence demonstrating that oral or dermal exposure to cadmium causes cancer. However, cadmium exposure via inhalation has been linked to cancer. Some epidemiological studies of workers exposed to cadmium suggest a possible connection between cadmium inhalation and lung and prostate cancer (23). Evidence from animal studies show that chronic inhalation of cadmium chloride produces an increased frequency of lung tumors in animals. Based on animals studies, the EPA has classified cadmium as a probable human carcinogen when inhaled. However, inhalation exposure of cadmium at this site is expected to be negligible.
Several populations may be sensitive to cadmium exposure. Those with dietary deficiencies in
calcium and protein, renal disease, and those who smoke are at an increased risk to the adverse
effects of cadmium. Children and fetuses may also be at an increased risk due to a higher
cadmium absorption rate than adults.
HEALTH OUTCOME DATA EVALUATION
ATSDR uses health outcome data to help characterize the overall health of a potentially exposed community and to delineate possible relationships between environmental exposures and adverse health outcomes. Health outcome data include medical records and tests, health studies, cancer incidence and mortality data, and demographic data. Several sources of health outcome data were available for SMDA. Community specific health data that were evaluated by an ATSDR physician include one resident's physical examination report, an area "Death Survey" conducted by two area residents, and a consultant's statement regarding the autopsy report of an area resident. General data on a county, state, and national level that were reviewed include vital statistics information, Cancer Incidence and Mortality reports, the Riggins Tape, and 1990 Census data.
A report of one citizen's physical examination was also evaluated by an ATSDR physician. The information provided is limited and does not allow for a full evaluation. In addition, the patient's age and family medical history is not given. The patient had a minimally elevated lactic dehydrogenase (LDH) level and a persistent rash mainly to his arms, legs, and to other body parts. The physical examination report concluded that the patient had hepatitis and possibly chloracne. However, the physical examination report did not mention anything regarding liver size, tenderness, jaundice, or gastrointestinal complaints, which are all associated with hepatitis. Also, there is no mention of the two classic lesions of chloracne, the chloracne cyst and the comedo.
The "Death Survey" conducted by two area residents was reviewed by an ATSDR physician. Additional information is needed to sufficiently address the issue of whether the deaths are in excess of expected numbers. The information needed includes lifestyle and risk factors for cardiovascular disease and cancer, the types of cancer, and the geographic boundaries of the survey.
The autopsy findings of a resident who lived adjacent to the landfill were questioned by area residents. The autopsy report stated that the death was caused by alcoholic cirrhosis and massive bilateral pneumonia. Family members claim that the deceased never consumed alcohol and thus sought other opinions on the cause of death. The autopsy report and medical records of the deceased were not available to ATSDR, however, the statements made by a consultant to the concerned citizens were provided to and reviewed by an ATSDR physician.
The consultant states that the cirrhosis could not have resulted from alcohol because acute pancreatitis or inflammation of the pancreas was not observed. However, pancreatitis is not a common occurrence in alcoholic cirrhosis. Thus, pancreatitis is not a prerequisite for the diagnosis of alcoholic cirrhosis. Also, the consultant totally disregards the role of massive bilateral pneumonia in the death of the resident. Pneumonia is a common complication in alcoholics. The consultant also rules out alcohol as the primary cause of death because massive destruction of the convoluted tubules of the kidney was noted in the autopsy report. He states that alcohol is not known to be toxic to the kidney. This is true, however, it certainly does not rule out alcohol as a contributing factor to the death. Moreover, several drugs used to treat pneumonia are toxic to the kidney and could have caused the observed damage.
The consultant's statement notes that cadmium was found in the deceased's liver in the parts per million range. The average expected concentrations for cadmium in the liver are 1.0-1.3 ppm. The levels of cadmium found in the deceased are needed to determine if they actually exceed the normal concentrations. The target organ for cadmium is the kidney and cadmium accumulates in the liver and lungs as well as the kidney. Smokers are more sensitive to cadmium's effects, so their levels are higher than non-smokers in general. The deceased's smoking history is not noted. Cadmium levels were not mentioned for organs other than the liver.
All the factors that determined the autopsy results are not possible to discern without the medical report. In addition, the evidence provided by the consultant does not accurately dispute any of the autopsy findings. There is also not any known plausible evidence of exposure from the landfill.
Census data from 1980 and cancer incidence and mortality data for Macomb County were examined to try to determine the expected cancer rates for the population of concern. The census data was analyzed to obtain the population estimated for the area of concern. A one mile radius around the site encompasses approximately 20% of Census tract number 2053. The population was 1,855 for this tract in 1980 while the population was 694,600 for Macomb County. Since the area of concern is one-fifth of the tract and the cancer data is available only on a county level, the cancer information is for a population 1000 fold greater than the population of concern. Therefore, information regarding expected cancer rates in the population of concern cannot be determined.
The evaluation of health outcome data by an ATSDR physician did not provide any clear
connections between reported adverse health effects in the local community and possible
exposure to landfill contamination. However, the health outcome data sources available did not
provide enough specific and complete information to adequately assess health outcomes that
may be related to this site.
COMMUNITY HEALTH CONCERNS EVALUATION
ATSDR staff met with citizens during the August 1990 site visit and the May 1991 EPA public meeting and discussed their health concerns. Those concerns are summarized in the "Community Health Concerns" section and are addressed as follows:
Several area citizens have had their liver enzymes tested for possible enzyme elevation. The laboratory test results for three children were evaluated by an ATSDR physician. According to the children's test results, the specific enzymes that directly test liver function, Serum Glutamic Oxaloacetic Transaminase (SGOT) and Serum Glutamic Pyruvic Transaminase (SGPT), are not elevated above the ranges normally found in children. The children's LDH and alkaline phosphatase levels are in the high normal range. However, measurement of total LDH is not a good indicator of adverse liver effects because it is present in all organs and liver disease may not produce a marked increase in LDH levels. Alkaline phosphatase is produced by several tissues, especially bone, intestine, liver, and placenta. Also, alkaline phosphatase levels are elevated during periods of increased calcium deposition into the bone such as childhood, adolescence, and advanced pregnancy. The slightly elevated levels of alkaline phosphatase in the three children are likely due to bone growth.
The incidence of elevated liver enzymes among the general public is not that uncommon due primarily to a large number of causative agents. The most common causes of elevated liver enzymes tend to be alcohol, viral hepatitis, and certain therapeutic drugs. Smoking and exposure to solvents may also contribute to elevated liver enzyme levels. As mentioned above, periods of bone growth can produce elevated levels of some liver enzymes.
Information regarding expected cancer rates in the population of concern cannot be determined. Cancer information is discussed in the "Health Outcome Data Evaluation" section.
Area citizens have documented a variety of health concerns that they believe may be caused by exposure to the landfill. These include persistent colds, skin rashes, headaches, ear infections, and eye irritations. To adequately address these concerns, more complete and specific information is needed.
Trichloroethylene, methylene chloride, and arsenic have all been detected at SMDA and all may cause skin rashes. However, the concentrations of these chemicals associated with skin irritation are higher than those present at SMDA. Methylene chloride, benzene, and toluene have been known to produce headaches after extended periods of exposure to high or unknown concentrations. However, with the limited information available, ATSDR is unable to relate the health problems experienced by the community to the chemicals present at SMDA.
A survey of area veterinarians was conducted in 1987 by the MTSCC to try to determine if any animal problems could be linked to exposure to the SMDA landfill. Any relationship of animal illness or death to the landfill could not be established (24). Also, one resident had the liver and kidney tissues from a dead cow that had grazed near the landfill analyzed for various heavy metals. The examination of sections of liver and kidney tissue by the Krause Veterinary Clinic revealed no abnormal histopathology (25). With the limited information available, ATSDR is unable to establish any relationship between animal health problems and exposure to the SMDA site.
A resident who grew crops adjacent to the landfill had three green tomatoes and four green peppers tested for various pesticides and heavy metals in 1982. The analysis detected zinc at 2 ppm in both crops and cadmium at 0.03 ppm in the green peppers (26). The normal levels of zinc range from 10-100 ppm in most crops and pastures (27). Typical cadmium levels in vegetables and grains range from 0.005 to 0.450 ppm (28). The levels of zinc and cadmium detected are not above normal concentrations and do not appear to be high enough to be of public health concern.
This cannot be determined without full evaluation of the medical report. Also, there is not any known plausible evidence of exposure from the landfill. This is discussed in the "Health Outcome Data Evaluation" section. In addition, the contaminant concentrations detected are not as high as those associated with death.
ATSDR cannot evaluate the effects of psychological stress combined with exposure to environmental contamination, because little information is available. Municipal water is now available to those residences affected by the groundwater contamination related to the site.
Next Section Table of Contents
