ENVIRONMENTAL CONTAMINANTS AND OTHER HAZARDS
To identify other facilities that might contribute to the contamination at the Duell & Gardner Landfill site, the MDPH searched the Toxic Chemical Release Inventory (TRI) data base for 1987, 1988, 1989, and 1990. The U.S. EPA compiles the TRI from reports provided by industries. There were no entries for the Duell & Gardner Landfill in the TRI. Searching the TRI for facilities in the same zip code (49445) as the Duell & Gardner Landfill yielded one -- the Nor-Am Chemical Co., located approximately 3 miles southwest of the landfill. Over the four years, Nor-Am reported releases of sulfuric acid, sodium hydroxide solution, methanol, hydrochloric acid, chlorine, acetone, cumene, toluene, and 1,2,4-trimethylbenzene to the air, and releases of methanol, hydrochloric acid, chlorine, acetone, toluene, and 1,2,4-trimethylbenzene to the waters of Little Bear Creek, a tributary that enters Bear Creek approximately 3 miles downstream from the landfill's vicinity. The releases to Little Bear Creek cannot reach the Duell & Gardner Landfill site area. The air releases are not likely to contribute to the environmental contamination in the landfill vicinity, due to the distance involved and the dissimilarity between the contaminants found on the site and the chemicals released from the facility.
Contaminants of concern at this site 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 Exposure Guides (EMEGs)
ATSDR Cancer Risk Evaluation Guides (CREGs)
Concentrations computed from the U.S. EPA Reference Dose (RfD) for chronic exposure of a child, assuming pica behavior for soil ingestion1
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. In addition, if the community has expressed specific concerns about exposure to a chemical, that chemical will be retained as a contaminant of concern.
All data in this section, unless cited otherwise, is from the final RI report (1).
Groundwater
The two residential wells on the site (PW-19 and PW-20 in Figure 2) were sampled for chemical analysis for volatile organic chemicals (VOCs) and inorganic chemicals by the MDNR in July 1981. No VOCs were detected, and the inorganic chemicals found did not exceed available comparison values (Table 2 in Appendix B). Iron was found in one well at 1,900 parts per billion (ppb) which did exceed the U.S. EPA's Secondary Maximum Contaminant Level (SMCL) of 300 ppb, a water quality standard which is based on aesthetic considerations such as color, taste, and odor.
Information on the monitoring wells installed on the site is summarized in Table 3 in Appendix B, and the locations are shown in Figure 3. Four monitoring wells (MW-1 through MW-4) were installed on the site in 1982, and the MDNR sampled them for chemical analysis in 1983. No "significant" concentrations of organic or inorganic chemicals were detected, except for 750 parts per billion (ppb) of zinc in MW-1 (the upgradient well) and 75 ppb zinc in MW-4. The other wells did not contain zinc above the detection limit of 50 ppb (5). Two more shallow monitoring wells (MW-10 and MW-11) were installed by the MDNR in January 1986. The MDNR sampled MW-1, MW-2, MW-3, and the two new wells in January 1986. Methylene chloride was found in MW-1, along with several other unidentified or tentatively identified chemicals. No further data from these samplings were presented in Reference 1.
During Phase I of the RI field work in September and October 1987, the RI contractors installed 24 additional monitoring wells on or close to the site. All monitoring wells on the site except MW-10 were sampled in October 1987. All the monitoring wells including MW-10 were sampled again in February 1989. During July and August 1989, the contractors installed 9 more monitoring wells. In September and October 1989, they sampled 35 of the monitoring wells, omitting wells MW-10, MW-11, and MW-20, which were dry, and MW-12, which was bent and unusable. Concentrations of contaminants of concern in water samples from monitoring wells on the site collected during the RI are listed in Table 4 in Appendix B.
The groundwater contamination with organic chemicals is found in two plumes, as shown in Figure 3, one predominantly aniline and N,N-dimethylaniline, the other primarily chloroform and carbon tetrachloride. As of 1989, the plumes had apparently not migrated far off the site, though the exact extent has only been inferred due to lack of further downgradient sampling locations. Chloroform and carbon tetrachloride were found in two shallow wells, MW-13 and MW-25S, but not in the deeper wells of the MW-25 cluster, MW-25I and MW-25D. Aniline and N,N-dimethylaniline were found in deeper wells, MW-14I, MW-14D, MW-14E, MW-18I, and MW-23D, but not in nearby shallow wells, MW-14S, MW-18, and MW-23S. Low levels of aniline, N,N-dimethylaniline, and crystal violet were found in the shallow wells MW-11 and MW-11R, though not in MW-8, less than 100 feet upgradient of the MW-11 cluster. The data indicate that there is a source area for aniline and related chemicals between MW-8 and MW-11, from which a plume of contaminants enters the groundwater and the contaminants sink as they migrate to the southeast with the groundwater flow.
Other organic contaminants of concern were found sporadically, in a few wells and usually not repeated from sampling round to sampling round. Beta-BHC was only detected in one sample, that from MW-21S in Round 3, to cite one example.
Analysis for inorganic chemicals was only done on the first and third rounds of sampling. All samples were field-filtered (through a 0.45 µm filter), therefore, the analysis measured the concentrations of dissolved metals. Concentrations in individual wells often varied greatly over the interval between samplings of nearly two years. Arsenic, beryllium, cadmium, and thallium were only detected once. Chromium, lead, and vanadium were detected several times but the comparison levels were exceeded only once for each metal. Antimony was detected once in each of four wells (MW-3, MW-13, MW-14E, and MW-14I) during round 3, all at concentrations above the comparison value. Wells located between the four, including the other wells in the MW-14 cluster, did not contain detectable antimony. MW-14D is screened between MW-14E and MW-14I in depth, and contained no detectable antimony. All the reported antimony concentrations were footnoted in the data tables in Reference 1 as, "Value is greater than or equal to the instrument detection limit, but less than the contract required detection limit." Neither of these detection limits is specified in Reference 1. Since the values reported are all above 30 ppb, when the comparison value is 4 ppb (derived from the RfD), it is possible that some of the samples reported as containing no detectable antimony may contain a concentration of the metal above the comparison value.
The zinc concentration exceeded the comparison value in round 1 sampling from MW-6S, MW-8, MW-11, MW-11R, MW-13, MW-16, MW-17, MW-18, and MW-23S. The zinc concentration in MW-13 exceeded the comparison value in round 3. The round 1 sample from MW-6S, an upgradient well used to establish background levels, contained the highest zinc concentration of any sample, 8,270 ppb, cited in Table 4. The round 3 sample from the same well contained 1,710 ppb zinc. The second highest zinc concentration was in MW-8, 4,210 ppb in round 1, 910 ppb in round 3. The locations of these wells seem to indicate that the high zinc concentrations may not have a common environmental source. The wells are generally not directly up- or downgradient from one another, except for MW-8, MW-11, MW-11R, and MW-23S, and in these cases, wells between MW-11 and MW-23S did not contain high levels of zinc. All the wells that had high zinc concentrations were made of galvanized steel, and, except for MW-11, had been recently installed at the time of the first round of sampling in the RI. Except for MW-11, which had gone dry and could not be sampled, and MW-13, these wells contained lower zinc concentrations in the third round of sampling. It appears that the high zinc concentrations found in the first round of sampling may be largely due to zinc being leached out of the new galvanized pipe in the monitoring wells. The round 1 results from MW-11, 2,640 ppb, and MW-11R, 2,660-2,900 ppb in duplicate samples, were marked as estimates due to an interference. The MW-13 result from round 3, 2,550 ppb, was marked as an estimate due to "Spike sample recovery not within control limits."
The RI contractors also sampled the two residential wells on the site during sampling rounds 1 and 3. No contaminants of concern were found at concentrations above available comparison values (Table 2 in Appendix B). Iron was again detected at concentrations above the SMCL.
Soil
In June 1979, the MDNR collected one soil sample and two samples from on-site drums for analysis. The soil sample contained 7.7 parts per million (ppm) of polychlorinated biphenyls (PCBs). The drum samples did not contain detectable levels of PCBs or other chlorinated hydrocarbons. Maximum concentrations of other on-site soil contaminants detected during sampling before 1986 include arsenic, 96 ppm; cobalt, 301 ppm; chromium, 21 ppm; and cyanide, 30 ppm (6). The presence of soil colors may indicate high concentrations of organic chemicals with 4 on-site purple stained areas believed to be due to gentian (or crystal) violet contamination.
Soil sampling during the RI included samples from borings and from test pits in the former landfill. The samples from the soil borings were collected from the surface level to 10 feet below ground level, and were composites of 1.5 to 2 feet of soil. The shallowest of these do not correspond with the ATSDR preference for surface soil samples. ATSDR recommends that surface soil samples be taken no more than 3 inches deep, but are usable, for evaluation of health effects from contact with and incidental ingestion of soils, if they are as much as 6 inches deep.
Concentrations of contaminants of concern found in the shallow soil samples (no more than 2 feet deep) are listed in Table 5 in Appendix B. Concentrations of contaminants of concern found in deeper soil samples, including samples from borings and test pits, are listed in Table 6 in Appendix B. As seen in Table 5, the concentrations of crystal violet, 4,4'-DDD, 4,4'-DDT, PCBs, arsenic, and chromium in shallow soil samples exceeded available comparison values. 1,1-Dichloroethane, aluminum, calcium, copper, iron, lead, magnesium, mercury, potassium, tin, vanadium, and zinc were also detected in the shallow soil samples, but no comparison values for these substances are available.
Air
Air monitoring for total hydrocarbon concentrations did not detect airborne contaminants during drum removal in 1986. However, high levels of organic vapors, an Organic Vapor Analysis (OVA) meter reading over 1,000 ppm, were reportedly detected during a test pitting operation in September, 1987. The lowest reading reported was 0.2-0.5 ppm. The RI contractors monitored ambient air for worker health and safety purposes during the Phase II test pitting operation in December 1989. No results of this monitoring are presented in the RI report (1).
Soil Gas
There was no report of sampling of soil gas on the landfill. This is a significant data gap in the RI, since landfills often generate methane through anaerobic decomposition of organic matter. Methane could pose a fire or explosion hazard.
Groundwater
Figure 2 shows the locations of 24 private wells on and near the Duell & Gardner Landfill site that were sampled during the RI and in the February 1993 MDNR sampling, including the two that are on the site itself (PW-19 and PW-20).(2) The sampled off-site wells are located mainly to the south of the site, with a few to the east.
The MDNR sampled PW-9 in July 1981, along with the on-site wells. No contaminants of concern were found at levels above available comparison values.
The RI contractors collected water samples from private residential wells in the site vicinity in three rounds, in October 1987, February 1989, and September 1989. The specific wells sampled in each round are listed in Table 7 in Appendix B. Concentrations of contaminants of concern found in water from these private wells are listed in Table 8 in Appendix B. None of the organic contaminants of concern were detected in more than one sample from any single well, either from different rounds or duplicate samples in the same round. The only instance in which any organic chemical was detected in multiple samples from the same well was when one well contained 15 parts per billion (ppb) of acetone in Round 1, 6 ppb in one sample in Round 2 but none detected in a duplicate sample, and none detected in Round 3. Acetone is not a contaminant of concern for this assessment, because the comparison value for drinking water (1,000 ppb, based on the RfD) was never exceeded.
None of the inorganic contaminants of concern that have established comparison values were found in the private wells at concentrations that exceeded the comparison values (Table 8). Only copper and potassium were found in the private wells at concentrations above those found in upgradient monitoring wells (MW-5S, MW-6S, and MW-7 in Figure 3).
The MDNR collected water samples from 10 residential wells south of the site in February 1993. The wells sampled were PW-5, -6, -7, -8, -10, -11, -12, -16, -17, and -24. PW-24, located a short distance outside the southwest corner of the site, had not been sampled before. No site-related contaminants were detected. Samples from five of the wells did contain carbon disulfide (maximum concentration 19 ppb) at levels well below the appropriate comparison value (1,000 ppb, based on the RfD) (7).
Surface Water and Sediments
The RI contractors collected samples of surface water and sediments from the tributary to Bear Creek and from the drainage ditch east of the site. Concentrations of contaminants of concern found in the surface water samples are listed in Table 9 in Appendix B, and the concentrations found in sediment samples are listed in Table 10.
An agricultural drainage ditch located south of the site was not investigated during the RI. At the MDNR public meeting mentioned above under "Community Health Concerns," area residents asked why it had not been investigated. The MDNR and U.S. EPA representatives present suggested that the ditch might be sampled during further remedial design investigation at the site. The MDNR collected 5 sediment samples from 4 locations along the ditch in February 1993. Concentrations of contaminants of concern found in these samples are listed in Table 11 in Appendix B. Neither crystal violet, aniline, or N,N-dimethylaniline were found in the samples. None of the contaminants of concern were detected at concentrations above comparison values. There is no indication of site-related contamination in the ditch (7). Only one of the five samples collected contained any detectable beta-BHC. That sample was a duplicate of one that contained no detectable beta-BHC.
C. Quality Assurance and Quality Control
In preparing this Health Assessment, the MDPH relied on the information provided in the referenced documents and assumed that adequate quality assurance and quality control measures were followed with regards to chain-of-custody, laboratory procedures, and data reporting. The validity of the analysis and conclusions drawn for this Health Assessment is determined by the reliability of the referenced information.
All the positive detections for antimony in groundwater from the RI were flagged in Reference 1 as being above the instrument detection limit but below the contract required detection limit. Several of the concentrations of zinc in the groundwater from the RI were reported in Reference 1 as estimates due to interferences or to spike sample recovery being outside control limits. Any qualifications on the data cited in the above sections of this assessment are discussed with the data.
The presence of 4,4'-DDT and 4,4'-DDD in the surface soils on the site but not 4,4'-DDE seems puzzling, since 4,4'-DDT degrades aerobically to 4,4'-DDE and anaerobically to 4,4'-DDD. It seems unlikely that anaerobic conditions would persist in the surface soil. The presence of heptachlor and aldrin in the environment usually represent a recent spill or application, since they are readily converted in the environment to their epoxides (heptachlor epoxide and dieldrin). It also seems unusual to find chlorinated pesticides in the groundwater and not at high levels in the soil.
Anaerobic degradation of organic materials such as household wastes can generate methane gas. Methane and other organic vapors can collect in confined areas to concentrations that exceed the limits of flammability, at which point a spark could cause fire or explosion. There is no record of analysis of soil gas from the landfill, so the danger from this source is not known. The landfill is covered with native, sandy soil, so anaerobic generation of methane is not likely under such a porous cover. Any vapors that might migrate elsewhere are more likely to migrate upwards through the surface sand and diffuse into the ambient air. The cap that is being considered for the landfill will include vents for any gas that might be generated under it.
To determine whether nearby residents are exposed to contaminants associated with a contamination 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 are or have in the past been present at the same time. 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 present. 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.
A. Completed Exposure Pathways
Surface Soil
There are elevated concentrations of various chemicals in the surface soil at various on-site locations. A worker or trespasser on the site could come into skin contact with the contaminated soil. The chemicals could then enter the body by absorption through the skin or by incidental ingestion. Exposures to contaminated soil have been learned of by MDPH through conversations with a resident who operated earth moving equipment on the site many years ago and came into direct contact with discolored soil. Additionally, signs of occasional trespass on the site have been noted by MDPH, MDNR, and U.S. EPA personnel. Remediation of the site that disturbs the waste may liberate volatile contaminants and contaminated dust. Transport of particulates and volatilization of VOCs should be carefully monitored during any remediation process. Of particular concern are the presence of aniline-based dyes (i.e. gentian violet) that could result in adverse human health effects if inhaled in large quantities.
Air
Volatile chemicals could evaporate from contaminated surface soil and be inhaled by anyone on or downwind of the site. Air monitoring on the site reported high concentrations of organic chemicals during one test-pitting operation. Dust from the contaminated areas could be inhaled, or be transported by the wind to spread the contamination off the site.
B. Potential Exposure Pathways
Groundwater
The wastes deposited on the site contain various organic chemicals. Rainwater percolating through the waste areas has washed the contaminants into the groundwater beneath the site, as indicated by analysis of groundwater samples collected during the RI. Private wells in the affected aquifer are used by residents in the vicinity of the site. Persons using water from contaminated wells would be exposed to contaminants by ingestion, by dermal exposure, or by inhalation of volatile chemicals secondary to household use. There is no indication to date that any of the nearby private wells contain site-related contaminants. The areal extent of the contamination plumes in the groundwater has not yet been completely determined by monitoring well sampling, though the available data indicate the plumes probably do not extend far beyond the southern site boundary. This groundwater exposure pathway is not completed. The pathway could become completed in the future, absent any remediation of the site, should the plumes extend to reach private wells or a new well for potable use be drilled into one of the plumes.
The only completed exposure pathways that have been documented at the site are for a worker or trespasser coming into contact with contaminated surface soil or breathing air containing chemicals. As mentioned above, there is only partial restriction of access to the site and all-terrain vehicle tracks have been seen on the site. Some area residents have worked and played on the site in the past and come in contact with discolored contaminated soil. Trespass has occurred in the past and is likely to occur in the future. Such trespass would probably be occasional, and only for short times. Nothing on the site would be especially attractive to trespassers. The contaminated areas are also secluded from public roadways by distance, wooded terrain, and fenced-off private property. For this evaluation, a trespasser will be assumed to be an adult, weighing 70 kilograms (154 pounds) and incidentally ingesting 100 mg of soil per day, spending an average of 2 hours per week in the contaminated areas of the site.
Exposures through the air will not be calculated because the available data does not identify the chemicals detected. In addition, air contamination has only been documented during excavation of the waste, which is not likely to occur except under the most strictly controlled circumstances. Only remedial workers on the site, who would be expected to take appropriate precautions against exposure, are likely to be exposed to highly contaminated air from the site.
Based on the shallow subsurface soil concentrations listed in Table 5 in Appendix B, and under the above assumptions, a trespasser's exposure to contaminants of concern in the soil at the site would probably not exceed Minimal Risk Levels (MRLs) or Reference Doses (RfDs) or incur a significantly increased cancer risk, for those chemicals for which MRLs, RfDs, or cancer potency factors are available. MRLs, developed by the ATSDR, and RfDs, developed by the U.S. EPA, are exposure levels below which it is commonly considered that non-cancer adverse health effects are not likely to occur. Extremely sensitive populations, such as the very young, the very old, those people whose immune systems have been impaired by other circumstances, and those with a special sensitivity to a specific chemical, may not be protected by the MRLs or RfDs. Cancer risks, as computed from exposure doses and potency factors, are considered significant if 1 additional case, above the number normally expected to occur, would occur in a population of 1,000,000 experiencing the exposure over their lifetimes.
Carbon tetrachloride, chloroform, 1,2-dichloroethane, methylene chloride, and tetrachloroethylene have all been classified as probable human carcinogens (U.S. EPA Class B2) by the U.S. EPA, though the classification for tetrachloroethylene is currently under review. A person consuming water containing the maximum concentration of any of these chemicals found in the groundwater at the site for a lifetime might incur a significantly increased cancer risk. These chemicals could result in other adverse health effects at high exposure levels, though it is very unlikely that exposure to the soil or water at this site would result in sufficient exposure to the chemicals to produce such non-cancer adverse health effects (8-12).
There is no MRL, RfD, or cancer slope factor available for 1,1-dichloroethane. A trespasser on the site is not likely to incidentally ingest sufficient soil to obtain the dose of 1,1-dichloroethane at which adverse health effects have been observed in laboratory animals. Health effects observed in laboratory animals who ingested 1,1-dichloroethane over long periods of time include decreased survival, decreased weight, and breast and uterine cancer (13). The U.S. EPA has classified 1,1-dichloroethane as a possible human carcinogen (U.S. EPA Class C). The available data does not permit evaluation of a potency factor for the chemical, and hence of the risk from exposure at the site.
Crystal violet (an aniline-based dye) and the related chemicals aniline and N,N-dimethylaniline can produce methemoglobinemia, cardiovascular collapse and respiratory failure (anoxia) when inhaled or ingested in large amounts. The U.S. EPA has classified aniline as a probable human carcinogen (U.S. EPA Class B2). Long-term exposure to soil or water containing the maximum levels of aniline found on the site could result in an increased cancer risk.
Polynuclear aromatic hydrocarbons, such as benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene, 2-methylnaphthalene, naphthalene, and phenanthrene, were found in the subsurface soil at the site and sediments from the agricultural ditch near the site in concentrations generally comparable to those found in background soils (see Table 5-5 in Reference 14). Only the benzo(a)pyrene concentration in one sediment sample exceeded a comparison value, and occasional exposure for short periods of time to the sediments in the ditch near the site is not likely to pose a significant increased cancer risk.
Trace levels of several persistent chlorinated hydrocarbon pesticides (beta- and gamma-BHC, chlordane, aldrin, and heptachlor) were detected in the groundwater at and near the site. DDT, DDE, and PCBs were found in soil on the site. These compounds are all considered probable (U.S. EPA Class B2) or possible (U.S. EPA Class C) human carcinogens by the U.S. EPA. They are also resistant to environmental degradation (15-20). Long-term exposure to the chemicals at the maximum concentrations found poses some increased cancer risk. As mentioned above in the Quality Assurance and Quality Control section, the detection of some of these chemicals in the groundwater but not in the soil casts some doubt on the accuracy of the groundwater findings.
Several inorganic chemicals were found on the site at concentrations above background levels, but only arsenic and chromium exceeded comparison values. The comparison value for chromium that was exceeded was for the metal in the hexavalent oxidation state, or chromium(VI), and chromium(VI) tends to be converted in the environment to the trivalent oxidation state, or chromium(III), which is much less toxic. Chromium(VI) compounds can be irritants to the skin and digestive system, can cause liver and kidney damage, and have been linked to cancer of the lung, particularly when inhaled. The U.S. EPA has classified chromium(VI), when inhaled, as a human carcinogen (U.S. EPA Class A) (21). Long-term exposure to arsenic may result in dermatitis, weight loss, peripheral neuritis, and upsets to the gastrointestinal system. Ingestion of arsenic is linked to cancer of the skin, liver, bladder, kidney, and lung. The U.S. EPA has classified arsenic as a human carcinogen (U.S. EPA Class A) (22). At the concentrations found on the site, the most likely adverse health effect from exposure to arsenic, chromium(VI), and other metals, is a low increased risk of contracting cancer on life-long exposure.
B. Health Outcome Data Evaluation
Based on the evaluations performed as part of this public health assessment, there are indications that humans that have worked and played on this site have been exposed to site-related contaminants. Based on the concentrations identified at the site, the exposures are not expected to be sufficient to cause long term adverse health effects. However, if higher concentrations of contaminants were present in the past, and if people were exposed for a long time, they may have incurred a low increased risk of contracting cancer.
The MDPH reviewed age-adjusted cancer mortality rates available from the Michigan Death Registry for Dalton, Muskegon, and Fruitland Townships, Muskegon County for the period of 1983-1987. The Duell & Gardner site is located in the south central part of Dalton Township. Fruitland Township is immediately west of Dalton Township. Muskegon Township is immediately south of Dalton Township. The number of deaths observed for each of the townships during this time period were compared to the number of deaths that would be expected based on the 1985 statewide age-specific mortality rates and the 1983-1987 estimated populations by age in the two townships. Population estimates could not be calculated by sex due to the unavailability of census data by sex for this area. A standard mortality ratio (SMR) was calculated by dividing the number of observed deaths by the number of expected deaths. An SMR of 1 would mean that the number of observed cancer deaths during the time interval was exactly equal to the number expected based upon the statewide rate; an SMR significantly lower than 1 would mean that the number of cases observed in the townships was less than expected, and; an SMR significantly greater than 1 would mean than the number of deaths were more than would be expected based upon the statewide rate. The number of deaths observed and expected, and the corresponding SMRs are presented in Table 12 for Dalton, Fruitland, and Muskegon Townships.
Although the actual numbers of deaths observed were fewer than expected based upon a statewide cancer death rate, the differences were not statistically significant (p = 0.05). Since the SMRs did not differ significantly from 1, there is no evidence in this statistical analysis that any of these townships had a higher or lower than expected number of deaths. In considering these calculations, one must keep in mind that they are based upon records for the entire townships involved. A more localized impact could be present but not be obvious when averaged within the larger population of the full township.
C. Community Health Concerns Evaluation
Concerns regarding this site, as expressed by area residents at and outside of public meetings, are addressed in this section of the Public Health Assessment. The following are responses addressed to the specific health concern topics listed earlier:
1. Whether the residential wells near the site are endangered by site-related contamination.
The private wells in the site area that are potentially endangered by contaminants migrating off the site through contaminated groundwater have been sampled on several occasions starting in 1981. The most recent sampling round prior to this availability session, in October 1989, was conducted as part of the Remedial Investigation. None of the sampling performed to date has detected contamination from the site in any of the private wells downgradient (in the direction of groundwater flow) from the site. The MDNR sampled residential wells downgradient of the site in February 1993. No contamination was found (7).
2. The need exists for better site restriction and more posting of warning signs along routes used by trespassers entering the site area.
A representative of the MDNR present at the December 10, 1992, meeting, on hearing of the need for better posting of warning signs, agreed to pursue installing additional signs at several locations where people are said to be entering the site. Additional signs were posted on December 30, 1992 (23). MDPH does not believe that those who occasionally trespass on the site would receive significant exposure by walking on contaminated soil, but recommends against any unnecessary exposure to contamination.
3. The possibility that people who played or worked on the site years ago might have health effects from this exposure occurring now or which may develop later.
There are latency periods (or time delays) between exposure to toxic substances and the onset of the illnesses they can cause. For some health effects such as cancer, these latency periods can be very long, sometimes decades. It is very difficult to assess the possibility of health effects related to this type of on-site exposure since we do not have good information about the actual level of exposure and the frequency with which people on the site may have been exposed. Breathing air contaminated with high levels of solvents such as those that were detected in some of the "hot spot" surface and subsurface soil can cause acute symptoms like headaches. These symptoms typically will diminish when the exposure stops. Exposure to carcinogenic contaminants will increase a person's overall lifetime risk of developing cancer.
4. The relationship of the drainage ditch south of the site boundary and the plume of contaminated water from sources on the site.
The drainage ditch in question runs east, south of the site, and joins another drain that empties into a tributary of Bear Creek. It is an intermittent drain, one that is dry for most of the year. When the ditches are draining the land adjacent to them, the water is most likely from surface runoff and rain infiltrating the surface soil and not likely to be from the aquifer that contains contaminants from the site. The MDNR collected sediment samples from the ditch in February 1993. There was no indication from the samples collected and analyzed that there had been any effect on the ditch attributable to the site (7).
5. Whether deer and other game hunted on site are contaminated and unsafe to eat.
MDPH does not consider the game that is present on site a health hazard for those who hunt and consume the meat. The contaminants that are present on site do not readily get taken up into (or bio-accumulate in) the plants on which deer and other game animals feed. Tests conducted on animal tissue by the MDNR at other hazardous waste sites have not shown this to be a significant exposure pathway.
6. One person mentioned that relatives of his who lived near the site had had health problems.
The attendee said he did not know whether the relatives considered the illnesses to be associated with the site, but he would check with them and contact the MDPH afterward. The relatives, the current site owners who live on the northern portion of the site, later contacted MDPH to describe the headaches they'd developed while working on the site. MDPH representatives answered their health questions and gave them information regarding site contamination.
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