PUBLIC HEALTH ASSESSMENT
WILLOW RUN SLUDGE LAGOON
YPSILANTI, WASHTENAW COUNTY, MICHIGAN
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 is not expected to result in more than 1 case of cancer in 1 million people exposed or any non-cancer health effects. Comparison values used in this assessment include:
ATSDR Environmental Media Exposure Guides (EMEGs)
ATSDR Cancer Risk Evaluation Guides (CREGs)
ATSDR Reference Dose Evaluation Guides (RMEGS): Concentrations computed from the U.S. EPA Reference Dose (RfD) for chronic exposure of a child, assuming pica behavior for soil ingestion(6)
U.S. EPA Drinking Water Health Advisories, Lifetime (LTHA)
U.S. EPA Safe Drinking Water Act Maximum Contaminant Levels (MCLs)
U.S. EPA Safe Drinking Water Act Maximum Contaminant Level Goals (MCLGs)
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. Contaminants of concern for this assessment are listed in Table 1.
Unless specifically cited otherwise, all environmental data in this section was obtained from the RI report (2).
To identify chemicals which might contribute to the environmental contamination at the Willow Run Sludge Lagoon site due to recent activities at nearby industrial facilities, the MDCH searched the Toxic Chemical Release Inventory (TRI) data base for 1987 through 1991. The U.S. EPA compiles the TRI from information provided by industries. The TRI contained entries for four facilities with the same postal ZIP code (48198) as the Willow Run Sludge Lagoon site: two General Motors (GM) plants located approximately 1 mile northwest of the site and two other facilities located near the center of the City of Ypsilanti, approximately 4 miles northwest of the site. The TRI also listed two facilities with ZIP code 48111, for Belleville, covering the area east of the site, both of which were approximately 6 miles northeast of the WRSL site. A search of the other Ypsilanti ZIP code, 48197, covering the area south and west of the Huron River, found two facilities that apparently had the wrong ZIP code listed, since their addresses indicated they are in the vicinity of Willow Run Airport, in ZIP 48198. One, Peerless Industries, is located east of the General Motors plants on Tyler Road, 0.5 mile north of the WRSL site, the other is approximately 2 miles north of the WRSL. The TRI listed five other facilities in ZIP code 48197, including a Ford Motor Company plant 2 miles south-southwest of the WRSL site and four in central Ypsilanti, 4 to 6 miles west to northwest of the WRSL. Because of their proximity to the site, the releases from the two GM plants and Peerless Industries are most likely to contribute to the environmental contamination at the site. The facility 2 miles north of the WRSL may be in the watershed of Willow Run Creek, however, they reported no releases to any surface water, only releases of acetone and glycol ethers to air in 1988. The releases from this and the other 9 facilities found in MDCH's search of the TRI are not likely to contribute to the contamination at the site because of the distance between the facilities and the site.
The two GM plants reported to the TRI that they had released acetone, ammonia, benzene, n-butyl alcohol, dichlorodifluoromethane (CFC-12), dichloromethane (methylene chloride), ethylbenzene, ethylene glycol, freon 113, glycol ethers, manganese, methanol, methyl ethyl ketone (MEK or 2-butanone), methyl isobutyl ketone (MIBK or 4-methyl-2-pentanone), propylene, sulfuric acid, toluene, and xylenes to the air; barium compounds, ethylene glycol, sodium hydroxide solution, and zinc compounds to the water of Tyler Pond on Willow Run Creek (upstream of the WRSL); and transferred chlorine, cyclohexane, diethanolamine, hydrochloric acid, methyl tert-butyl ether, nickel and nickel compounds, nitric acid, phosphoric acid, and 1,2,4-trimethylbenzene to other disposal facilities with no reported environmental releases. Peerless Industries reported air releases of 1,1,1-trichloroethane between 1987 and 1989, with no reports for later years.
The air releases of volatile chemicals from the two GM plants and Peerless Industries are not likely to have any discernible effect on the contamination at the WRSL site, considering the distance and that the sources are not upwind of the WRSL site by the local prevailing winds. The ethylene glycol released to Tyler Pond would be rapidly metabolized by naturally-occurring microorganisms, and any effects on water quality in the pond and Willow Run Creek would be transient (17). The releases of barium and zinc compounds to the water of Tyler Pond may have affected the water quality in Willow Run Creek. These releases were only reported in 1988 and 1989. Barium and zinc were included as contaminants of concern for this assessment based on the concentrations in environmental media and the criteria listed above.
For the purposes of this assessment, the site will be defined as the lagoon including all area within the fence, the outlet, and Ypsilanti Drain No. 8 between the outlet and Willow Run Creek.
In 1979, the MDNR collected sediment samples (grab samples, depth not further specified) from four locations in the lagoon and one in the outlet (18). Concentrations of contaminants of concern (taken from the RI report ) are summarized in Table 2. During the RI in 1989 and 1990, the contractors collected sediment samples (depth not specified) from the lagoon, the outlet, Ypsilanti Drain No. 8, one of the leachate seeps northwest of the lagoon, and Willow Run Creek. The concentrations of contaminants of concern in RI samples from the lagoon, the outlet, and the seep are also summarized in Table 2. The results of analyses of the samples from the Drain are summarized in Table 3. The upstream samples from the drain were collected just above the outlet from the lagoon.
Table 2 shows that the concentrations of metals and inorganic chemicals in sediment were generally highest in samples from the lagoon, with samples from the outlet next and from the seep lowest. Significant exceptions to this trend were arsenic (highest in the seep), barium (the seep was higher than the outlet, but lower than the lagoon), manganese (highest in the outlet), and vanadium (no significant trend). The laboratory reported that the concentrations of PAHs were considered estimates, generally below the reliable detection limit for the method though above the detection limit of the instrument used. No reliable trends can be identified in this data.
In sediment samples from Ypsilanti Drain No. 8 (Table 3), the concentrations of contaminants of concern were generally higher in samples collected downstream of the lagoon outlet than upstream. Concentrations of cadmium, chromium, lead, and PCBs were significantly higher in the downstream samples than in upstream ones. Concentrations of PAHs were considered estimates, and were as often higher in the upstream samples as in the downstream ones.
In 1979, the MDNR collected a sample of water from the outflow of the lagoon, and found that it contained 37.6 parts per billion (ppb) of polychlorinated biphenyls (PCBs). In 1981, the MDNR collected surface water samples from the outlet of the lagoon and Ypsilanti Drain No. 8 upstream of the site outlet. They collected samples from the outlet of the lagoon in July and October, and found substantial change from one date to the other, from 0.33 ppb total PCBs in July to no detectable (limit 0.1 ppb) in October. The U.S. EPA FIT collected a sample from the drain approximately halfway between the WRSL outlet and Willow Run Creek in October 1982. Concentrations of contaminants of concern found in the samples from the outlet are summarized in Table 4, and those from Ypsilanti Drain No. 8 are in Table 5 (1).
During the RI in 1989 and 1990, the contractors collected surface water samples from the lagoon, the outlet, Ypsilanti Drain No. 8, one of the leachate seeps northwest of the lagoon, and Willow Run Creek. Concentrations of contaminants of concern in water from the lagoon, the outlet, and the seep are summarized in Table 4, while those in water from the drain are included in Table 5. The upstream samples from the drain were collected just above the outlet from the lagoon. The samples were not field filtered. Some of the results may reflect sediments suspended in the water, since the reported PCBs concentrations substantially exceed the solubilities of the chemicals in water (19). As with the sediment samples, the concentrations of contaminants of concern are generally highest in water from the lagoon, then water from the outlet, then the seep. Again, arsenic goes against the general trend, with the seep having the highest concentration, as does manganese, with the highest concentration in the outlet in 1989 and in the seep in 1990. The concentrations in water from the ditch are generally higher in the downstream samples than in the upstream samples, especially arsenic and manganese.
During the ESI in 1991, the MDNR collected a water sample from a Fons Landfill leachate seep. The ESI report (Reference 4) does not indicate where this sample was collected. The concentrations of contaminants of concern in this sample are also listed in Table 4. The sample also contained chlorobenzene, ethylbenzene, toluene, and xylenes at concentrations below the corresponding comparison values.
In 1990, the RI contractors collected two soil samples that included surface materials, one that was a composite of the top 5.5 feet of soil from near the northwest end of the sludge disposal area, and a composite of the top 2 feet of soil from a borehole southwest of the outlet. ATSDR prefers that surface soil samples consist of samples of the top 3 inches of soil. Neither of these qualifies as a surface soil sample by the ATSDR criterion. In addition, two samples, neither within the lagoon, are not adequate to characterize the surface material at the site. Concentrations of contaminants of concern from these samples are listed in Table 6. The lagoon sediment sample from the RI in Table 2 might be a surface sample, but there is not enough description of the sample in the RI Report to identify it as one. Table 6 shows that the concentrations found in the sample from the northwest side of the lagoon were generally higher than those found in the southwest. The contaminants in the soil on the northwest side of the lagoon most probably come from the leachate seeps from the Fons Landfill.
The RI contractors collected samples of the sludge from the lagoon during 1989. These were sub-surface samples, at least 2 feet below the ground surface, and composited from material as deep as 13.5 feet. Very high concentrations of PCBs, chromium, cadmium, barium, manganese, and zinc were found in these samples (Table 7).
The RI contractors collected samples of soil from 5 feet below the bottom of the sludge in the lagoon, and from soil borings including those used for monitoring wells. Concentrations found of contaminants of concern are summarized in Table 8. The concentrations of inorganic chemicals found in the samples do not substantially change between the lagoon proper and surrounding locations, though organic chemicals, including polycyclic aromatic hydrocarbons (PAHs) and PCBs, were found under the lagoon but not in surrounding sub-surface soil.
Groundwater Monitoring Wells
In 1982, a Field Investigation Team (FIT) investigating contamination in Willow Run Creek drilled eleven monitoring wells in the vicinity of the Creek. One of these wells (W-4, see Figure 2) was located on the west side of the WRSL, and is within the lagoon fence. They sampled this well in June and October 1982, and found no organic chemicals above their detection limits, but several inorganic contaminants of concern were found (Table 9).
Surface Water and Sediments
The FIT report (1) summarizes data from earlier studies (1977 through 1981) of Willow Run Creek. These studies collected surface water and sediment samples from the creek, the G.M. Ponds and Tyler Pond upstream of the WRSL site, Edison Pond downstream of the site near Belleville Lake, Belleville Lake, and Ford Lake (west and upstream of Belleville Lake along the Huron River) (see (4)). The FIT investigators collected surface water samples from the G.M. Ponds, Tyler Pond, Willow Run Creek, and Edison Pond. The results from the Willow Run Creek samples are summarized in Table 10 (surface water) and Table 11 (sediment). The downstream creek samples from the FIT study (1982) were collected from Edison Pond. The concentrations of contaminants of concern in samples from the G.M. and Tyler Ponds upstream of the site, Edison Pond at the mouth of the creek, and Lake Belleville are summarized in Table 12 (surface water) and Table 13 (sediment) (1). The 1978 and 1979 sediment samples were collected using a coring technique, 9 inches deep or less for samples from Willow Run Creek, Tyler Pond, and Lake Belleville, 2 to 6 feet deep, divided into top, middle, and bottom samples, for samples from Edison Pond (20, 21). The top, middle, and bottom samples were not distinguished in the compilation of Table 13.
During the RI in 1990, the contractors collected surface water and sediment samples from Willow Run Creek near the confluence of Ypsilanti Drain No. 8. They collected two water samples, one each upstream and downstream of the confluence, and four sediment samples, two each upstream and downstream. Concentrations of contaminants of concern are also summarized in Table 10 for surface water and Table 11 for the sediment. The depth of the sediment samples are not described in the RI Report.
In 1990, the RI contractors collected sediment samples, depth not specified, from Ypsilanti Drain No. 8 above the outlet of the underground drain and from the underground drain outlet, approximately 600 feet west of the site. The contaminants of concern found in these samples are summarized in Table 14. The sediments from the outlet contained higher concentrations of PAHs and metals than the sediments from the drain above the outlet.
In 1991, the MDNR conducted an Expanded Site Investigation (ESI) of the Willow Run Creek Area. This investigation included collection of surface water and sediment samples from all along the creek, from above the G.M. Ponds to Belleville Lake. They also collected water and sediment samples from the Willow Run Separator Drain, which drains Willow Run Airport property including the closed Airport Landfill and enters the creek from the east a few hundred feet downstream of the confluence of Ypsilanti Drain No. 8 with the creek. Concentrations of contaminants of concern found in these samples are summarized in Table 10 (Willow Run Creek, surface water), Table 11 (Willow Run Creek, sediment), Table 12 (ponds, surface water), Table 13 (ponds, sediment), Table 15 (Willow Run Separator Drain, surface water), and Table 16 (Willow Run Separator Drain, sediment). They collected sediment samples using a coring technique, with samples ranging from 2 to 18 inches deep. At their sampling locations in Tyler Pond and Edison Pond, they took cores ranging from 2 to 6 feet long, and extracted three samples from each core, a top, middle, and bottom. The length of each sample is not stated. In most cases, the top sample was probably from the surface of the sediments, but two cores start a foot below the sediment surface. The length of the sample is not specified in Reference 4. Table 13 does not differentiate between the top, middle, and bottom samples.
As seen in Table 10, several metals, including arsenic, boron, cadmium, chromium, lead, manganese, nickel, thallium, and vanadium, have been found at concentrations above the comparison values in water samples collected from Willow Run Creek. The concentrations of these metals were generally higher upstream of Ypsilanti Drain No. 8 than downstream, due to other sources of contamination in the creek watershed. On the other hand, as seen in Table 11, concentrations of these metals in sediment samples from Willow Run Creek are generally higher downstream of Ypsilanti Drain No. 8 than upstream, though some increase further below the Willow Run Separator Drain. The sediments also contain PCBs and PAHs at concentrations above comparison values. Table 12 and Table 13 show that Tyler Pond contained generally higher concentrations of contaminants, including metals, PAHs, and PCBs, than other ponds along the creek, only slightly higher in water samples from the pond, more pronounced in the sediment samples. The PAH concentrations in the sediments are generally within the ranges of background values for urban soils (Reference 22, Table 5-3).
During the EE/CA of the Willow Run Creek site from January through March 1994, the contractors collected samples of sediment from Willow Run Creek, the North and South G.M. Ponds, Tyler Pond, Lake Belleville, and the Willow Run Separator Drain. Analytical results from these samples are included in Table 11 (Willow Run Creek), Table 13 (ponds), and Table 16 (Separator Drain) (6).
Groundwater Monitoring Wells
In 1982, the FIT contractors drilled eleven monitoring wells in the vicinity of the Creek. Two of these were located near the WRSL, W-3 near the lagoon fence at the southeast corner of the lagoon and W-5 approximately 800 feet northeast of the lagoon (Figure 2). The FIT collected samples of water from these wells in June and October 1982. The June sample from W-5 contained 10.5 ppb toluene, marked as possible laboratory or sample contamination, and none of the samples contained any other organic chemical at concentrations above the detection limit. Concentrations found of inorganic chemicals of concern are summarized in Table 17. Arsenic and manganese were found in higher concentrations in W-3 than in W-5, though barium, lead, and zinc concentrations were higher in the upgradient well (1).
A water sample collected during the FIT from a monitoring well located east of Willow Run Creek, northeast of the lagoon, contained traces of various volatile organic chemicals, probably due to inadvertent contamination from activities at Willow Run Airport. A sample collected in November 1982 from a monitoring well east of Willow Run Creek near the outlet from Tyler Pond contained low concentrations of several PAHs. A sample collected from the same well in October 1982 contained no organic chemicals. Those were the only samples from the other monitoring wells that contained any organic chemicals. The November sample from the well near the Tyler Pond outlet contained a high concentration of zinc (the October sample was not analyzed for inorganic chemicals). Water from a monitoring well south of Interstate 94 contained high concentrations of arsenic and manganese (Table 18) (1).
In 1989, the RI contractors drilled nine monitoring wells located outside the perimeter of the site fence. Six of these wells were shallow, screened at approximately 10 feet below grade, and three were deep, screened at 80 feet or more below grade. The contractors collected water samples from these wells in November 1989 and January 1990. Water from well MW-2-89, a shallow well located north (upgradient) of the lagoon (Figure 2), contained several organic chemicals that were not found in other wells and higher concentrations of inorganic chemicals than the other wells (Table 19). MW-2-89 also contained chlorobenzene, xylenes, 2,4-dimethylphenol, and phenol at concentrations below the appropriate comparison values. None of these chemicals were present in the other wells. The RI contractors attributed the presence of the organic chemicals and elevated levels of inorganic chemicals in this well to leachate from the Fons Landfill, located north of the site. Two wells in a cluster at the southeast corner of the lagoon (MW-4U-89 and MW-4D-89 in Figure 2) contained elevated concentrations of arsenic (both wells) and manganese (MW-4U-89). These wells are located less than 50 feet southwest of well W-3 from the FIT.
During the MDNR ESI of the Willow Run Creek area in 1991, the MDNR collected groundwater samples from 5 monitoring wells near the WRSL site, including MW-2-89 and one of the cluster of wells near the southeast corner of the lagoon. The analytical results for the two wells closest to the lagoon show a similar pattern of elevated concentrations to that found in the RI investigation (Table 19) (4). The sample from MW-2-89 also contained chlorobenzene and xylenes at concentrations below the corresponding comparison values. The concentrations of organic chemicals found in well MW-2-89 were similar to those found in water collected from a leachate seep at the Fons Landfill during the ESI. The sample collected from a monitoring well located east of the landfill, between the landfill and Willow Run Creek, contained a trace of benzene and elevated concentrations of arsenic, barium, cobalt, lead, manganese, and zinc (Table 18) (4).
In 1993, a contractor for the U.S. EPA collected samples of water from several monitoring wells around the Fons and Old Wayne Disposal Landfills, north and south of the WRSL respectively. The wells sampled included MW-2-89, a new well (MW-8-93) northeast of MW-2-89, and three new wells between the Old Wayne Disposal Landfill and Ypsilanti Drain No. 8. The analytical results indicate continuing contamination in the groundwater apparently coming from the landfills (Table 20) (6).
During the EE/CA for the site in 1994, the contractor collected samples of groundwater from monitoring wells located throughout the area of Willow Run Creek, including the areas around the G.M. Ponds, Tyler Pond, the industrial area north of Tyler Road, and the east bank of Willow Run Creek. Water from one of the wells near the South G.M. Pond contained traces of PCBs, benzo(a)pyrene, 1,1-dichloroethylene, and 1,1,1-trichloroethane. Comparatively high concentrations of metals were found in water from a monitoring well near a small closed landfill near the South G.M. Pond (Table 18) (6).
Groundwater Domestic, Industrial, and Municipal Wells
In 1978, water from three domestic or industrial wells in the vicinity of Willow Run Creek, one 0.5 mile north of the WRSL, one 0.4 mile southeast of the WRSL, and one 0.75 mile southeast of the site, was sampled and analyzed for PCBs. None were found in any sample at a detection limit of 0.1 part per billion (ppb) (1). In 1981, water from 5 domestic wells in the vicinity of an active landfill located approximately 1.5 miles east of the WRSL were sampled and analyzed in two rounds of four wells each, in July and September. One well that was sampled in July was not resampled in September, and a well that had not been sampled in July was sampled in September. The concentrations found of contaminants of concern are summarized in Table 21. All four wells sampled in July contained PCBs, but no wells did in September (detection limit 1 ppb). The FIT report attributed the PCBs in the domestic wells to localized sources, though the detections may also have been due to laboratory error (1). The FIT sampled the industrial well located 0.4 mile southeast of the WRSL in 1982. Again, no PCBs were found, and no other organic chemicals above the detection limits. The detected concentrations of inorganic contaminants of concern are also summarized in Table 21 (1). The RI did not include any sampling of residential wells.
During the ESI in April 1991, the MDNR collected water samples from two Ypsilanti Township municipal wells located approximately 1.25 miles south-southwest from the WRSL. The samples contained no organic contaminants of concern. Concentrations of inorganic contaminants of concern are also summarized in Table 21 (4). The concentrations found of barium, cadmium, and manganese do not exceed MCLs, though the manganese concentration does exceed the Secondary Maximum Contaminant Level established by the U.S. EPA based on other than health-based criteria, such as color, odor, and taste.
The MDNR ESI in 1991 collected surface soil samples, 0 to 4 inches deep, from the vicinity of Willow Run Creek. The concentrations of contaminants of concern found are summarized in Table 22 (4). The concentrations of chromium, lead, and zinc found were somewhat elevated compared to background levels (Reference 23 and Reference 24, Table 5.1). The PAH concentrations were comparable to urban background levels (Reference 22, Table 5-3).
During the EE/CA in March 1994, the U.S. EPA contractors collected soil samples (depth not specified) from the area of South G.M. Pond, the industrial plant area north of Tyler Road, the Airport Landfill, and the backyard and garden of a residence along the South I-94 Service Road near Willow Run Creek. The samples from the industrial plant area contained elevated concentrations of metals and PAHs (Table 22). Toluene was the only organic chemical found in the samples from the residence (at 0.078 ppm, below the RMEG of 400 ppm). Inorganic chemicals found were generally within normal background ranges (Table 23) (6).
Biota Belleville Lake
As part of their Fish Contamination Monitoring Program, in May 1988 the MDNR collected ten carp and ten walleye from Belleville Lake. A MDCH laboratory analyzed the fish for mercury, dieldrin, hexachlorobenzene, octachlorostyrene, PCBs, various chlordane congeners, heptachlor and heptachlor epoxide, aldrin, gamma-BHC (Lindane), terphenyl, toxaphene, 4,4'-DDD, 4,4'-DDE, 4,4'-DDT, mirex, pentachlorostyrene, hexachlorostyrene, heptachlorostyrene, and polybrominated biphenyls (PBBs). Heptachlor, aldrin, gamma-BHC (Lindane), terphenyl, toxaphene, mirex, pentachlorostyrene, hexachlorostyrene, heptachlorostyrene, and PBBs were not detected in any sample (detection limits ranged from 0.001 ppm for the chlorinated styrenes to 0.25 ppm for terphenyl). The concentrations of the contaminants detected are summarized in Table 24 (25). Only one walleye and one carp exceeded the MDCH Level of Concerns for mercury and PCBs (0.5 ppm mercury, 2.0 ppm PCBs), respectively.
There is no information available on where in the lake these fish were collected. Fish tend to range over some distance, and it is normally assumed that fish collected anywhere in a small lake are representative of the entire lake's population. Belleville Lake, however, is fairly long and narrow, with several causeways that nearly divide the lake. There might be separate populations of fish in the various sections of the lake.
Biota Tyler and Edison Ponds
During the EE/CA in May 1994, the contractors collected samples of bottom-dwelling macroinvertebrates from Tyler Pond and Edison Pond. From the numbers and species present, "it was not possible to draw any conclusion concerning ecological impact of contaminants on the species present in the ponds." The species present tended to be highly tolerant of contamination and other environmental impacts, with no intolerant species present. "The absence of intolerant macroinvertebrate species suggests that the contaminated sediments present in both ponds is resulting in diminished water quality, which, in turn, potentially could be affecting site macroinvertebrate populations." (Reference 6, quotes from page 39.)
In preparing this Health Assessment, the MDCH 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. Any qualification on the data cited in this assessment is discussed with the data.
As mentioned above, the detection of PCBs in water samples from domestic wells near the site may have been due to laboratory error. One sample of surface water (unfiltered) reportedly contained a concentration of PCBs substantially in excess of the solubility of the chemicals in water. The PCBs found in this sample were probably in suspended sediments.
The lagoon itself has been fenced since 1986, and the outlet area since 1990, restricting access. The lagoon contained water at the time of the MDPH site visit on April 6, 1994, but it is reported to dry out in the summer. When the lagoon is dry, the sediment-covered sludge is reported to be unstable. Trespassers on the lagoon might sink to an unknown depth and have difficulty getting out. The outlet area and Ypsilanti Drain No. 8 in the site vicinity are natural ravines, heavily overgrown and with steep banks.
To determine whether nearby residents are exposed to contaminants migrating from the site, ATSDR evaluates the environmental and human components that lead to human exposure. An exposure pathway contains five major elements: a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population.
An exposure pathway is considered a completed pathway if there is evidence that all five of these elements are or have in the past been present. A pathway is considered a potential pathway if one or more of these elements is not known to be or have been present, but could be or have been. An exposure pathway can be eliminated from consideration if one of the elements is not present and could never be present. The following sections discuss the most important exposure pathways at this site.
As mentioned in the Environmental Contaminants and Other Hazards section above, there is not sufficient information available to characterize the surface material on the site. The three samples collected during the RI that may include surface material, including the sediment sample from the lagoon, contain metals and PAHs at concentrations potentially of health concern (Table 2 and Table 6). The lagoon does contain water during wet seasons, which would reduce the potential for contact with the sediments, but the sediments are exposed during other times of the year. A worker or trespasser who goes onto the site may come into contact with contaminated soil and be exposed to the contaminants by direct dermal contact, incidental ingestion, or inhalation of fugitive dust. The lagoon itself was fenced in 1986, with an extension to enclose the outlet in 1990. There is a locked gate on the access road to the site at McGregor Road. These fences deter access to the site by trespassers, but there have been reports of individuals gaining access to the lagoon (27). Airport maintenance personnel, however, had regular access to the lagoon area for maintenance of a runway light that is located inside the lagoon fence. In 1990, a fence was constructed between this runway light and the lagoon proper. It is not possible from the available information to estimate how many people may have been exposed to contaminated sediments in the past. The fencing currently in place around the lagoon and outlet should adequately deter access.
During dry periods, fugitive dust can be blown off-site. Most of the site is heavily vegetated, reducing the possibility that fugitive dust would be generated. Meteorological information reported in the RI report indicates that the prevailing winds in the site area are from the west to southwest, though the prevalence is weak and winds can come from nearly any direction. There is 1,500 feet or more of open, vacant space between the site and any active facility or residence where dust from the site might settle out or disperse and dilute. This open space includes two closed landfills, which might also be sources of contaminated fugitive dust. The open space around the site shows signs of unauthorized recreational use. It is not possible from the available information to estimate how many people might be exposed by this route.
Sediments in Ypsilanti Drain No. 8 also contain contaminants, and the stream is seasonal, not flowing in dry periods. This might result in exposure through direct contact or fugitive dust, as described above. The stream is not specifically fenced, so exposure by contact might continue. It is not possible from the available information to estimate how many people might be exposed by this route.
There are residences along Willow Run Creek south of Interstate 94 and along Edison Pond. There is also a public park between Edison Pond and Belleville Lake, with a swimming beach on the lake. Residents along the creek and pond and people using the park for recreation may come into contact with sediments in Willow Run Creek and Edison Pond. It is not known how many people might be exposed to the sediments by this pathway.
Biota Belleville Lake Fish
There is an active sport fishery in Belleville Lake. Two fish samples collected from the lake in 1988 contained PCBs or mercury at concentrations above the MDCH Level of Health Concern. There are other potential sources for these chemicals in the Huron River watershed above Belleville Lake. The MDCH has issued an advisory concerning consumption of sport fish from any inland lake, impoundment, or reservoir in the state, including Belleville Lake, due to pervasive mercury contamination. The advisory reads:
No one should eat more than one meal a week of fish of the following kinds and
sizes from any of Michigan's inland lakes or reservoirs: rock bass, perch, or
crappie over 9 inches in length; largemouth bass, smallmouth bass, walleye,
northern pike, or muskie of any size. Nursing mothers, pregnant women, women
who intend to have children, and children under age 15 should not eat more than
one meal per month of the fish species listed above. Because humans excrete
mercury over time, visitors or residents who only eat fish for one to two weeks per
year can safely consume several meals during that period. (28)
MDCH issues advisories to restrict consumption when the mercury concentration in fish collected from a waterbody exceeds 0.5 ppm, and advises no consumption of fish containing more than 1.5 ppm mercury. No fish from Lake Belleville contained a concentration of mercury above 1.5 ppm, therefore the general advisory is considered adequately protective. Only one fish of twenty (one of ten carp) in the sample exceeded the FDA Action Level for PCBs (2.0 ppm), which the MDCH uses to establish their advisories. The MDCH did not consider this adequate evidence for the issuing of a consumption advisory on carp. No other chemicals exceeded MDCH fish consumption advisory levels.
The surface water in the lagoon, Ypsilanti Drain No. 8, Willow Run Creek, and ponds and tributaries along the creek contains PCBs, arsenic, zinc, and other contaminants at concentrations potentially of human health concern. There is no record of use of water from the Willow Run Creek system for potable purposes. The nearest municipal surface water intake downstream from the site on record is located in Lake Erie near Monroe, Michigan, approximately 30 miles from the site. Contamination from Willow Run Creek would be diluted and dispersed over the distance to below detectable levels or levels of health concern.
Residents along Edison Pond used water from the pond for watering lawns and a fire-suppression system at Willow Run Airport formerly used water from Tyler Pond. These uses, particularly lawn watering, can result in human exposure to contaminants in the water, through dermal contact and incidental ingestion. There is a public park between Edison Pond and Belleville Lake with a swimming beach on the lake. People having access to the site area might come into contact with water in the various streams and water bodies, and thereby be exposed to the contaminants in the water by dermal contact and incidental ingestion. It is impossible from the available information to estimate the number of people who might have been exposed to the surface water in the area.
B. Potential Exposure Pathways
The data does not indicate any effect from the material in the sludge lagoon on the groundwater in the site area. There are indications of contamination in the groundwater north (upgradient) of the lagoon, attributed to a closed landfill in that direction. This contamination plume appears to be limited in area, and the only known wells in the plume area are monitoring wells. The contaminated aquifer is thought to discharge to the nearby surface water bodies, Ypsilanti Drain No. 8 and Willow Run Creek. There are no known producing wells between the landfill and the drain or creek. Based on current and likely future land use patterns, there is not likely to be a well drilled in the affected area in the future. The nearest producing well downgradient of the site, 0.4 miles to the southeast across Willow Run Creek, was described in 1982 as an industrial well not used for consumption purposes (1). The well has since been capped and the facility it served connected to a municipal water system (14).
Biota Willow Run Creek Fish
Runoff and discharges from the Willow Run Sludge Lagoon and other sources of contamination along Willow Run Creek have resulted in contamination of the water and sediments in the creek with metals, PCBs, and other organic chemicals. Fish living in the creek could absorb metals and PCBs from the water and sediment. People who catch and eat the fish could be exposed to the contaminants. There is no record of any study or sampling of fish from the creek to document contamination in the fish. There is no indication of any active fishery on the creek above Edison Pond, though there has not been any survey of anglers in the area. A resident who lives on the north shore of Edison Pond told MDPH staff at a U.S. EPA public meeting that the creek had had a resident fish population in the past, but a discharge of heated water, from an industrial facility, upstream of Edison Pond had eliminated all fish from the creek. Two anglers on Belleville Lake at the discharge from Willow Run Creek also indicated that there were no fish in the creek.
Exposure doses for the various chemicals at this site are evaluated by comparison with health-related standards. The primary standards used for consideration of non-cancer adverse health effects are the Minimal Risk Levels (MRLs) established by the ATSDR and Reference Doses (RfDs) and Reference Concentrations (RfCs) established by the U.S. EPA. If an exposure dose does not exceed the MRL, RfD, or RfC, it is generally accepted that there would be little risk of adverse non-cancer health effects occurring. The MRLs, RfDs, and RfCs may not be sufficiently protective for especially susceptible individuals, such as the very young, the very old, those whose systems have been weakened by other causes, and those with a high sensitivity to a specific chemical.
The exposure doses will also be compared, as appropriate, to experimental and epidemiological data. The exposure doses will be compared to the highest doses at which no adverse health effects were observed (No Observed Adverse Effect Levels, or NOAELs) and to the lowest doses at which adverse health effects were observed (Lowest Observed Adverse Effect Levels, or LOAELs).
The risk of contracting cancer after exposure to a carcinogen is computed from the extent of the exposure and a cancer potency factor derived from experimental or epidemiologic studies. This yields an estimated risk in terms of the number of additional cases of cancer that are likely to develop in a large population that undergoes the exposure compared to an equal-size population that has not been exposed. The slope factors are computed as upper bounds, with appropriate safety factors, and the actual risk is likely to be lower, and may be as low as zero. For this assessment, a significant additional risk of developing cancer is one additional case of cancer in a population of 1 million people experiencing the exposure over a lifetime of 70 years.
Exposure doses for this assessment are computed using the following standard assumptions: an adult weighing 70 kilograms (154 pounds) who drinks 2 liters (approximately 2 quarts) of water a day and incidentally ingests 100 milligrams of soil per day; a child weighing 10 kilograms (22 pounds) who drinks 1 liter (approximately 1 quart) of water per day and incidentally ingests 200 milligrams of soil per day, or, if subject to pica behavior, deliberately ingests 5,000 milligrams of soil per day. Pica behavior is an abnormal urge to consume non-food substances, such as soil, that most commonly occurs between ages 2 and 5.
As described above in the Pathways Analysis section, the only completed pathways for human exposure at the site are those involving surface material, fish in Lake Belleville, and surface water. The following discussion only addresses those contaminants of concern listed in Table 1 which were found at concentrations above the comparison values in one or more of these media. Acetone, benzene, dibenzofuran, and 1,4-dichlorobenzene were only found at concentrations above the comparison values in media that people are not exposed to, such as the sludge, subsurface soil, sediments in the creek and ponds, and groundwater.
Very young children are not likely to be on or near the WRSL site without supervision under the current or foreseeable land uses of the site and its vicinity. It is also unlikely that anyone would spend a large fraction of their time in the site vicinity because the site is remote from residential areas. To be conservative, exposure doses will be computed based on a child between 6 and 11 years of age, weighing 30 kilograms and incidentally ingesting 250 milligrams of soil per day, visiting the site one day per week. The concentrations used will be the maximums of those found in sediments from the lagoon (Table 2), other on-site soil samples that include surface materials (Table 6), and soil samples from the Willow Run Creek area (Table 22).
U.S. residents consume an average of 12 grams of fish and shellfish per day (Reference 24, Table E.1). This consumption rate is equivalent to one 225-gram (0.5 pound) meal of fish approximately every three weeks. Many people, particularly sport anglers and their families, might eat considerably more fish than the average. This evaluation will consider an exposure dose to contaminants in the most highly contaminated fish from Belleville Lake based on a more conservative assumption of one 225-gram meal of fish per week, a daily average of 32 grams per day.
Exposure to surface water in the site area would most likely be infrequent, isolated events. To model the exposure conservatively, we'll assume that the young trespasser described above incidentally consumes 10 milliliters of water from one of the water bodies near the site each time he visits. The concentrations used are the maximums reported in any surface water body (Table 4, Table 5, Table 10, Table 12), without considering access restriction or whether the samples were filtered.
Any adult or child who trespasses on the site might incidentally ingest enough PCBs from the sediment in the lagoon on the site to exceed the chronic ingestion MRL for non-cancer adverse health effects. A child trespasser might incidentally ingest enough PCBs from the sediment to exceed the LOAEL the MRL was based on, for decreased immune-system response in laboratory animals. A trespasser who incidentally drinks water from the lagoon might exceed the MRL but would not likely exceed any available LOAELs. Laboratory animals who were fed PCBs developed cancer of the liver, though there is no epidemiological data available linking exposure to PCBs with cancer in humans. The U.S. EPA has classified PCBs as probable human carcinogens (U.S. EPA Class B2 ) (19). A person who regularly trespasses on the site for his or her lifetime might incidentally ingest enough PCBs from the sediments or water in the lagoon to incur a high increased risk of contracting cancer.
A person who trespasses at Tyler Pond during a dry spell might incidentally ingest enough PCBs from the sediment to exceed the chronic ingestion MRL for non-cancer health effects, though no one, adult or child, would likely exceed the doses at which adverse health effects have been observed. A person who regularly trespasses at the Pond for his or her lifetime might incidentally ingest enough PCBs from the sediment to incur a high increased risk of contracting cancer. A person who regularly trespasses elsewhere in the site vicinity for his or her lifetime might incidentally ingest enough PCBs from the sediment in Ypsilanti Drain No. 8 or Willow Run Creek to incur a low increased risk of contracting cancer. He or she would not likely reach the chronic ingestion MRL for non-cancer adverse health effects. Drinking water from the creek or ponds along it would not likely result in a dose above the MRL or any apparent increased cancer risk.
Only one fish of the 20 collected from Belleville Lake in May 1988 contained PCBs in excess of the FDA Action Level or the MDCH Level of Concern. MDCH concluded that it would not be likely that fish caught from the lake would include a significant fraction of fish containing PCB concentrations above the Level of Concern, so MDCH has not issued an advisory on consumption of fish from the lake because of the PCB content. It has been argued, however, that the FDA Action Level for PCBs in fish may not adequately protect sensitive human populations. A person who consumes one meal of fish per week, all of which fish contains the maximum concentration of PCBs found in fish (carp) from Belleville Lake, might ingest enough PCBs to exceed the MRL (ingestion, chronic) for non-cancer adverse health effects. The dose of PCBs from the fish would not likely exceed the doses at which adverse health effects have been observed. A person who consumes one meal of fish per week, all of which fish contains the maximum concentration of PCBs found in fish (carp) from Belleville Lake, might incur a high increased risk of contracting cancer.
No one is likely to ingest enough chloroform from the surface water on and near the site to exceed the MRLs or RfDs. There is not sufficient evidence available to link exposure to chloroform with cancer in humans. Laboratory animals whose feed contained chloroform developed an increased incidence of cancers of the liver, kidneys, and lymphatic system. The U.S. EPA has classified chloroform as a probable human carcinogen (U.S. EPA Class B2) (29). Trespassers in the site area are not likely to ingest enough chloroform from the surface water to incur an apparent increased risk of contracting cancer.
- 1,2-Dichloroethane (1,2-DCA)
There are no ingestion MRLs or RfDs available for 1,2-dichloroethane (1,2-DCA). It is not likely that anyone will ingest enough 1,2-DCA from the surface water at the site to exceed the doses at which adverse non-cancer health effects have been observed. There is not sufficient evidence available to link exposure to 1,2-DCA with cancer in humans. Laboratory animals whose food or drinking water contained 1,2-DCA developed an increased incidence of cancers of the spleen, liver, pancreas, adrenal gland, stomach, lung, breast, and other organs. The U.S. EPA has classified 1,2-dichloroethane as a probable human carcinogen (U.S. EPA Class B2) (30). A person who drinks surface water from the site area is not likely to ingest enough 1,2-DCA to incur any apparent increased risk of developing cancer.
There are no ingestion MRLs available for 1,1,1-trichloroethane. The U.S. EPA has withdrawn its RfD for the chemical. No adult or child who trespasses on the site is likely to incidentally ingest enough 1,1,1-trichloroethane to exceed the former U.S. EPA RfD or the doses at which adverse health effects have been observed. There is no evidence available linking exposure to 1,1,1-trichloroethane with cancer (31).
No one is likely to ingest enough trichloroethylene from the surface water at the site to exceed the intermediate-term MRL for non-cancer adverse health effects. There are no MRLs available for other exposure durations and the U.S. EPA RfD is under review. No one is likely to ingest enough trichloroethylene from the surface water or soil at the site to exceed the doses at which adverse health effects have been observed. Laboratory animals whose feed contained trichloroethylene developed liver cancer. There is not sufficient information available on whether exposure to trichloroethylene causes cancer in humans. The U.S. EPA formerly classified trichloroethylene as a probable human carcinogen (U.S. EPA Class B2), but is currently reconsidering the classification (32). No one is likely to consume enough trichloroethylene from the surface water or soil at the site to incur a significant increased cancer risk.
Semi-Volatile Organic Chemicals
No one is likely to ingest enough bis(2-ethylhexyl)phthalate (BEHP) from the surface water or any other environmental medium on or near the site to exceed the U.S. EPA chronic RfD or the MRLs for acute- or intermediate-term ingestion exposure. There is no evidence available that humans exposed to BEHP develop cancer. Laboratory animals whose food contained BEHP developed an increased incidence of liver cancer. The U.S. EPA has classified BEHP as a probable human carcinogen (U.S. EPA Class B2) (33). No one is likely to ingest enough BEHP from the environmental media at the site to incur a significantly increased risk of developing cancer.
There is little information available on the toxic effects of exposure to di-n-octylphthalate (DNOP). There is a report in the literature that one worker who was continuously exposed to the chemical in his employment developed an asthmatic reaction (34). Laboratory animals fed food containing the chemical developed enlarged livers, though no indications of changes in the organ's function were reported. DNOP has generally been found to be less toxic than the related compound bis(2-ethylhexyl)phthalate (BEHP). The exposure dose of DNOP experienced by anyone from the soil and water on or near the site is not likely to exceed the MRL for BEHP, and therefore is not likely to result in any adverse non-cancer health effects. There is no evidence available that exposure to DNOP causes cancer, though one experiment with laboratory animals indicates that ingestion of DNOP can increase the carcinogenic effects of other chemicals (33, 34).
- Polycyclic Aromatic Hydrocarbons (PAHs)
No adult or child who trespasses on the site is likely to incidentally ingest enough of any of the PAHs from the sediment or surface water to exceed the acute-term ingestion MRL for benzo(a)pyrene or any dose of any PAH at which non-cancer adverse health effects have been observed. Of the PAHs found in the surface materials, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, chrysene, and indeno(1,2,3-cd)pyrene have been classified by the U.S. EPA as probable carcinogens (U.S. EPA Class B2). Some laboratory animals who were fed benzo(a)anthracene and benzo(a)pyrene developed stomach cancer. Some animals who had other PAHs applied to their skin developed skin cancers. There is no evidence linking exposure to 2-methylnaphthalene, naphthalene, or phenanthrene with cancer (22, 35). A person who trespasses in the site vicinity regularly for his or her lifetime might incidentally ingest enough PAHs from the sediment from the lagoon, Ypsilanti Drain No. 8, or Willow Run Creek to incur a low increased risk of contracting cancer. The PAH concentrations in the sediment from the site vicinity are comparable to those found in urban soils (Reference 22, Table 5-3).
Metals and Inorganic Chemicals
No adult or child who trespasses on the site is likely to incidentally ingest enough arsenic from the sediments in the lagoon to reach the chronic ingestion MRL or RfD for non-cancer adverse health effects. A child trespasser would not likely ingest enough arsenic from the surface water to exceed the chronic ingestion MRL. Ingestion of arsenic and arsenic compounds has been linked to cancer of the skin and other sites in humans via epidemiological studies and laboratory studies of animals. The U.S. EPA has classified arsenic and its compounds as known human carcinogens (U.S. EPA Class A). A person who trespasses on the site regularly for his lifetime might incidentally ingest enough arsenic from the sediments to incur a low increased risk of contracting skin cancer. A person who regularly trespasses in the site area and incidentally ingests water from the surface water bodies would not be likely ingest enough arsenic from the water to incur any apparent increased risk of contracting cancer. There is not enough information available to evaluate the increased risk of contracting cancer of other sites from ingestion of arsenic compounds (36).
No one is likely to ingest enough beryllium from the soil or sediments at or near the site to exceed the RfD for non-cancer adverse health effects. Epidemiological studies of workers in beryllium factories have yielded limited indications that exposure to the metal may lead to lung cancer. Laboratory animals who breathed air containing beryllium compounds developed an increased incidence of lung cancer. There is no evidence available that ingestion of beryllium causes cancer. The U.S. EPA has classified beryllium as a probable human carcinogen (U.S. EPA Class B2) (37). Based on the animal inhalation data, a trespasser in the site area is not likely to ingest enough beryllium to incur an apparent increased risk of lung cancer.
No adult or child trespassing on the site is likely to incidentally ingest enough cadmium from the sediments of the lagoon, from drinking the surface water, or from doing both, to exceed the chronic ingestion MRL for non-cancer adverse health effects. There is some equivocal evidence linking inhalation exposure to cadmium with lung cancer from epidemiologic studies of workers, and some laboratory animals who inhaled cadmium developed lung cancer. The U.S. EPA has classified cadmium as a probable human carcinogen by inhalation (U.S. EPA Class B1). There is not enough evidence available to determine whether ingestion of cadmium causes cancer, nor to estimate the increased risk of contracting cancer from exposure at the site (38).
The toxicity of chromium-containing compounds is strongly dependent on the oxidation state of the chromium in the compound. Compounds containing trivalent chromium, or chromium(III), are relatively non-toxic except at extremely high doses. Chromium(III) is an essential trace element in the diet. Compounds containing hexavalent chromium, or chromium(VI), are considerably more toxic. The analytical reports summarized in this assessment made no distinction between the valence states of chromium, reporting the total chromium present. Chemical reactions in the environment tend to reduce chromium(VI) to chromium(III). No adult or child is likely to incidentally ingest enough chromium from the soil to exceed the chronic RfD for chromium(III), but a child trespasser might incidentally ingest enough chromium from the soil to exceed the chronic RfD for chromium(VI) for non-cancer adverse health effects. The child trespasser would not likely ingest enough chromium to exceed doses at which adverse health effects have been observed. No one is likely to ingest enough chromium from the surface water on the site to exceed the RfD for either valence state. Inhalation of chromium(VI) compounds has been linked to lung cancer in epidemiologic studies of workers in chromium-using factories and in laboratory studies of animals. The U.S. EPA has classified chromium(VI) compounds as known human carcinogens by inhalation (U.S. EPA Class A). There is not sufficient information available to evaluate the cancer risk from ingestion exposure to chromium(VI) compounds. There is no evidence available to indicate that chromium(III) compounds cause cancer (39).
There are no MRLs or RfDs available for copper. No adult or child who trespasses on the site is likely to incidentally ingest enough copper from the sediments to exceed the doses at which adverse health effects have been observed. The concentration of copper in the surface water near the site is less than the U.S. EPA Maximum Contaminant Level Goal, so it is unlikely that anyone would ingest enough copper from the surface water to incur adverse health effects. There is no evidence available linking exposure to copper with cancer (40).
There are no ingestion MRLs or RfDs available for lead. No adult or child who trespasses on the site is likely to incidentally ingest enough lead from the sediments or surface water to exceed the doses at which adverse health effects have been observed. Lead is a cumulative poison, and long-term exposure to low doses could produce effects similar to those produced by higher doses over shorter times. Lead can interfere with development, particularly of the nervous system. Laboratory animals who were fed food containing lead compounds developed an increased number of kidney cancers. The U.S. EPA has classified lead as a probable human carcinogen (U.S. EPA Class B2). The available evidence is not sufficient to evaluate the risk of cancer from exposure to lead in the material at this site (41).
A young trespasser on the site area might ingest enough manganese from the sediments at the site to exceed the RfD for non-cancer adverse health effects. He or she would not likely exceed the dose at which adverse health effects have been observed. There is no evidence available that links exposure to manganese with cancer (42).
No adult or child who trespasses on the site is likely to incidentally ingest enough mercury from the sediments in the lagoon to reach the acute or intermediate-term ingestion MRLs for organic or inorganic mercury compounds or to exceed the doses at which adverse health effects have been observed from longer-term exposure studies. There is no available evidence to indicate that mercury exposure causes cancer (43).
A person who consumes one meal of fish per week, all of which contains the maximum concentration of mercury found in fish (walleye) from Belleville Lake, might ingest enough mercury to exceed an MRL for non-cancer adverse health effects from acute ingestion of organic compounds of mercury. The exposure dose of mercury from consumption of the fish would not exceed the doses at which adverse health effects have been observed for ingestion of mercury, including organic and inorganic mercury compounds.
No adult or child trespassing on the site is likely to incidentally ingest enough nickel from the sediments or surface water on or near the site to exceed the chronic ingestion RfD for non-cancer adverse health effects. Inhalation of nickel refinery dust and nickel subsulfide (Ni3S2) has been linked to cancer of the lung and nasal passages in epidemiological studies of nickel refinery workers and in laboratory studies on animals. The U.S. EPA has classified nickel refinery dust and nickel subsulfide as human carcinogens (U.S. EPA Class A). The International Agency for Research on Cancer (IARC) has classified all nickel compounds as human carcinogens by inhalation (Class 1). There is no evidence available linking ingestion of nickel compounds with cancer (44).
There are no ingestion MRLs or RfDs for thallium. No one is likely to ingest enough thallium from the sediment or surface water on or near the site to exceed the doses at which adverse health effects have been observed. The concentrations in surface water samples from Ypsilanti Drain No. 8 and Willow Run Creek exceed the U.S. EPA Drinking Water Health Advisory (Lifetime) (0.4 ppb) and Maximum Contaminant Level (2 ppb) and Maximum Contaminant Level Goal (0.5 ppb). There is no evidence available to link exposure to thallium with cancer (45).
- Other Metals and Inorganic Chemicals
No one is likely to ingest enough antimony, barium, boron, cobalt, cyanide, selenium, silver, vanadium, or zinc from the sediment or surface water at or near the WRSL site to exceed available MRLs, RfDs, or levels at which adverse health effects have been observed for non-cancer adverse health effects. There is no evidence available that links exposure to any of these metals or inorganic chemicals with cancer (46, 47, 48, 49, 50, 51, 52, 53, 54). No one is likely to experience any adverse health effects from exposure to these chemicals at or near the WRSL site.
A person eating fish from Belleville Lake is not likely to ingest enough chlordane and its congeners, DDT and its metabolites, dieldrin, heptachlor epoxide, or hexachlorobenzene to exceed available MRLs (ingestion), RfDs, or levels at which non-cancer adverse health effects have been observed. All of these chemicals are considered probable human carcinogens (U.S. EPA Class B2), based on animal laboratory studies that showed an increase of cancer of the liver on ingestion of the chemicals. Epidemiological studies have not shown a relationship between exposure to the chemicals and cancer in humans (55, 56, 57, 58, 59). A person who eats one meal of fish per week, all of which fish contain the maximum concentrations of these chemicals found in the fish from Belleville Lake, might incur a significantly increased risk of contracting cancer. There is no information available on health effects from exposure to octachlorostyrene.
Water and sediments from Edison Pond and Belleville Lake
Edison Pond and Belleville Lake are in a residential area, and there is a public park between the pond and the lake with a swimming beach on the lake. People living near the pond and people using the park are likely to be exposed to water and sediments from the pond and lake, at least occasionally. As seen in Table 12, water from Edison Pond and Belleville Lake has contained cadmium, lead, manganese, nickel, and PCB concentrations at levels at which it would not be advisable to use the water as a primary household water supply. However, occasional exposure to, including consumption of, water from the pond and lake is not likely to result in adverse health effects. Similarly, as seen in Table 13, sediments from Edison Pond and Belleville Lake contain metals, PAHs and PCBs at concentrations above comparison values. The concentrations of PAHs are comparable to those found in background urban soils (Reference 22, Table 5-3). Again, the concentrations of contaminants of concern found in these sediments are not high enough that occasional exposure is likely to result in adverse health effects.
There have been no community health concerns expressed that can be related to any specific health outcome, nor is there any means for identifying the people exposed to the site. Therefore, no health outcome data have been consulted for this assessment.
Following are MDCH's responses to the health-related concerns voiced at the U.S. EPA-sponsored public meeting on January 26, 1993.
1. What impact has the WRSL site had on fish from Willow Run Creek and Belleville Lake? What are the health effects from consumption of fish containing the levels of contamination found in Belleville Lake?
- There is no record of any study or sampling of fish resident in Willow Run Creek. The
water quality in Willow Run Creek has been severely degraded because of releases from
several sources in its watershed, including the WRSL site. This degradation of the water
quality can be expected to affect any resident fish, though the extent of the effects are not
known in the absence of data. The fish collected from Belleville Lake in 1988 contained
no unusual levels of contamination compared to other lakes in the State. The MDCH has
not issued any special advisories concerning Belleville Lake. See the Toxicological
Evaluation section above for a detailed discussion of the potential health effects from
consumption of fish from Belleville Lake.
2. Are there hazards in the air coming off the lagoon?
- The primary contaminants in the lagoon are PCBs and metals. These are not particularly
volatile, however, they might be carried in fugitive dust blowing from exposed sediments
in the lagoon during dry seasons.
3. Is there a need to restrict access to other ponds and lagoons near the site because of physical hazards?
- The U.S. EPA does not consider this to be an urgent need. The ponds and lagoons pose
no more physical hazard than similar landscape features elsewhere.
At the January 12, 1995, MDNR public meeting on the Willow Run Creek proposed remedial action plan, Brendan Boyle of the MDPH sought out the commenter who mentioned the people eating fish, and asked the commenter for more information. The commenter referred him to another area resident. John Hesse of the MDPH contacted this resident, and established that her statements to the original commenter might have been misinterpreted. The locations where the resident had seen people fishing were not along Willow Run Creek, but were on the Huron River upstream from Belleville Lake (60). During a visit to the site area in June 1995, MDPH staff interviewed two anglers who were fishing in Belleville Lake at the outlet from Willow Run Creek and a resident of the area. All three agreed that there was currently no fish or fishing in Willow Run Creek.
Brendan Boyle and Jim Bedford of MDCH have corresponded with the area resident that reported health problems, and have offered further consultation to him and his physician. Adverse health effects following exposure to PCBs have mainly been reported in people who worked with PCBs or came into extensive contact with PCBs in commercial formulations. MDCH has not had any reports of adverse health effects developing in people exposed to PCBs in the environment, even in instances of extensive contact with soils containing much more PCBs than are found in the Willow Run Creek area.
The Michigan Department of Public Health released a draft of this Public Health Assessment for public comment on January 31, 1996. The public comment period lasted until March 1, 1996. No comments were received in this period.