PUBLIC HEALTH ASSESSMENT
WOODLAWN COMPANY LANDFILL
WOODLAWN, CECIL COUNTY, MARYLAND
The Woodlawn Landfill site is situated at the intersection of Firetower and Waibel Roads in
northwestern Cecil County, about 2.5 miles northeast of the town of Port Deposit. The site currently
operates as a transfer station. During the late 1950's and early 1960's, the site was quarried for sand
and gravel. It was purchased in 1965 by Cecil county and operated as a landfill (receiving both
municipal and industrial waste) until 1979, when it was closed under State order. Polyvinyl
chloride (PVC) sludge 
was disposed in two areas in the northeast corner of the site from 1978 to
1981. Before 1978, PVC sludge was disposed wherever active landfilling operations were taking
place. Groundwater from monitoring wells that are located off site or just within the site boundaries
have elevated levels of some volatile organic chemical contaminants, including benzene, methylene
chloride and vinyl chloride. Metals that were found at elevated concentrations in some of the
monitoring well samples include cadmium, magnesium, manganese, mercury and sodium. A total
of 18 residential wells are within a 1/2 mile radius of the site. It is estimated that those wells supply
drinking water to about 50 to 60 people. Local residents have expressed concern regarding potential
health effects that could result from drinking contaminated water and about potential exposure to
contaminants in the air. Area residents have also expressed concerns that domestic animals may be harmed by exposure to site-related contaminants.
The exposure pathway of primary concern is ingestion and inhalation of contaminants in groundwater. Vinyl chloride has been discovered at a low concentration in one residential well. In the spring of 1991, a treatment system was installed to decrease levels of vinyl chloride in water used by the people. Groundwater modeling based on current conditions predicts that contaminants will migrate to other residential wells in the future, if remedial action is not taken. Adverse health effects would not be expected to result from exposure to the low level of vinyl chloride that has been found in one residential well. Other exposure pathways of potential concern include incidental ingestion of, dermal contact with, and inhalation of contaminants by site trespassers. Based on the environmental sampling that has been conducted on the site, it appears unlikely that trespassers would currently be exposed to hazardous levels of contaminants. It appears that the environmental sampling that has been conducted both on and off of the site is sufficient to adequately characterize the extent of contamination. It is concluded that the site poses a public health hazard because of the potential for future exposure of local residents to groundwater contaminants.
Recommendations to protect public health include the following:
1) Establish a regular groundwater monitoring program for residential wells
near the landfill;
2) Further restrict access to the site, especially during future remediation
activities; and,
3) Conduct monitoring for airborne contaminants and employ dust suppression
techniques during future remediation activities that may release volatile contaminants
or generate dust.
To determine if public health actions are needed, ATSDR's Health Activities Recommendation Panel (HARP) has evaluated the data and information developed in the Woodlawn Landfill Public Health Assessment. Because there are no indications that people have been exposed to contaminants at levels that may cause illness or disease, HARP determined that no follow-up health activities are indicated at this time. If new information becomes available indicating exposure at levels of concern, ATSDR will evaluate that information to determine what actions, if any, are necessary.
To further ensure that public health issues are addressed, a plan of actions has been developed. The plan includes the following commitments by the Maryland Department of the Environment (MDE):
A. Site Description and History
The former Woodlawn Landfill (WL) occupies a site of approximately 37 acres at the intersection of Firetower and Waibel Roads in northwestern Cecil County, about 2.5 miles northeast of the town of Port Deposit, Maryland. The site is owned and was operated by Cecil County. Figure 1 shows the site and its immediate vicinity. An unnamed creek flows to the northwest through the southern portion of site property.
The property was operated as a sand and gravel quarry from the late 1950's to the early 1960's. In 1965 the property was purchased by Cecil County and used as a county landfill. The landfill received both municipal and industrial wastes until 1979, when it was closed under state order. Disposal of PVC sludge in designated disposal cells continued until 1981. Waste disposal records do not exist for the landfill, except for the on-site disposal of 1,272 tons of polyvinyl chloride sludge by the Firestone Tire and Rubber Company during 1979 and 1980. The sludge was disposed in two separate areas in the northeast corner of the site (see Cells A, B, and C in Figure 1). Cecil County continues to operate a transfer station adjacent to the site. The transfer station is used to unload refuse from residents and commercial vehicles, compact this refuse and reload it onto county vehicles. Cecil County also operates a recycling center at the transfer station.
A Preliminary Assessment (PA) of the landfill was conducted by the Maryland Solid Waste Management Administration in June 1982. Groundwater monitoring has been conducted at the landfill by the State since 1983, and both the State and Cecil County have periodically monitored the water from nearby residential wells. Vinyl chloride was detected in a private well, and a treatment system was installed in Spring 1991 to decrease levels to which well users may be exposed. A development restriction area was established near the landfill by the State of Maryland in 1987. The restriction area was revised in 1989 and again in 1991. A zone surrounding the landfill was established in which any new water supplies are prohibited. Another zone exists to the north of the site in which new water supplies are allowed on existing lots and an outer circle has been established around the site, within which the development of new subdivisions is prohibited.
Woodlawn Landfill was placed on the National Priorities List (NPL) in July 1987. A preliminary health assessment of the site was completed by the Agency for Toxic Substances and Disease Registry (ATSDR) in May 1988 (1). In June 1989 a Remedial Investigation / Feasibility Study (RI/FS) was initiated by International Technology (IT) Corporation, a contractor hired by Bridgestone/Firestone, Inc. (formerly the Firestone Tire and Rubber Company) and Cecil County. The RI/FS is in part designed to determine the movement of groundwater within the landfill and to characterize the major site contaminants and the extent to which those contaminants have migrated off the site. The RI/FS is required by a Consent Order that was entered into on December 28, 1988, among Bridgestone / Firestone, Inc., Cecil County, MD and the U.S. Environmental Protection Agency (EPA).
In cooperation with ATSDR, Maryland Department of the Environment (MDE) will evaluate the public health significance of this site. MDE will evaluate the possibility of adverse health effects associated with site exposures and will recommend actions to reduce or prevent such exposures.
The site was visited on August 6, 1991, by Peter Ashley, a health assessor employed by MDE. Mr. Ashley was accompanied by an employee of the Cecil County Health Department. The following observations were made:
The cleared area to the west of the transfer station was being used to store drums of monitoring well water. IT Corporation employees were encountered on the site at the time of the visit. One of the IT workers noted that in the past he had seen dirt bike and all-terrain vehicle (ATV) tracks on the site. Another IT employee had seen signs of deer hunting (wooden hunting platforms) in the wooded area west of the site. The landfill boundary is not obvious in this area and it may be the case that some hunting has occurred on the site property.
An area was observed between the dirt road and the northern boundary of the site (near monitoring wells ITB-1 and ITS-1; see Figure 1) that contained remnants of 2 previous campfires as well as discarded cans and bottles. The site is easily accessed from this point and the boundary is not posted. Large signs warning against site entry were observed along Waibel Road, just south of the junction with Firetower Road.
Small residential developments and farms were observed in the area surrounding the landfill. The farm land appeared to be primarily used for grazing cattle and growing corn and hay. No significant changes were seen during the October 1992 visit.
C. Demographics, Land Use, and Natural Resource Use
Demographics
Based on the 1990 census, Cecil county has a total population of 71,347. About 95% of this population is white; 4% of the remaining population is black, and the rest (1%) are of other racial origins. The average population density of Cecil County is 205 persons per square mile. The population density of the census tract in which the landfill is located is 235 persons per square mile. Based on this population density, the estimated population within a one mile radius of the site is about 700 people. The 1990 population of Cecil County was 18% greater than the population in 1980.
The population living within a 1/2 mile radius of the landfill is estimated at 56 people. This is based on the number of residential wells found within this distance from the site and the observation during the site visit that single family residences generally had their own wells. In making this estimate it is also assumed that there is an average of 2.8 people per residence (1990 census data).
Land Use
The land adjacent to the Woodlawn landfill is zoned primarily for agricultural and low density residential development. Agricultural zoning allows for single family dwellings to be built with a density of one unit per three acres. Low density residential development allows for one housing unit per acre (personal communication, Cecil County Planning Office). There is also some land to the south of the landfill that is zoned for mobile home housing. There are 2 houses located immediately adjacent to the site; one is separated from the southern site boundary by Waibel road, and the other is on Firetower road, directly across from the transfer station.
The former Bainbridge Naval Training center is about 1.5 miles south of the site. The center was operated by the Navy until the mid-1970's. After that time it was operated by the U.S. Dept. of Labor, and was called the Chesapeake Job Corps Center. The center is currently inactive.
Natural Resource Use
Residents living near Woodlawn Landfill (in all directions from the landfill) use groundwater from private wells as their household water supply. Residential wells are generally drilled into a fractured bedrock aquifer (an aquifer is a permeable body of rock or soil and the groundwater that it contains). There are at least 20 residential wells located within a 1/2 mile radius of the landfill. Vinyl chloride was detected at low levels in one well, and a treatment system was installed to remove the vinyl chloride.
The nearest municipal water supply to the site is found in the town of Port Deposit, about 2.5 miles southwest of the site. This town uses surface water from the adjacent Susquehanna river. This water supply also serves the nearby Chesapeake Job Corps Center. There are also 2 mobile home parks southeast of the site that use wells to supply potable water to residents. The Oaklane mobile home park is located off of Doctor Jack Road, about 3/4 mile southeast of the site, and the Maple Hill park is about 1.5 miles southeast of the site, off of Tome Memorial Highway.
The most commonly grown crops in the area are corn and soybeans. There is also some dairy farming in the site vicinity.
As noted previously, the wooded area west of the landfill is used for hunting deer.
Available health data bases can sometimes be used to determine whether or not certain health effects occur more frequently in Cecil County than in the State of Maryland as a whole. This section describes these data bases; their evaluation occurs in the Public Health Implications section.
The Maryland Department of Health and Mental Hygiene (DHMH) keeps a registry of birth defects for the state of Maryland. The registry includes incidence data (the number of new cases that are identified over a given time period) for 12 sentinel birth defects that hospitals are required to report to the state. The birth defects data are available at the county level. Cancer mortality data are also available at the county level for the time period 1983 to 1987. These data were reviewed for Cecil County, and are further evaluated in the Public Health Implications section.
Vital statistics (births and deaths) reports are available for Maryland counties from the early 1960's through 1987.
Environmental health officials with Cecil County, the State of Maryland, and EPA were questioned regarding their knowledge of community health concerns related to the Woodlawn Landfill. It was noted that some residents have expressed concern over potential health effects from exposure to contaminants in groundwater (2). Those concerns have been expressed at public meetings that have been held to keep the public informed on the site. The most recent public meeting was held on December 12, 1991, in Perryville, Maryland, and was attended by a member of the MDE health assessment team. Some local residents also submitted concerns in writing to MDE during the comment period on the draft Woodlawn Landfill Public Health Assessment (December 14, 1992, to January 17, 1993).
Two residents who live directly east of the site expressed concern (March 1992) over the source and possible health effects of strong ammonia-like odors that they have detected in the air. One resident noted that he has detected this odor in the air on several occasions during early evening hours. In a recent incident (March 11, 1992) a woman became faint after exposure to strong odors and emergency personnel were called to the scene. In a subsequent conversation the woman noted that she had been working indoors with strong cleaning solutions and she believed that her symptoms were likely due to that exposure (personal communication with local residents).
Concern has also been expressed by the community regarding possible effects of landfill contaminants on domestic animals. That concern was raised by area residents who attended a public meeting on the landfill that was held in August 1990. Other concerns that were raised at the August 1990 and December 1991 meetings concerned the development restriction area that has been established near the site landfill.
ATSDR public health assessments focus on possible public health impacts of hazardous waste sites. Possible health risks to wild or domestic animals will not be addressed in detail. However, chemical contaminants may have similar effects on humans and some types of domestic or wild animals. This public health assessment will not discuss the development restriction area or other concerns that do not relate to public health.
ENVIRONMENTAL CONTAMINATION AND PHYSICAL HAZARDS
The tables in this section list the contaminants of concern in various media at the Woodlawn Landfill. The listing of these contaminants does not necessarily indicate that a health threat exists. This public health assessment will evaluate these contaminants in subsequent sections and will indicate whether exposure to them has public health significance. Selection of these contaminants were based on the following factors:
Comparison values are derived from health-based data. For example, the groundwater comparison values are concentrations of substances that, when present in drinking water, would not be expected to result in adverse health effects following chronic (i.e., lifetime) exposure or short-term (acute) exposure. Some of the comparison values (i.e., Maximum Contaminant Levels (MCL) and Proposed Maximum Contaminant Levels (PMCLs) also take into account the cost and technological feasibility associated with achieving those levels in drinking water. Comparison values have been calculated by ATSDR for chemicals for which ATSDR has developed Minimal Risk Levels (MRLs). Where ATSDR values are not available, drinking water standards or guidelines calculated from health data developed by EPA have been used.
To identify facilities that could possibly contribute to the chemical contamination near Woodlawn Landfill, MDE searched the 1987, 1988 and 1989 Toxic Chemicals Release Inventory (TRI). The TRI data base was developed by EPA from the chemical release (air, water, soil) information provided by certain industries. The database was searched by zip code area and did not list any facilities in the site area that are releasing toxic chemicals.
The data presented in this subsection are the result of on-site sampling that was conducted by IT Corporation in February and March of 1991. IT Corporation is under contract to perform the RI/FS for Woodlawn Landfill.
1. Seeps and Leachate Soils
Table 1 lists the range of the concentrations of contaminants that were measured in on-site seepage and seepage soils (3). Seeps are areas where water (and dissolved or suspended contaminants) are draining from the landfill through the overlying soil. Seepage water and stained seepage soils were sampled from four areas of the site (south central, southeastern, and the northwestern part of the site, and in a settling basin in the south-central area of the landfill). Seepage soils were sampled from the top six inches of stained soil from each seepage area.
Four soil and water samples may not adequately characterize the existing contamination in seeps and leachate soils on the 37-acre site; however, it does provide an indication of the types of contaminants that are present in those media. The substances that were identified are solvents (volatile), other organic compounds (semivolatiles) and metals. Those contaminants are commonly found at sites such as Woodlawn Landfill that have received mixed industrial and municipal wastes. Most of the volatile compounds that were detected in the samples (e.g., toluene, xylenes) are common industrial solvents. The organic chemical (volatiles or semivolatiles) that was found in the highest concentration was bis-(2-ethylhexyl) phthalate (BEHP).
2. Borings in Waste
A total of 14 borings were made in various parts of the landfill using hollow-stem augers with an approximate 4 inch inside diameter (3). The borings were located on the basis of the greatest likelihood of contacting representative waste materials. Borings were collected and analyzed to help better characterize the buried waste and subsurface contamination at the landfill. The borings were extended to various depths and were terminated when the augers reached natural soils beneath the waste. Samples from three different zones were analyzed for each boring: the upper 6 inches of soil, from within the waste, and in natural soils beneath the waste. In addition, if present, one sample each of sludges, oils, and powders were analyzed.
Table 2 lists the contaminants that were found in the top 6 inches of soils. Only those substances are listed because of the potential for human exposure through direct contact to the surface soils. (Note: Surface soils are considered to be the top 3 inches of soil; however, no samples were taken of only the top 3 inches. The top 6 inches of soil may over or under estimate the concentrations of contaminants available for human contact, but the concentrations do provide estimates.) The samples were mixed, so it is not possible to distinguish substances found in surface soil ( 3 inches deep) from those in subsurface soil (> 3 inches deep). The concentrations of contaminants that were found in the top layer of soil are generally low. The highest contaminant concentration that was found in the top 6 inches of soil was 15,000 parts per billion (ppb) for the plasticizing agent BEHP.
Only one of the deeper borings located polyvinyl chloride (PVC) sludge. This sludge had concentrations of vinyl chloride of up to 8,300 ppb (the significance of vinyl chloride will be discussed in subsequent sections). The polyvinyl chloride sludge was disposed in two areas in the northeast corner of the site (see areas marked as cells A, B, and C in Figure 1). Other volatile organic compounds that were found in the borings included chloroethanes, chlorobenzene, toluene, acetone, 2-butanone, and xylenes. BEHP was found in all borings in concentrations of up to 240,000 ppb.
The metals that were found in the highest concentrations in the borings were aluminum and iron. The heavy metals lead and mercury were found in many of the samples from waste borings.
3. Groundwater
Table 3 shows the range of contaminant concentrations that were measured in groundwater samples from 29 on-site monitoring wells (4). Perched water (shallow groundwater underlaid by a layer of clay that obstructs its downward movement) is found in two areas of the site. Groundwater on and near the site is also found in a saturated soil aquifer that consists of permeable soils above bedrock. The deepest aquifer on the site is the bedrock aquifer and consists of groundwater in fractured bedrock. Most of the residential wells near the site extend into the bedrock aquifer. The general direction of groundwater movement in the site area is southwest, in the direction of the Susquehanna river; however, because the landfill is situated on a hill, groundwater also flows in several directions towards small streams north, west and south of the site.
Three rounds of groundwater sampling were conducted during the remedial investigation. Sampling occurred in March 1990 (Round 1), November 1990 (Round 2) and February to April 1991 (Round 3). Round 1 and 2 samples were analyzed for volatile and semivolatile organic compounds and inorganic substances (except selenium and antimony). Round 3 samples were analyzed for vinyl chloride and semivolatile organic compounds. Table 3 includes comparison values for the listed substances in drinking water.
Common volatile organic compounds (VOC's) that were detected in the groundwater include acetone, 2-butanone, benzene, ethylbenzene, toluene and xylenes. Vinyl chloride (also a volatile organic compound) was present in several on-site monitoring wells, with the highest concentration (520 ppb) measured in a monitoring well (F-6) that was installed in saturated soil, south of the largest sludge disposal area. Vinyl chloride was found at a concentration of 31 ppb in a bedrock monitoring well (ITB-1) placed along the northern boundary of the site and at a concentration of 13 ppb in an on-site saturated soil monitoring well (B-6) near the southern site boundary. Low concentrations of the pesticide alpha-BHC (lindane) were found in two monitoring wells. Metals that were most commonly found in groundwater at what appeared to be elevated concentrations include iron, magnesium, manganese, and sodium. Contaminants that were detected in concentrations that exceed the available comparison values include benzene, cadmium, manganese and vinyl chloride. Vinyl chloride exceeded the comparison value by the largest margin.
EPA requested that Cecil County conduct an investigation of the septic system that serves the on-site transfer station. This study was conducted by Environmental Resources Management (ERM), Inc. (5). Site investigators observed that the station had an underground septic tank and leach field that received both sewage and fluids that resulted from the compaction of solid waste. The investigation was designed to ascertain the extent to which the compaction fluids (which would be expected to contain common solvents, pesticides, etc.) were contaminating soils and groundwater. A monitoring well was placed near the leach field as part of the investigation; it was sampled in February 1991. The contaminants that were detected in this monitoring well were similar to those detected in the septic tank. The VOCs 1,2-dichloroethane and trichloroethylene were found in the monitoring well sample at a concentration of 410 ppb and 60 ppb, respectively (compared to MCLs for both of 5 ppb). Some of the contaminants that were found in this well were not found in any of the other on-site monitoring wells. Low levels of contaminants were discovered in soil samples collected at various depths (surface and subsurface) from the original drain field.
In the transfer station study report it is concluded that the station was not a significant source of groundwater contamination, based primarily on the fact that soils were not found to be contaminated. State officials would not accept this conclusion because they believed it to be based on inadequate sampling data (personal communication with John Fairbank, MDE site manager). Additional soil sampling and analysis was more recently performed, and the results suggested that the soils were not a significant source of contamination. The county installed a new septic system drain field at the transfer station in May 1990, prior to the initiation of the drainfield study. Compaction fluids are now collected in a separate tank that is periodically pumped out.
Off-site sampling was conducted on surface water, groundwater and sediment (3). Groundwater was sampled from the private wells of residents living in the site vicinity and sediment and surface waters were sampled from the unnamed creek that flows through the southern portion of the site.
1. Surface Water and Sediment
Surface water and sediments were sampled on two separate occasions from the unnamed creek that flows through the southern portion of the site. Samples were first collected from two different sites during February - March 1990 and additional sampling of six different areas was conducted in February 1991. The February 1991 sampling included a drainage (referred to as a swale) that flows into the stream from the southern portion of the site.
During the 1990 sampling, samples were collected from areas that are immediately downstream and upstream from where the southern boundary of the site intersects the stream. A number of compounds were identified in the downstream but not the upstream sediment. These compounds include benzoic acid, pentachlorophenol, and five chemicals within the class known as polyaromatic hydrocarbons (PAHs). The PAHs are commonly occurring environmental contaminants that can be formed when organic substances are burned. Open burning was conducted on-site during the 1970's. A number of metals were also found at higher concentrations in the downstream sediments; these include cobalt, iron, magnesium, manganese, nickel and vanadium. It is not possible to draw any conclusions based on only two samples; however, these results do suggest that the downstream sediment may contain low concentrations of contaminants that have migrated from the site. No rationale was provided for the selection of the two areas that were sampled in February 1990.
The 1991 sampling showed the presence of one organic compound (pyrene) at low concentrations in one downstream water sample but not in any of the upstream samples. Metals that appeared to be slightly elevated in downstream as opposed to upstream water samples included calcium, magnesium and manganese.
The organic chemical (plasticizing agent) BEHP was identified in both upstream and downstream sediment samples that were collected in 1991. A number of metals were found at higher concentrations in the sediments from the swale in the southern region of the landfill as compared to sediments that were sampled from both upstream and downstream areas of the stream. These metals include aluminum, barium, calcium, copper, iron, magnesium, potassium and zinc.
A biological survey of the unnamed creek was conducted in August 1991 by field biologists from IT Corporation (letter from G.B. Markert, Bridgestone-Firestone, Inc. to D. Rossi, U.S.EPA; February, 6, 1992). This type of survey can be used to identify negative effects of pollution on a surface water body such as the creek. Certain types of aquatic insects are sensitive to pollutants, whereas other types are more tolerant. In this study, dip net samples of aquatic insects were taken at 2 sampling stations; one upstream and one downstream from the site. The insects from each station were then examined to see if there was any evidence of a negative impact from site contaminants on the downstream segment of the stream. Although there were fewer insects collected from the downstream site, the type and diversity (the total number of different species) of insects recovered did not indicate that there was a negative impact from the site.
2. Groundwater
Wells of 13 private residences located near the site were sampled and analyzed during November 1990 (see Figure 2) (4). Vinyl chloride (VC) was identified at a low concentration (0.18 parts per billion) in the well of one residence (P309) located approximately 1,000 feet northeast of the site boundary. An on-site treatment system has been installed at this residence, and the well water is being tested at regular intervals to ensure that the system is operating correctly. One residential well (P207), which is located near the entrance to the transfer station, was not sampled in November 1990. The well at this residence was sampled in February 1992 and the water was tested for a wide range of potential chemical contaminants. Only chloroform was detected at a low concentration (6 ppb) in this sample; however, it is unlikely that this is due to site contamination. Chloroform was not found in groundwater from on-site monitoring wells and is a common laboratory contaminant. This well will be resampled to see if chloroform is again identified (personal communication with Charles Smyser, Cecil County Health Department).
VC was not identified in the water from two residential wells (P487 and P501) located immediately to the south of the residential well in which the contaminant was found (i.e., between the well and the landfill). The lack of detectable VC in these wells might be due to the fact that they are considerably deeper than the well in which it was found. It has been postulated that following pumping, as the deeper wells are refilled with water following its depletion from use, water flows down the well wall, allowing any VC to volatilize from the water (personal communication with J. Fairbank of the MDE). VC was identified, however, in a new bedrock monitoring well (ITB-6) that was installed a short distance southwest of the residential well in which it was identified. This well is about 600 feet north of the site boundary. There were no other indications that any site-related contaminants had migrated through the groundwater from the landfill and into any of the residential wells that were sampled.
A number of monitoring wells (approximately 9) were placed along the northern and western boundaries of the site, with some of these wells placed a short distance outside of the site boundaries. It is likely that contaminants detected in groundwater from wells placed on or near the site boundary would have migrated off of the site.
Some contaminants were detected at low concentrations (parts per billion) in groundwater from the monitoring wells placed near the site boundaries. Table 4 lists the contaminants that were detected in those wells and the range of concentrations that were found. Comparison values for these chemicals are also listed. Contaminants that were detected in concentrations that exceed available comparison values include benzene, methylene chloride, manganese and vinyl chloride. The concentrations of toluene and lindane that were detected in the off-site wells are considerably lower than their respective comparison values. The chemical bis-2-ethylhexyl phthalate (BEHP) was found at a concentration of 21 ppb in a saturated soil monitoring well (B-5) located near the landfill's southern boundary.
Table 4 also lists the range of concentrations of some inorganic substances (metals) that were detected in those monitoring wells, possibly at elevated concentrations. It is difficult to determine whether or not the metal concentrations indicate contamination by the landfill because metals occur naturally in groundwater at varying "background" concentrations. The metals in Table 4 are listed because they were found at concentrations that are considerably higher than those reported for any of the residential wells that were tested.
EPA sampled the water from 7 residential wells located 1/3 to 1/2 mile north of the site along Firetower and Colora Roads and Behm Lane in August 1991 (personal communication with Debra Rossi, EPA site manager). The water was analyzed for volatile organic compounds using a method that could accurately detect contaminants down to a concentration of 5 ppb. No contaminants were found in the sampled water. Although concentrations of vinyl chloride below the 5 ppb cutoff would be of concern for long-term exposure, it is unlikely that those wells are contaminated. This is based on their distance from the site and the fact that most of the water from wells that are closer to the site was not contaminated.
Small wells called peizometers were also placed outside of the site boundaries in order to study the direction of groundwater flow. The information gained from these and other wells were used by IT Corporation to construct a computer-generated model of the extent of current groundwater contamination by vinyl chloride. The lowest concentration of vinyl chloride that was modelled was 0.15 ppb. This is the lowest concentration that can be reliably detected using current analytical methods. The model predicted that the vinyl chloride plume (the edge of the contaminated groundwater) had reached one domestic well (P506 south of the site). If no cleanup actions were initiated at the site, the model predicts that the vinyl chloride plume would reach more residential wells during the next 20 year period.
The model provides a "best estimate" of the extent of groundwater contamination. It should be noted that the groundwater near the site that is used for drinking water is found in fractured (cracked) bedrock. There are no available computer programs to model this type of material. The computer program that was used assumes that the groundwater is found in a different type of material. This is a source of uncertainty in the groundwater modelling. The extent to which the model reflects actual conditions can only be determined through additional groundwater sampling.
C. Quality Assurance and Quality Control
A summary of the Quality Assurance/Quality Control (QA/QC) data analysis was included in the RI/FS (3,4). Data validation procedures followed the Quality Assurance Project Plan (QAPP) as well as EPA guidelines for data analysis. The data for soil borings were within QC limits for volatile organic compounds, semi-volatile compounds, and pesticides/polychlorinated biphenyls (PCBs). The results of metal analyses for some soil boring samples did not meet QC criteria and could not be accepted into the data base. QA/QC data for surface water and sediments were considered adequate for all target chemicals except metals.
The analysis of groundwater data showed that these data were within QA/QC guidelines for all target chemicals (all chemicals for which samples were analyzed) except metals. The metals data were reevaluated and it was found that the metals that were outside of the QC limits were not present at the landfill. Based on that finding, the metals detected at the landfill were accepted into the data base.
Some pieces of scrap metal were observed on the site during the site visit. Some of the scrap is large enough for a child trespasser to climb on. This activity could potentially cause injury to the child because of sharp edges, etc.
The build-up of explosive gases is a potential problem at former landfills, such as Woodlawn, that have received mixed solid wastes. The major problem is with the build-up of methane, a gas that is formed from the decomposition of organic materials (i.e., garbage). Although there has been no on-site monitoring specifically for explosive gases, it is unlikely that the build-up of such gases poses a problem to nearby residences. The distance between the area of the landfill where the mixed wastes are buried and the closest residences is sufficient to allow the gases to gradually escape through the overlying soils (which are porous) and not reach nearby homes (personal communication with J. Fairbank, MDE project manager). The potential problem of site-generated gases will be addressed during design of the final site remediation plan.
Exposure pathways are analyzed in order to determine the means by which individuals (primarily local residents) may be exposed to site contaminants. An exposure pathway consists of five elements: a source of contamination; transport through an environmental medium; a point of exposure; a route of human exposure; and an exposed population.
Exposure pathways can be described as completed, potential, or eliminated. In a completed exposure pathway, the 5 elements exist and indicate that exposure to a contaminant has occurred in the past or is occurring. A "potential" exposure pathway indicates that at least one of the five elements is missing. It is possible that the missing element exists (e.g., an exposed population) but has not been identified. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring, or could occur in the future.
A. Completed Exposure Pathways
Groundwater Pathway
A completed exposure pathway exists for Woodlawn Landfill-related contaminants through use of contaminated groundwater in a private well. As discussed in the previous section, vinyl chloride was identified in one residential well at a concentration of 0.18 parts per billion. A treatment system has reduced the exposure levels. The estimated exposed population in this case is 3 people. It may be true that vinyl chloride has reached more private wells in the vicinity of the landfill but is present at a concentration that is below the level that can be reliably detected (0.15 parts per billion). Because the plume of vinyl chloride and other contaminants will spread out over time, it is highly likely that this would become a completed pathway in the future for a greater number of local residents.
B. Potential Exposure Pathways
Table 5 lists a number of potential exposure pathways with respect to site-related contaminants. These pathways include on-site surface soils and seeps, off-site sediment and groundwater, and ambient air both on and off of the site. Any one of these pathways may have been completed in the past or may become complete in the future. The pathways are listed as potential pathways because it is not known whether or not individuals have actually been exposed to site contaminants through any of them.
Keeping in mind current site conditions and available environmental sampling data (Tables 1 and 2) that indicate a low level of contamination in surface media, it is unlikely that the exposure pathways listed in Table 5 represent significant current sources of exposure to site-related contaminants. Also, only a small number of individuals would have the opportunity to be exposed to on-site contaminants, this population consisting primarily of people who occasionally trespass onto the site.
Potential exposure to surface contaminants could become greater in the future. For example, the potential for exposure to surface contaminants could increase in significance during site remediation, when more highly contaminated soils and sludges are exposed. Site workers, visitors, and nearby on-lookers would have an increased likelihood of coming into contact with the contaminants both in the soils and in airborne particles and gases released from the volatile compounds.
Exposure to contaminated stream sediments (in the unnamed creek) is listed as a potential exposure pathway; however, it is unlikely that this is currently a significant exposure pathway. There was little evidence of site-related contamination in stream sediments and the stream is not easily accessed, nor is it large enough to serve as a major source of recreation.
Exposure to contaminated groundwater in residential wells is listed as a potential exposure pathway with respect to residents whose wells are currently uncontaminated but may become contaminated in the future. As previously discussed, other wells may become contaminated as the plume continues to migrate.
Although there are no available sampling data for ambient air, it is unlikely that there would be any measurable quantities of airborne contaminants either on or off of the site. There are no areas, such as surface lagoons, where significant quantities of volatile contaminants are directly exposed to the air and the site is heavily vegetated, which helps to minimize the creation of contaminated airborne dust. The one exception may be during remediation if subsurface soils are excavated.
TABLE 5. POTENTIAL EXPOSURE PATHWAYS
| PATHWAY | MEDIA AND TRANSPORT | POINT OF EXPOSURE | ROUTE OF EXPOSURE | EXPOSED POPULATION |
| On-site surface soil | surface soil | contaminated areas on site | ingestion, skin contact | site trespassers; landfill workers |
| On-site seeps | surface water | on-site seeps | ingestion, skin contact |
site trespassers; landfill workers |
| Ambient air | air | on site, nearby residences |
inhalation | site trespassers; local residents; workers |
| Off-site groundwater | groundwater | residences | ingestion, inhalation, skin contact |
residents in vicinity of landfill |
| Off-site sediment | contaminated surface water and sediment | off-site sediment (stream) | skin contact | recreational users of the unnamed creek |
This section discusses the health effects that can be caused by exposure to site contaminants, evaluates state and local health data bases, and addresses specific community health concerns. To assist in the evaluation of the potential health effects of chemicals commonly found at hazardous waste sites, ATSDR has developed a series of Toxicological Profiles. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status. When sufficient information is available for a chemical, ATSDR has developed Minimal Risk Levels (MRL). A MRL is an estimate of daily human exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for each route of exposure, such as ingestion, inhalation, and dermal absorption and for the length of exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greater than 365 days).
People are often concerned about the potential for environmental contaminants to cause cancer in exposed individuals. To help put this concern into perspective, it is important to realize that Americans now have about a 1-in-3 chance of developing cancer during their lifetimes (6). Although the causes of all cancers are not understood, scientists agree that lifestyle factors, such as one's diet and smoking status, are important risk factors for some of the most common cancers (such as lung and colon cancer). Exposure to low levels of environmental contaminants are likely to cause only a very small increase in a person's risk of developing cancer.
Two of the contaminants that have been identified in on-site groundwater (benzene and vinyl chloride) are considered human carcinogens because of studies that have shown an increased rate of certain types of cancer in workers who were exposed to these chemicals for extended periods of time in the workplace. It may be true that exposure to very low concentrations of these chemicals, such as the levels identified in on- and off-site groundwater, would pose no cancer risk at all. However, government agencies that are concerned with protecting public health generally make the conservative (the most health protective) assumption that the risk of cancer is increased with any exposure to such chemicals. The same conservative assumption is made for another chemical (BEHP) that has only been shown to cause cancer in animals that are exposed to relatively high concentrations of the chemical in their diets over their lifespans.
Not all of the substances included in Tables 1 through 4 are discussed below. An emphasis has been placed on contaminants that are included in Table 4 (off-site monitoring wells) because of evidence that these contaminants are being transported off of the site. Also, some contaminants that are not discussed have a relatively low degree of toxicity in humans (e.g., iron and sodium in Table 3). As was mentioned in previous sections, the only known completed exposure pathway is for vinyl chloride in groundwater.
Organic compounds
Benzene-- Benzene is a major industrial chemical that is made from coal and oil. Benzene also occurs naturally in many plants and animals. Benzene is known to be a human carcinogen (7). Leukemia (cancer of the tissues that form the white blood cells) has occurred in some workers exposed to benzene for periods of less than 5 and up to 30 years. Long-term exposures of humans to benzene may also affect normal blood production. Human and animal studies also indicate that benzene is harmful to the immune system. Exposure of pregnant animals to benzene has resulted in adverse effects on fetuses; however, there is no clear evidence of adverse reproductive effects in humans (7). Benzene has been identified in the water of monitoring wells on and off of the landfill, but it has not been identified in any residential wells near the site.
The highest concentrations of benzene that have been identified in both on- and off-site groundwater monitoring wells are 75 and approximately 2 ppb, respectively. The on-site concentration is considerably higher than the Maximum Contaminant Level for benzene of 5 ppb. Lifetime exposure of people to this concentration in drinking water would pose an unacceptably high cancer risk (7). Benzene was not identified in any of the residential wells that were tested; therefore, no risk of adverse cancer or non-cancer effects are expected to people in the community as a result of benzene at the site. Should private well water become contaminated with benzene in the future, any human exposure to the water should evaluated for possible adverse health effects at that time.
Bis(2-ethylhexyl)phthalate (BEHP)-- BEHP is a chemical that is commonly used to make plastics more flexible. Plastics may contain from 1 to 40% BEHP by weight. Humans are primarily exposed to BEHP through foods that come into contact with packaging material that contains it. There are no studies on the health effects of BEHP in humans, although there have been no reports of adverse health effects in workers who are exposed to BEHP (8). Studies in which laboratory animals (rats and mice) were given BEHP in food have shown that adverse effects on the liver and developing fetuses occur at the lowest levels of exposure. BEHP has also produced liver cancer in rats exposed to high concentrations of the chemical in food over a two year period (8).
Low concentrations of BEHP (up to 140 ppb) were found in on- and off-site groundwater. This concentration would not be expected to cause any adverse health effects in exposed individuals; however, lifetime exposure to this concentration (140 ppb) in drinking water might result in a slight increase in an individual's cancer risk (8). The highest level of BEHP found in on-site leachate soils is 5,800 ppb. This level of BEHP in soil does not represent a significant health hazard. This chemical does not evaporate easily and is not easily absorbed through the skin (8).
Methylene Chloride-- Methylene chloride is a widely used industrial solvent and paint stripper. In humans, exposure to sufficiently high concentrations of methylene chloride in air (about 500 ppm) can cause irritation to the eyes, nose and throat (9). Exposure to these levels can also cause central nervous system symptoms similar to those caused by alcohol intoxication. Methylene chloride has caused cancer of the liver and lung in laboratory animals exposed by inhalation to high levels of the chemical over a lifetime. The chemical has also caused liver cancer in laboratory animals following long-term oral exposure. There is no evidence for an increase in cancer deaths in humans occupationally exposed to methylene chloride (9). Methylene chloride was identified in off-site monitoring wells, but it was not found in residential wells near the site.
Methylene chloride was found in both on- and off-site monitoring wells at a highest concentration of 38 ppb. Lifetime exposure of people to this level of methylene chloride in drinking water might result in a slight increase in an individual's risk of developing cancer should private wells ever become contaminated (9). At present, no one is exposed to the contaminant; therefore, no adverse health effects as a result of methylene chloride are expected to occur.
Vinyl chloride-- Humans occupationally exposed to high levels of vinyl chloride vapors have shown damage to the liver, central nervous system and peripheral blood circulation (10). Long-term occupational exposures have also been associated with cancer of the liver and possibly the brain. Exposure of laboratory animals to vinyl chloride vapor has also caused liver cancer (10).
There is no information on the effects of vinyl chloride in humans following oral exposure. Oral exposure of laboratory animals to vinyl chloride has caused liver toxicity and cancer of the liver. ATSDR has developed a Minimal Risk Level (MRL) for long-term oral exposure to vinyl chloride of 0.0013 mg/kg/day (10). This is equivalent to a concentration in drinking water of about 30 parts per billion (ppb). No non-cancer adverse health effects would be expected from long-term exposure to the low concentration of vinyl chloride that was found in one residential well (the highest concentration observed was about 0.2 ppb). Long-term exposure to this level of vinyl chloride in drinking water might result in little to a slight increase in the individual's risk of developing cancer during his or her lifetime (10).
Metals
Manganese-- Manganese is a naturally occurring substance found in many types of rock. People are regularly exposed to low levels of manganese in water, air, soil and food (11). A certain amount of manganese in the diet is believed to be necessary for good health. Manganese has caused disease in workers exposed to high levels of manganese-containing dust in the air for a year or longer. Symptoms of the disease include mental and emotional disturbances and incoordination. It is not known whether or not oral exposure of humans to manganese can cause the disease associated with dust exposure (11). Manganese has not been found at increased concentrations in residential wells near the landfill; therefore, no risk of adverse health effects are expected to people in the community as a result of manganese at the site. However, it has been found in on-site and off-site monitoring wells at levels that are higher than the health comparison value. Should private well water become contaminated with manganese in the future, any human exposure to the water should evaluated for possible adverse health effects at that time.
C. Health Outcome Data Evaluation
As noted previously, the Maryland Department of Health and Mental Hygiene has vital statistics (births and deaths) and birth defects data available for given time periods at the county level. In the discussion that follows, the rates for Cecil County are compared to rates for the State as a whole.
MDE believes that it is very unlikely that people have been exposed to sufficient quantities of contaminants from the Woodlawn Landfill to result in any detectable increases in exposure-related illness. This notwithstanding, an evaluation of the available health outcome data is included in this section. A number of points should be considered when these data are evaluated with respect to the potential impact of exposure to site-related contaminants. These points include the following:
It should be noted that if the public health assessment team at MDE suspected that exposure to site-related contaminants was causing disease or illness in an exposed population, MDE would recommend that a more detailed study of this population be initiated. This recommendation will also be made if a review of health outcome data that become available in the future indicates the need for a more detailed investigation.
With the above points in mind, the following health outcome data have been reviewed for Cecil County:
Data for the occurrence of thirteen separate birth defects (referred to as sentinel defects) are available for Maryland at the county level for the years 1984 to 1988. During this time period, the incidence rate for infants born with one or more of the 13 defects was 95.9 per 10,000 for Cecil county (34 infants out of 3,547 total births) as compared to 63.8 per 10,000 (1,920 infants out of 300,882 total births) for the State of Maryland as a whole. The two types of birth defects that occurred at a significantly higher rate (based on statistical analysis) among Cecil County births as compared to the state as a whole were spina bifida with or without hydrocephaly (14.1 per 10,000 live births for the county as opposed to 5.3 per 10,000 live births for the state) and Down Syndrome (19.7 per 10,000 live births for the county as opposed to 7.2 per 10,000 live births for the state).
The birth defect rates for spina bifida and Down Syndrome in Cecil county are based on totals of 5 and 7 cases, respectively, out of the 3,547 births that occurred in the county during the 4 year period. These rates are thus based on a relatively small number of cases.
The increased rate of the 2 birth defects that was observed in Cecil County during the four year period is not likely due to exposure to contaminants from the Woodlawn Landfill. The only known completed exposure pathway for this site is for a very low concentration of vinyl chloride in the drinking water supply of one residence. Local residents may also have been exposed to airborne contaminants; however, this would likely have been an infrequent exposure to low concentrations of volatile chemicals, and would not be expected to cause adverse health effects. Spina bifida has been associated with dietary deficiencies in the mother and Down Syndrome is more prevalent when the mother is older. Other possible causes of those birth defects are not clearly understood.
Cancer Mortality
Age-adjusted (to 1970 U.S. population) death rates are available at the county level for the period of 1983 to 1987. Average annual cancer death rates per 100,000 population were not significantly different (based on statistical analysis) for Cecil County as compared to the State of Maryland as a whole for the most common forms of cancer (see below).
| Maryland | Cecil County | |
| (cancer death rates per 100,000) | ||
| Bronchus/Lung | 53 | 56 |
| Breast | 30 | 22 |
| Prostate | 27 | 26 |
| Bladder | 4 | 4 |
| Cervix | 3 | 1 |
| Colon | 20 | 20 |
| Lymphoma | 6 | 6 |
| Esophagus | 5 | 3 |
| Melanoma | 2 | 3 |
| All other | 43 | 43 |
As noted previously, no conclusions can be made regarding the impact of site-related contaminants on the health of exposed individuals based on our evaluation of the available health outcome data. It can be concluded that during the period from 1983 to 1987, residents of Cecil County did not die from the cancers listed above at rates that differed significantly from the residents of the State of Maryland as a whole. It can further be concluded that 2 of 13 birth defects occurred at a significantly higher rate in the county as compared to the state as a whole during the period from 1984 to 1988.
The increased rate of those birth defects are not likely a result of environmental exposures to contaminants from the site because people are known to have only been exposed to low levels of vinyl chloride, which has not been associated with those birth defects. Spina bifida has been associated with dietary deficiencies (folic acid) of the mother and Down Syndrome is more prevalent when the mother is older. Other factors that may be associated with the birth defects are not clearly understood.
D. Community Health Concerns Evaluation
1) The potential hazard posed by exposure to contaminated groundwater.
A low concentration of vinyl chloride (approximately 0.2 ppb) has been discovered in one residential well. Vinyl chloride is considered a human carcinogen as a result of observations of increased rates of cancer (primarily of the liver) in workers who were exposed to high levels of the chemical. The level of vinyl chloride that was observed in the well is one tenth of the Maximum Contaminant Level (MCL) of 2 ppb that has been established by the U.S. EPA for public drinking water supplies. Based on conservative exposure assumptions, residents that drink and bathe for a lifetime in water contaminated with the low concentration (i.e., about 0.2 ppb) that was discovered in the residential well, may result in a very slight increase of risk of developing cancer. In the residence where vinyl chloride was discovered, continued exposure has been prevented by the installation of a water treatment system.
No contaminants have been detected in other residential wells that have been tested in the site vicinity (i.e., along Firetower, Colora and Waibel roads). Residents living near the site who are concerned about possible contamination of their groundwater can have the water tested by making arrangements with the Cecil County Health Department.
2) The source and possible health effects of odors detected by residents living near the site.
Two residents living on Firetower road, east of the site, have complained of encountering strong, ammonia-like odors. One resident stated that he encountered these odors during the early evening hours on several occasions. Because the identity of the gases causing these odors is not known, it is not possible to discuss the potential health effects associated with exposure. The odors were described as strong and irritating. In one reported incident a woman became light-headed following exposure to chemicals in air. This woman had been using cleaning products prior to this incident and this may have caused or contributed to her symptoms.
The source of these odors is not known. Gases that are generated by landfills such as Woodlawn in the greatest amounts include carbon dioxide, methane, nitrogen, and occasionally hydrogen sulfide (12). These gases are all odorless with the exception of hydrogen sulfide, which has a strong rotten-egg odor. Volatile organic compounds such as vinyl chloride, toluene, and benzene can also be present in lower concentrations.
A possible source of ammonia-like odors in the area around the site is from the spreading of manure on fields as well as its storage in manure ponds. A dairy farm that stores manure in ponds is located about 1 mile north of the site. Also, ammonia-containing fertilizers are sometimes applied directly to fields.
3) Potential effects of site-related contaminants on domestic animals.
The main surface pathway for the off-site transport of contaminants appears to be the unnamed creek that flows through the site. The stream water and sediment samples that were analyzed showed only very low levels of contamination at the time of sampling. Also, the results of biological sampling of the stream did not indicate that the site was adversely affecting water quality in the downstream section.
Based on these results, it does not appear that the stream would currently pose a health hazard to domestic animals that drink from it downstream of the landfill.
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