PUBLIC HEALTH ASSESSMENT
MIDDLESEX SAMPLING PLANT (USDOE)
MIDDLESEX, MIDDLESEX COUNTY, NEW JERSEY
The Agency for Toxic Substances and Disease Registry (ATSDR) has prepared this public health assessment to evaluate the potential for contaminants at the Middlesex Sampling Plant (MSP), Middlesex, New Jersey, to harm people living near or accessing the site. By reviewing existing data, ATSDR determined that soil, sediment, and shallow groundwater at the site, as well as soil in certain off-site locations, is contaminated with arsenic, chromium, lead, and radionuclides at concentrations considered to be of health concern. However, based on its evaluation, ATSDR determined that no exposures posing public health hazards are occurring now or are likely to occur in the future, as long as safety precautions are followed during future excavation activities at the site. However, ATSDR determined that there might have been past exposures to certain arsenic, lead, uranium and radium contaminated media associated with the MSP site.
The MSP site occupies about 9.6 acres in Middlesex, New Jersey. Originally, the site served as an asphalt paint manufacturing plant from 1910 until 1943, when it was converted into a government uranium ore sampling and storage facility. From 1943 until 1967, the U.S. Department of Energy used the site primarily for sampling, analysis, storage, and shipment of uranium, beryllium, and thorium ores. Over the years, the buildings and surface soil at the site and on nearby parcels of land became contaminated with metals, including arsenic, lead, and chromium, uranium and radium. Some contaminants leached through the soil to the groundwater beneath the site, migrated with soil/sediment through the on-site culvert system/drainage ditch, or migrated via airborne transport. When the site was leveled in 1947 or 1948, contaminated excess soil was sent to the Middlesex Municipal Landfill for use as cover. Some of this soil was also used as fill at a nearby residence and at the rectory and playground of the Church of Our Lady of Mount Virgin at the corner of Harris and Drake Street in Middlesex Borough. After detecting elevated low levels of uranium in surface-water samples collected downstream, the U.S. Environmental Protection Agency (EPA) placed MSP on the National Priorities List of hazardous waste sites in February 1999.
As part of the public health assessment process, ATSDR conducted site visits and met with representatives from the community, U.S. Army Corps of Engineers, and EPA. During the site visits, ATSDR did not identify any immediate public health hazards, but determined that additional information was needed to more fully evaluate potential exposure to contaminated soil and groundwater, and to a lesser extent to surface water/sediment and air.
ATSDR evaluated available environmental data and information about the MSP site and the surrounding community to assess whether harmful exposures occurred in the past, are occurring, or could occur in the future. ATSDR has determined that former residents of, or visitors to, properties with contaminated fill might have been exposed in the past to site-related contaminants, including arsenic, lead, radium, uranium, and other radionuclides at unknown levels. The primary exposure pathway was inadvertent ingestion of contaminated surface soil. Because radionuclides associated with MSP emit radon gas, radon progeny and ionizing radiation, exposure also might have occurred from breathing indoor air containing elevated radon and its progeny or from exposure to external gamma radiation. Former workers at the MSP site were also at risk from contact with soil, inhalation of radon and dust, and direct contact with uranium, thorium, and beryllium ores and the byproducts generated during the ore sampling process.
The grassy area on the southern border of the site has a large population of ticks, and special care should be taken by anyone walking through the area to check for ticks on their scalp or skin.
Workers at the site, particularly those who worked in the process building, were exposed to radon gas and airborne particulates during their workday. The full extent of exposure to airborne particulates during former operations remains uncertain due to limited sampling data and information about actual exposure.
Several measures have been taken to remove contaminants from the structures and surface of the MSP site and from nearby affected properties. Any remaining contaminated soils at the site are covered with asphalt and grass, and access is limited. ATSDR concludes that, under these conditions, the site poses no current public health hazard.
During future remediation efforts, remedial workers must be adequately protected from contaminants associated with the material buried beneath the site. As an additional precautionary measure, ATSDR further recommends that, until the site is fully remediated and free of potential physical hazards, more efforts should be made to secure the site (e.g., fix gaps in gates) from trespassing. As long as workers are protected and trespassing is restricted during remediation, no future public health hazards should occur.
A private well survey indicates that approximately 140 private wells are in the vicinity of the MSP site. Recent monitoring of several private wells near the MSP site found some radionuclides and metals in the well water, but at levels below health concern. Nearby private wells should be regularly monitored for contaminant migration in the future.
The Middlesex Sampling Plant (MSP) is a 9.6-acre site located at 239 Mountain Avenue in the Borough of Middlesex in Middlesex County, New Jersey (see Figure 1). The site is bordered on the east by residential and commercial properties; on the west by a scrap metal facility; on the north by the Lehigh Valley railroad line; and on the south by vacant marshy land and fields. The unoccupied site is surrounded by a 7-foot-high chain-link fence with gates at the main entrance on Mountain Avenue, and at the Wood and Williams Street entrance. Most of the site (70 percent) is covered with asphalt; only an office building, a garage, and two foundation slabs from buildings demolished in 1996 remain on site.
The 239 Mountain Avenue property was originally developed in 1910 as an asphalt paint manufacturing plant, consisting of a large two-story brick warehouse, a boiler house, a garage, an administration building, a dye warehouse, and four smaller outbuildings. The name of the paint manufacturer is unknown. The company went broke in 1913 and was bought by American Marietta Company. Under new management, the American Asphalt Company became successful, particularly after other colors, such as aluminum, were added to the standard black available (Sloan, 1983).
In October 1943, the U.S. Army Corps of Engineers leased the brick warehouse for the Manhattan Engineer District (MED) as one of the industrial sites chosen to perform different operations as part of the United States' efforts to develop the atomic bomb. In late 1943, a stockpile of 1,200 tons of uranium ore from the Belgian Congo was sent to the MSP site for sampling, weighing, and assaying. Far greater tonnage of uranium, and later beryllium and thorium ores, were gradually shipped from Africa and India into Staton Island and then to the MSP site.
Once the ore was sampled, weighed, and assayed, it was shipped from MSP to the Linde Refinery, Tonawanda, New York, where it was processed into black oxide or sodium di-uranate concentrates. These concentrates were further processed at various locations and eventually shipped to the Hanford nuclear reactors at Richland, Washington, for use in plutonium production. The plutonium was shipped to Los Alamos National Laboratory in New Mexico for use in developing the atom bomb (DOE, 1980).
In 1946, the Atomic Energy Commission (AEC) condemned and purchased the leased properties when the MED was deactivated. Uranium oxide (Q-11) remained the chief material processed, but after 1950, magnesium di-uranate precipitate (MgX) and beryl ore (INX) were also processed there (Cahalane, 1958).
Processing of the ores primarily occurred in one of several on-site buildings. These buildings included the original American Marietta warehouse, which was converted to the process building where the ore was sampled and assayed; a concrete thaw house, which stored ore in need of thawing; and a new boiler house, which housed the boiler for the process building. The site also housed a Quonset hut for enclosed storage, an administration building, and a garage.
Wastewater from the process building entered a 500-cubic-foot settling tank, where it was filtered to remove solids and then released to the drainage ditch that carried surface water off site. An underground conduit system also fed the drainage ditch. Process waste might have also entered a sump system that flowed to a catch basin located between the process building and the garage. (see Figure 2). In 1947, the approximately 9.6-acre site was surrounded by a chain-link fence and 8 acres were paved with asphalt to provide a drum storage area (DOE, 1997). By 1955, AEC terminated primary activities at MSP but continued on-site storage and sampling of thorium residues until 1967, when they ceased all activities at the site. From 1969 until 1979, the U.S. Navy used the site as a reserve training center for the U.S. Marine Sixth Motor Transport Battalion training center from 1969 to 1979. No commercial or industrial activities have been conducted at MSP since 1980.
During the years that the MSP was operational, the buildings, grounds, and nearby parcels of land became contaminated mainly from spillage and subsequent migration mechanisms (BNI, 1995). The metal contamination probably resulted from on-site ore sampling processes or from typical operations and past accidental spills at the American Marietta paint manufacturing plant. Some the contamination has leached through the soil to the groundwater beneath the site, migrated with particles through the on-site culvert system/drainage ditch, or migrated through the air. When the site was leveled and asphalted in 1947, excess soil, which was contaminated with spilled ore and metals, was sent to the Middlesex Municipal Landfill (MML) for use as cover. Some of this soil was also used as fill at a nearby residence and at the rectory and playground of the Church of Our Lady of Mount Virgin at the corner of Harris and Drake Street in Middlesex Borough (SAIC, 1995).
After AEC activities stopped in 1967, Isotope, Inc., a contractor for the AEC, decontaminated the site. Isotope sandblasted or cleaned structures at the site, removed a foot of soil from a tunnel under the process building, and cleaned and/or covered the underground settling tank, sump, and various pits. Additionally, portions of the process building, including the loading dock and the conveyor building, were completely removed. Approximately one-half inch of the top of the asphaltic concrete covering about 8 acres of the site was removed, and contaminated soil was excavated. Resulting debris was shipped by railroad cars to an off-site burial area. Following an AEC survey to assess the radiologic conditions at the site, the property was released for unrestricted access (ORNL, 1977).
In 1960, elevated gamma radiation levels were detected at the Middlesex Municipal Landfill by civil defense monitors during a local civil defense exercise. A survey conducted by the AEC found external gamma radiation levels at 20 to 50 times background over an approximate one-half acre area. The AEC removed approximately 650 cubic yards of the contaminated material most near the surface and covered the area with about two feet of uncontaminated dirt, lowering external gamma radiation levels to less than 0.05 mR/hour (ORNL, 1978).
The Oak Ridge National Laboratory (ORNL) conducted another radiological survey of the MSP site in 1976. Elevated concentrations of radon in buildings from elevated levels of radium in soil were identified, suggesting the need for further characterization of on-site conditions (ORNL, 1977). A subsequent aerial survey identified radiologic contamination on adjacent and nearby residential, commercial, and vacant properties.
In 1980, the MSP site was placed under the DOE's Formerly Utilized Sites Remedial Action Program (FUSRAP). The FUSRAP identifies and decontaminates sites where radioactive contamination remains after operations are carried out under contract with the MED and AEC. This program was administered by DOE until 1997, when it was transferred to the U.S. Army Corps of Engineers (USACE).
Under the FUSRAP program, DOE began to investigate environmental conditions at the MSP site to determine the nature and extent of radiologic releases to the soil, groundwater, surface water/sediment, and air on and immediately near the site. In 1991, volatile organic compounds (VOCs) and metals were added to the annual environmental surveillance program. Various site investigations and environmental surveillance monitoring indicated that elevated levels of contaminants were present in on-site soil, groundwater beneath the site, and surface water moving through the site. The suspected on-site sources include the facility soil, on-site storage piles (the "vicinity properties" [VP] and the MML piles discussed below), and possible contaminated buried features including the settling tank, the sump, the tunnel under the process building and the partial basement. The original contaminants of primary concern to DOE at MSP were the natural radioactive elements uranium, radium, and, to a lesser extent, thorium. Uranium and radium and their decay products were also detected in off-site locations where MSP soil was used as fill or where contaminants migrated via airborne transport.
After investigations revealed radioactivity in off-site soil, DOE conducted a two-phase removal action. During Phase I, which began in 1980, contaminated soils (and sediments) were removed from four of the most heavily contaminated off-site properties, including the residential property, the rectory of the Church of Our Lady of Mount Virgin in Middlesex Borough, and portions of the church playground. During Phase II, completed in 1981, more contaminated soil and sediment were excavated from the on-site drainage ditch and from 29 adjacent, lesser contaminated properties, where contaminants had settled via airborne transport. The approximately 35,200 cubic yards (yd3) of contaminated soils from both Phase I and II were placed in the VP pile at the MSP site. In addition, in 1984, approximately 15,600 yd3 of radiologic contaminated soil and waste (originally from the MSP site) were excavated from the MML site and placed in a separate interim storage pile at MSP, called the MML pile. An additional 15,600 yd3 were removed from the landfill and added to the on-site MML pile in 1986, bringing the estimated total volume of the pile to 31,200 yd3. Both the VP and MML piles were constructed on an asphalt base with appropriate "curbing" to control contaminant migration and covered to prevent erosion and airborne transport of contaminated soil (SAIC, 1995). The MML pile was also connected to a newly installed leachate collection system. In 1998, the MML pile was removed from MSP and disposed of at a certified hazardous material landfill. Removal and disposal of the VP pile was completed in 1999.
Starting in 1996, DOE initiated a series of actions to remove or remediate contamination at the MSP site and to further eliminate potential off-site migration. These actions included removing additional sediment from the on-site drainage ditch and demolishing the existing process building (DOE, 1997a). During 1996, monitoring detected total uranium in an off-site monitoring well located south and downgradient of the site and, in 1997, uranium was detected in an off-site surface water body. By February 1999, EPA had listed the MSP site on the National Priorities List of sites because of concerns about radioactive contamination in surface water and contamination of wetlands and a sensitive environment (EPA, 1999).
As part of the public health assessment (PHA) process, representatives of the Agency for Toxic Substances and Disease Registry (ATSDR) visited MSP on July 14-16, 1999. During the visit, ATSDR staff members met with representatives of the Middlebrook Regional Health Commission, toured the perimeter of the site, and reviewed the local health department's historical documents pertaining to environmental sampling and remediation activities.
During the site visit, ATSDR staff noted that all three gates at MSP were closed and padlocked. "No Unauthorized Access" signs were prominently displayed at each gate area. Although no holes or gaps in the perimeter fence were noted, it appeared that entry to the site could be gained through a gap between the gate and the fence located at the Wood Avenue entrance on the eastern side of the site. No on-site bike trails or footpaths were evident, but a number of tennis balls were found in the grass around the perimeter of the asphalt pad. The surface soil at MSP is predominantly covered with asphalt, concrete, small shrubs, grass, and other vegetation. No visible airborne dust was observed.
Although high grass and vegetation provide some cover, the south drainage ditch was accessible by ATSDR staff and potentially by the general public (Figure 2). However, there were no obvious signs, such as worn foot paths or bicycle tracks, indicating that access had occurred. The high grass on the southern border of the site has a large population of ticks, and special care should be taken by anyone walking through the area to check for ticks on their scalp or skin.
On December 16, 1999, ATSDR representatives revisited the site, met with representatives of USACE and EPA, and met with community members at a public availability meeting at the Middlesex High School. Following the visit, ATSDR developed a fact sheet to further answer questions about MSP and ATSDR's involvement at the site. ATSDR mailed the fact sheet in January 2000 to more than 4,500 Middlesex and Piscataway community members living in an approximate 1-mile radius of the site. Through the mailing, community members were encouraged to share with ATSDR any health concerns they might have regarding possible exposures to site contamination. ATSDR heard from community members through more than 175 responses, including 106 letters expressing health concerns and questions. ATSDR addresses their concerns in the "Community Health Concern" section of this PHA.
Several of the community members responding to ATSDR's mailing questioned whether their private well water was safe for drinking. Because information about the private wells was not available at the time to answer this question definitively, ATSDR sampled well water from nearby private wells in February 2000 and again in April 2000. The results of the private well sampling are discussed in the "Evaluation of the Groundwater Exposure Pathway" section of this PHA. During the visit in April 2000, ATSDR reviewed the documents in the MSP reading repository located at the Middlesex Library. The repository contains extensive information on the history of the site and on subsequent operations and remediation effort at and around the MSP.
ATSDR examines demographic information, or population information, to identify sensitive populations, such as young children and the elderly, in the vicinity of a site. Demographics also provide a particular area's residential history--information that helps ATSDR assess time frames of potential human exposure to contaminants. Demographic information collected by the U.S. Bureau of Census (1990) indicates that 11,318 people live within one mile of the MSP site. Roughly one-tenth (10 percent) of the residents are 6 years or younger and about one-tenth of the population (11 percent) is 65 or older (see Figure 3).
ATSDR also reviewed land use at and near the MSP site to identify valuable information on the activities conducted in the surrounding area and the possibility of exposure through these activities. The land surrounding the MSP site consists of a mixture of residences, commercial, industrial properties, and undeveloped land (see Figures 1 and 2). Auto salvage shops border the site to the immediate northwest and along a portion of the eastern boundary. Most of the nearby residences are located along the eastern side of the site, where the nearest residence sits approximately 100 feet away from the site boundary (SAIC, 1995). The residence on Williams Street, that received contaminated soil from the MSP site is located approximately 1 mile to the east of the MSP site. The Church of Our Lady of Mount Virgin is located approximately one-half mile west, and the MML site is located just less than a mile northwest from the site (see Figure 2).
The nearest surface water to MSP is the Main Stream, which flows just south of the site. The Main Stream, a freshwater tributary of the Raritan River, is classified by EPA and the New Jersey Department of Environmental Protection as a supply source for public drinking water. The nearest drinking water intakes are located in the Raritan River, approximately 3.3 miles south (downstream) of the site. An on-site drainage ditch known as the south drainage ditch converges with the Main Stream about 0.25 miles south of the site, which then flows into Ambrose Brook. (All on-site surface water moved through an underground drainage system ditch either directly to the southern drainage ditch or to a settling basin and then to the drainage ditch.) Ambrose Brook empties into Green Brook just before it joins the Raritan River (SAIC, 1995). Instead of public water, a number of residents near the MSP site rely on private wells for their drinking water and for domestic use. Those private wells draw water from the same aquifer that lies beneath the site. According to a 1990 private well survey, approximately 140 private wells are located within a mile of the MSP (BNI, 1991).
Middlesex County contains many parks, wilderness areas, and golf courses. The county government presently operates 19 county parks, encompassing 7,020 acres. Thirteen of these locations contain active recreational facilities, and five are conservation areas or are being held for future development. The New Jersey Department of Fish, Game, and Wildlife (NJDFGW) stocks the Green Brook and the Raritan River with adult trout for fishing. The NJDFGW has also identified other edible fish in the Raritan, including stripped bass, American shad, and northern pike. Vacant land south of the site abuts the Main Stream and provides habitat for wildlife (e.g., birds, small animals, deer). People have been observed fishing in the Raritan River, but hunting in the area is prohibited.
ATSDR searched the EPA's Toxics Release Inventory (TRI) database for reports of chemical releases within 3 miles of the MSP site for 1997--the most recent year for which data are available. The TRI database contains extensive emissions data for a wide range of industries. However, the TRI data are self-reported, and the accuracy of the reporting facilities is not known. Also, the TRI regulations require facilities to disclose releases of a wide range of hazardous pollutants, but not for all contaminants released to the environment. Therefore, the data described should not be viewed as a comprehensive inventory of emissions in the area of the MSP site.
Eight facilities in the TRI are located within 3 miles of the MSP site; those sites include one facility in Bound Brook, two facilities in Middlesex and in Plainsfield, and three facilities in Piscataway. Five facilities reported releases to the air of VOCs, semivolatile organic compound (SVOCs), and/or metals; no releases to the surface water or from the on-site landfill were reported. None of the facilities has reported releases of chemicals identified at the MSP or at affected off-site properties (e.g., private home on Williams St. and the church rectory). ATSDR identified 34 facilities in a 5-mile radius of the site, and 72 facilities are within a 10-mile radius, suggesting that the area is highly industrial.
In preparing this PHA, ATSDR reviewed and evaluated information provided in the referenced documents. Documents prepared for DOE and USACE's FUSRAP program must meet specific standards for adequate quality assurance and control measures for chain-of-custody procedures, laboratory procedures, and data reporting. The environmental data presented in this PHA are from DOE and USACE, and include investigations of the radiological surveys of on-site and off-site locations, as well as from information provided by New Jersey Department of Environmental Protection (NJDEP). Based on our evaluation, ATSDR determined that the quality of environmental data available in site-related documents is adequate to make public health decisions. Spatial distribution of sampling locations, sampling frequency, concentration changes over time, and the correlation between the selected list of analytical parameters and suspected environmental contaminants are factors considered by ATSDR when determining the contaminants to which individuals could be exposed.
ATSDR also collected groundwater and private well water samples. Sampling and laboratory analysis of these samples were completed using acceptable methods, and data validation was performed using appropriate analytical criteria. The adequacy and number of replicate and blank samples were checked to verify detection of contaminants, and information on background concentrations was accounted for in the interpretation of the analysis data. Laboratory quality controls and procedures used to verify instrument reliability were reviewed.
In this section, ATSDR discusses the radionuclides and chemical contaminants detected at or near the Middlesex Sampling Plant (MSP) site. Because a release of a radionuclide or chemical into the environment does not always result in human exposure, ATSDR further evaluated how people might come in contact with these materials/contaminants and the potential for these exposures to cause harm to people. ATSDR uses a conservative exposure evaluation process to consider how people might come in contact with, or be exposed to, contaminated media (see Figure 4). Specifically, ATSDR determines whether an exposure could occur through ingestion, dermal (skin) contact, or inhalation of vapors, and considers the likely length (duration) and frequency of the exposure.
If exposure was, or is possible, ATSDR then considers whether radionuclides or chemicals were or are present at levels that might be harmful to people. ATSDR does this by screening the concentrations of chemical contaminants in an environmental medium against health-based comparison values (CVs). These CVs are concentrations that health scientists have determined are not expected to cause adverse effects, even when assuming very conservative/safe exposure scenarios. Because CVs are not thresholds of toxicity, environmental levels that exceed comparison values would not necessarily produce adverse health effects. If a chemical is found in the environment at levels exceeding its corresponding CV, ATSDR examines potential exposure variables and the toxicology of the contaminant. ATSDR emphasizes that regardless of the level of contamination, a public health hazard exists only if people come in contact with, or are otherwise exposed to, harmful levels of contaminated media.
After an initial review of potential health hazards at the MSP site, ATSDR determined that exposure to contaminated soil, groundwater, surface water/sediment, and air (radon and particulates) required further evaluation. ATSDR selected these pathways because of the evidence of contamination and the potential of human contact with the contaminated media. Following the strategy outlined in Figure 4, ATSDR examined whether human exposure to harmful levels of contaminants via these pathways existed in the past, exists now, or could potentially exist in the future. For the soil, groundwater, and surface water/sediment pathways, ATSDR identified radium (measured as radium-226 or radium-228), uranium (measured as total uranium or uranium-238), arsenic, chromium, and lead as the primary contaminants of concern because their concentration exceeded a comparison value in one or more media/pathways. (1) In this PHA, ATSDR focuses its evaluation on the concentrations of and potential exposures to these contaminants of concern.
- ATSDR did not identify any current completed exposure pathways to radionuclides or metals.
- ATSDR did not identify any potential future exposure pathways.
- ATSDR did not identify any completed or potential pathways associated with the food chain pathway.
- ATSDR identified completed past exposure pathways to site-related radionuclides and metals to include:
- Inhalation of radon (and radioactive dust particulates by workers).
- Inadvertent ingestion of soil (and associated exposure to gamma radiation).
ATSDR summarizes its evaluation of completed and potential exposure pathways in Table 2 and describes them in more detail in the discussion that follows. For the terminology used in this report, see Appendices B, C, and D; see Appendix B for an explanation of the different types of CVs; see Appendix C for a glossary of terms used in the PHA; see Appendix D for a discussion on radiation and radioactive material.
On-Site Surface Soil (2)
Radiologic Contamination: Several investigations have been conducted to characterize the extent of radiologic contamination at the MSP site. In 1976, Oak Ridge National Laboratory (ORNL) surveyed the MSP site and surrounding properties for residual alpha and beta-gamma radiation levels, radon and radon progeny concentrations in on-site buildings, external gamma radiation levels, and radium soil concentrations (ORNL, 1978). (Please refer to Appendix D for a description of radiologic parameters and their decay products). Another assessment was conducted in 1980 as part of Phase I and Phase II "vicinity properties" (VP) pile cleanup activities. An additional radiologic survey followed in 1983 to prepare for the construction of the Municipal Middlesex Landfill (MML) interim storage pile. Soil samples collected through these sampling events were analyzed for radium-226, thorium-232, and uranium-238. Since these sampling activities, most of the site has been covered with asphalt and the interim storage piles have been removed.
ATSDR evaluated the soil sampling results, comparing the radium-226, uranium-238, and thorium-232 levels to available National Council on Radiation Protection and Measurements (NCRP) surface soil guidelines (Report #129, 1999). As shown in Table 3, on-site soils (asphalt and underlying soils) were contaminated, primarily with radium-226, uranium-238, and, to a lesser extent, thorium-232. Radium-226 activity levels ranged up to 736 picocuries per gram (pCi/g), which is above the EPA Standard (per 40 CFR 192) of 5 pCi/g in the first 15 centimeters of soil. (3) The maximum concentrations of uranium-238 (up to 961 pCi/g) and thorium-232 (up to 19.3 pCi/g) were also elevated. As much as 17,000 cubic yards (yd3) of asphalt and underlying soil on the MSP site is reportedly contaminated with radionuclides. The highest radionuclide concentrations were found primarily along the east side of the property in the vicinity of the process building and beneath the MML pile (SAIC, 1995).
Non-Radiologic Contamination: In 1991, the New Jersey Department of Environmental Protection (NJDEP) requested the U.S. Department of Energy (DOE) to characterize the nature and extent of non-radiologic constituents in soil and in the interim storage piles. Prior to that time, monitoring was not conducted because DOE did not suspect that the site had processed or released chemicals and/or metals. The on-site soil was analyzed for volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), metals, pesticides, and polychlorinated biphenyls (PCBs). ATSDR compared the sampling results to available ATSDR CVs or New Jersey residential remediation standards.
The monitoring revealed that certain metals and polycyclic aromatic hydrocarbons (PAHs) were present in the soil. Lead (up to 382 parts per million [ppm]) was found at concentrations above NJDEP's standard local background concentrations. Arsenic was found at concentrations below NJDEP standards but above ATSDR's CV of 500 ppb (up to 5,430 parts per billion [ppb]). (Also, sampling detected beryllium [up to 1.7 ppm], cadmium [up to 3.1 ppm] at levels above NJDEP standards). Seven individual PAHs thought to have carcinogenic potential, including benzo(a)pyrene (45 ppm), chrysene (51 ppm), and dibenzo(a,h)anthracene (15 ppm), were present in the soil at concentrations greater than their respective ATSDR CV and/or proposed New Jersey soil remediation standards (SAIC, 1995).
Concentrations of other analytes, including VOCs, pesticides, and PCBs, were well below NJDEP residential soil remediation standards--values similar to ATSDR CVs. Seven SVOCs exceeded ATSDR CVs. The SVOCs, all polycyclic aromatic hydrocarbons (PAHs), were found within the top 2 feet of soil on the eastern edge of the two interim storage piles near Wood Street.
MML Pile (Soil)
As noted, about 15,600 yd3 of radiologic contaminated soil from the MSP site was sent to the MML in 1948. The contaminated soil was eventually returned to the MSP in 1984. Material in the MML pile was analyzed in 1991 at the request of the NJDEP to determine the nature and amount of radiologic and chemical contamination. Based on this evaluation, the MML pile was determined to be co-mingled waste, containing both radioactive material and chemical constituents (SAIC, 1995). The radionuclides radium-226 and thorium-232, and uranium-238 were detected in the pile material, with maximum concentrations exceeding EPA standards (see Table 5). As Table 6 indicates, several metals and PAHs were detected. The maximum concentration of arsenic, cadmium, and lead exceeded ATSDR CVs; chromium was not detected and beryllium was found at levels below its CV. Seven individual PAHs thought to have carcinogenic potential, including benzo(a)pyrene (62 ppm), chrysene (60 ppm), and dibenzo(a,h)anthracene (33 ppm), were present in the soil at concentrations greater than their respective ATSDR CV and/or proposed New Jersey soil remediation standards (SAIC, 1995).
VP Pile (Soil)
The VP pile contained approximately 35,300 yd3 of contaminated soil that was removed in 1980-1981 from four of the most heavily contaminated off-site properties, including a private home on Williams Street, portions of the playground of the Church of Our Lady of Mount Virgin, the church rectory, and 29 other lesser contaminated properties. The pile has since been removed from the MSP site. Table 7 lists the metals and PAHs detected in the VP pile soil. As noted, the maximum concentrations of arsenic, lead, and six individual PAHs exceeded ATSDR CVs and the proposed New Jersey soil remediation standards (SAIC, 1995).
Radiologic Contamination: A previous owner of a house on Williams Street had notified DOE that he had taken soil from the MSP site to use as fill in the yard in 1948. It is strongly suspected that the same is true for the rectory at the Church of Our Lady of Mount Virgin, located at the corner of Harris and Drake Street in Middlesex Borough. Church records indicate that a rectory was approved for the property in 1947, but the church records lack information on when the rectory was built or if and where the dirt had been placed on the property before construction of the rectory. In 1978, ORNL conducted a one-time sampling of surface (and subsurface) soil for radium-226, and in some cases, for uranium-238, thorium-230, and lead-210 activity levels at the Williams Street locations, the church rectory, and a playground across from church.
ORNL also surveyed portions of Blocks 318 and 319 in Middlesex Borough because of concern about wind and water transport of contaminated materials from the MSP. Block 318 is bounded by Lehigh Valley Railroad to the north; Mountain Avenue, Wood Avenue, and the MSP site to the east; the borough line to the south; and Cedar Avenue to the west. Block 319 is bounded by Wood Avenue, Mountain Avenue, Williams Street, and the MSP site.
No other sampling are available to characterize the non-radiological contamination in off-site soil prior to its removal. The one-time sampling event found levels of uranium and radium above screening levels, and the results are summarized in Table 8. Contaminated soil was removed from these locations during 1980-1981 and placed in the interim storage known as the VP pile at the MSP site.
At high enough levels, radionuclides in the soil can emit detectable external gamma radiation (see box). Persons in close contact with contaminated soil might therefore be additionally exposed to radiation released as gamma radiation. ORNL measured radiologic activity as external gamma radiation 1 meter above ground surface at the off-site locations. The results of the monitoring are presented in Table 9. As the table indicates, gamma radiation levels exceeded EPA/DOE standard levels at several of the surveyed properties. The highest levels were found at the Williams Street property and the church rectory. At the Williams Street property, external gamma radiation levels in the house ranged up to 17 microroentgen per hour (R/hour), or about twice the natural background concentrations, while levels in the front yard ranged from 50 to 300 R/hour, which is as much as 40 times greater than background. Elevated levels of external gamma radiation were measured inside the rectory (up to 44 R/hour) and its surrounding property (up to 220 R/hour). According to the environmental analysis report completed in 1979, the radiological survey measurements do not indicate that homes on these properties are contaminated with radioactivity, but rather that contamination exists near the surface of these properties (ORNL, 1978).
Past Exposure: Radium, uranium, other radionuclides, and metals were detected in the surface (and subsurface soils) at the MSP site. Workers from 1943 to 1967 and Marines in training at the site from 1969 to 1979 could have come in contact with harmful levels of contaminated soil during their routine responsibilities. Adequate information on the frequency, duration, and magnitude of potential exposures is not available to allow an evaluation of this exposure. Frequent public exposure (non-worker) to the on-site soil contamination in the past was highly unlikely due to access restrictions at the site. Specifically, the 7-foot chain-link fence that surrounds the MSP site limits unauthorized access to the site. Furthermore, signs stating "No Unauthorized Access" are prominently displayed at the entrance gates to ensure continued limited access. Although there was (and still is) a noticeable gap between the gates at the Wood Avenue entrance, any exposure to soil contaminants by trespassers in the past was probably infrequent and brief and not of health concern.
Current and Future Exposures: Today, little, if any, chance of exposure to contaminated soil exists because most of the contaminated surface soil was removed from the site, and the site is largely covered with asphalt. Currently inaccessible contaminated subsurface soil could be exposed during future excavation or construction. No harmful exposures are expected in the future as long as the site is secured from trespassing, and construction or remediation workers are adequately protected during future site activities.
Elevated levels of radiologic material (radium, uranium, and other radionuclides), metals (i.e., arsenic, lead, and uranium [as a metal]), and PAHs were detected or suspected to be present in the past in the surface soil at three off-site locations: 1) a private residence on Williams Street; 2) the playground; and 3) the MML site. The contaminated soil was removed in 1980-1981, therefore no exposures to contaminated soil at off-site locations are occurring now or are expected to occur in the future.
Past Exposure: To determine whether harmful exposures to contaminants in off-site soil could have occurred in the past, ATSDR estimated exposures doses for radionuclides, metals, and PAHs using hypothetical exposure scenarios at these locations. ATSDR assumed that incidental ingestion was the primary route of exposure in the past. Deriving exposure doses requires evaluating contaminant concentrations to which people might have been exposed and how often and how long exposure to those contaminants occurred. However, ATSDR lacks complete information about exposures at these locations. For example, ATSDR does not know how much, if any, radionuclide surface contamination was washed or blown away prior to sampling in 1978. In the absence of sufficient historical sampling data prior to removal, ATSDR assumed that an individual incidentally ingested soil containing the highest concentrations of radionuclides, metals, and PAHs detected in the waste piles (worst-case scenario).
For the Williams Street address and the playground, ATSDR evaluated exposure of three different age groups because of difference in behavior patterns by age: a pica child (age 1-6 years), a non-pica child (age 1-6 years), an older child (age 10 years), and an adult. Pica behavior refers to the repeated ingestion of non-nutritive items such as soil. Young children tend to exhibit pica behavior because of their frequent hand-to-mouth activity that occurs during play. ATSDR assumed that pica and non-pica children came in contact with contaminated soil at the Williams Street residence, even though it is not certain whether any children lived or played at this property before the contaminated soil was removed. ATSDR also evaluated hypothetical exposures via landfill worker and trespasser exposure (a non-pica child) at the MML site.
ATSDR then compared the estimated doses to health-based guidelines to determine whether exposure could pose harmful effects. When evaluating exposure to lead in soil, ATSDR estimated blood lead levels because ATSDR's health guideline for lead is based on blood lead levels rather than on an exposure doses.
Based on ATSDR's assessment of hypothetical exposures at off-site locations, exposures to the maximum concentrations of PAHs resulted in exposure doses below health-based guidelines and are, therefore, not of public health concern. Certain estimated exposures to metals resulted in doses greater than health guidelines. For example, exposure based on the hypothetical exposure of a trespasser to arsenic at the MML site and for exposures of children and adults to uranium (as a metal) at the Williams Street property and at the playground (based on estimated maximum concentrations) resulted in exposure doses greater than their minimal risk level or reference dose. Other exposures of children and adults at the Williams Street property/playground and for the trespasser at the MML site were all below health-based guidelines. Exposure doses to PAHs and metals for the landfill workers were above health-based guidelines.
When evaluating exposures to radionuclides in off-site soil, ATSDR found that the estimated doses would not exceed any health guidelines as a result of exposures at the playground and at the MML site and when assuming exposure at the Williams Street property resulted from incidental ingestion of the average concentrations of radionuclides in soil.
Based on this evaluation, ATSDR finds that routine exposure in the past to the highest levels of radionuclides in soil (and external gamma radiation) and certain metals at the Williams Street property, and the highest levels of certain metals and PAHs at the MML site, could have potentially caused harmful effects to individuals.
Current and Future Exposures: No off-site exposures to site-related radionuclides or metals in surface soil are occurring now, nor are they expected to occur in the future because the contaminated soil was removed from off-site locations in 1980-1981. Currently inaccessible contaminated subsurface soil could be exposed during future excavation or construction. No future public health hazards are expected as long as the site is secured from trespassing and construction or remediation workers are adequately protected during future site activities.
The Passaic Formation is a major aquifer in the western part of Middlesex County and adjoining Essex County. The portion of the aquifer, or groundwater system, beneath the MSP site was originally described as a "single aquifer composed of unconsolidated material (both sediment and weathered bedrock) and fractured bedrock." More recent interpretations suggest that the aquifer in the area of the MSP site consists of a leaky, multiunit (seven units, including two weathered bedrock units) aquifer system that allows groundwater to move through fractures in two weathered bedrock units to the underlying deeper (unweathered) bedrock (SAIC, 1997). The presumed existence of this multiunit system suggests that the water table fluctuates within the two weathered bedrock units, coming in contact with contaminated fill and sediment associated with the on-site process building sump (SAIC, 1997). As the shallow aquifer moves through the site, it very likely comes in contact with contaminated subsurface fill materials. As of 1997, groundwater was present between approximately 2 feet and 8 feet below ground surface (BNI, 1998). Groundwater in the upper part of the aquifer might discharge to an adjacent water stream that is south of the site. As indicated by a groundwater divide, groundwater flows both north and south from the sump near the process building (see Figure 5) (SAIC, 1997). Water flowing northward from the sump trends toward a northwesterly direction, and water flowing southward generally trends southwestwardly, except under conditions of low groundwater elevations, when the groundwater shifts to a more southeasterly direction (BNI, 1998).
The groundwater beneath the MSP site is part of an aquifer used for domestic, municipal, and industrial water supplies in Middlesex County and surrounding counties. As of 1992, approximately 140 private water-supply wells existed within 1 mile of the MSP, and most of these wells draw from the deeper aquifer. Also, 19 municipal wells were located within a 4-mile radius of the site. The nearest public well field to the site, the Elizabethtown Water Company's Sebring's Mills well field, is located approximately 1.25 miles northwest and upgradient of the site. This well field, however, has not operated since 1978 (SAIC, 1995).
Summary of Groundwater Monitoring Activity
Since the early 1980s, groundwater beneath the MSP site and in its immediate vicinity has been monitored to characterize the nature and extent of environmental contamination. In 1980-1981, DOE installed 20 groundwater monitoring wells, 18 on-site wells and 2 downgradient off-site wells. These wells were originally used to support geotechnical evaluations, but some wells were also sampled sporadically to characterize contamination beneath the site and to track contaminant movement. Starting in 1982, DOE established a standardized groundwater surveillance program. Between 1982 and 1993, DOE sampled 19 of the 20 wells (17 on site and 2 off site) quarterly for radium-226 and total uranium. In 1985, DOE also started sampling 12 monitoring wells in the network for New Jersey priority pollutants (VOCs and SVOCs); in 1990, DOE added metals and thorium-232 to the analyses. After achieving consistent results over several years from the 19 wells in the monitoring network, DOE reduced its sampling to seven wells on an annual basis (SAIC, 1995).
In 1994, DOE abandoned the existing wells (except one) and upgraded the groundwater monitoring well network to meet more stringent standards by adding seven new shallow (upper bedrock) wells near on-site waste areas (six on-site wells, B18W24S to B18W29S, and one immediately downgradient off-site well, B18W30S). All of the new wells were screened between 11 and 15 feet. Since 1994, the water samples collected annually from these wells have been analyzed for radium-226, radium-228, thorium-230, thorium-232, total uranium, VOCs, SVOCs, and metals.
Independent of the DOE sampling, ATSDR sampled a subset of the private and monitoring wells in February and April 2000. In February 2000, ATSDR sampled two on-site wells, one off-site well, and 14 nearby private wells. ATSDR resampled three of the private wells in April 2000, along with three additional private wells and all of the MSP monitoring wells. Samples were analyzed for radium-226, radium-228, uranium-238, arsenic, chromium (total and hexavalent), lead, and manganese, and selected samples were analyzed for uranium-234 and uranium-235. ATSDR focused its evaluation of groundwater on the five contaminants of concern: radium, uranium, arsenic, chromium, and lead. The results from these sampling programs/events are discussed below.
Radiologic Contamination: ATSDR reviewed the monitoring data for radionuclides in on-site groundwater (see Table 10) and compared the detected concentrations to EPA maximum contaminant level (MCL) and/or DOE drinking water criteria. Of the radiologic contaminants measured, total uranium has been detected most frequently at concentrations above EPA's MCL of 30 µg/L (micrograms per liter). All the data for total uranium, reviewed by ATSDR, was reported in the units pCi/L (picocurie per liter). EPA's MCL for total uranium is roughly equivalent to 20 pCi/L.
Between 1982 and 1993, elevated total uranium levels were consistently detected in one well located between the northern edge of the MML and the process building sump (maximum annual average of 143 pCi/L) and fairly consistently measured in another well, located near the southeastern edge of the MSP site (maximum annual average of 192 pCi/L). (4) Total uranium concentrations in these wells increased until the mid-to-late 1980s, when they started decreasing but never falling below uranium's CV. Other radiologic constituents were detected infrequently, and generally in low concentrations. With the exception of sporadic detections of radium-226 and thorium-232, most levels in groundwater were well below screening levels.
Since 1994 (when the new well monitoring system was installed), elevated levels of total uranium have again been detected in the northern portion of the site, where total uranium levels in one well (B18W24S) reached 275.68 pCi/L in 1997, declined to 206 pCi/l in 1998, and then rose to 391 pCi/l in 2000. In another well (B18W25S) located on the northwest perimeter, total uranium concentrations increased from 16.15 pCi/L in 1997 to 178 pCi/L in 1999, but had dropped to 53 pCi/L during the April 2000 sampling event (BNI, 1997, 1998, 1999a, 1999b; ATSDR, 2000a, 2000b).
Non-Radiologic Contamination: As shown in Table 11, arsenic, lead, and chromium have been found in on-site groundwater at levels above ATSDR CVs or EPA action levels. Total chromium, possibly used in paint pigments and/or ore assays, has been detected at substantially increasing concentrations in a monitoring well (B18W29S) located along the southern boundary of the site. The February 2000 sampling round found up to 25,700 ppb, concentrations well above ATSDR's CV of 100 ppb. Hexavalent chromium, the most toxic form of chromium to humans, was not detected during the sampling and the chromium (total) concentrations dipped to 1,400 ppb in April 2000. Aluminum, iron, and manganese routinely exceeded their CVs. These metals are common constituents of soils, and their presence is probably not related to an on-site source (SAIC, 1995).
Sampling also found VOCs, including trichloroethylene (TCE), benzene, and methyl-tert-butylether (MTBE) sporadically at levels above ATSDR's CVs along the western-southern boundary of the site. Because of the nature of the VOCs and their sporadic occurrences on site, they have not been linked to a specific on-site source. They might have migrated from soil containing gasoline, lubricating fluids, or petroleum-based constituents, such as those found at nearby upgradient industrial facilities.
Off-Site Groundwater Monitoring Wells
Between 1982 and 1993, DOE monitored two downgradient off-site groundwater monitoring wells (14 and 15) on a quarterly basis. Since updating the monitoring network in 1994, DOE reduced their monitoring to one off-site well located approximately 150 feet downgradient from the site and near the drainage ditch (B18W30S) on an annual basis. Off-site samples have been analyzed for the same parameters as the on-site samples.
As Table 12 indicates, only very low levels of radionuclides were detected in off-site monitoring wells between 1982 and 1993. Elevated levels of radionuclides beyond site boundaries first became apparent in 1996, when 144 pCi/L of total uranium was measured in the monitoring well (B18W30S) located just south of the site. The elevated concentration of total uranium was possibly attributed to dissolved uranium moving through the shallow groundwater from the nearby drainage ditch. DOE removed the contaminated sediments from the drainage ditch between August and September 1996. The total uranium concentrations in the monitoring well water decreased in the next sampling round to 19.7 pCi/L, and was most recently detected at levels below 10 pCi/l in April 2000 (BNI 1997a; ATSDR, 2000a, 2000b).
Off-site concentrations of arsenic, chromium, and lead, in the MSP monitoring wells have varied over the years. Although metals have been detected sporadically at concentrations above ATSDR CVs and/or EPA MCLs (see Table 13), the levels are much lower than on-site concentrations.
After detecting high concentrations of total uranium in the off-site monitoring well in 1996, DOE began monitoring two private drinking water wells (one shallow well and one deep well) located on a private residential property immediately south and downgradient of the MSP site, and near the monitoring well. DOE analyzed the samples for the same parameters as the on-site samples. Also, in response to nearby residents' concerns about their private well water, ATSDR sponsored sampling of private wells within an approximate 1 to 1.25-mile radius of the MSP site. In February 2000, ATSDR sampled 14 private wells, and in April 2000, ATSDR sampled three additional wells and resampled three of the previously sampled wells. At each private well sampling location, two samples were collected: one sample from the kitchen cold water tap (immediately after turning on the faucet) and the other sample from the tap closest to the well head (after the well had been purged for 15 minutes). ATSDR analyzed the unfiltered samples for a subset of analytes, including arsenic, total chromium, hexavalent chromium, lead, manganese, uranium, gamma spectroscopy, radium-226, and radium-228, and uranium (uranium-238, uranium-234, and uranium-235).
Private well monitoring results for radionuclides are presented in Table 12. As shown in the table, radiologic constituents were detected in private well water, but at levels below comparison values. During ATSDR's February 2000 sampling, radium was detected in water drawn from the kitchen tap at one residence at a concentration of 2 pCi/L, but still below EPA's MCL of 5 pCi/L for radium-226 and radium-228 combined. Follow-up sampling in April 2000, indicated lower levels of radium-226 (less than or equal to 0.2 pCi/L) were present in this well and in all other tested private wells (ATSDR 2000a, 2000b). Uranium (total) concentrations were less than the EPA MCL of 30 pCi/l.
Arsenic was detected at concentrations of 3.9 ppb and 8.1 ppb in water drawn from the kitchen taps of two residences. (Arsenic was also detected at concentrations up to 2.5 ppb in the flush samples taken from taps located near the well heads of these two residences and at a third residence.) These arsenic concentrations are less than EPA's current MCL of 50 ppb. Chromium and lead were also detected in the kitchen tap samples, but at concentrations below their respective ATSDR's CV and EPA's action level. (5) Estimated concentrations of uranium (as a metal) in private well water were below EPA's MCL of 20 ppb.
Past, Current, and Future Exposures: Groundwater beneath the site is contaminated with radium, uranium, metals (e.g., arsenic, chromium, and lead) and VOCs (e.g., benzene, MTBE). The date the site was connected to the municipal water system is unknown. Prior to that, it is not known whether the paint manufacturer or MSP relied on private wells for drinking water. If at one time these facilities obtained their drinking water from on-site private wells that drew from groundwater, former employees might have been exposed to contaminants when they drank water or otherwise used the water for washing.
No exposures to contaminated groundwater immediately beneath the site are occurring or are expected to occur in the future. The site obtains its drinking water from the municipal water supplier; no on-site private wells currently draw water from the contaminated groundwater; and there are no plans to use this groundwater in the future.
Past, Current, and Future Exposures: Many people in the area of the MSP site obtain their drinking water from the Elizabeth Water Company, which relies on groundwater sources. Drinking water supplied by the Elizabethtown Water Company has met and continues to meet drinking water standards. The Elizabethtown Water Company, as with any large municipal water supplier, is required under EPA's Safe Drinking Water Act and state and local regulations to regularly test the public water supply and maintain safe water.
Several residents who live near the MSP site obtain their drinking water from private wells. Monitoring revealed that water from all of these wells contained radium-226 and uranium, but at levels below EPA's drinking water standards. The origin of the radium and uranium is unknown and could possibly be related to naturally occurring sources. Arsenic was also detected in well water from two kitchen taps at levels above ATSDR's comparison value (0.02 ppb) but below EPA's current MCL of 50 ppb. Because ATSDR's CVs are screening tools, and the value for arsenic is based on very conservative assumptions about prolonged exposure, exposure to arsenic in well water at concentrations below the comparison values would not be expected to result in harmful health effects. To evaluate whether arsenic at levels measured in the private wells is associated with any unhealthy effects, ATSDR derived exposure doses using conservative assumptions on how often people drink water and how much they drink. Because some uncertainty exists regarding how long arsenic has been in the well--no sampling data prior to February 2000--ATSDR conservatively assumed that an adult consumed well water for 30 years and a child for 6 years. These conservative estimates allow ATSDR to safely evaluate the likelihood, if any, that arsenic in the private well water could cause harm.
ATSDR's review of the toxicologic literature for arsenic suggests that the levels in the private well water are generally much lower than arsenic levels shown to cause cancer or other adverse health effects in humans exposed to arsenic in their drinking water.
Surface water runoff and any sediment leave the MSP site through a small drainage ditch located near the middle of the southern boundary of the site (see Figure 6). The drainage ditch extends southward approximately 500 feet, where it turns southwestward and parallels the course of the main ditch for approximately 800 feet before it converges with the Main Stream. The Main Stream empties into Ambrose Brook, which then empties into Green Brook just before joining the Raritan River. After detecting radionuclides in sediment exceeding DOE criteria (surface soil cleanup), DOE excavated approximately 150 feet of the ditch south of the outfall and installed an activated carbon groundwater filter at the outfall in 1996. DOE also removed smaller, isolated areas of contamination located between the bend in the ditch and the main ditch (BNI, 1998).
Summary of Surface Water/Sediment Monitoring Activity
Between 1980 and 1993, surface water and sediment samples were routinely collected from the south drainage ditch and analyzed for radium-226, and selected samples were analyzed for metals, total uranium, radium-228, thorium-230, and thorium-232. Sampling resumed in 1996 to evaluate the performance of the activated carbon groundwater treatment system at the outfall. Samples were generally taken at the outfall, near the confluence of the drainage ditch leaving the site and the main ditch and farther downstream. DOE conducted more extensive sediment sampling several times to better define the extent of radiologic contamination in sediment along the ditch.
Radionuclides have been detected in surface water samples taken from the drainage ditch (see Table 14). The highest concentrations of radium-226 and uranium were measured between 1980 and 1993 at the plant outfall; substantially lower concentrations were measured at all other sampling sites and during later sampling events (BNI, 1997, 1998; SAIC, 1995). Radium and thorium concentrations were generally indistinguishable from upstream or background surface water concentrations. Metals were a common constituent of surface waters, and elevated levels were detected in the Main Stream and in the drainage ditch leading off the MSP site. Between 1990 and 1993, elevated levels of lead were found near the outfall. Even higher concentrations of lead were found in an upstream sample, possibly suggesting other off-site sources of lead. Much lower concentrations of arsenic and lead were detected in 1996 and 1997 (ATSDR, 2000b).
Sediment monitoring results are presented in Table 15. Elevated levels of radium-226 were measured in all downstream sediment samples. The radium-226 contamination appeared to be confined to the top 0.5 feet of ditch sediment. Contaminated sediment above background levels was detected as far as 175 feet downstream from the MSP site. In general, radium-226 and total uranium concentrations decreased with time, but the other radionuclides lacked a discernable pattern. Migration of on-site sediments through surface water drainage does not appear to be the primary source of ditch contamination, rather contaminated soil beneath MSP is most likely the source of contamination in the south drainage ditch. Metals, including arsenic and lead, were not elevated above screening levels (BNI, 1997, 1998; SAIC, 1995).
Past, Current, and Future Exposures: Surface water at the plant outfall and in the Main Stream contained arsenic, lead, and radionuclides. However, it is unlikely that harmful exposure to contaminated surface water or sediment occurred. First, any exposure is minimal because there is no known use of the Main Stream or outfall area for routine recreational purposes, such as swimming or fishing. Second, contaminant concentrations detected in the surface water and sediment are too low to pose a health hazard for sporadic and infrequent exposures, typical of trespassing.
The grassy area on the southern border of the site, around the drainage ditch, has a large population of ticks, and special care should be taken by anyone walking through the area to check for ticks on their scalp or skin.
Past operations at MSP--such as the sampling, storing, and shipping of radioactive ore, and both the construction and removal of the interim storage piles resulted in the release of wind-blown soil particles and radon gas. In the following section, ATSDR discusses available monitoring data and potential health consequences of exposure to particulate matter originating from the site and from radon gas released from site-related soil.
On-Site Radon Levels
Limited sampling suggest that high levels of radon gas were once present at the site. In 1976, ORNL measured radon in on-site buildings using both grab and continuos monitoring techniques (ORNL, 1977). Later, between 1982 and 1993, DOE surveyed buildings and the outdoor environment for radon gas as part of their environmental surveillance program (SAIC, 1995). As Table 16 indicates, radon (up to 29 pCi/L ) at levels above EPA's indoor guideline of 4 pCi/L were detected in on-site buildings. Monitoring found the highest levels in the lower level of the process building in 1977. Lower levels, but still above EPA's guideline, were found in 1982-1993. Uranium- and radium-contaminated soil beneath and adjacent to the building was the suspected source of radon. Outdoor concentrations of radon at the site from 1982 to 1993 reached 5 pCi/L--with the highest detected levels just slightly exceeding the DOE outdoor guideline of 3 pCi/L. The highest outdoor concentrations of radon-222 were detected near the external wall of the process building, and much lower concentrations were found along the site perimeter. In 1996, DOE demolished the process building. Radon monitoring resumed in 1996 and 1997, and as expected, lower levels (up to 1.6 pCi/L) below EPA and DOE guidelines were found at on-site sampling locations (four perimeter locations of the site, an on-site location, and in the administration building) (BNI, 1998; SAIC, 1995).
Off-Site Radon Levels
In June 1978, ORNL surveyed radiologic parameters at the rectory of the Church of Our Lady of Mount Virgin (ORNL, 1978). Radon monitoring was not conducted at the Williams Street residence or at other off-site locations. Continuous measurement of radon-222 activity levels were made for 10 days in the basement and for 3 days in a street-level bedroom of the four-level structure. Radon concentrations in the rectory basement reached 92 pCi/L, well above EPA's action level for radon-222 of 4 pCi/L, and levels in the bedroom reached 2.5 pCi/L. Radon had apparently entered the rectory through a sump in the concrete floor in the basement (ORNL, 1978). (6) The suspected source of radon, the contaminated fill, was removed in 1980-1981.
On-Site Particulate Emissions
As previously noted, historical operations at MSP-- such as the sampling, storing, and shipping of radioactive ore, and the construction and removal of the two interim storage piles-- resulted in wind-blown dust and emissions of radioactive particles, organic compounds and metals. In 1996 and 1997, DOE estimated potential emissions from multiple sources, including wind erosion, excavation of soil from the streambed and plant outfall, transfer of soil for off-site disposal, and demolition of two on-site buildings. (The airborne particulate release rates were estimated using historical site soil contaminant concentrations, but it is not known if the average or maximum values were considered.) The model results suggest that an individual living 240 feet (80 meters) east of the site would have incurred a maximum whole body dose of 0.04 mrem/yr in 1996 and 0.00096 mrem/yr in 1997, doses that are well below the EPA and DOE standard of 10 mrem/yr for airborne particulates containing radionuclides (BNI, 1998).
Past Exposure: Workers at the site, particularly those who worked in the process building, were exposed to radon gas and airborne particulates during their workday. As with worker exposure to on-site soil, the full extent of exposure to airborne particulates during former operations remains uncertain due to limited sampling data and information about actual exposure.
Current and Future Exposures: No harmful exposures are occurring, nor are they expected to occur in the future. Recent monitoring of radon and particulate levels have not detected concentrations that would pose a public health hazard at the perimeter of the MSP site.
Past Exposure: Anyone living at the rectory at the Church of Our Lady of Mount Virgin was likely exposed to radon gas that had entered the rectory from the surrounding soil. (Although radon monitoring is not available for the Williams Street residence, ATSDR assumes that the same is true of that location.) Monitoring during June 1978 revealed radon (up to 92 pCi/L) inside the rectory at levels above EPA's guideline of 4 pCi/l. The highest levels were found in an office in the basement. Because the sampling occurred during warm weather months, even higher exposure could have occurred during cold weather months, when the structure was less ventilated. Most residents did not reside at the rectory for a very long time. With the exception of one resident who lived at the rectory for 24 years, most of the other 15 residents (since 1944) lived there for 2 years or less, according to information from the Church of Our Lady of Mount Virgin. ATSDR reviewed the toxicologic literature on radon to further assess whether the levels might have posed a public health hazard to former residents of the church rectory.
Based on our review of the toxicologic literature, people exposed to elevated levels of radon could be at risk of developing lung cancer. Smoking history is one of the major risk factors that influence the development of lung cancer from exposure to radon gas. If residents of the rectory (or at the Williams Street residence) smoked and were exposed to very high levels of radon and progeny, they could be at an elevated risk of developing lung cancer.
The risk to a smoker from radon and progeny is considerably greater than that to a non-smoker, but the risk to the non-smoker at high exposure levels is not zero. Smoking potentiates the risk of radon induced lung cancer. The risk of radon induced lung cancer is small and typically has a long latency period, and is dose dependant.
Current and Future Exposure: No harmful exposures are occurring, nor are they expected to occur in the future. The suspected source of radon--the contaminated soil--was removed in 1980-1981.
The MSP site is surrounded by residential areas, light industrial/business areas, and park areas. Biota are considered a potential human exposure pathway because site-related contaminants can be taken up from water, sediment, and food by aquatic organisms and by terrestrial animals through the food chain or ingestion of sediment and soil. For example, some of the heavy metals and radionuclides that have been detected in the sediment, groundwater, and surface water can accumulate and concentrate in aquatic biota (e.g., fish and mussel). The Raritan River has several species of edible fish, including trout, bass, shad, and pike. During the investigation, ATSDR learned that the trout in the Raritan are raised in fish farms and stocked by New Jersey and would not pose a public health hazard. Sampling of the other edible fish species would be necessary to completely eliminate this pathway from further consideration. However, ATSDR does not consider this a significant pathway because of the low concentrations of contaminants that have been detected in the surface water and sediment and because it is unlikely that anyone is subsisting on fish caught in the Raritan River.
The area around the MSP site is not used for farming or ranching. Although there is evidence of deer and smaller game in the vicinity of the MSP, hunting in the area is prohibited.
As of part the public health assessment process for the Middlesex Sampling Plant (MSP) site, ATSDR has gathered information about health concerns related to the MSP site. In gathering the information, ATSDR met with members of the Middlesex community at a public availability meeting; interviewed local, state, and federal agency representatives who are responsible for addressing community issues; and contacted residents in a 1-mile radius of the MSP site.
Many community members expressed concern about the numbers of people in the area with cancer and wanted to know if it is related to exposure to contaminants from the MSP site. They were concerned about the following specific cancers, either because the respondent, a friend, or a family member had been diagnosed with the cancer or because there was a concern about the number of people in the community with the condition. The number enclosed in parenthesis indicates the number of persons expressing the concern.
- Breast Cancer (9)
- Testicular Cancer (6)
- Prostate Cancer (4)
- Brain Cancer (2)
- Colon Cancer (2)
- Leukemia (1)
- Ovarian Cancer (2)
- Acinic Cell Carcinoma Cancer (parotid gland--large saliva gland) (1)
- Cervical Cancer (1)
- Lung Cancer(1)
- Throat Cancer (1)
- Tongue Cancer (lateral side) (1)
- Canine (dog) died from cancer (1)
- Unspecified Cancer (70)
Residents reported a range of noncarcinogenic conditions that they suspect might be caused by living near the MSP site, working at the MSP site either when it was operating or during the cleanup, or playing on or near the MSP site as children. The number enclosed in parenthesis indicates the number of persons expressing the concern.
- Kidney Failure (5)
- Children with Asthma (12)
- Asthmatic Problems (4)
- Headaches (2)
- Irritable Bowel Syndrome (2)
- Thyroid Nodule (2)
- Chronic Fatigue (1)
- Cold Urticaria (1)
- Difficulty Breathing (1)
- Fractured Ribs (1)
- Hyper-reactive Airway Disease (RADS) (1)
- Hypothyroidism (1)
- Legally Disabled (1)
- Lung Disease (1)
- Lupus (1)
- Nausea (1)
- Respiratory Problems (1)
- Savcadosis (1)
- Sinus Infections (1)
- Stomach Problems (1)
- Thyroid Problems (1)
The contaminants identified at a sufficiently high concentration to be a potential health hazard included lead, arsenic, uranium and radium. Following ingestion and/or inhalation, lead and arsenic have been associated with lung diseases, neurological, reproductive developmental, nausea and kidney failure. Uranium either ingested or inhaled has potentially been associated with kidney damage and kidney failure, and exposure to ingested radium has been linked to specific types of bone cancer and postulated to cause various types of other cancers such as lung cancer. ATSDR, however, was not able to determine if any additive or synergistic effects on humans exist following intakes of one or more of these contaminants. External exposure to gamma radiation from materials such as radium, are known to cause leukemia; however, those exposures are in excess of 10 rem delivered over a short period of time (less than 5 years).
Also, ATSDR determined that the presence of these contaminants in areas outside the boundaries of the Middlesex plant were not at a sufficiently high concentration to cause adverse health effects individually. However, based on our analysis of the on-site data and operational history of the plant, ATSDR believes that workers would be the only population group that might have sufficient exposure to these materials to suffer adverse health effects.
The New Jersey Department of Health and Senior Services (NJDHSS) conducted a cancer incidence analysis of populations living near the Middlesex Sampling Plant (MSP), at the request of ATSDR. (7) The request was made because the MSP was recently added to EPA's National Priorities List of Superfund sites and because of excess cancer concerns perceived by local citizens. The strategy for this investigation was to conduct a parallel analysis of a recent NJDHSS study of other Superfund sites across New Jersey with similar contamination. (8) In the MSP evaluation, as in the earlier study of cancer in communities with radiologically contaminated Superfund sites, total cancer incidence and 11 select site-specific cancer groupings were evaluated. The select cancer types analyzed included: bladder, brain, central nervous system, pancreas, lung and pleura, leukemia, non-Hodgkin's lymphoma, liver, bone, kidney, thyroid, and breast. These site-specific cancers were chosen by ATSDR and NJDHSS staff because they represent groupings that might be more sensitive to the effects of radiation.
The study area consisted of four census tracts: the census tract where the MSP facility resided and three surrounding census tracts where off-site contamination occurred. Standardized incidence ratios (SIRs) were calculated for all cancers combined and the 11 site-specific cancers for 2 evaluation time periods. The first evaluation time period, 1979-1991, corresponds to the earlier study conducted by the NJDHSS. The second evaluation time period, 1992-1998, represents the remaining years of available data. The four census tracts were evaluated together and each separately. Expected numbers were calculated using average state incidence rates and U.S. census data to estimate the population.
For the time period 1979-1991, total cancer incidence and the incidence for many site-specific cancer groups for the populations living near the MSP were lower than expected for the entire study area and each census tract. The only SIR significantly elevated was in census tract 1 (Middlesex Borough) for leukemia in males (SIR=1.92; confidence interval =1.02, 3.28). During the later time period (1992-1998), total cancer incidence was higher than in the earlier period, particularly in the two Piscataway census tracts. Leukemia incidence in males from census tract 1 was not elevated (SIR=0.27) from 1992-1998.
Total cancer incidence for the entire study area during the period 1979-1991 was not significantly higher than expected when compared to average state incidence rates. The higher SIRs detected for the period 1992-1998 could be due to the aging of the population and/or population growth. Significant population growth occurred in Piscataway Township's study area as evidenced by the increased number of census tracts designated for that area from 1980-1990. Because there was little agreement in the results across the four census tracts or between time periods, it is not likely that the few elevations detected are related to site contamination. Consequently, no further follow-up of cancer incidence appears warranted for this site at this time.
ATSDR recognizes that infants and children might be more sensitive than adults to environmental exposure in communities faced with contamination of their water, soil, air, or food. This sensitivity is a result of the following factors: (1) children are more likely to be exposed to certain media such as soil when they play outdoors; (2) children are shorter and therefore might be more likely to breathe dust, soil, and vapors close to the ground; and (3) children are smaller than adults and therefore might receive a higher dose of chemical exposure relative to their body weight. Children also can sustain permanent damage if exposed to toxic substances during critical growth stages. ATSDR is committed to evaluating children's special interests at sites such as the MSP site as part of its Child Health Initiative.
ATSDR has attempted to identify populations in the vicinity of the MSP site and any completed exposure pathways to these children. Children are not typically present at the MSP site, the site is inactive and access is restricted by a perimeter fence. Like other people living at or near property containing fill from the MSP site, children might have inadvertently ingested contaminated soil, been exposed to gamma radiation, or inhaled or ingested airborne particulates. These exposure pathways are discussed in detail in "Evaluation of Environmental Contamination and Potential Exposure Pathway" section of this PHA.
Conclusions regarding potential past, current, and future exposures to various environmental media on and in the vicinity of the Middlesex Sampling Plant (MSP) site are based on a thorough evaluation of remedial site investigation data, groundwater and surface-water monitoring data, private well water data, and observations made during site visits. On the basis of its evaluation, ATSDR reached the following conclusions:
- Former workers and former marines in training likely came in contact with contaminated media during their routine responsibilities at the MSP site in the past. Adequate information is not available to fully evaluate past exposure of the workers or marines to site radionuclides or other contaminants.
- ATSDR has determined that no public health hazard is associated with:
- Current and future uses of the site. Today, no exposure is occurring because the site is inactive; most of the contaminated soil has been removed; little exposed soil remains at the site; and only low levels of radon have been detected. No harmful future exposures are expected as long as the site is secured and workers are adequately protected during any future remediation activities.
- Surface-water/sediment pathway. Surface water in the immediate area of the site is not used in ways (i.e., recreational uses) that would encourage long-term or frequent contact with surface water or sediment. Contaminant concentrations detected in the surface water and sediment are too low to pose a health hazard from any potential sporadic and infrequent exposures.
- Groundwater/drinking water pathway. Although groundwater beneath the site is contaminated, it has never been used for drinking and there are no plans to use the groundwater in the future. Recent monitoring indicates that elevated concentrations of uranium and arsenic have migrated to a downgradient off-site monitoring well. In light of this finding, water from selected, nearby private wells has been tested and found to not have elevated levels of contaminants, and all were below EPA's current drinking water standards.
- ATSDR has determined a past indeterminate exposure to radionuclides and metals in soils.
- ATSDR has determined that the grassy area on the southern border of the site, around the drainage ditch, has a large population of ticks that could pose a potential health threat from tick-borne illnesses.
ATSDR recommends the following actions to ensure that people are not exposed to unhealthy levels of contaminants on or near the Middlesex Sampling Plant (MSP) site:
- Available information suggests that subsurface structures/materials from the former paint manufacturing facility are buried beneath the MSP site. In the event that these structures/materials are removed in the future, remedial workers must be adequately protected from possibly harmful levels of contaminants associated with the buried items.
- Until the site is fully remediated and free of potential physical hazards, additional efforts should be made to secure the site (e.g., fix gaps in gates) from unauthorized (trespasser) access.
- No follow-up community study activity(s) are warranted at this time, because:
- ATSDR has determined that no public health hazard is associated with current and future uses of the site, and
- it is not feasible to identify the select individuals who may have had past off site exposures (i.e., residents of or visitors to the properties that might have received fill, trespassers to the MML pile. However, if additional information becomes available (i.e., list of individuals/addresses that received contaminated fill, years lived at address, usual occupation), the feasibility of a health study will be evaluated.
The Public Health Action Plan (PHAP) for the Middlesex Sampling Plant (MSP) site contains a description of actions taken and those to be taken by ATSDR, the U.S. Army Corps of Engineers (USACE), the U.S. Environmental Protection Agency, and the New Jersey Department of Environmental Protection at and in the vicinity of the site after the completion of this PHA. The purpose of the PHAP is to ensure that this PHA not only identifies public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The public health actions that are completed, being implemented, or planned are as follows:
- DOE and ORNL have conducted several soil monitoring events to characterize the nature and extent of contamination in soil at the site and in the vicinity.
- DOE removed most structures from the site and covered the site with a layer of asphalt.
- In 1980-1981, DOE excavated contaminated soil from properties in the vicinity of the MSP site known or suspected to have been affected by MSP contaminants and excavated sediment from the south drainage ditch. DOE stockpiled the excavated material on site in a covered pile known as the "vicinity property" pile. USACE removed the pile in 1999.
- In 1981, DOE excavated soil and waste from the MSP site (which originated from the MSP site) and stored these materials in a separate covered interim storage pile at MSP known as the Municipal Middlesex Landfill (MML) pile. USACE (DOE) removed this pile from the site in 1998.
- ATSDR visited the site in July and December 1999 and met with representatives of the USACE, the agency currently responsible for the cleanup of the site. During the December 1999 visit, ATSDR provided information to and addressed questions from community member residents attending a public availability session (coordinated by USACE) held at a local school.
- In January 2000, ATSDR mailed a fact sheet to each residence within a 1-mile radius of the site. ATSDR received health concerns via mail and phone calls from more than 90 community members with questions or concerns about the MSP site. ATSDR reviewed each concern and question submitted by the public.
- In February 2000, ATSDR sampled 14 area private wells and 3 groundwater monitoring wells. ATSDR sampled an additional three wells and resampled three previously sample wells in April 2000.
- In June 2000, ATSDR requested that the NJDHSS conduct a cancer incidence analysis of populations living near the MSP. This analysis was completed and the final report was made available in January 2001.
- The USACE will complete a remedial investigation/feasibility study of the MSP site.
- ATSDR will hold a public availability meeting in Middlesex Borough to further address community health concerns about the MSP site.
Michael Brooks, CHP
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Office of Regional Operations
D. Kevin Horton
Division of Health Studies
Eastern Research Group
Eastern Research Group
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Edward A. Tupin
Senior Health Physicist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Ronald L. Kathren, Ph.D., CHP
John H. Mennear, Ph.D.
Paul Visintainer, Ph.D.
Agency for Toxic Substances and Disease Registry (ATSDR). 1998. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Arsenic (Update). August 1998.
ATSDR. 1999. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Ionizing Radiation. September 1999.
ATSDR. 2000a. Groundwater and private well water results of sampling conducted on February 2-5, 2000.
ATSDR. 2000b. Groundwater and private well water results of sampling conducted on April 5-7, 2000.
Atomic Energy Commission (AEC). 1974. Radiation Survey Report for the Borough of Middlesex Municipal Landfill Site. June, 1974
Bechtel National, Inc. (BNI). 1992 Middlesex Sampling Plant environmental report for calendar year 1992, DOE/OR/2194-342. September 1992.
BNI. 1993. Middlesex Sampling Plant environmental report for calendar year 1992, DOE/OR/2194-366. May 1993.
BNI. 1997. Environmental surveillance results for 1996 for the Middlesex Sampling Plant, FUSRAP Technical Memorandum (118-97-007), Rev 0. May 21, 1997.
BNI. 1998. Environmental surveillance results for 1997 for the Middlesex Sampling Plant, FUSRAP Technical Memorandum (118-97-007), Rev 0. May 21, 1998.
BNI. 1999a. Groundwater analytical results 1998. October 7, 1999.
BNI. 1999b. EM Data for MSP (IIQR 1999), groundwater analytical results. 1999.
Cahalane, R.W. 1958, History of the Middlesex Sampling Plant, National Lead Company of Ohio. February, 1958.
CDC, 1991. Centers for Disease Control. Preventing Lead Poisoning in Young Children, A Statement by the CDC.
U.S. Department of Health and Human Services, Public Health Service, October 1991. Department of Energy (DOE). 1997. Letter from Jason Darby, DOE, to Alida Kuras, U.S. Environmental Protection Agency. RE: Latest hazard ranking score. July 25, 1997.
DOE. 1998. Hazard ranking system evaluation for the Middlesex Sampling Plant site. June 1998.
Environmental Protection Agency (EPA). 1996. Drinking Water Regulations and Health Advisories, EPA-822-R-96-001, Office of Water. February 1996.
Michalski, A. and Britton, R. 1997. The role of bedding fractures in the hydrogeology of sedimentary bedrock-evidence from the Newark Basin, New Jersey. Ground Water. 35:(2):318-327.
National Council on Radiation Protection And Measurements 1999. Recommended Screening Limits for Contaminated Surface Soil, NCRP Report #129.
Oak Ridge National Laboratories (ORNL). 1977. Radiological survey of the Middlesex Sampling Plant, Middlesex, New Jersey. Health and Safety Research Division, Oak Ridge National Laboratories. July 1977.
ORNL. 1978. Radiological surveys of properties in the Middlesex, New Jersey, area. Health and Safety Research Division, Oak Ridge National Laboratories. October 1978.
Parker, R.A. 1993. Stratigraphic relations of the sedimentary rocks below the Lower Jurassic Orange Mountain Basalt, Northern Newark Basin, New Jersey and New York. U.S. Geological Survey Mis. Field Studies Map MF-2208.
Science Applications International Corporation (SAIC). 1995. Science Applications International Corporation characterization report for the Middlesex Sampling Plant, Volume I, ESC-FUSRAP. August 1995.
SAIC. 1997a. Middlesex Sampling Plant Historic District. Historic American Engineering Record. January 1997.
SAIC. 1997b. Middlesex Sampling Plant bedrock hydrogeologic assessment. December 1997.
Sloan, Allan. 1983. Three Plus One Equals Billions: The Bendix-Martin Marietta War. New York: Arbor House.
TRI88. 1990. Toxic Chemical Release Inventory. National Library of Medicine, National Toxicology Information Program, Bethesda, MDUSGS 1995. Occurrence of the gasoline additive MTBE in shallow ground water in urban and agricultural areas. Fact Sheet FS-114-95. U.S. Geological Survey, National Water-Quality Assessment (NWQA) Program. (Web address: www.epa.gov/tri).
Weston, Inc., Roy F. 1980. Final report-hydrogeology of the Former Middlesex Sampling Plant Site, Middlesex, New Jersey. prepared for the Oak Ridge National Laboratory, Tennessee. October 1980.
1. Beryllium, cadmium, thorium-230, thorium-232, and lead-210 were also detected in soil, groundwater, or surface water/sediment, but less frequently and at lower concentrations than the selected contaminants of concern. Where pertinent, ATSDR also presents information on environmental concentrations of these metals and radionuclides.
2. ATSDR typically considers the top 3 inches of soil as representing surface soil. No soil samples fitting this definition were collected from the MSP site. Because most of the site was covered with asphalt, soil samples collected from the MSP site and referred to as surface soil samples consisted of a mix of asphalt and underlying soil (up to 2 feet below ground surface).
3. The units for radiologic contamination is expressed in two systems. One system, referred to as the conventional system, expresses units in picocuries per gram. The other system, known as the Systeme International, uses becquerels per kilogram. One becquerel equals 27 x 10-12 curies.
4. Sampling conducted in 1980 and 1981--before the groundwater surveillance program was standardized--indicates that three wells (of 19 sampled) along the eastern edge of the MSP also contained radium-226 at levels slightly above the combined MCL for radium-226 and radium-228.
5. Lead was detected at 16 ppb--and just slightly above EPA's action level of 15 ppb--in a flush sample taken from a tap near the well head. No lead was reported in the sample collected from this residence's kitchen tap. This indicates that the lead in the sample is leaching from the pipes in the house, not from the groundwater.
6. The short-term radon measurements might not be representative of radon concentrations in the air inside the rectory over a period of a year. In particular, the first level of the rectory was very well ventilated during the summer months, when sampling occurred. Therefore, the measured radon concentrations on that street level might be higher during colder months, when ventilation in the rectory is not as good (ORNL, 1978).
7. Agency for Toxic Substances and Disease Registry. 2001. Public health consultation analysis of cancer incidence near the Middlesex Sampling Plant. Atlanta: U.S. Department of Health and Human Services.
8. Agency for Toxic Substances and Disease Registry. 1999. Cancer incidence in populations living near radiologically contaminated superfund sites in New Jersey. Atlanta: U.S. Department of Health and Human Services.