PUBLIC HEALTH ASSESSMENT
HONEYBROOK, CHESTER COUNTY, PENNSYLVANIA
The Welsh Landfill site (AKA Welsh Road/Barkman Landfill) National Priorities List site is located near the top of Welsh Mountain, Honey Brook Township, Chester County, Pennsylvania. The landfill was operated as an unpermitted solid waste disposal facility from 1963-1977 and is currently operated as a waste transfer station. Monitoring of on-site surface soil, water, and sediment and off-site groundwater, subsurface soil, and sediment revealed a number of contaminants in these media including volatile organic compounds, semi-volatile organics, and metals. Residents near the site are supplied with bottled water because of the contamination of their wells. Environmental pathways for the migration of site-contaminants to off-site areas include those associated with groundwater and surface and subsurface soil. Human exposure to site contaminants may occur through ingestion and dermal contact with contaminated groundwater, dusts or volatilized contaminants. The proposed remediation of the site by EPA should eliminate or significantly reduce the potential for the completion of human exposure pathways to site contaminants by capping the site and supplying public water to affected residences. However, several owners of potentially affected residential wells have refused hook-up to the proposed waterline.
This site is considered a public health hazard because of past exposure to site contaminants by individuals through the use of contaminated groundwater as their potable water supply. The Agency for Toxic Substances and Disease Registry (ATSDR) will undertake community health education for those persons who are or were exposed to contaminants in their domestic well water supplies. Particular attention will be given to those persons who refused to hook-up to the municipal water supplies.
The Welsh Road site (AKA Welsh Road/Barkman Landfill) is listed by the U.S. Environmental Protection Agency (EPA) on the National Priorities List (NPL). The approximately 8-acre site was an unpermitted residential and commercial refuse disposal facility that operated from 1963-1977. After 1977, the landfill continued to operate in defiance of legal action to support a closure plan. Various investigations conducted in the 1980s revealed that industrial and hazardous wastes had been accepted at the site. In 1980, sampling showed that several of the domestic wells in the site vicinity were contaminated with both organic and inorganic compounds. The site currently is used as a waste transfer station.
The Agency for Toxic Substances and Disease Registry (ATSDR) has provided several health consultations regarding this site. In September 1984, ATSDR reviewed sampling results of drum contents and concluded that, although the data suggested that the site should be cleaned up, there was no indication that an imminent or significant hazard to public health existed or that immediate action was necessary. In June 1985, from a review of drinking water well data, ATSDR concluded that a potential health hazard existed through the ingestion of contaminated groundwater, and recommended further characterization of the site. In July 1985, ATSDR amplified these conclusions and recommendations, identifying wells that should not be used. ATSDR also reviewed limited soil sampling data and concluded that the site did not present a direct contact hazard to the public (1). ATSDR issued a Preliminary Health Assessment for the site on December 2, 1988.
A Remedial Investigation (RI) was completed on December 8, 1988, by SMC Martin, Inc. A final Public Health Evaluation was submitted in January 1990 prepared by Baker/TSA, Inc. The RI did include sampling of groundwater and subsurface soil adjacent to the site; however, on-site groundwater and subsurface soil was not done. EPA has two operable work units for this site. Plans for operable unit two includes sampling of on-site and off-site groundwater (2). Operable unit one, for which a Record of Decision (ROD) was finalized in June 1990, relates to the contaminated residential drinking water wells and landfill soils (3). The ROD for operable unit one calls for a landfill cap which will preclude the sampling of on-site subsurface soils and for construction of a water line to the homes. In 1985, EPA conducted a drum removal action on the site. These drums, approximately 20, contained toluene, ethylbenzene and 1,2-dichloropropane, the same chemicals found in the groundwater in 1985 (3,4,5). EPA is planning to begin construction of a waterline in March 1992--to provide to those nearby residences with contaminated private wells a permanent alternate water supply--construction should be completed by March 1993. According to the EPA Remedial Project Manger, some individuals have refused hook-up to this waterline. EPA is also planning to construct a landfill cap over contaminated soils and to fence the site. These actions should be completed by December 1993.
The Welsh Road site was visited on March 1, 1990 by James Fox, K. Sivarajah, and Gary Schultz, of Pennsylvania Health Department, Charles Walters of ATSDR, and representatives from the Department of Environmental Resources (PADER), EPA, and Honey Brook Township. The main area of the Barkman Landfill was entered from Welsh Road via a gravel parking lot which leads to a dirt road that transgresses the dumping activities. A large garage and mobile office trailer are located near the entrance. Gasoline pumps and probably underground tanks are located in front of the garage.
The surface of the landfill is covered with dumpsters, abandoned trucks, cars, school buses, empty underground storage tanks, refrigerators, industrial and household wastes, drums and debris. The southern portion of the landfill was once used for burning and there is no vegetation in this area. Also, two small areas of dead trees exist along the southern border. The landfill is scarcely vegetated and many areas showed obvious soil contamination.
A partial fence exists at the entrance area to the landfill, but the site is easily accessible from the other boundaries. Homes are adjacent to the landfill in close proximity on the east and west boundaries.
The EPA Remedial Project Manager (RPM) was contacted in December 1991 to determine the current site status in relation to the observations made during the March 1990 site visit. The RPM indicated that the major physical hazards, such as, dumpsters, abandoned trucks, cars etc., have been removed from the rear of the landfill in preparation for the capping of the site.
The Welsh Road site is situated in a semi-rural area about 1.25 miles north of Honey Brook, Pennsylvania. The site is topographically elevated and is located near the top of Welsh Mountain. Residential family dwellings are located within a half-mile radius north, east and west. Several homes are adjacent to the landfill (see map, Appendix A). The southern boundary of the site is agriculture land. Small game animals are reported to be present in the area. The site itself is an active salvage operation. The homes outside of Honey Brook all use private wells for their potable water supply, and about 50 homes in the immediate vicinity of the site (Appendix B) are currently being supplied bottled water for drinking and cooking. It is noted in the RI that "some" homes have charcoal filter systems connected to their wells for removal of VOC's.
State and local health outcome data were not evaluated for this site (see Public Health Implications--Health Outcome Evaluation Section for details).
Each individual living adjacent to the site is concerned with the site's impact on their private well water. Odor complaints have been voiced in the past and there was reportedly an episode of acute toxicity in 1979 involving four children in a home adjacent to the site who were being affected by fumes emanating from barrels on the site. The people are also concerned with the fumes of volatile organic compounds (VOC's) in their water when taking a shower. To our knowledge, there are no known organized community groups that have expressed any site-related health concern. This information was relayed to PADOH by the two Honey Brook Township personnel during the site visit.
The PADOH placed a legal notice in The Daily Record newspaper, Coatesville, Pennsylvania, on August 19, 1991, informing the public regarding the availability of the public health assessment for comment. No comments were received during the 30-day comment period which ended September 20, 1991.
To identify possible facilities that could contribute to the air, surface water, and soil contamination near the Welsh Road site, ATSDR and PADOH searched the 1987, 1988, and 1989 Toxic Release Inventory (TRI). TRI is developed by the EPA from the chemical release information provided by certain industries. TRI did not contain information on toxic release in Honey Brook or in the zip code in which the site is located.
Sampling on-site has been confined to composite soil (3" to 15"), surface water, surface sediments, and air. No deep subsurface soil or groundwater monitoring wells have been established on-site for this phase of investigation (6), although monitoring wells are found adjacent to the site. The latest data are from the RI samples that were collected in 1987-1988. 1985 data were also reviewed.
The air sampling data did not reveal any elevated levels of contaminants. Chloroform (0.014 mg/m3) and hydrogen chloride (4.1 mg/m3) were detected at the western perimeter of the site only.
Composite soil samples and sediment samples revealed the presence of some site-related chemicals such as polynuclear aromatic hydrocarbons (PAHs), arsenic, cadmium, lead and nickel (see Table 1).
The level of contaminants in the surface water samples on-site did not appear to represent a significant level to be of public health concern.
On-site sampling consisted of the following: one pond sediment sample, two surface water samples from a seep and the pond, and eleven composite soil samples, some from areas that were stained, indicating possible previous spill areas. The composite soil samples were collected from three inches to a depth of 15 inches.
|PAH (Benzo (a) anthracene)||950||ND|
ND = Non-Detectable
Off-site composite soil sampling was more intensive and also included deeper soil (up to 36") and groundwater samples that were not taken on-site. The groundwater samples were obtained both from monitoring wells as well as residential wells in the immediate area of the site. Most residential wells are east and west of the site.
Air and surface water samples were collected and only low levels of contamination or no detection of contamination was reported.
The off-site composite soil and sediment contaminants detected slightly above natural background included arsenic, cadmium, lead and nickel (see Table 2). PAH's also were detected in the sediment adjacent to the site. The majority of the soil and sediment contamination is present near the landfill, suggesting the landfill as the source. Some samples were collected from visible leachates.
|PAH (Benzo (a) anthracene)||ND||670|
ND = Non-Detectable
Groundwater sampling was done by using several old monitoring wells, new monitoring wells, and residential wells. Two rounds of sampling were done during the RI and a third round of residential samples were collected after the RI (April 1, 1989). Two of the monitoring wells are adjacent to the site boundary, others are slightly farther away from the boundary (downgradient).
The compounds detected in the groundwater that are of concern are chloroform, benzene, trichloroethylene (TCE), tetrachloroethylene (PCE), cadmium, lead and mercury (see Table 3).
|Monitoring Wells||Residential Wells|
|PAH (Benzo (a) anthracene)||ND||ND|
ND = Non-Detectable
* = Above maximum contamination level (MCL)
In preparing this public health assessment, PADOH relies on the information provided in the referenced documents and assumes that adequate quality assurance and quality control measures were followed regarding chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn for this public health assessment is determined by the availability and reliability of the referenced information.
The major physical hazards, which were observed during the March 1990 site visit, have been removed from the site.
The environmental pathways of concern are migration of contaminants off-site via surface water, ground water, and ambient air.
Soil Pathway. Results on the on-site, composite soil samples indicate that portions of the landfill's surface soils are contaminated with both organic and inorganic hazardous chemicals. Because the sampling depth varied from 3 to 36 inches for only 15 locations both on and off the site, there is no comprehensive description of surface (top 3 inches) soil contamination. The on-site samples were generally less than 8 inches deep with concentrations of contaminants considerably higher than the off-site composite soil samples 3 feet deep. The top 3 inches of the soil column are important because that is the portion of the soil column most likely to be eroded or serve as a point of human exposure.
Furthermore, the soil sample locations (though chosen because of visual evidence of probable contamination) are neither systematic (grid) nor extensive enough to provide assurance that areas of maximum soil contamination have been discovered and delineated.
Soil sampling and analyses do indicate that the on-site soils serve as reservoir of contaminants available for migration via wind or water erosion and leaching into the groundwater.
Surface Water and Sediment Pathways. Located on the southeastern side of Welsh Mountain, the site slopes to the south and southeast with an estimated 140 foot elevation difference from the high to low points on-site. The site and the immediately surrounding area drains to the West Branch of Brandywine Creek, located approximately 1 mile south of the site.
Analysis of sediments from a "intermittent pond" on the northern border of the landfill indicates the presence of metal contaminants and PAH's. Analytical results from sediment samples from a drainage approximately 2,000 feet down slope from the site boundary also indicated inorganic contaminants, as well as organic compounds. Therefore, limited sampling indicates off-site migration of contaminants via surface water and sediments.
Groundwater Pathway. Two groundwater flow zones exist immediately beneath the site, a saprolite (weathered bedrock) or overburden zone at the top of the water table and a bedrock zone in the underlying fractures and joints of the Hellam Conglomerate. Immediately south of the site, the lithology of the bedrock zone includes changes to a granodiorite with flow also in the fractures and joints of that hard rock type. Pump tests performed during the RI clearly demonstrate a vertical connection between the overburden zone and the bedrock zone. The pump tests also indicate a preferential hydraulic connection along the geologic contact between the Hellam Conglomerate and the granodiorite.
Flow in the overburden zone is via connected pores in the clayey geologic materials formed from weathered bedrock. Groundwater flow is southward. Groundwater flow in the bedrock is influenced by the structure and direction of the fractures and joints, as well as the surface topography. However, pumping from nearby residential wells may also influence flow in individual or groups of fractures intercepted by the pumping well.
The groundwater associated exposure pathway through ingestion in the past of residential well water contaminated with VOC's and metals is of public health concern. Dermal contact and inhalation of the volatile compounds in the residential wells during domestic use of the water continues to be a public health concern. The recent groundwater sampling data indicate the presence of inorganic and organic chemical compounds. Even though the homes in the immediate area are supplied with bottled water for drinking, human exposure through inhalation and dermal contact is still occurring. If the residential wells were used for drinking, then, also human exposure through ingestion can occur and has occurred in the past. A present and future completed exposure pathway exists for those residents who refused to hook-up to the waterline.
The soil associated pathway is a potential health concern due to the possibility of ingestion and/or dermal contact with contaminated soil as an additional source of exposure. There is evidence that contamination is migrating off-site, however, these potential exposures cannot be fully assessed because of the absence of comprehensive, current data for surface soils and subsurface soils both on-site and off-site.
The analysis of sediments on the northern border of the landfill indicates the presence of metals and PAH's. Sediment sample data down slope (south) from the site also indicated inorganic and organic off-site migration of contaminants via surface water and sediments and a potential for human exposure via incidental ingestion or dermal contact.
Those substances with a health concern from the volatilization of groundwater are chloroform, benzene, TCE, PCE, and mercury. Chemicals of concern through the route of ingestion of groundwater includes these volatile compounds and the metals lead and cadmium. The ingestion and inhalation of volatile compounds from the groundwater could potentially affect those using the water as a domestic water supply. Presently about 50 residential units are within 0.25 mile radius of the site, each using the groundwater for showering. These homes are currently being supplied bottled water for drinking and cooking, but these residents were exposed in the past. "Some" of the homes have carbon filters, but it is not known if proper maintenance of these systems is being done.
The contaminants in the soil could be an added source of exposure, either from inhalation of fugitive dusts or dermal contact, and include the PAH's and metals (arsenic, cadmium and lead). The population exposed through soil ingestion or dermal contact would be minimal and the greatest risk would be for on-site workers and children in the immediate area or those who came on-site.
Since the landfill is located on sloped land and people live (topographically) downgradient from the site, migration of surficial contaminants via surface water runoff may result in exposure to contaminated surface water, soil, and sediments. Contact with on-site contaminants may be a health concern since the site is unrestricted and there are reports of unauthorized visits to the site by locals (1).
Chloroform causes anesthetic effects via inhalation and also may produce liver and kidney damage in humans and animals. Chloroform also can be absorbed by ingestion and to a lesser extent by dermal contact. Chloroform has not been directly linked by epidemiological studies to human cancer; however, it has been implicated in the etiology of cancer associated with consumption of drinking water containing chloroform and other halomethanes formed during drinking water chlorination. The U.S. EPA classifies chloroform as a B2 carcinogen, a probable human carcinogen by the oral route (8). The estimate for persons exposed to chloroform at the maximum level detected in the residential wells in the past, will have low increased risk of developing cancer over a lifetime. However, because of a theoretical increase in the rate of cancer, this past exposure is considered unacceptable.
Benzene exposure through inhalation or ingestion from the groundwater may produce adverse effects on the blood, the central nervous system, and the immune system. Benzene is considered to be a human carcinogen. Human health studies have demonstrated significant excesses of leukemia, multiple myeloma, and lymphatic cancers as well as chromosomal aberrations to be associated with exposure to benzene. While systemic effects are not readily observed following direct contact of small amounts of benzene with the skin, repeated or prolonged contact with the liquid may cause dermatitis. This has not been reported at this site and would not be expected (9). The level of contamination of benzene in the residential wells is above the current EPA's MCL of 5 ppb (maximum 7 ppb), and it must be considered as an added threat with chronic exposures. The maximum benzene exposure at this site in the past indicates no apparent increased cancer risk over a lifetime. However, because of a theoretical increase in the rate of cancer, this past exposure is considered unacceptable.
TCE and PCE are low level contaminants in the off-site groundwater and residential wells. The ingestion of high doses of these chemicals by laboratory animals has been associated with fatty infiltration of the liver and the production of hepatic damage. In addition, epidemiological studies have demonstrated that the ingestion of large doses of TCE and PCE by humans may result in hepatic toxicity. However, the reported concentrations detected in groundwater would not be expected to cause significant noncarcinogenic hepatic toxicity (10,11).
TCE and PCE have also been shown to be carcinogenic in laboratory animals. Although no data convincingly demonstrate TCE or PCE to be carcinogenic in man, the positive results in animal studies warrant concern for human exposures to these chemicals. Chronic exposure to the concentrations of TCE and PCE detected in groundwater samples could pose a no apparent increased lifetime carcinogenic risk to humans due to past exposure. However, because of a theoretical increase in the rate of cancer, this past exposure is considered unacceptable. Furthermore, simultaneous exposure to multiple VOC could increase the risk because of potential additive interactive carcinogenic effects. Therefore, the long-term use of VOC contaminated water in the home for potable and nonpotable purposes may pose a public health hazard. A number of studies have shown that exposure to VOC during activities such as showering may equal if not exceed the exposure from ingestion.
Some PAH's are known carcinogens, however, the majority of the toxic effects following exposure to PAH's concern the skin and eyes. These include comedones, skin tumors, erythema and edema of the eyelids, conjunctivitis, photophobia, and temporary changes in vision. The soil and sediment samples reveal some elevation of concern for chronic exposure of children or workers (12) should they frequent the areas of contamination on a routine basis.
The lead levels found in the surface water is not a public health concern. Although the lead levels found in the residential wells (maximum 106 ppb) is a public health concern based on past exposures, these levels of contamination are not believed to be a significant concern now because the exposure pathway has been eliminated by supplying bottled water to the effected residents. The sediment samples (22,300 ppb) and soil samples (11,000 ppb) would not be a significant source. If any residents are not using the bottled water, then a potential is present, because the lead may be elevated to a level of concern.
Exposure to lead is particularly dangerous for the fetus, because of its great sensitivity during development, and for young children, because they ingest more lead through normal mouthing activity, absorb more of the lead that they ingest, and are more sensitive to its effects. Exposure of a mother to lead results in the transfer of lead to the fetus and may cause preterm birth, reduced birth weight, and decreased intelligence quotient (IQ) in the infant. Lead exposure may increase blood pressure in middle-aged men. At high levels of exposure, lead can severely damage the brain and kidneys in adults or children. In addition, high levels of exposure to lead will cause abortion and damage the male reproductive system. The effects of lead are the same regardless of whether it enters the body through breathing or ingestion (13).
Elevated mercury levels (maximum 8.2 ug/l) in residential water exceeds EPA's MCL of 2 ug/l and can pose a chronic health threat through ingestion, inhalation, and dermal exposure and therefore, the mercury in the water is of a public health concern due to past exposures.
Chronic mercury toxicity depends on the chemical form (elemental, organic compounds, inorganic salts) and the route and duration of exposure. Elemental mercury and the inorganic forms of mercury salts are generally poorly absorbed orally, while the organic forms of mercury are generally well absorbed orally. Most forms of mercury vaporize fairly readily, particularly when heated, and are generally well absorbed by the inhalation route. Chronic mercury toxicity consists primarily of neurological and renal effects, with neurological effects being most prevalent. Neurological effects range from initial tremors and progress through trembling, personality disorders, excitability, hallucination, and delirium. Renal effects consist of glomerular disease with subsequent proteinuria, and rarely occur without accompanying neuropathy (14). The reported concentrations detected in groundwater in the past would not be expected to cause adverse effects since exposure has now been limited.
Chronic oral exposure to highly elevated cadmium levels produces primary renal disease (decreased tubular resorption with accompanying proteinuria) and secondary skeletal disease (osteomalacia, osteoporosis, spontaneous fractures) as a result of prolonged, excessive renal calcium loss. Available evidence also indicates a possible role of cadmium in hypertensive disease. Cadmium concentrations at this site exceed EPA's MCL and PMCLG more than 2-fold and 4-fold, respectively, in both off-site groundwater and residential wells (15), but are not likely to result in any adverse health effects unless exposures were allowed to persist.
Health outcome data are gathered routinely and reviewed. However, no further analysis of available data was performed at this site because when the number of exposed persons is small, even at high exposure concentrations, any adverse health outcome would not be discernible through the analysis of aggregate health outcome data. Furthermore, no specific concerns were expressed regarding adverse health outcomes by the community around the site.
Based on the information reviewed, ATSDR and PADOH have concluded that this site is of public health hazard resulting from past exposures through the use of contaminated residential well water at concentrations that may result in adverse health effects. Human exposure to VOC's and metals has occurred in the past and may be presently occurring through ingestion and dermal contact with the contaminated groundwater or through inhalation of the volatilized components in the residential well water. Also, there is a potential for future human exposure to metals and PAH's to occur through direct contact with contaminated soil, sediment, or groundwater, through ingestion of groundwater, and through inhalation of contaminant-laden fugitive dusts. These present and future exposure concerns should be eliminated or significant reduced once the EPA remedial actions (see Public Health Actions below) have been completed.
There is limited direct human exposure to contaminants at the site. All affected homes within 0.25 mile are presently being supplied bottled water. In spite of these facts, the potential exists for an increased incidence of cancer as a result of inhalation of chloroform, TCE, and other organic chemicals volatilized from groundwater during routine domestic uses such as showering, bathing, and cleaning; also, past exposures of individuals using contaminated wells for drinking is evident.
Limited on-site soil and no on-site groundwater analyses were done, thus we have no evidence of concentrations on-site that could migrate off-site in time.
- The Welsh Road Landfill site has been evaluated by ATSDR's Health Activities Recommendation Panel for appropriate follow-up with respect to health activities. ATSDR is planning to conduct community health education for those persons who are or were exposed to contaminants in their domestic wells. Particular attention will be given to those persons who refused hook-up to the municipal water supplies.
- Because of the possible inhalation of volatile organic contaminants during domestic use of groundwater, some permanent alternate water supply should be considered for the homes whose private wells have been affected or will become affected in the future. Possibly, the Honey Brook water system could be extended to the affected area around the site where the private wells have been contaminated.
- Site access should be restricted to prevent children from playing on the site. Contact with surface contaminants would be eliminated or significantly decreased by this measure.
- Fugitive dusts and surface water runoff should be controlled. This would reduce the risk associated with inhalation and direct contact with site-related contaminants in the immediate off-site area.
- Additional field investigations are needed to adequately characterize the extent of contamination of on-site groundwater, surface soil, and subsurface soil as well as off-site surface soil.
Public Health Actions Planned
Based on the recommendation of the HARP, ATSDR will undertake the following public health action:
- Community health education for those persons who are or were exposed to contaminants in their domestic water supplies. Particular attention will be given to those persons who refused hook-up to the municipal water supplies.
Furthermore, the EPA has indicated that they plan to take the following actions related to the recommendations in the health assessment:
- EPA is planning to begin construction of a waterline in March 1992 to provide to those nearby residences with contaminated private wells a permanent alternate water supply--construction should be completed by March 1993. This action should eliminate the possibility of inhalation of volatile organic compounds during the domestic use of groundwater.
- EPA is planning to construct a landfill cap over contaminated soils and to fence the site. These action should be completed by December 1993. These actions would eliminate or significantly reduce the potential for dermal exposure by children to surface soil contaminants and to any remaining physical hazards. If these measures are implemented as described, it would eliminate the need for additional surface and subsurface soil investigations. The landfill cap, when completed, will reduce the risk associated with inhalation and direct contact with contaminated fugitive dusts and surface water runoff.
- As part of the implementation of the ground water remediation, EPA is planning additional characterization of the extent of groundwater contamination.
This public health assessment was prepared by the Pennsylvania Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health assessment was initiated.
Gregory V. Ulirsch
Technical Project Officer, SPS, RPB, DHAC
The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this public health assessment and concurs with its findings.
Division Director, DHAC, ATSDR
James M. Fox, M.D.
Division of Environmental Health
Pennsylvania Department of Health
Kandiah Sivarajah, Ph.D.
State Toxicologist; Project Officer
Division of Environmental Health
Pennsylvania Department of Health
ATSDR Regional Representative
Public Health Advisor
Office of the Assistant Administrator, ATSDR
ATSDR Technical Project Officer
Gregory V. Ulirsch
Technical Project Officer
Division Health Assessment and Consultation
Remedial Programs Branch
- Preliminary Health Assessment, Welsh Road/Barkman Landfill Site, Chester County, Pennsylvania, ATSDR, December 2, 1988.
- Proposed Plan, Welsh Road/Barkman Landfill Superfund Site, PADER, USEPA, January 1990.
- Draft Record of Decision, Welsh Landfill Superfund Site, May 9, 1990.
- Analytical Report, Wadsworth Testing Laboratories, Inc., April 22, 1985.
- Review of Welsh Landfill Well and Soil Samples, Weston-Sper, July 1985.
- Remedial Investigation Report for the Welsh Road/Barkman Landfill Site, December 8, 1988, JMC Martin, Inc.
- Final Public Health Evaluation, Welsh Road/Barkman Landfill Site, Baker/TSA, Inc., January 1990.
- Toxicological Profile for Chloroform, ATSDR, U.S. Public Health Service, Atlanta, Georgia, January 1989.
- Toxicological Profile for Benzene, ATSDR, U.S. Public Health Service, Atlanta, Georgia, May 1989.
- Toxicology Profile for Trichloroethylene, ATSDR, U.S. Public Health Service, Atlanta, Georgia, October 1989.
- Draft Toxicological Profile for Tetrachloroethylene, ATSDR, U.S. Public Health Service, Atlanta, Georgia, December 1987.
- IARC Monographs on the Evaluation of the Carcinogens Risk of Chemicals to Humans, Polynuclear Aromatic Compounds, Part 4, Bitumens, Coal-tars and Derived Products, Shale-oils and Soots, Volume 35, January 1985.
- Draft Toxicology Profile for Lead, ATSDR, U.S. Public Health Service, Atlanta, Georgia, February 1988.
- Toxicological Profile for Mercury, ATSDR, U.S. Public Health Service, Atlanta, Georgia, December 1989.
- Toxicological Profile for Cadmium, ATSDR, U.S. Public Health Service, Atlanta, Georgia, March 1989.