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Review of June 2001 Private Well Sampling Results



At the request of the U.S. Environmental Protection Agency in Region III (EPA), the PennsylvaniaDepartment of Health (PADOH), working under a Cooperative Agreement with the Agency forToxic Substances and Disease Registry (ATSDR), prepared this Health Consultation (HC) todetermine if residents near the Watson Johnson Landfill (the Site) are exposed to trichloroethene(TCE) in their private well water at levels that would harm their health.

Exposure to TCE represents no apparent health hazard for all of the residents living in locationsdiscussed in this HC. With the exception of one home south of the Site, well water from all privatewells discussed in this HC contained levels of TCE that were less than the federal drinking waterstandard. The levels of TCE present in a few residential wells along Richlandtown Pike do not posea threat to the health of the residents using their wells. TCE was also present in a few residentialwells south of the site. All residents living south of the site in homes where well water was sampledand the results discussed in this HC are using bottled water or carbon filtration units to mitigate orprevent exposure to TCE.

There are private residential wells south of the Site in the area of concern that were not sampled andcould not be evaluated in this HC. We do not know if residents using water from these wells areexposed to TCE because data are not available. Therefore, exposure to TCE in water from theunsampled residential wells south of the Site is an indeterminate public health hazard due to lack ofdata. We recommend sampling of all residential wells in the area immediately south of the Site.

The interpretation, conclusions, and recommendations regarding the Watson Johnson Landfill aresite specific and do not necessarily apply to any other site.


The Watson Johnson Landfill is in Richland Township, Bucks County, Pennsylvania. The Site liesabout 2000 feet south of East Pumping Station Road and 2000 feet west of Route 212. Theapproximately 32-acre landfill is northeast of the Tohickon Creek and 750 feet south of a farmhouseon East Pumping Station Road (Figures 1 & 2). Based on a review of aerial photography, it appearsthat the landfill began operations sometime after 1955. However, there is anecdotal information thatthe landfill began accepting wastes as early as 1936. In the mid 1960s the landfill accepted 3,200tons of waste from W.R. Grace & Company's Quakertown chemical facility. The landfill has beeninactive since 1973 [1].

Geology in the Quakertown area is dominated by the Brunswick Formation. This formationconsists mostly of reddish brown shale and sandstone that have developed a well-defined system ofvertical joints and faults. Secondary porosity (groundwater moving through joints and faults) is theprimary pathway for the ground water flow. The ground water flow through the BrunswickFormation is difficult to determine due to the different size and frequency of the fractures. Thewater table is approximately 15-35 feet from the land surface, and the saturated thickness isapproximately 150 feet. The shallow ground water is expected to flow toward the Tohickon Creek,southwest of the Site [1].

Approximately 90 people are served by private residential wells (RWs) near the Site. DuringSeptember 1998, EPA sampled several RWs near the Site. During July 1999, EPA also sampledseveral RWs, a water supply well serving the Walnut Bank Farm Development and twoQuakertown Borough Water Supply (QBWS) wells. PADOH and ATSDR evaluated the results ofEPA's sampling and prepared a health consultation (HC) to address their findings [1]. The HCrecommended that additional sampling of wells not previously sampled in an area south of the Sitebe conducted to determine if contaminants were migrating offsite to the south.

During June 2001, EPA sampled residential wells south of the Site in the recommended area (Figure 3). TCE was detected in four of the residential wells (Table 1). The maximum concentration ofTCE in well water (RW-31) in this area was 15.0 micrograms per liter (µg/L). EPA also sampledRWs near the Site along Richlandtown Pike. TCE was present in a few of the private wells (RWs 3-6 & RW-30) along Richlandtown Pike at concentrations ranging from an estimated 0.1 µg/L to aknown concentration of 4.0 µg/L in RW-30 [2]. In this HC, we evaluate the results of EPA'ssampling and determine the public health significance of exposure to TCE detected in severalresidential wells.


On August 20, 2001, J.E. Godfrey, Hydrogeologist and Robert M. Stroman, Health Assessor fromPADOH surveyed the topography around the study area to determine the location of the homessampled in June 2001. During this Site Visit, homes near the Watson Johnson Landfill wereobserved that are reported to have TCE present in their private well water.

On August 28 and 31, 2001, Dr. Geroncio Fajardo and Robert Stroman met with residents alongNorth Ambler (RW-31), Woodland Avenue (RW-14 and RW-20), North Penrose (RW-16), andRichlandtown Pike (RW-30), where TCE was detected in their private wells. Fajardo and Stromandiscussed with the residents possible public health implications if exposure were to occur for alifetime. During the visit, residents living in the homes served by RWs 14, 16, 20, 30, and 31shared the information that they use bottled water for cooking and drinking. Residents living in thehome served by RW-20 also have an in-line carbon filtration unit that is designed to preventexposure from all pathways (ingestion, inhalation, and dermal) to volatile organic compounds, including TCE.


Very low concentrations (less than 0.3 µg/L) of TCE are present in a few of the residential wells along Richlandtown Pike. The levels are below levels of health concern and do not threaten the health of the residents using their well water. A low concentration of TCE (4 µg/L) present in one residential well in this area is also below a level of health concern and does not threaten the health of the residents using that well water.

TCE is also present in a few residential wells south of the Site along North Ambler Street, Woodland Avenue and North Penrose Street at concentrations ranging from 0.8 µg/L to 15.0 µg/L (Table 1). With the exception of one home along North Ambler Street that has a concentration of 15.0 µg/L of TCE in its well, all the other homes that were sampled during this investigation contained TCE in their well water at concentrations of less than EPA's maximum contaminant level of 5.0 µg/L.

Exposure to TCE at a concentration of 15.0 µg/L which is above the federal drinking water standard, in the home along North Ambler Street, will not threaten the health of the residents of this home who use this water during bathing and showering. This family uses bottled water for drinking and cooking. Exposure to TCE during bathing and showering in all of the other homes (south of the Site) evaluated in this HC will also not threaten the health of the residents using their well water. All residents south of the Site whose private well water was sampled during this investigation use bottled water or have inline carbon filtration units to mitigate or eliminate their exposure to TCE.

To determine the public health significance of past exposure to TCE in well water, we assume a maximum residential exposure to TCE in off-site ground water of 15.0 µg/L and a worst case exposure period of 45 years since the landfill appears to be in operation after 1955. This is a very conservative approach because exposure should be currently limited to showering and bathing (inhalation of volatile TCE) for the residents using bottled water and would only occur for residents using an inline carbon filtration unit in the event that the filter became full (saturated with TCE) and was not cleaned or replaced.

To determine the possible health effects of site-specific chemicals, ATSDR has developed health-based comparison values (CVs) that are chemical-specific concentrations to help identifyenvironmental contaminants of health concern. We use CVs to determine which contaminantsrequire further evaluation. These values include Environmental Media Evaluation Guides(EMEGs,) and Reference Dose Media Evaluation Guides (RMEGs) for noncancerous health effectsand Cancer Risk Evaluation Guides (CREGs) for cancerous health effects. If environmental mediaguides cannot be established because of a lack of available health data, other comparison valuesmay be used to select a contaminant for further evaluation. While media concentrations less than aCV are unlikely to pose a health threat, media concentrations above a CV do not necessarilyrepresent a health threat. Therefore, CVs should not be used as predictors of adverse health effectsor for setting clean-up levels.

PADOH also researches scientific literature and uses the ATSDR's minimal risk levels (MRLs), theEPA's reference doses (RfDs), and the EPA's Cancer Slope Factors (CSFs). MRLs are estimates ofdaily exposure to contaminants below which noncancerous adverse health effects are unlikely tooccur. RfDs are estimates (with uncertainty spanning perhaps an order of magnitude) of daily oralexposure, in milligrams per kilogram per day (mg/kg/day), to the general public (including sensitivegroups) that are likely to be without an appreciable risk of noncancerous harmful effects during alifetime (70 years). When RfDs and MRLs are not available, a no observed adverse effect level(NOAEL) or lowest observed adverse effect level (LOAEL) may be used to estimate levels belowwhich no adverse health effects (noncancerous) are expected.

Health guidelines such as MRLs and RfDs, however, do not consider the risk of developing cancer. To evaluate exposure to carcinogens, EPA has established CSFs for inhalation and ingestion thatdefine the relationship between exposure doses and the likelihood of an increased risk of cancer,compared with controls that have not been exposed to the chemical. Usually derived from animal oroccupational studies, cancer slope factors are used to calculate the exposure dose likely to result inone excess cancer case per one million persons exposed over a lifetime (70 years).

Because children generally receive higher doses of contaminants than adults under similarcircumstances, the PADOH uses the higher doses in forming its conclusions about the health effectsof exposures to site-related contaminants when children are known or thought to be involved (seeChild Health Initiative section). Also readers should note that researchers conduct animal studiesusing doses at levels much higher than those experienced by most people exposed to contaminatedgroundwater originating from hazardous waste sites.

In evaluating the residential exposures from private wells, PADOH estimated exposures for children and adults from the three routes of exposure (inhalation, ingestion, and dermal). Assuming that the inhalation dose and dermal dose are approximately equal to the estimated ingestion dose, the respective doses for children and adults would be three times the ingestion dose. This is a conservative assumption because the dermal dose should be less than the ingestion and inhalation doses.

Trichloroethene (TCE)

TCE is a nonflammable, colorless liquid with a somewhat sweet odor and a sweet, burning taste. Itis used mainly as a solvent to remove grease from metal parts, but it is also an ingredient inadhesives, paint removers, typewriter correction fluids, and spot removers. TCE is not thought tooccur naturally in the environment. However, it is present in some underground water sources andmany surface waters as a result of the manufacture, use, and disposal of the chemical. TCE does notbuild up significantly in plants and animals, which includes humans [3].

Noncarcinogenic-Health Effects

To evaluate for acute exposure (14 days or less), we assumed that children living near the Site consumed one liter of water per day contaminated with TCE at the highest detected level of 15.0 µg/L. In this scenario, PADOH believes that children would not have experienced noncancerous adverse health effects because the estimated dose experienced at that level is less than the ATSDR's acute oral Minimal Risk Level ((MRL) by a factor of about 133. Similarly, assuming that adults living near the Site consumed two liters of water per day contaminated with TCE at a level of 15.0 µg/L, the estimated dose experienced at this level from all exposure routes (i.e., ingestion, inhalation and dermal) is also below the acute MRL by a factor of about 500. Therefore, we do not expect any adverse noncancer health effects to occur from short-term exposure to TCE at this site.

For chronic exposure, ATSDR has not expanded a chronic oral MRL for TCE [4]. The EPA hasplaced the RfD for TCE under review [5]. Therefore, PADOH evaluated the potential fornoncancerous health effects after long-term exposure at the levels found during this investigationusing the available toxicological literature. PADOH does not expect any noncancerous healtheffects when multiple exposure routes (inhalation, ingestion and dermal contacts) are evaluated. The estimated total dose for children and adults would be 0.0045 and 0.0012 milligrams perkilogram per day (mg/kg/day), respectively. The estimated total doses are several thousand timesbelow doses at which adverse health effects would be expected based on animal studies [4]. Therefore, we also do not expect any noncancer adverse health effects to occur from chronicexposure to TCE at this site.

Carcinogenic Health Effects

In studies using high doses of TCE in animals, tumors in the lungs, liver and testes were found,providing some evidence that a high dose of TCE can cause cancer in experimental animals [3]. Based on the limited data in humans regarding TCE exposure and cancer, and evidence that highdoses of TCE can cause cancer in animals, the International Agency for Research on Cancer (IARC)has determined that TCE is probably carcinogenic to humans. Recently, the Department of Healthand Human Services (National Toxicology Program) determined that TCE may reasonably beanticipated to be a carcinogen. This was based on limited evidence from studies in humans,sufficient evidence of malignant tumor formation in experimental animals, and convincing relevantinformation that TCE acts through mechanisms indicating it would likely cause cancer in humans. Currently, the National Toxicology Program is considering possible upgrading of TCE to a knownhuman carcinogen. The EPA is also reviewing its classification for TCE's carcinogenicity inhumans [4].

Epidemiological data are limited for evaluating the carcinogenicity of TCE in humans. Studies havesuggested that occupational exposure to TCE causes cancer of the liver, biliary tract and non-Hodgkin's lymphoma. Another study has indicated that occupational exposure to TCE has beenassociated with cancer of the kidneys [6]. However, the actual exposure levels were not provided inthese studies. There is one study that used the concentration of a TCE urinary metabolite (known astrichloroacetic acid or TCA) and inferred the level of exposure experienced by study subjects. Theinvestigators reported that a urinary TCA level below 50 mg/L corresponds to a TCE exposureconcentration of 20 parts per million (ppm). They found no correlation between exposureconcentration or exposure time and cancer incidence [4]. However, because TCE is a probablehuman carcinogen, PADOH recommends that exposure to TCE should be eliminated or reduced tothe lowest level possible.

In order to evaluate the possible cancer risk associated with the exposures to TCE at the maximum concentration (15.0 µg/L) that occurred to people who used contaminated well water during this investigation, we calculated the theoretical cancer risk using the cancer slope factor (CSF) of (0.011 mg/kg/day)-1 that EPA has placed under review. These calculations are based on the assumptions that 1) there is no safe level of exposure to a chemical that may cause cancer, 2) a person is exposed for a lifetime to the chemical, and 3) that inhalation and dermal doses are approximately equal to the estimated ingestion dose. However, these calculated risks are not exact and tend to overestimate the risk associated with exposures that occurred. Based on the theoretical cancer risk estimation for those people who were exposed to TCE at the maximum concentration (15.0 µg/L) for the past 45 years, the predicted cancer occurrence would be about nine additional cancers per 1,000,000 people [4]. Therefore, it is our opinion that (possible) past exposure to TCE (for 45 years) posed no significant cancer risk for the people who used water from the private wells.


PADOH and ATSDR recognize that the unique vulnerabilities of infants and children demandspecial emphasis in communities faced with contamination of environmental media. As part ofATSDR's Child Health Initiative, ATSDR public health consultations indicate whether site-relatedexposures are of particular concern for children.

In general, children appear to be more sensitive to the effects of TCE, presumably because of ahigher body burden. However, there is no evidence that the pharmacokinetics (absorption,distribution, metabolism, and excretion) of TCE differ in children [4].


PADOH and ATSDR conclude the following:

  1. Exposure to TCE represents no apparent health hazard for all of the residents living in homes discussed in this HC.
  2. Potential exposure to TCE in unsampled private wells south of the Site represents anindeterminate public health hazard due to lack of data.
  3. Further investigation to confirm whether TCE is migrating offsite beneath the TohickonCreek at levels of health concern and impacting additional residential wells (not evaluated inthis HC) south of the Site is necessary.


  1. Discuss the public health implications of past exposure to TCE with residents exposed to thiscontaminant in their private wells.
  2. Define the groundwater contamination plume to determine if the TCE present in private residential wells and the Quakertown Municipal Wells is originating at the Site.
  3. Conduct additional sampling of wells not previously sampled in the area south of the siteapproximately bounded by Heller Road, Highland Avenue, Penrose Street, and WoodlandAvenue.
  4. Evaluate future sampling data and prepare a public health assessment or health consultation that will address our findings.


  1. PADOH met with affected residents identified in this HC and discussed the public healthsignificance of their past exposure to TCE-contaminated well water. PADOH will continueto be available to answer residents health questions as more information becomes available.
  2. EPA will consider defining the groundwater contamination plume to determine if the TCEpresent in private residential wells and the Quakertown Municipal Wells is originating at theSite as part of the Remedial Investigation.
  3. In consultation with PADOH, EPA will attempt to conduct additional sampling of wells notpreviously sampled in the area south of the site approximately bounded by Heller Road,Highland Avenue, Penrose Street, and Woodland Avenue as part of the RemedialInvestigation.
  4. Following receipt sampling results, PADOH will evaluate future sampling data and prepare a public health assessment or health consultation that will address its findings.


  1. U.S. Agency for Toxic Substances and Disease Registry (ATSDR), Health Consultation forthe Watson Johnson Landfill in Richland Township, Bucks County, Pennsylvania,CERCLIS NO. PAD980706824. Atlanta: ATSDR, February 9, 2001.
  2. Facsimile [July 9, 2001 EPA (Gerry Hoover) Sampling Data Results] to Robert Stroman,Pennsylvania Department of Health, from Lora Siegmann Werner, ATSDR Region III, July20, 2001.
  3. Agency for Toxic Substances and Disease Registry (ATSDR). ToxFAQ forTrichloroethylene. September 1997. URL
  4. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile forTrichloroethylene (Update), U.S. Public Health Service. Atlanta, Georgia: ATSDR,September 1997.
  5. United States Environmental Protection Agency. Integrated Risk Information SystemDatabase. URL 9/12/2001.
  6. U.S. Department of Health & Human Services. Public Health Service, National Toxicology Program, 9th Report on Carcinogens 2000.


Robert M Stroman, B.S., Pharm.
Health Assessor
Pennsylvania Department of Health

Geroncio C. Fajardo, M.D., M.B.A., M.S.
Epidemiology Program Specialist
Pennsylvania Department of Health


This Watson Johnson Landfill Site Health Consultation has been prepared by the PennsylvaniaDepartment of Health under Cooperative Agreement with the Agency for Toxic Substances andDisease Registry (ATSDR). It is in accordance with approved methodology and procedures existingat the time the health consultation was initiated.

Roberta Erlwein
Technical Project Officer, SPS, SSAB, DHAC

The Division of Health Assessment and Consultation, ATSDR, has reviewed this HealthConsultation and concurs with its findings.

Sven E. Rodenbeck
for Richard E. Gillig


Site Location Map
Figure 1. Site Location Map

Site Location Map
Figure 2. Site Location Map

Site Map
Figure 3. Site Map

Table 1. Levels of trichloroethene detected in residential wells sampled

Residential Wells (RW) Trichloroethene (TCE)*
RW-3 0.1 J**
RW-4 0.1 J
RW-5 0.2 J
RW-6 0.1 J
RW-14 1.0
RW-16 0.8
RW-20 4.0
RW-30 4.0
RW-31 15.0

* All results in ug/L or ppb
** J = analyte present; reported value is estimated; concentration is outside the range for accurate quantitation

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