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HEALTH CONSULTATION

TEMPLE-STUART
BALDWINVILLE, WORCESTER COUNTY, MASSACHUSETTS


Use of trade names and commercial sources is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry or the U.S. Department of Health and Human Services.


BACKGROUND AND STATEMENT OF ISSUES

The U.S. Environmental Protection Agency (EPA) Region I office in Boston asked the Agency for Toxic Substances and Disease Registry (ATSDR) to review and evaluate soil data collected from the inactive landfill at the Temple Stuart site in Baldwinville, Worcester County, Massachusetts (GA [2]. The purpose of this health consultation is to determine whether levels of polychlorinated biphenyls (PCBs), arsenic, and lead found in soils at the site pose a public health threat.

The Temple Stuart site is located on 23-acres in the Baldwinville section of Templeton, Massachusetts. Several abandoned structures are on the site, and an on-site warehouse is still in limited use. The adjacent inactive landfill is unsecured and located on approximately 5 acres along the northeastern portion of the site. The landfill occupies a former wetland, with the water levels in the uncovered portions of the wetland dependent on drought conditions. The landfill stands approximately 5 feet from its base to the top. Some areas, particularly at the edge of the landfill, are heavily vegetated with trees. The center of the landfill is flat, lightly vegetated, and shows evidence of vehicular and foot traffic, including household dumping. Residential areas are located southeast and southwest of the site, with the nearest residences located within ΒΌ mile [1].

First occupied in 1884, the site has served as the location for the manufacture of wooden containers and wooden furniture. According to the Removal Site Investigation report, several suspected sources of PCBs were found, including transformers and light ballasts/capacitors [1]. Previous sampling activities at the site indicated the presence of PCBs, metals, as well as other contaminants. Other wastes produced at the site include crankcase oil, paint thinners, lacquer, and glue [1].


ATSDR EVALUATION PROCESS

The potential health effects associated with environmental exposure to hazardous substances depend on several factors, including the type and amount of the contaminant; the way the person is exposed; the length of exposure; the amount of the contaminant absorbed by the body; site-specific conditions; genetic factors; and individual lifestyle factors. ATSDR provides public health advice on the basis of a review of toxicological literature, a comparison of levels of environmental contaminants detected at a site to published comparison values, an evaluation of potential exposure pathways and duration of exposure, and the characteristics of the exposed population.

ATSDR uses different comparison values (chemical-specific, health-based standards and guidelines) derived by various government agencies to screen contaminants and identify those that could require further evaluation of their potential to cause adverse health effects. While concentrations at or below the relevant comparison values might reasonably be considered safe, concentrations above these values will not necessarily cause harm. ATSDR uses site-specific exposure scenarios and performs a more in-depth evaluation for substances with detected concentration levels above the screening values.

The most likely human exposure to contaminants found in surface soil is incidental ingestion and/or dermal contact. Inhalation is not considered a significant exposure pathway for surface soil. Exposure to surface soil is typically much more frequent in residential settings than in non-residential ones. Also, workers who participate in onsite activities such as soil trenching and removal are more likely to have greater exposures to surface (and subsurface) soils than will intermittent, casual site visitors.

ATSDR used the following comparison values for this health consultation: the environmental media evaluation guides (EMEGs), cancer risk evaluation guides (CREGs), minimal risk levels (MRLs), cancer effect levels (CELs), and the ATSDR interim guidance for public health assessment evaluations of arsenic-contaminated soils for residential scenarios.


DISCUSSION

On October 21 and 22, 2002, EPA collected a total of 52 surface soil grab samples at the landfill. The samples were collected from a depth of 0-3 inches in areas that are currently accessible to the public. The samples were screened for PCBs and metals at an on-site mobile laboratory. Ten of the 52 samples were also sent off site to the U.S. Environmental Protection Agency (EPA) New England Laboratory (EPA-NE lab) for confirmatory analysis [2].

Previously, the Massachusetts Department of Environmental Protection (MA DEP) conducted sampling investigations at the site. MA DEP collected surface soil samples (0-1 foot depth) as well as subsurface soil samples from borings and test pits. PCBs and metals were found in subsurface soils along with organic compounds that might serve to mobilize PCBs [3].

EPA resampled the landfill area based on the results from the MA DEP investigations. Sampling locations were determined by terrain and vegetation. In addition, samples were collected in locations likely to have the highest contaminant levels due to potential leaching of PCBs and metals, i.e., along the base of the landfill. EPA collected samples during drought conditions making it difficult in some cases to distinguish between surface soil and sediment. All samples were treated and labeled as surface soil samples [3].

PCBs

All 52 grab surface soil samples were tested on site for PCBs using a mobile gas chromatograph (GC) field screening method. PCB screening results ranged from non-detect to 164 parts per million (ppm) with an average level of 16.6 ppm [2]. The 10 confirmatory laboratory results ranged from non-detect to 230 ppm with an average 76.7 ppm [2].

In most cases, laboratory PCB results were consistent with the corresponding screening results. However, in a few samples the field and laboratory results differed. These differences may have resulted from changes in the moisture content of the samples. Field samples were reported on a wet weight basis and confirmation samples were reported per dry weight [3].

EPA has set a soil clean-up level of 1 ppm for PCBs in residential settings. Although access to the site is unrestricted, the public's exposure to onsite surface soils is expected to be intermittent and sporadic. Since the distances, conditions, and terrain restrict the recurring access of children to the most contaminated site areas, ATSDR evaluated a reasonable worst case scenario involving adults. ATSDR evaluated a scenario in which for one day each week, a 70 kilogram (kg) adult consumes 100 milligrams (mg) of the most PCB-contaminated surface soil (230 ppm). This exposure dose (0.00047 mg/kg/day) would be approximately 20 times higher than the ATSDR chronic Minimal Risk Level (MRL) of 0.00002 mg/kg/day. However, this dose is more than 10 times lower than the lowest-observed-adverse-effect level (LOAEL) on which the MRL is based (0.005 mg/kg/day).

The MRL was obtained by dividing the LOAEL by an uncertainty factor of 300, which includes a factor of 3 to account for the extrapolation from animals to humans. This factor of 3 reflects the default assumption that humans are more sensitive than laboratory animals. However, humans are actually known to be less sensitive to the effects of PCBs than rhesus monkeys which were used in this study [4]. In addition, these monkeys were fed encapsulated PCBs (i.e., Aroclor 1254) in feed (7 days a week for 23 months), which would have been much more bioavailable than "aged" PCB residues in soil. In addition, the MRL is based on an immunological endpoint that is not actually an adverse effect [5]. Immunological parameters normally exhibit an enormous range of variability, without having any negative impact on the organism's health.

The CREG for PCBs (0.4 ppm) is based primarily on high-dose liver tumors in rodents that are apparently induced by a promoter mechanism rather than by mutagenesis. In a large epidemiological study of PCB-exposed workers, no significant increases in total cancer mortality were seen in either male or female workers (including the most highly exposed) occupationally exposed to PCBs between 1946 and 1977, nor were any of the previously reported specific excesses in cancer mortality confirmed [6].

The ATSDR Toxicological Profile for PCBs reports a lowest Cancer Effect Level (CEL) (1.25 mg/kg/day) for liver cancer in F-344 rats fed PCBs for 104-105 weeks or 2 years which corresponds to the majority of a rat's lifetime [5]. To get a numerically identical dose from soil contaminated at a level of 230 ppm, a 70 kg adult would have to consume over one-third kilogram of soil per day (or almost 190 times the ATSDR default value) for several decades.

ATSDR evaluated a reasonable worst-case exposure using the highest level of PCBs found in surface soil. Based on a scenario in which exposures to these landfill surface soils are limited and sporadic, ATSDR does not consider PCB exposures likely to cause adverse health effects.

Metals

There were 52 surface soil samples were analyzed for arsenic and lead using the Niton® X-ray fluorescence spectrum analyzer. Ten of these samples were then submitted to the EPA-NE lab for confirmatory analysis.

Arsenic

The screening results showed all arsenic levels below detection (< 60 ppm). In addition, all confirmatory laboratory results indicated levels below the reporting limit of 40 ppm.

For this evaluation, ATSDR assumed a worst case scenario in which arsenic might be present at levels approaching 40 ppm in the confirmatory samples. This theoretical level slightly exceeds the lower ATSDR interim guidance screening range of 30-250 ppm. This screening range is used to evaluate risks for cancer and non-cancer effects from exposure to arsenic-contaminated soils in residential scenarios [7]. Exposures to landfill surfaces soils at this site are expected to be limited and intermittent. As a result, ATSDR does not expect adverse health effects from exposure to the levels of arsenic found.

Lead

Screening levels for lead ranged from non-detect (<40 ppm) to 612 ppm. The confirmatory sample levels reported by the EPA-NE lab ranged from non-detect to 290 ppm.

ATSDR has not established a Minimal Risk Level (MRL) for lead nor has EPA established a reference concentration for lead. However, the EPA Office of Solid Waste and Emergency Response recommends a 400 ppm screening level for lead in residential soil at Superfund sites [8].

All confirmation samples showed lead levels less than 400 ppm. Only one of the 52 screening samples showed a lead level above 400 ppm (612 ppm) and the average screening result was 61 ppm. As a result, ATSDR does not expect exposure to lead in surface soils to pose a health threat at this site.


CONCLUSION

On the basis of available information about the most likely frequency and duration of current exposures at the Temple Stuart landfill, ATSDR concludes that the levels of PCBs, arsenic and lead found in surface soils are not expected to pose a public health hazard.


RECOMMENDATION

ATSDR will reassess the public health determination should children frequent the site. In addition, any other future changes in site usage, including industrial activities, should be reevaluated to assess potential increases in human exposure to landfill surface soils.


REFERENCES

  1. Roy F. Weston, Inc. Removal program preliminary assessment/site investigation report for the Temple Stuart Site, Baldwinville, Massachusetts. Wilmington, MA. Roy F. Weston, Inc.; 2001 Nov 9.

  2. US Environmental Protection Agency. Memorandum to William Sweet from Mary Ellen Stanton concerning request for Health Consultation: Temple Stuart Site Baldwinville, Massachusetts. Boston, Massachusetts. November 22, 2002.

  3. Agency for Toxic Substances and Disease Registry. Memorandum to Gregory M. Zarus from William Sweet concerning the Baldwinville site. December 10, 2002.

  4. Tryphonas H, Hayward S, O'Grady L, et al. 1989. Immunotoxicity studies of PCB (Arochlor 1254) in the adult rhesus (Macaca mulatto) monkey - preliminary report. Int J Immunopharmacol 11:199-206.

  5. Agency for Toxic Substances and Disease Registry. Toxicological profile for polychlorinated biphenyls (PCBs). Atlanta: US Department of Health and Human Services; 2000.

  6. Kimbrough RD, Doemland ML, LeVois ME. 1999. Mortality in male and female capacitor workers exposed to polychlorinated biphenyls. Journal of Occupational and Environmental Medicine 41:161-171.

  7. Agency for Toxic Substances and Disease Registry. Interim guidance for public health assessment evaluations of arsenic-contaminated soils for residential scenarios. Atlanta: US Department of Health and Human Services; 2001 Feb 26.

  8. US Environmental Protection Agency, Solid Waste and Emergency Response. Revised interim soil lead guidance for CERCLA sites and RCRA corrective action facilities; Directive #9355.4-12. Washington DC; US Environmental Protection Agency, Office of Solid Waste and Emergency Response; 1994.

PREPARERS OF REPORT

Prepared by

Gail E. Scogin
Environmental Health Scientist
Exposure Investigations Section
Exposure Investigations and Consultations Branch
Division of Health Assessments and Consultation
Agency for Toxic Substances and Disease Registry


Reviewed by

Gregory M. Zarus
Strike Team Leader
Exposure Investigations and Consultation Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

Donald Joe, PE
Chief, Petition Response section
Exposure Investigations and Consultation Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry



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