BACKGROUND AND STATEMENT OF ISSUES
The Region I U.S. Environmental Protection Agency (EPA) has requested that the Agency for Toxic Substances and Disease Registry(ATSDR) provide health consultations assessing the public health threat from polychlorinated biphenyl (PCB) contamination on properties associated with the General Electric (G.E.) site in Pittsfield, Massachusetts . This health consultation will address PCB contamination at the Allendale Public School. The evaluation will be based on information contained in a data package furnished by EPA, along with information acquired during a site visit conducted by ATSDR, EPA, and the Massachusetts Department of Public Health (MDPH) on March 13, 1998.
The Allendale Public School encompasses approximately 12 acres, and is located in a mixed commercial/residential area . The school is surrounded by residential properties on three sides. The Pittsfield Generating Company (formerly the Altresco Corporation) is located southeast of the school property. The school building covers approximately 30,000 square feet . The majority of the property is located south of the school, and includes two baseball fields and an open grass area.
In 1950, during the construction phase of the school, PCB contaminated fill from the G.E. facility was used to level the terrain . In January 1990, the Massachusetts Department of Environmental Protection (MDEP) conducted initial sampling of the school property and identified PCB contamination in the soil. Two soil samples collected in the southeast part of the site exceeded a 2 parts per million (ppm) "level of concern" for the site. Additional sampling resulted in the decision to cap part of the school property. In 1991, a cap consisting of a GEOTEX liner with two feet of clean fill was placed over a five acre portion of the school property where PCBs exceeded 2 ppm in the top two feet of soil .
In response to MDEP's request for additional remedial action, G.E. collected surface and subsurface soil samples in an effort to characterize the full extent of contamination . Sampling was conducted around the southeast part of the site, and expanded to other parts of the school property. In 1996, as part of G.E.'s "Imminent Hazard Evaluation", 114 surface (0-6-inches) and near surface (6-to 12-inches) samples were collected from the school property. Additional sampling events were also conducted to determine the vertical and horizontal extent of contamination.
PCBs in the surface soil (0- to 6-inches) ranged from non-detect to 23 ppm with the majority of the samples showing concentrations less than 2 ppm. A localized area of contamination was identified in the school yard outside the boundary of the cap. Samples taken at this location averaged approximately 3-to-4 ppm.
Subsurface PCB concentrations (various depths) at this site ranged from non-detect to 810 ppm. The highest PCB levels were detected beneath the cap. Only a small percentage of subsurface samples collected outside the cap exceeded 2 ppm.
PCBs are a group of 209 synthetic organic chemicals that have varying levels of toxicity. In humans, long-term exposure to PCBs can effect the skin, liver, reproductive and endocrine systems . While human evidence of PCB carcinogenicity is limited, animal studies provide sufficient evidence. EPA has characterized PCBs as "probable human carcinogens" .
Humans are exposed to PCBs through multiple pathways. In addition to the ingestion of soil, water, and inhalation of contaminated air, food serves as a major source of PCB exposure. The potential health threat from environmental PCBs is dependent on factors such as concentration in media, completed exposure pathways, frequency of exposure, and duration of exposure.
At this site, students and children from the surrounding residential areas are likely to play on site and be exposed to the surface soil. Exposure is typically limited to the top few inches of soil where incidental ingestion of contaminated soil may occur. To a lesser degree, dermal absorption of PCBs may also occur from contact with the soil. The area on site with the highest concentration of PCBs in the surface soil (average 3-to-4 ppm) is located in the field outside of the cap. To reach an exposure dose of potential concern for this level of PCB, an individual would need to spend most of their day on the contaminated soil, almost every day of the year for well over 30 years. Such a scenario is unlikely given the present use of the site and the relatively localized extent of the contamination.
If future excavations or erosion of the cap should occur, toxicologically significant levels of PCBs may be brought to the surface. The cap is an interim measure requiring periodic inspections to ensure its effectiveness as a barrier to exposure.
Based on the information provided, ATSDR concludes the following:
1. Surface soil concentrations of PCBs on the school property do not pose a public health hazard.
2. The cap is an interim measure that is serving as an effective barrier to subsurface contamination until a permanent solution can be implemented.
Timothy Walker, MS
Environmental Health Specialist
Concurred: Richard Canady, PhD, DABT