In collaboration with Vermont state and school officials, we conducted a research study to measure emissions of polychlorinated biphenyls (PCBs) from room surfaces in Vermont schools. Our study, the largest of its kind, investigated the sources of airborne PCBs in indoor school environments. Using simultaneous deployment of air samplers and emission samplers, we measured airborne PCBs in 16 schools and 98 school rooms constructed prior to 1980. There was a wide range in PCB air concentrations (1.7-5700 ng m-3, n = 159) and surface emissions (33-830,000 ng m-2 d-1, n = 182) across different schools as well as between rooms in the same school. We found that emissions of PCB congeners from walls, floors, ceiling and wall expansion joint caulking, and spray insulation explain the airborne PCB congener concentrations in many rooms. Our emission samplers identified three distinct types of building materials with emissions exceeding 30,000 ng m-2 d-1 including expansion joint sealant (up to 480,000 ng m-2 d-1), glass block windows (up to 30,000 ng m-2 d-1), and fireproof coating on steel columns (up to 830,000 ng m-2 d-1). Consequently, school staff have an estimated excess lifetime cancer risk from both dioxin-like and nondioxin-like PCBs that ranges from 1.3 × 10-8 to 1.7 × 10-4 for central tendency exposure, and 2.8 × 10-8 to 3.8 × 10-4 for reasonable maximum exposure (State of Vermont's target cancer risk = 1 × 10-6). Although production has been banned for decades, our study illustrates that PCBs continue to pose an exposure risk to occupants due to their long history of use in building materials. Our findings underscore the risks associated with the historic presence of PCB-containing building materials, offering critical insights for community efforts aimed at reducing exposure among children and school staff in thousands of schools across the country.
Hua et al. (Tue,) studied this question.