Polychlorinated biphenyls in the exterior caulk of San Francisco Bay Area buildings, California, USA

Extensive evidence of the adverse impacts of polychlorinated biphenyls (PCBs) to wildlife, domestic animals, and humans has now been documented for over 40years. Despite the ban on production and new use of PCBs in the United States in 1979, a number of fish consumption advisories remain in effect, and there remains considerable uncertainty regarding ongoing environmental sources and management alternatives. Using a blind sampling approach, 25 caulk samples were collected from the exterior of ten buildings in the San Francisco Bay Area and analyzed for PCBs using congener-specific gas chromatography–mass spectrometry (GC–MS) and chlorine using portable X-ray fluorescence (XRF). PCBs were detected in 88% of the caulk samples collected from the study area buildings, with 40% exceeding 50ppm. Detectable PCB concentrations ranged from 1 to 220,000ppm. These data are consistent with previous studies in other cities that have identified relatively high concentrations of PCBs in concrete and masonry buildings built between 1950 and 1980. Portable XRF was not a good predictor of the PCB content in caulk and the results indicate that portable XRF analysis may only be useful for identifying caulk that contains low concentrations of Cl (≤10,000ppm) and by extension low or no PCBs. A geographic information system-based approach was used to estimate that 10,500kg of PCBs remain in interior and exterior caulk in buildings located in the study area, which equates to an average of 4.7kg PCBs per building. The presence of high concentrations in the exterior caulk of currently standing buildings suggests that building caulk may be an ongoing source of PCBs to the San Francisco Bay Area environment. Further studies to expand the currently small international dataset on PCBs in caulking materials in buildings of countries that produced or imported PCBs appear justified in the context of both human health and possible ongoing environmental release. •The first survey of PCBs in caulk in buildings in the San Francisco Bay Area.•PCBs detected in 88% of the caulk samples with 40% exceeding 50 ppm.•PCB concentrations in caulk were comparable to those in other locations.•An estimated 10,500 kg of PCBs remain in caulk in study area buildings.•Portable XRF may be used to identify caulk containing