Continuing sources of PCBs: The significance of building sealants

To investigate the significance of building sealants as a remaining source of PCBs to the environment a combined measurement campaign and GIS-based stock estimation were undertaken for Toronto, Canada. This showed that 14% of buildings measured had detectable quantities of PCBs present in sealants, with concentrations from 0.57 mg/g to 82 mg/g (n = 95). We then constructed a GIS-based database of remaining PCB-containing sealants in Toronto. This showed that there is an estimated 13 t still present in the city. Mass balance calculations showed that up to 9% had been lost via volatilization alone. This potentially has important implications for both human exposure and the continued presence of PCBs in the environment.