The past use of building materials that contained polychlorinated biphenyls (PCBs) is prompting public concern and expensive PCB removal projects. Building materials that may contain PCBs include paint, caulk, floor finishes and many other interior and exterior construction components manufactured before 1972. While initial concern about PCBs in buildings has focused on schools, it is likely that PCB-containing materials will also be found in many residential, commercial, and industrial structures.

In buildings, the primary route of human exposure is the inhalation of PCBs that volatilize out of building materials. The USEPA has indicated that inhalation of airborne PCBs may pose a significant human exposure pathway in schools. EPA’s approach to PCBs in schools is evolving quickly. Initial estimates of health risk from indoor PCBs were calculated using risk assessment methods and EPA published toxicity factors. Recently, EPA established guidance titled “Public Health Levels for PCBs in Indoor School Air” to assist school systems in remediation efforts. These criteria are intended to be “prudent public health levels that maintain PCB exposures below the 'reference dose' – the amount of PCB exposure that EPA does not believe will cause harm."

This article considers two factors central to the accurate assessment of PCB indoor air risk: 1) the difference in the chemical make up of PCBs in air compared to the chemical make up of the PCBs in the building materials they originated from; and 2) how the variability in certain commercial lots of PCBs (Aroclors) can result in different degrees of toxicity. Each of these factors may act to significantly modify the level of risk associated with the inhalation of PCBs in buildings. At the present time, EPA has not incorporated these factors into its calculation of its Public Health Levels.