Indoor PCBs can be problematic!

This paper (Inhalation and Dietary Exposure to PCBs in Urban and Rural Cohorts via Congener-Specific Measurements) published by Ampleman et al. in the latest issue of Environmental Science & Technology did a very comprehensive study on indoor PCB levels and once again highlighted the important contribution of polychlorinated biphenyls (PCBs) from indoor sources to human exposure.

PCBs are persistent organic chemicals that were used in construction materials and electrical products produced before 1979. PCBs have been demonstrated to cause cancer, as well as a variety of other adverse health effects on the immune system, reproductive system, nervous system, and endocrine system. See the USEPA website for more information.

With regulations, PCB levels in the general environment have decreased substantially. However, in buildings built between 1950 and 1979, indoor concentrations of PCBs may still be  at high levels. Based on my previous studies, PCB concentrations measured in the air of contaminated buildings in Toronto Canada can be over 100 ng/m3 (http://pubs.acs.org/doi/abs/10.1021/es102767g, http://pubs.acs.org/doi/abs/10.1021/es2032373)   Human with an inhalation rate of 18m3/d would inhale ~1600 ng/d assuming 90% of time spent in the indoor environment. For people with body weight of 70 kg, body weight normalized exposure just from inhalation would be over 20 ng/kg bw /d

The U.S. EPA has calculated 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. EPA's reference dose (RfD) is 20 ng PCB/kg body weight per day.

Based on the information provided by the USEPA, "the largest source of PCB exposure for most individuals in uncontaminated buildings is diet, which contributes roughly 50-60% to total PCB exposure.Typical indoor and outdoor air contains a small amount of PCBs, and inhalation exposure accounts for another 25 to 35% of total exposure. Together, these non-school sources of PCBs generally result in exposures that are significantly below the reference dose. "

However, for PCB contaminated indoor environment, indoor exposure pathway could be even higher than dietary exposure and pose health risk to inhabitants. While environmental regulations require PCB contaminated soil and sediment to be remediated, how about PCB contaminated indoor environment then?