Mitigating emissions of semi-volatile polychlorinated biphenyls (PCBs) from contaminated sediments using aerobic bioaugmentation

Polychlorinated biphenyls (PCBs) were produced and distributed in a variety of industrial and consumer products throughout the 20th century until their commercial use was banned in the United States in 1979. Today, PCBs still contaminate our natural environment and pose a persistent threat to human and ecological health. Consumption of PCB-contaminated food is the primary route of human exposure to PCBs, but research performed at the Iowa Superfund Research Program (ISRP) has shown how common they are in the air we breathe. PCBs are continuously released at low levels from water bodies where PCBs were improperly disposed of years earlier. The release of these compounds to the air is accelerated by traditional cleanup methods, such as dredging.

Human health can be better protected by remediating these sites using alternative, non-invasive techniques that do not disturb contaminated sediment to the same degree as dredging. The remediation technique investigated in this work is a process called ‘bioremediation’. Bioremediation harnesses the natural capabilities of microbes to break down PCBs before they can be released to the atmosphere, where humans can be exposed through inhalation or consumption of food that has accumulated PCBs. This document describes results from lab-scale experiments which directly measured PCB biodegradation and show that the emissions of certain PCBs from contaminated sediment to the air can be significantly lowered when PCB-degrading microorganisms are present. These results suggest that it may be possible to reduce human inhalation exposure to PCBs by using bioremediation at PCB-contaminated sites as an alternative to, or in combination with, traditional remediation technologies.