Integrated Risk Information System (IRIS) Assessment of PCBs: Supporting Data

Polychlorinated biphenyls (PCBs) were produced commercially in the United States from 1929-1977 for use in a wide variety of applications. Unfortunately, the unique chemical properties of PCBs that made them so useful (e.g., thermal stability, resistance to acids and bases, low water solubility) also contributed to their resistance to degradation, bioaccumulation in food chains, and toxicity. Although the commercial manufacture of PCBs was banned in the United States in 1979, even today, PCBs are ubiquitous in human blood, adipose tissue, and breast milk. PCBs can be found in marine and fresh water fish, and fish consumption constitutes a major source of human exposure to these chemicals. Inhalation has also been shown to be a contributor to total PCB exposure, especially in indoor settings where PCB sources exist. General population exposure may also occur via dermal contact with PCBs in soil or other media, or incidental ingestion of PCB-contaminated soil or dust. Currently, there are two Integrated Risk Information System (IRIS) reference doses (RfDs) available for use in assessing human health risk associated with PCB exposure, one for the commercial PCB mixture Aroclor 1016 established in 1993, and another for Aroclor 1254 established in 1994. PCB research since the time that these values were published has provided additional information to be considered in a new IRIS assessment currently under development to evaluate noncancer human health hazards associated with PCB exposure. This presentation will provide an overview of the hazard identification and dose-response strategies planned for the new assessment as well as a summary of the the types of research data considered to support assessment development.

Impact/Purpose

This presentation will be delivered at the annual External Advisory Committee meeting of the University of Iowa's Superfund Research Program (ISRP). Although the manufacture of PCBs was banned in the U.S. in 1979, many buildings constructed before then, including many public schools, still contain potential sources of indoor air PCB contamination. In some indoor settings and for some age groups, inhalation may contribute more to total PCB exposure than any other route of exposure. EPA regional offices have already struggled to address this issue in New York, Oregon, North Dakota, Massachusetts, California, and Vermont. In the future, this issue is expected to impact numerous school districts and municipalities nationwide. Although PCB exposure has been associated with human health effects, data specific to the inhalation route are sparse. ISRP research is focused on health problems associated with PCB exposure, including airborne PCB sources and effects of inhalation exposure. The goal of this presentation is to communicate with the ISRP regarding their research and how it is considered for integration into the ongoing IRIS PCB assessment.

Citation

Lehmann, G. Integrated Risk Information System (IRIS) Assessment of PCBs: Supporting Data. University of Iowa Superfund Research Program External Advisory Committee Meeting, Iowa City, IA, October 19 - 26, 2022.