This webinar series focuses on polychlorinated biphenyls (PCBs) in schools and features SRP grantees, as well as EPA and international partners. During this first session, EPA Regional Risk Assessment Coordinator Mark Maddaloni will give a brief overview of PCBs and the issue of PCBs in the environment, particularly in schools. Following his introduction, Kent Thomas, an EPA Research Physical Scientist, will discuss the sources and levels of PCBs in indoor environments, and Peter Thorne, a professor and SRP researcher at the University of Iowa, will discuss human exposure to PCBs, routes of exposure, and reducing exposures.
Kent Thomas
Research Physical Scientist, Human Exposure and Atmospheric Sciences Division, Exposure Measurements and Analysis Branch, U.S. EPA
Sources and Levels of PCBs in Indoor Environments
PCBs in buildings have been studied in recent years to identify and characterize sources, measure indoor concentrations, and for exposure assessment. The goal of this research is to inform risk management decision-making, particularly in schools and other buildings where children are present. Sealants and light ballasts are common PCB sources in older buildings, while absorption of PCBs by other materials may create secondary sources. PCBs are measured in indoor air, on surfaces, and in dust and soil; often with considerable within- and between-building variability resulting from differences in source, ventilation, or other factors. Different approaches for environmental sampling and analysis of PCBs as Aroclors, homologs, or individual congeners have implications for exposure assessment, indoor modeling, and informing cost-effective remediation.
Peter Thorne
Professor and Head, Department of Occupational and Environmental Health
Sources and Levels of PCBs in Indoor Environments
Recent child cohort and school measurement studies have shed new light on the importance of indoor air exposures arising in homes and schools. Modeling of children's exposures in schools with PCB sources shows >80% of the estimated absorbed dose results from inhalation with the remainder from ingestion of dust/soil and dermal contact. Active and passive sampling with measurement of all 209 PCB congeners demonstrates inhalation exposures are most prominent for the mono- to penta-chlorinated PCBs. Biomonitoring of exposures by analysis of blood samples for parent PCB congeners and selected hydroxy metabolites has emerged as a means to estimate body burden. Challenging this approach are the low levels of PCBs in the blood as compared to other body compartments. Animal inhalation exposure studies to a Chicago Air Mixture demonstrate rapid disposition and metabolism of inhaled PCBs from the lung to the blood, liver, brain and adipose tissue with half-lives less than 20 hours. We suggest that for most people, inhalation presents the primary route of PCB exposure and public health efforts should be directed toward monitoring and reducing these exposures, particularly among children.
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