Using Long-Term Trends of PCBs in Fish Caught in Maryland Waters to Assess the Effectiveness of Management Actions

Abstract

Historical data sets collected to establish fish consumption advisories are a valuable source of information on pollutant levels in the waterbodies, changes from management actions, and additional work that remains. In this study, fish PCB concentrations across 323 monitoring stations in Maryland over 3 decades were curated and used to perform spatial and temporal analysis. Five watersheds out of 25 were identified as highly impacted by PCBs, including Upper Chesapeake Bay. Known areas of contamination were better predictors of PCBs in fish than generic land use or toxic release information, but PCB transport across watersheds may also explain PCBs in watersheds with little or no known local sources. Impacted watersheds showed slow nationally consistent natural attenuation rates ranging from 2% to 6% yr⁻¹, except the Gunpowder-Patapsco near Baltimore, MD, where no temporal trend was observed since 1996. The overall study showed that PCB source mitigation implemented across Maryland and surrounding states helped recoveries, but more efforts are needed to fully control all PCB sources (legacy and ongoing) that are still impacting the fish. As the scientific and regulatory communities struggle to address new and emerging pollutants, this study demonstrates the unfinished work to rid our waters of widespread legacy carcinogens.