Spatiotemporal trends in polychlorinated biphenyl concentrations in seafood based on long-term monitoring and remediation in New Bedford Harbor, Massachusetts

Electrical manufacturing near New Bedford Harbor (NBH), MA in the mid-1900s led to severe polychlorinated biphenyl (PCB) contamination, which resulted in the harbors designation as a Superfund Site. Restrictions on the harvest of seafood from NBH have been in effect since 1979. Efforts to reduce the overall mass of PCBs in NBH by dredging PCB-contaminated sediments have been ongoing since the late 1980s. One goal of dredging is to reduce PCB concentrations in NBH seafood, monitored annually by Massachusetts Department of Environmental Protection (DEP) and Massachusetts Division of Marine Fisheries (MDMF). We used PCB concentrations in quahogs (2003-2016) and scup (2003-2014) to evaluate PCB distribution across seafood management areas and over time. Seafood PCB concentrations were used to evaluate improvements in environmental quality by examining total PCBs and patterns of PCB congeners within homolog groups, and by assessing human cancer risk from seafood consumption in the past (1980) and present (2012-2016). PCB concentrations in quahogs generally declined with increased time and distance from the PCB source, as does the cancer risk associated with their consumption. PCB concentrations in scup follow similar spatial patterns but show high annual variability. We conclude that quahogs are a reliable proxy for in-situ conditions, environmental quality, and human health risk.