Polychlorinated biphenyls (PCBs) are a group of synthetic chemicals produced for industrial use worldwide and manufactured from 1929 to 1979, when production was largely banned in the United States. PCBs remain in products manufactured prior to 1979 and continue to be released into the environment. In addition, unintentional and low-level production of PCBs is still occurring, so they can also be found in some newer products. Their toxicity, persistence in the environment, and ability to concentrate up the aquatic food web is of particular concern for the health of species including Chinook salmon, seabirds, marine mammals, and apex predators like killer whales, and can affect the safety of seafood consumption.
PCBs remain a concern
Although PCB levels are declining in some species and locations, levels in many species have remained unchanged for at least two decades. Toxics monitoring using caged mussels has shown significant PCB accumulation throughout the Puget Sound nearshore, indicating contamination remains widespread.
PCBs continue to accumulate to levels that are harmful to fish, and the biomagnification of PCBs in apex predators such as Southern Resident Killer Whales impairs their health and recovery. The presence of PCBs in seafood also leads to restrictions on how much fish we can safely consume, and can lead to the disproportionate exposure of people to PCBs across demographic groups. Fish consumption advisories have been issued by the Washington State Department of Health (DOH) due to elevated PCB levels in resident Chinook salmon in all marine areas. PCBs account for the majority of Puget Sound seafood consumption advisories issued by DOH.
Focused sampling of particulate organic matter and krill in Elliott Bay and the Lower Duwamish River in late 2021 and 2022 have pointed to this area as a potential source of PCBs to the broader Puget Sound pelagic food web.
How PCBs are being managed
Focused clean-ups in highly contaminated areas such as Commencement Bay and the lower Duwamish River have removed PCBs from the sediments and helped prevent future contamination from nearby land or watershed sources. Toxic cleanup sites can be found on the Washington State Department of Ecology Toxics Clean Up map. Continued work, including reductions in loadings, is needed to reduce PCB levels below those known to impair fish and human health in developed estuary and nearshore habitats in Central and South Puget Sound. Research has shown that green stormwater infrastructure can substantially reduce PCB concentrations from stormwater (PDF). There is ongoing development of a regional recovery plan, known as the Toxics in Fish Implementation Strategy, that will help focus long-term efforts to reduce the impacts of toxic contaminants in fish.