"Before the public learned about PFAS, so-called “forever chemicals,” there were other toxic chemicals in the environment arguably worthy of the same nickname.
Polychlorinated biphenyls, or PCBs, haven’t been produced since 1979, after studies found that exposure to them could cause a variety of harmful health effects, including cancer. But they were so widely used before then and so long-lasting that they still impair water quality in much of the tidal Chesapeake Bay and its tributaries.
PCBs differ from PFAS (per- and polyfluoroalkyl substances) in key respects. PFAS dissolve readily in water, which has made them a major threat in drinking water. PCBs are not as mobile, tending to accumulate in the sediment of rivers and streams.
But both chemical groups bioaccumulate, meaning they build up in the blood or fat of animals that ingest them. And like PFAS, PCBs have proven stubbornly resistant to efforts aimed at removing them from the Bay’s water and sediment."
Timothy B. Wheeler reports for the Bay Journal February 17, 2026.
