Nonlegacy PCBs: Pigment Manufacturing By-Products Get a Second Look

A 87 P olychlorinated biphenyls (PCBs) were commercially manufactured in the United States from about 1930 until 1979, when their production was banned under the Toxic Substances Control Act (TSCA) because of concerns about their extreme environmental persistence, ability to bioaccumulate, and adverse human health effects.PCBs were used in numerous industrial and consumer applications, most notably as insulation fluids in electrical transformers and generators but also in products including fluorescent lamp ballasts, caulk, and carbonless copy paper.These now-discontinued manufactured chemicals have received a great deal of attention in terms of research and environmental remediation.But other, lesser-known PCBs continue to be generated and released into the environment, not from intentionally created commercial products but as unintentional by-products of manufacturing processes including, according to recent studies, those used to make certain pigments used in dyes, inks, and paints.PCBs do not occur naturally, and once in the environment they can last for decades.Until recently, PCBs that were being detected in the environment were thought to come entirely from "legacy" sources.Yet developments in analytical technology have given researchers a better understanding of PCB sources, of the patterns of individual PCBs (or congeners) that are being detected environmentally, and the fate of PCBs in the environment-how they move between soil, sediment, water, and air.These advances have also enabled the detection of individual congeners at very low levels and the identification of many new and ongoing sources of PCBs beyond those resulting from historical commercial mixtures.