PCBs (polychlorinated biphenyls) have made a comeback. First brought to international attention in the late 1960s by outbreaks of "Yusho disease"¹ in Japan and by discovery of trace concentrations in United States' fish, wildlife, food, food packaging, and human tissue,² these synthetic industrial-electrical compounds were thought to have been brought under domestic control in 1972. At that time, Monsanto Corporation, the sole United States manufacturer, voluntarily restricted sales to "closed" uses such as electrical transformers and capacitors.

As if to underscore their remarkable persistence in the environment, and to demonstrate their propensity for biomagnification in the food chain, PCBs have once again begun to appear in dangerous concentrations in fish in major American waterways, including the Great Lakes and the Hudson, Ohio, Mississippi, Missouri, Columbia, Sacramento, Rio Grande, and Yukon Rivers.³ This persistence, due to a remarkable chemical and physical stability, not only accounts for the ubiquity of PCBs, but also explains their usefulness in electrical and heat-transfer applications, where they are prized for their nonflammability and constant dielectric properties. Most important, the longevity of PCBs serves to highlight the shortcomings of current federal government approaches to regulating toxic substances.