The sources of the sediment samples used in this study are described in previous publications (2,12−17) and the references cited therein. Sediment characteristics are summarized in Table 1. Triplicate sediment samples from Lake Hartwell and Hunters Point were characterized for PCBs following USEPA methods 3550B (hexane:acetone sonication), 3630B (activated granular copper to remove elemental sulfur), 3630C (silica gel column cleanup), and 8082 (PCB congener analysis). Duplicate sediment samples from Grasse River, Milwaukee River, and Niagara River were characterized following USEPA methods 3660B (sulfur cleanup), 3665A (sulfuric acid clean up), 3630C, and 8082. Triplicate sediment samples from Crab Orchard Lake were characterized using a sulfuric acid and copper cleanup followed by PCB congener analysis.