FIG. 1.

Structure of halogenated biphenyls, showing the numbering scheme (A) and the dechlorination of a major heptachlorobiphenyl by Process N, Processes N plus LP, and Process P (B). Each chlorinated or brominated biphenyl congener can have from 1 to 10 halogens (chlorines or bromines) at the positions shown in panel A. The halogens at positions 2 and 6 on either ring are designated ortho, those at carbons 3 and 5 are designated meta, and those at carbon 4 are designated para. Panel B shows one of the major components of Aroclor 1260 and the terminal dechlorination products produced from this congener by Process N, Processes N plus LP, and Process P. The most extensive chlorine removal results from sequential dechlorination by Processes N and LP (27).