1,1'-Biphenyl, 2,2',3,3',5,6,6'-heptachloro- 2,2',3,3',5,6,6'-HEPTACHLOROBIPHENYL 2,2',3,3',5,6,6'-Heptachloro-1,1'-biphenyl 2,3,5,6,2',3',6'-Heptachlorobiphenyl 2,3,6,2',3',5',6'-Heptachlorobiphenyl 52663-64-6 PCB 179