1,1'-Biphenyl, 2,2',3,3',5,5',6-heptachloro- 2,2',3,3',5,5',6-HEPTACHLOROBIPHENYL 2,2',3,3',5,5',6-Heptachloro-1,1'-biphenyl 2,3,5,2',3',5',6'-Heptachlorobiphenyl 2,3,5,6,2',3',5'-Heptachlorobiphenyl 52663-67-9 PCB 178