1,2,3,6,7,8-HEXACHLORODIBENZOFURAN 1,2,3,6,7,8-Hexa polychlorinated dibenzofuran 1,2,3,6,7,8-Hexachlorodibenzofuran [Dioxin and dioxin-like compounds] 2,3,4,7,8,9-Hexachlorodibenzofuran 57117-44-9 Dibenzofuran, 1,2,3,6,7,8-hexachloro- F 121