Polychlorinated dibenzofurans

For example, 2,3,7,8-tetrachlorodibenzofuran (TCDF) has chlorine atoms substituted for each of the hydrogens on the number 2, 3, 7, and 8 carbons (see structure in the upper left corner of the second image).

PCDFs tend to co-occur with polychlorinated dibenzodioxins (PCDDs).

PCDFs can be formed by pyrolysis or incineration at temperatures below 1200 °C of chlorine containing products, such as PVC, PCBs, and other organochlorides, or of non-chlorine containing products in the presence of chlorine donors.

Occupational exposure to PCDFs may occur through inhalation and contact with the skin, although intake even in workers at waste incineration plants is not particularly high.

[2][3] For general population the most important source is food of animal origin like with other dioxin-like compounds.

General chemical structure of PCDFs, where 1 ≤ n+m ≤ 8
Structures of the ten 2,3,7,8-substituted PCDF congeners that are toxicologically of most relevance