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"The skin disease, chloracne, as well as other toxic effects, is brought about by ingestion of large quantities of dioxin (2,3,7,8-TCDD)."

I don't have your background, but I have read about PCB exposure to Japanese and Italians and the victims had chloracne from ingesting the PCBs. I believe that the PCBs in Japan are contaminated with dioxins. The was a case where PCB from a heat transfer system got into some cooking oil which was sent to a town in Japan. The people who eat the food cooked in the PCB contaminated oil got chloracne, but they did not die.

Poly-chlorinated biphenyls (PCBs) were designed principally for their coolant and fire-retardent properties as insulating oil for electrical transformers including small ballasts for fluorescent lights that you might find in older household fixtures.

For it to get somehow mixed with cooking oil is a blunder worthy of the blind cook who baked a cake using only baking powder, water and eggs.

I really, really wish I could post some molecular structures here. The structure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is two benzene rings joined by a pair of oxygens in the para configuration. On the outer edges are 4 carbons, one in each corner. You can see a picture at this website. PCBs are similar to dioxins, except that there is only one oxygen between the two benzene rings. It takes a dose of PCBs 100 to 1000 times the size of a dose of TCDD to cause symptoms of toxicity, but the symptoms are the same and mediated by the same receptor. (In other words, the Japanese you mentioned were not exposed to TCDD.) Unlike TCDD, PCBs were manufactured commercially until the 1970s and several million tons of them are still around. There have been incidents in the US where people and livestock were exposed to PCBs.

I think the Italians you read about were exposed to TCDD; there was an industrial accident in July 1976 where over a kilogram of TCDD contaminated more than 200,000 people, mostly in Seveso, Italy. None of these people died from the TCDD, but EVERY animal in the area died or had to be put down.