It is an enzyme that makes the coal tar a carcinogen. Polycyclic aromatic hydratase or something similar to that, PAH for short. Coal tar treatment for people with psoriasis does not appear to increase their risk of skin cancer.
I’ll have to look it up and refresh my memory later.
Interesting. Thanks for the clarification.
So, on one hand these folks are saying that she possibly had psoriasis and took creosote to relieve the itching, and then conclude that it was the creosote that gave her cancer.