I never use my cast iron Dutch oven without thoroughly preheating it. It's in the oven at 450f for an hour before I put bread in or directly on a campfire for an hour between dishes. Heat sterilisation guidelines fall below that so anything organic is completely charred. Before using it I just dump out the ash. Whatever contamination risk there is, I probably trust that pot over anything coming out of my dishwasher.
I never use my cast iron Dutch oven without thoroughly preheating it. It's in the oven at 450f for an hour before I put bread in or directly on a campfire for an hour between dishes. Heat sterilisation guidelines fall below that so anything organic is completely charred. Before using it I just dump out the ash. Whatever contamination risk there is, I probably trust that pot over anything coming out of my dishwasher.