Of course, lettuce or cabbage cut up and processed in sealed bags nowadays has been pre-washed before packaging. But if it is unpackaged, raw produce, it’s wise to wash it before consuming it.
I still wash the bagged stuff. I don’t know if there’s a chemical or something added, but I detect a strange odor/taste on it.
I am sorry to hear you have this affection. You should seek help for it. Its called paranoid obsessive compulsive disorder.