Are you skeptical of the germ theory of disease?
I find https://viroliegy.com/ convincing on the virus question, and I'm pretty skeptical of the pathogenic qualities of bacteria now also. I suspect that if bacteria (or for that matter mold or fungus) contaminate a food for a long period they might produce toxic substances, but a spore of one of these microorganisms seems unlikely to me to culture harmfully inside a healthy human.
I'm also skeptical of the mutation theory of cancer, and partial to the metabolic theory promoted by Dr. Thomas Seyfried. https://youtu.be/Oijv5ZGqo-I