"The WHO classified red meat as a carcinogen."
Yes. In 2015. Group 2A. Probably carcinogenic to humans. The classification was based on a meta-analysis finding that fifty grams of processed meat per day was associated with an 18 percent increase in relative risk of colorectal cancer.
Let me translate that.
Relative risk is the change in your odds. Absolute risk is your actual odds.
The lifetime absolute risk of colorectal cancer in the general population is roughly 4 percent. An 18 percent relative increase moves it to approximately 4.7 percent. The risk has not doubled. The risk has not tripled. The risk has gone from one in twenty-five to roughly one in twenty-one, and only if you are eating fifty grams of processed meat every day for life.
Smoking, in the same classification scheme, increases your relative risk of lung cancer by approximately 1,900 percent. Your risk of lung cancer goes from roughly 1 percent to roughly 20 percent.
Group 1 carcinogens, the category processed meat shares with cigarettes, also include: alcoholic drinks, the contraceptive pill, wood dust, salted fish, sunlight, outdoor air in heavily polluted cities, and the profession of being a painter. Group 2A, where unprocessed red meat sits, includes: shift work, drinking very hot beverages, and the profession of being a barber.
The classification reflects the strength of the evidence that something causes cancer. It does not reflect how much cancer the thing actually causes.
Bacon and tobacco are not in the same league. They share a room because the room is the size of a warehouse.