lets see, in a person's daily life where do all the radiations sources one comes across come from?
1. The sun.
2. Cosmic rays from space.
3. The burning of petroleum products and coal. (This is a big one nobody talks about).
4. Radon gas emissions.
5. Cigarette smoke (especially if the tobacco was grown in uranium rich soil)
6. Airplane flights, especially high altitude jets.
7. Electrical outlets and appliances inside the home.
8. Heavy industrial electrical equipment (electric motors and generators, welders etc...)
9. Medical X-rays and other medical methods.
10. Cell phones, computer monitors, electric light bulbs... and the list goes on and on.
As to how much cancer is caused by any of these sources is really dependent on the amount of exposure and how susceptible one is to the condition. I'm certain that living itself is carcinogenic... so where do you draw the line... Where do you force people to label their products as "carcinogenic"? I'm sure the money spent labeling these products if spent in the research for the cure for cancer could be better spent than trying to label all these products. The solution is obvious, and that is the education of people to the dangers involved in anything done in excess. As this is usually the root of anything that causes cancer and other conditions. It's the constant irritation the body's immune system undergoes that must cope with these irritants. Hopefully through time the human species will evolve an immunity (or create one) to the "cancer" condition, but even that may prove ro be carcinogenic. Cancer kills, find a cure for it, but learn to live with it until then.