There is now good evidence to show that smokers’ lung cancer is due to radioactivity carried down into the lungs with smoke. Radioactive lead contained in tobacco is volatilized by the heat of burning and condenses onto the membranous lining of the airways, especially where the passages divide (bifurcations). Over the years, more and more radioactive lead (which “decays” into radioactive polonium) accumulates. Whether or not it stays at these sites largely depends upon how normal a person’s lungs remain.
If damaged beyond repair by tar and infection, the membrane’s lining cells lose their cilia (tail-like processes that, by constantly beating, waft inhaled particles up and out of the chest) and become unable to rid themselves of the radioactive contamination.
Eight groups of scientists recently wrote about this to New England Journal of Medicine, which published their letters together in the same issue (307:309). Most significantly, they reported, discovery of radioactive lead in smoke has been the most powerful anti-smoking influence they had ever encountered. News of it, apparently, has convinced many heavy smokers, for the first time, to stop smoking immediately.
It has also been found that the cancer-producing effect of smoking may not all be due to damage done directly to the lungs. According to the Medical Journal of Australia (2:425), the lymphocytes (one of the many types of white blood cell that defend the body against invading microorganisms) in smokers become much more sluggish than usual.
In particular, the ability of the lymphocytes to become “killer cells,” which attack any other cells of the body that begin to behave abnormally (e.g: become cancerous), is greatly reduced by smoking. This could explain why smokers have so many more infections than non-smokers, and why their tumors, such as melanomas, grow and spread more quickly to other parts of the body. Because the lymphocytes quickly regain their normal killer cell activities when smoking is stopped, it is never too late to give up the habit.
*72\143\2*