"Sure, here's the answer to your riddle. Each culture has it's unique set of circumstances, climate, diet and lifestyles."
Actually, the biggest factor in all of this is genetics. As you state above, exposure to tobacco smoke plays absolutely no role and first hand smoking creates a slightly higher risk.
With regards to your list of chemicals that you provided, they are encountered daily by everyone in doses far higher than the doses delivered by cigarettes. One example is Arsenic, it is contained in our water supply at higher doses than it is contained in cigarettes.
When the EPA was asked to set exposure limits to SHS, they found that they already had exposure limits set for the elements contained in SHS. These already established limits far exceeded the levels even possible to be reached in a closed room with many smokers constantly smoking cigarettes. When requested to lower the exposure limits to include SHS, they found that it would have made manufacturing impossible.
There is one MAJOR difference, and that is the method of delivery. When you ingest something, it is digested; and only selected components are pulled through the stomach and intestinal walls. Many impurities are thus screened out, this is the way our bodies work.
However, when you inhale, you bypass a great many of your body's defence mechanisms. I would argue that the amount of these chemicals that wind up in your bloodstream through smoking, is exponentially higher than an identical level brought in through consumption.
Also, you put words in my mouth. I have never stated this
"As you state above, exposure to tobacco smoke plays absolutely no role and first hand smoking creates a slightly higher risk.
This was unfair of you. I do not make assinie statements, and indicate that you posted the same, I would expect the same courtesy in return. I don't seriously believe that you think this is the truth. I doubt you will find ANY MD who would say that there is any truth in that statement. The link between smoking and lung cancer, heart disease, liver problems ect. has been demonstrated time and time again. One person challenged me to provide 'unbiased' links, then chastised me for using .gov and .edu as sources. I intentionally avoided the .com suffix; as these are commercial entities with a vested financial interest.
With regard to Japanese Lung cancer rates, there are 2 points of diverence. First of all, do Japanese cigarettes contain the same known carcinogens used by US cigarette companies? Secondly, smoking in Japan is only recently coming into vogue. To fully appreciate the consequences of smoking takes time. Smoking is an accumulative damage issue. You typically won't get lung cancer from 1 cigarette; but the odds of developing respiratory problems increase over time.