You know what is funny? First, let's agree on something here
If A=B, and B=C, does it follow that A=C?
Ok, now let's apply this knowledge we've learned to real life:
Over 40 organic compounds have been isolated, purified, and characterized from tobacco which have all proven to be potent carcinogens. These substances, when taken alone and administered to lab rats, will cause mutations in cellular DNA which cause uncontrolled division and proliferation of cancerous cells. So if it is true that these substances by themselves can cause cancer, and that these substabces are indeed present in tobacco, then doesn't it naturally follow that tobacco causes cancer? I will accept that smokers realize this and choose to smoke anyways; what I cannot understand though, is how a smoker could deny that smoking presents a significant risk to their health. Are the researchers who came out with these data liars? The only explanation I have is that the people who deny the health risks of tobacco are either ignorant, or lying to themselves. I challenge anyone to find a single article which shows that tobacco is a safe substance.