All the "4000 different chemicals" and poisonous stuff you guys mention aren't all in the cigarette to begin with. You may think "oh they sit down with each other and think 'okay how we gonna kill people today... let's put poop, rat poison, tar, etc. in the cigarette'" but, it's actually you, the end user, who is manufacturing the vast majority of the chemicals. Think of the the tobacco curing process, the substance that holds the cigarette together, preservatives, and the tobacco and paper itself. Lighting that complex arrangement of chemicals on fire will definitely make thousands more different chemicals.... so yeah.