Some prominent medical sources even claim that there are over 7000 chemicals in tobacco smoke. The rumor seems to be passed around with no reference.
Wikipedia makes a more believable claim that
More than 4,000 chemical compounds are created by burning a cigarette.
If you look at the list of additives to cigarettes, many of them, like maple syrup, basil oil, cocoa, are safe elsewhere and probably not present in most cigarettes. However, my question is what the claimed 4,000 compounds really means. Does it mean that if you burn every type of cigarette in the world, you'll get over 4,000 different possibilities of chemical? Or does it mean that the average cigarette, when burned, contains over 4,000 compounds?
Is it even unusual for 4,000 different chemicals to be in smoke? Would a grilling steak subject to the same methods produce as many carcinogenic compounds in its smoke?