Is tobacco bad for your health and why?

because all smoke is carcinogenic (causes cancer), wether its from a campfire or a cigarette, theres always a chance of dying when you inhale it, or at least that's what everyone seems to think. the thing is some tobacco companies add chemicals, anything from pesticides to potect the plants to additives to make it taste different. that plus the niccotine, which is in all cigarettes because it produces the nicotine buzz, is addictive. so smoking a cigarette or two will do about as much harm as sitting next to a campfire for a few minutes. but then after a few cigarettes the addiction begins to set in, which would grow and grow, until your inhaling huge amounts of cancer causing substances. which increases your chances of getting lung cancer.

The above answer is completely misleading. Not all smoke is carcinogenic. Marijuana smoke does not show to cause cancer. Tobacco itself is not bad, but cigarettes are bad because of the radioactive pesticides they use.

Any smoke produced from the burning of carboniferous compounds (including marijuana, gas appliances, candles, etc.) is considered carcinogenic - some based on scientific findings, some on political grounds.

Bananas, nuts, sunflower seeds and other foods high in potassium contain traces of the radioactive isotope K40, so they could be also considered as carcinogenic. It's nothing to do with science any more, I'm afraid - it's politics and vested corporate interests.