ABSTRACT
Cigarette smoke contains around 4000 different compounds and its carcinogenic effect is due to chemicals such as benzo[a] pyrene, not nicotine. When someone smokes tobacco, most of its nicotine content is destroyed. But the small amount that survives is rapidly carried - in less than 10 s - in the blood from the lungs to the brain, where it binds to ‘nicotinic’ acetylcholine receptors, and stimulates the release of neurotransmitters. A cigarette contains less than 10 mg of nicotine, but most of that is oxidized to other compounds on being smoked, with maybe 1 mg of nicotine being delivered to the smoker’s lungs. Of course, people trying to give up smoking often resort to nicotine patches, because nicotine is absorbed through the skin. When the insects absorb and inhale it, nicotine binds to their acetylcholine receptors, paralyzing the insect. It is good for the plant, but bad for most insects.
