Tobacco: nicotine

Tobacco contains nicotine, a powerful neurotoxin that is particularly harmful to insects. A lethal dose of nicotine is contained in as little as one half of a cigar or three cigarettes; however, only a small fraction of the nicotine contained in these products is actually released into the smoke, and most clinically significant cases of nicotine poisoning are the result of concentrated forms of the compound used as insecticides. Tobacco leaves are often smoked (see tobacco smoking) in the form of a cigar or cigarette, or in a smoking pipe, or in a water pipe or a hookah.