A whole typical cigarette contains around 10-12mg of nicotine. The wiki says 30-60mg is potentially fatal to an adult, but that it could potentially take as much as 500mg. So for an adult, unlikely. For a child, I see mixed things saying 1 cigarette could be fatal. This says 1-13mg per kg for an infant. So maybe, depending on the size of the butt and the child?
A whole typical cigarette contains around 10-12mg of nicotine. The wiki says 30-60mg is potentially fatal to an adult, but that it could potentially take as much as 500mg. So for an adult, unlikely. For a child, I see mixed things saying 1 cigarette could be fatal. This says 1-13mg per kg for an infant. So maybe, depending on the size of the butt and the child?