Tar. This ingredient, which gives cigarettes flavor, is the same thick black substance used to pave roads and driveways.
Formaldehyde. This is the same stuff used to preserve dead animals, like the frogs dissected in some biology classes.
Cyanide, which is also a main ingredient in rat poison.
Lead. It's also found in some kinds of paint.
Acetone, which is a common ingredient in paint and nail polish remover.
Ammonia. Besides the fact that it's in many household cleaners, it's also in cigarettes.
Carbon monoxide, a common pollutant and the same stuff that escapes from the exhaust in cars.
Hydrazine, a chemical used in jets and rocket fuel.