Cigarettes aren't done causing damage when you put them out. Whether the tally of discarded butts worldwide is 4.5 trillion or 5.6 trillion, it represents an enormous amount of nicotine and heavy metals deposited in the environment. But what if the contents of your ashtray had a useful application? According to Chinese researchers, they might. Seeking a use for all that junk, the scientists tested the chemicals in cigarette butts for their effects on a kind of steel used in oil and gas pipelines.