You know that smoking is bad for your health. However, scientists have just shed additional light on how those toxic chemicals can wreck your body. A newly published study has determined that a pack-a-day smoker typically produces 333 DNA mutations per year, and only about half of them (150) are in the lungs. There are also mutations in the larynx (97), pharynx (39), mouth (23), bladder (18) and liver (6). Many of those mutations are harmless, but you're effectively rolling the dice with every year that you puff -- you're triggering a "cascade" of gene damage that could lead to cancer.