According to the U.S. Department of Health and Human Services, cigarette smoke has over thirty known human carcinogens.
Mutation can be described as a change in the nucleotide sequence of DNA. It can occur either spontaneously or is induced by the environment. These changes, if occur in gametes, are inherited from one generation to the succeeding ones. Mutations are of many types such as frameshift mutation (insertion or deletion of nucleotides), base pair substitutions (a purine or a pyrimidine is substituted by another purine or pyrimidine), and chromosomal rearrangement (inversion or translocation of multiple genes).