Carcinogenicity of tobacco smoke

Since NNN is present in ppm levels in tobacco and in microgram amounts in the smoke of a cigarette, it may contribute to the carcinogenicity of tobacco smoke. 

In 1997, Stohs et al. (27A110) reviewed the potential of metal ions reacting in conjunction with other constituents of tobacco smoke to cause cellular damage by free radical reactions. Various studies had demonstrated the role of reactive oxygen species in the toxicity of transition metals. They conclnded that the presence of several reactive metal ions in tobacco smoke indicates that there may be a role for metal ions in the subsequent toxicity and carcinogenicity of tobacco smoke. They described the metal-catalyzed mechanisms that might be involved. 

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