[mistercow]

While it was dishonest to cut the sentence off in the middle, the lack of epidemiological evidence basically puts nicotine in the same camp as a ton of other substances that have "carcinogenic potential" but aren't considered a risk. Basically, it's plausible that nicotine is carcinogenic to some degree, but with the carcinogenicity of tobacco explained entirely by other factors, there's no real reason to believe that it's a significant risk, especially for bystanders.