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Not all carcinogens are mutagens. Alcohol and estrogen, for example, do not damage DNA.

It's one of the assumptions of the Ames test that mutagenicity implies carcinogenicity, but is this always the case? I assumed that it was, but then I saw one of the comments here. I did some more research but the internet seems to be reluctant to be definitive on the subject. This guy claims no, but I'd prefer sources or at least a response that handles counterexamples like HPV. This paper claims yes, but doesn't list any specific examples. Some mutagens might be more specific to genes involved in cell cycle regulation, so I could see how a weak mutagen is a powerful carcinogen.

My question is, can you go the other way? Are there mutagens that just do not cause cancer? If they do not exist or are not known to exist, are they even possible?

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All mutagens are potential carcinogens. Unless the mutagen is highly specific to a site.

HPV is not carcinogenic. It causes oncogenic transformation of a cell because of certain proteins that it codes for. Retroviruses can randomly integrate near an oncogene and cause oncogenic transformation (This is a mutation in principle. Not a point mutation though. They can also integrate within a gene and knock it out). Alcohol and estrogen are also not carcinogens. A mutated estrogen receptor can lead to cancer. Estrogen is just a signal.

If you consider the new tools developed for site directed mutagenesis, such as ZFN, CRISPR-Cas and TALEN as mutagens then they are not carcinogenic. However the term mutagen is not used for these molecules. Mutagen almost always refers to a molecule that causes random mutagenesis thereby making it a carcinogen.

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ZFNs in particular fit quite neatly the counter-example I was looking for above. Good answer. –  Resonating Jun 26 at 19:49

I'm no expert on the matter, but just quoting from Wikipedia:

Mutagens are not necessarily carcinogens, and vice versa. Sodium Azide for example may be mutagenic (and highly toxic), but it has not been shown to be carcinogenic.

It cites Toxicology And Carcinogenesis Studies Of Sodium Azide.

So it would appear the answer is no. Not all mutagens carcinogens.

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Sodium azide is only mutagenic part of the time(half of the strains tested), and there's ncbi.nlm.nih.gov/pubmed/2671718 this paper that shows that sodium azide isn't a mutagen in mammals. It's still poisonous (cerebral necrosis!) but neither a mutagen nor a carcinogen in mammals. –  Resonating Jun 25 at 16:02
    
It seems like there should be a counter-example (a mutagen with zero or negligible carcinogenicity) but I can't find one. –  Resonating Jun 25 at 16:04

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