Short-term tests and the myth of the non-clastogenic mutagen

I suggest that there are several good reasons for retaining mammalian cell mutation assays in a basic test package for genotoxicity and that the possible existence of a non-clastogenic mammalian mutagen is not one of them. I put forward a number of propositions, not necessarily original, concerning in vitro assays, including their need for repetition, the inappropriateness of rodent carcinogenicity as a reference point for validation, the need for assays to corroborate rather than complement each other, the need for ongoing validation and development, and the need for as complete an in vitro package as possible in order to avoid unnecessary animal experimentation.