Furylfuramide (AF-2), which had been used as a food additive, was banned in 1974 in Japan, since it was strongly positive in mutation assays with bacteria as well as in chromosome aberration tests in cultured mammalian cells, and finally proved to be carcinogenic in rodents.  Since that time, the mutagenicity (genotoxicity) tests have been adopted in toxicology test guidelines for a variety of chemical substances to be registered in Japan.
     This home-page; "The MUTANTS", is a database on nearly 1700 compounds (including natural substances) which have been tested for their mutagenicity (genotoxicity) by the systems of different genetic end-points. The compounds were arranged alphabetically  with their CAS numbers, general uses and molecular weight as well as their chemical structures.
     Test results of each compound were summarized in tubular forms, with appropriate abbreviations.  References of the papers from which data was cited were also noted.
     The test results were evaluated quantitatively rather than qualitatively、e.g. the minimum (Min.) or maximum (Max.) concentration for positive or negative results, respectively.
     The contents will be periodically revised, however, the author hopes that all data will be useful for the researchers who are interested in genetic safety of chemicals.