We have previously described a sensitive bacterial test for detecting carcinogens as mutagens. We show here that 89% (150/169) The present work stems from a biochemistry class experiment in which hundreds of commercial products were tested for mutagenicity. Only two products were found to be mutagenic: cigarette smoke tar (8) and an oxidative-type hair dye.Since 20,000,000 people (10), mainly women, dye their hair in the U.S. we have made a detailed study of hair dye mutagenicity. 2423The two main types of hair dyes are the "semi-permanent" or direct color dyes and the "permanent" or oxidative-tN pe dyes in which H202 is used to oxidize aromatic diamines with the production of larger colored molecules which are trapped in the hair shaft. We have concentrated on the oxidativetype dyes since they account for about 75% (11) of the $250,000,000/year hair dye market. The oxidative dye package consists of one bottle containing a mixture of aromatic amines, aromatic nitro derivatives, and phenols in a vehicle liquid (12,13), and a bottle of H202 with which it is mixed immediately before use. RESULTSWe first tested about 30 oxidative-type hair (lye fz cmulations for reversion of our standard tester strains. Almost all of these were mutagenic when tested on strain TA1538, indicating the production of frameshift-type mutations. Strain TA1535 was not reverted, indicating a lack of base-pair substitution mutations; the other frameshift tester strain, TA1537, with a different specificity also was not reverted. We have, therefore, used strain TA1538 to test 169 different oxidative-type dye formulations; these were all the products we could find in two local drug stores. Each hair dye preparation has been tested both before and after mixing with H202.

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