Issue Date: January 23, 2006
We at Rohm and Haas read with interest "Keeping Well-Preserved" (C&EN, Nov. 14, 2005, page 25), your article about cosmetic preservatives and the attendant reference to isothiazolinones.
As a class, isothiazolinone preservatives are currently approved for use in numerous applications, including cosmetic products. Assessment of the safe use of isothiazolinone preservatives in this diverse range of applications has necessitated the generation of data from a comprehensive battery of toxicological tests. These tests covered the spectrum of toxicological end points from acute toxicity through to carcinogenicity. Included in this battery of tests were a range of in vitro and in vivo mutagenicity tests, which covered the full range of end points, from point mutation to chromosome aberrations.
From the results obtained in this battery, the overall conclusion is that the isothiazolinone preservatives do not pose a mutagenic risk to humans. Further support for the lack of toxicity for DNA [genotoxicity] can be drawn from the carcinogenicity studies performed on a representative isothiazolinone preservative, chloromethylisothiazolinone/methylisothiazolinone (CMI/MI). In both the rat and the mouse, CMI/MI was shown to be noncarcinogenic.
Our data packages have been subjected to extensive regulatory review by U.S., European, Japanese, and other regulatory authorities, and in all cases the chemistries have been approved for use in the applications in which they are currently used. In conclusion, isothiazolinones are clearly safe preservatives. There is no credible scientific basis for suggesting otherwise today.
As one of many producers of isothiazolinones, we appreciate the opportunity to present the facts.
Michael F. Wooder
Rohm and Haas, U.K.
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