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EC accept Comet assay

March 18th, 2014

The European Commission Member State Committee have accepted that the Comet assay can be used to follow up in vitro mutagenicity results. This can be combined with an in vivo micronucleus assay, which will give more information to establish the potential of a chemical to damage DNA without the need for a second animal study. The mutagenicity testing strategy was discussed in the Members State Committee meeting held in November 2013, for which the minutes are now available.

The Comet assay is a test to determine the potential for mutagenicity of a chemical, which can be used as an in vitro assay, in which cells are exposed to the chemical, or an in vivo assay, in which animals are dosed with the suspected mutagen. There is not yet an OECD guideline for the study, though there are internationally agreed protocols, and EFSA have produced guidance for the assay. It will be helpful when an OECD guideline has been established, as it will then be possible to propose testing for REACH compliance, without needing to submit a study protocol, as is currently required.

As the in vivo Comet assay becomes more commonly used, especially with concurrent data for other in vivo genetic toxicity endpoints, it will be possible to assess the usefulness of the assay as an indicator of mutagenicity (changes to DNA) and cytogenicity (changes to chromosomes).