The use of reporter genes for mutagenicity testing in animals

Chemical substances capable of modifying the body’s genetic material (DNA) possess genotoxic properties. Mutations are irreversible changes to DNA. Such changes can affect any of the various types of cells in the body, and can lead to cancer. In addition, mutations in germ cells can also be transmitted to future generations. Assays for genotoxic properties in chemical substances form the basis for measures aimed at reducing these risks. Genotoxicity can be established using a variety of assays. Mutagenicity assays are particularly important, as they can identify changes in DNA. Using in vivo assays, experimental animals are exposed to the substance under investigation. In vitro assays involve the use of cells or microorganisms. If in vitro and in vivo assays produce contradictory results, then more weight is usually given to the experimental animal results, since these organisms more closely resemble human beings. Indirect evidence is also taken into account when reaching a verdict with regard to genotoxicity. This can relate to (in vitro or in vivo) assays of the formation of DNA adducts (covalent bonding to DNA). In this advisory report, the in vivo data is similarly conclusive, therefore ‘genotoxic’ (or ‘non-genotoxic’) really means ‘genotoxic in vivo’ (or ‘non-genotoxic in vivo’).