Unscheduled DNA synthesis (UDS) test with mammalian liver cells in vivo

The unscheduled DNA synthesis test is a short-term genotoxicity assay that allows identification of substances that induce DNA repair in liver cells of treated animals. This endpoint can be assessed by determining the uptake of radiolabelled nucleotide after excision-repair in cells that are not undergoing scheduled (S-phase) DNA synthesis. Here we describe the protocol for performing this well-known primary DNA damage test following the OECD guideline No. 486, EC, and published international recommendations.