Oxidative-stress-driven in vivo mutagenesis induced by oral administration of potassium bromate in the small intestines of gpt delta mice

•In the mouse, the practical threshold dose for mutagenicity induced by oral potassium bromate was 0.2–0.6 g/L.•The threshold was not affected by Nrf2-KO status.•Elevated G-to-T transversions are likely to drive tumorigenesis.•G-to-T transversion at nucleotide 406 on TGAA in gpt is a hallmark of oxidative stress.•8-Oxo-dG formation at T(A)GAA is a possible initiating event in tumorigenesis.