Figure 1 CaCo₂ cells exposed to 0.1% methylene blue (MB) or 0.1% indigo carmine (IC) either in white light or in the dark for 2 min. Control cells (CON) were treated with white light only (no dye). Data are presented as mean (SE) tail DNA (%) for three experiments. Both the DNA damage from the alkaline comet assay (CA; no fill) and the additional damage with Fapy‐DNA‐glycosylase (FPG; fill) are shown. (A) Significance at p<0.001 relative to control cells in the alkaline or FPG‐modified comet assay. (B) Significance at p<0.001 in methylene blue versus indigo carmine cells under the same experimental conditions (either in the light or in the dark) in the alkaline or the FPG‐modified comet assay. (C) Significance at p<0.001 in methylene blue‐treated cells in the light versus in the dark in the alkaline or FPG‐modified comet assay.