in both prokaryotes and eukaryotes including plants, Cr5 toxicity is largely attributed to its easy diffusion across the cell membrane, reduction within cells producing free radicals and reactive oxygen species which further aggravate its toxicity.
Cr5 enters into cells as an oxyanion(chromate/dichromate) through nonspecific anion channels in membranes due to the structural resemblance of chromates to sulfates and phosphate ions.
within cell, Cr5 is formed sequentially by its metabolic reduction to cr4, cr5, and finally to biologically stable cr3 generating free radicals.