I have some sensitivities to chemicals and I would itch if the toilet water contained anything irritating - splashes or the fumes would do it. I would disinfect the toilet after flushing then wash in a bidet or with water from a container in the shower/tub. Then I would wash my bottom with a weak solution of ethanol or vodka to kill organisms on the skin. And use the solution to disinfect the toilet seat and hands. Pure clorox (not the over-the counter polluted chlorine bleaches)is Ok to disinfect the toilet but flush the toilet before sitting down. I wear gloves when I wash after defecating. I find that washing the vaginal area with plain water from a container is effective for vaginal and bottom itching. It is also possible to get allergic reactions from toilet water - look up urticaria.