Don't wash food in Potassium Permangenate! Manganism is a nasty illness, quite like lead or mercury poisoning with additional apparent Parkinsonism. It's not just welders who get Manganism: it's a reasonably common affliction of folk making or taking semi-synthetic drugs, caused by Manganese in its Potassium Permangenate form, where it's sometimes used as an oxidiser. (In an interesting twist, Manganese in a molecule used to replace lead as a petrol additive has also caused health problems).

As a strong oxidiser, it's useful as a disinfectant, but so's bleach, ammonia and chlorine. I might wash my feet in them, or put them on a sore, if I was recommended to, but I'd stop short of washing my food in them, unless I was working in some kind of proper dose-controlled conditions and working in the mechanically-recovered meat industry!

/If/ there's a significant quantity of Lead on the surface of fruit, and /if/ it's not effective only to wash it off with water, /then/ a chelator like Citrate might be worth it. I suspect industry would use EDTA, but Citrate is probably easier to get hold of and easier to safely dose. Though most lead is probably easily washed off in dust or else internalised in the fruit.

Stay off Chromic Acid cider too! ;-)

(Fwiw, I do eat roadside blackberries, after washing them).