food safety - Why should (or shouldn't) we wash rice ...
About arsenic, the FDA says "rinsing rice before cooking has a minimal effect on the arsenic content of the cooked grain. Rinsing does, however, wash off iron, folate, thiamin and niacin from polished and parboiled rice." That link includes tables of reductions of those vitamins and minerals by rinsing, and also by cooking in excess water.