How You Cook Rice Influences the Arsenic Level

Abstract

Inorganic Arsenic, iAs, is a well-known carcinogenic compound. It is therefore important to decrease the exposure of iAs as much as possible. In this work the levels of iAs and total arsenic (totAs) are determined in twelve samples of common rice brands, before and after cooking: i) in a recommended volume of water, and ii) in an extra volume of water which is poured off when the rice is ready to eat. The study mimics the way of cooking rice in the house holds; Ordinary pan has been used, salt has been added, and the tap water at hand has been used. The mean levels of iAs and totAs in unboiled rice were 110 μg/kg and 133 μg/kg respectively. The corresponding mean iAs level in the boiled rice, prepared as recommended with cooking to dryness, was about the same as in the unboiled rice. The mean levels, of iAs and totAs in the rice boiled in an excess amount of water was significantly reduced, between 40-70 percent. Furthermore, also other metals were analysed at the same time, e.g. nickel decreased and uranium increased significantly in the rice boiled in excess of water.