If it is considered that drinking 800 mL of water per day containing an arsenic concentration equal to the US EPA maximum contaminant level (MCL), delivers the dose to an adult that corresponds to a 1 in 10,000 excess risk of lung cancer.  How much rice, containing 150 µg kg^-1 of inorganic arsenic, would be safe to eat per day if only 500 mL of this water was drunk per day, and excess arsenic-free water was used to cook the rice in such a way that 50% of the inorganic arsenic was discarded?