I'm not convinced that US-grown rice is immune from possessing significant levels of inorganic arsenic. My understanding is that because the root system of rice is submersed, it's not so much that the surrounding water may contain higher or lower levels of arsenic. But more that the water itself facilitates faster, more efficient absorption of said element into the plant. Inorganic arsenic comes from the soil. It leaches into the water, which transfers to the rice plants. Since naturally occurring soil levels of inorganic arsenic may be relatively high at any given location on our planet, I think that US-grown rice can be substantially hazardous as well.
http://grist.org/food/theres-arsenic...-it-got-there/