Rice contains more of the carcinogen arsenic than other grains, but researchers at Queen’s University Belfast, UK found that cooking rice in a simple coffee pot removed about half the arsenic.
From Nature:
The standard method for making rice — boiling it in a pot until it soaks up all the liquid — binds into place any arsenic contained in the rice and the cooking water.
On the basis of earlier work, (plant and soil scientist Andrew) Meharg and his colleagues knew that arsenic levels drop when rice is thoroughly rinsed and then cooked in an excessive amount of water. The method helps even when the cooking water contains arsenic.
Meharg and colleagues found that using this method with increasing proportions of water removed progressively more arsenic — up to a 57% reduction with a ratio of 12 parts water to one part rice. That result confirmed that the arsenic is 'mobile' in liquid water, and thus can be removed….
“We just took something that’s in everybody’s kitchen and applied it to show a principle,” he says.