Rice usually grows in perpetually flooded fields that provide a reducing and anoxic environment. In such an environment, arsenic becomes bioavailable and gets released from the soil. Plants can then readily take it up. Rice in a typical Asian diet can lead to daily arsenic exposures equivalent to drinking 2 L of water that is at or above the World Health Organization's limit for arsenic of 10 µg/L. Researchers have found that growing rice on dry fields cuts arsenic levels in the grains by 90% but also slashes yields.
A different farming method has been catching on fast in Bangladesh as a way to save water. In it, farmers irrigate their fields and then wait up to 10 days to let their paddies dry out before irrigating again. Stephan Hug, an aquatic geochemist at the Swiss Federal Institute of Aquatic Science and Technology, and colleagues in Switzerland and Bangladesh wondered if intermittent irrigation could also lessen plant exposure to arsenic….
Drying rice in the sun in Bangladesh, shot by Shahnoor Habib Munmun, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license
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