The Physics Police

The Physics Police

Wednesday, August 14, 2013

Arsenic Rice

Earlier this month, a Discover Magazine blog post appeared with the headline Toxin Found in Most U.S. Rice Causes Genetic Damage. Use of the word "toxin" place of "arsenic" bothers the heck out of me, but I digress.

This blog post reports on the findings of a study in Nature titled High arsenic in rice is associated with elevated genotoxic effects in humans.

This study found "elevated genotoxic effects" in subjects who consumed rice with concentrations of arsenic as low as 200 μg/kg, which is approximately equal to 200 parts per billion.

This study was conducted in India, so what about U.S. rice, as mentioned in the blog headline?

Last year, Consumer Reports tested a variety of brands of U.S. rice for arsenic. From their results, I calculated the average total arsenic in U.S. rice is 227 ppb.

Does that mean eating rice is dangerous? Not really, because in the study, the daily intake of rice was in excess of 540 grams. You can expect zero health effects from U.S. rice, unless you eat a lot.
540 grams * (200 ppm / 227 ppm) = 475 grams per day
That's about a pound per day, or 30% daily intake of calories. Some people may eat this much, but that's a lot of rice, if you ask me.

Like other heavy metals, arsenic will accumulate in the body if intake exceeds the body's ability to excrete. As with fish, which can be high in heavy metals, maybe don't eat rice every single day.

If you do eat rice everyday, you might avoid rice grown in areas like Texas, which have high levels of arsenic in the ground. To compare brands, check out those Consumer Report results.

Don't be afraid to eat rice.

It's good for ya.

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