July 13, 2013 (foodconsumer.org) -- A study in Environmental Science and Technology has found rice bran contains 10 to 20 fold higher arsenic than bulk rice grains.

The study shows that inorganic arsenic, which is the toxic form of arsenic, can be as high as 1 mg/kg (1 ppm), which is 100 times higher than the limit the EPA set for drinking water (0.01 ppm).

Rice bran is sold as a dietary supplement or used in certain foods as a healthy food  ingredient.  Particularly of concern are rice bran soluables from the U.S. and Japan, which are found to contain 0.61 to 1.9 mg/kg, according to the authors.

In 2012, the FDA released data to show that most rice products contain 3.5 to 6.8 mcg per serving.  Adult Asian Americans may commonly use five to six servings a day, which mean they have intake of 30 mcg per day on average.  For rice grains, one serving in the FDA report is defined as 45 grams and adults may use 3 servings per meal and two meals a day. 

The daily intake limit for inorganic arsenic is 0.01 mg of arsenic per day even though there is no safe threshold for arsenic, meaning any amount can pose a risk.   So those rice eaters may have their daily intake of arsenic six times higher than the limit assumed to be acceptable by the EU and US regulations.

In a study report released recently by Johns Hopkins University, lifetime exposure to a dose of 0.11 mcg per day results in 3.7 cases of bladder cancer and lung cancer per 100,000 exposed persons.

If the association was be applied to arsenic in rice, then rice eaters who have daily intake of 30 mcg of arsenic for their lifetime would have a cancer risk of 3.7x270= 999 cases of cancer per 100,000 exposed persons, which is 1% of exposed persons.

Studies show that rice produced in the U.S. contains far higher arsenic than rice produced other countries.

To lower the risk, rice eaters may want to eat less rice and more other grains like wheat.  And taking antioxidants as dietary supplements may also help reduce the cancer risk as they can help relieve oxidative stress induced by toxic metals such as arsenic. (reporting by David Liu, PHD)