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Researchers have found that levels of arsenic in rice milk exceed EU and US drinking water standards.

Andrew Meharg and colleagues at the University of Aberdeen, UK, have shown that people drinking rice milk are exposed to high levels of inorganic arsenic. It is well known that rice can contain high levels of, predominately inorganic, arsenic - a known human carcinogen. However the levels of inorganic arsenic in milk made from rice, a cow milk alternative for vegans and lactose intolerant sufferers, have not previously been of concern. 

Meharg's team analysed samples of rice milk to see if inorganic arsenic transfers from the rice into the milk. They tested commercially available and home-made milks, made from globally sourced white and brown rice grains. And they also looked at arsenic levels in soy and oat milk.

EU regulations set limits on the amount of arsenic allowed in drinking water, and the US specifically limits inorganic arsenic levels. Neither closely regulates arsenic in foods, and it is not clear which category rice milk falls into.  

Meharg found that all the commercial rice milks exceeded the EU limit for water and 12 out of 15 samples exceeded the US standard with the median total arsenic value being seven times greater than in soy and oat milk samples. 

David Polya at the University of Manchester, UK, is an expert on the risks of environmental chemicals to humans, and says that the research highlights 'an inconsistency in the regulatory treatment of carcinogens, such as arsenic, between food and drink. Groups particularly at risk, such as vegans, are not identified by average exposure estimates,' he adds. 

Meharg says that his research group has recently received funding to begin breeding rice plants that take up less arsenic. He also intends to characterise the bio-availability of arsenic from rice in humans to add to the evidence that this exposure route is concerning.