Arsenic in rice milk exceeds EU and US drinking water standards
Commercial rice milk contains levels of inorganic arsenic – a chronic human carcinogen – up to three times higher than EU or two times higher than US drinking water standards, say researchers in the Royal Society of Chemistry’s Journal of Environmental Monitoring.
Background: Rice milk is made commercially as an alternative
to animal-derived milk such as cows' milk. It is aimed those who are
lactose intolerant, are on a macrobiotic diet or are vegetarian/vegan.
It lacks the proteins, vitamins and minerals that cows' milk provides,
so commercial rice milk is often fortified with these additives.
Inorganic arsenic is a chronic human carcinogen. Under EU legislation, total arsenic levels in drinking water should not exceed 10 μg l−1, while in the US this figure is set at 10 μg l−1 inorganic arsenic.
It is well known that rice can contain high levels of predominately
inorganic arsenic (see the News section below), however the levels of arsenic in rice milk have not previously been of
The new study: The interdisciplinary group of researchers from the University of Aberdeen, UK, analysed samples of rice milk to see if inorganic arsenic transfers from the rice into the milk. Different brands and varieties of rice milk, including organic,
non-organic and flavoured, were bought from local supermarkets. They also made
"home-made' rice milk, from rice grown in different parts of the world,
with a commercially-available machine.
They showed that of four brands of commercial rice milk tested, all exceeded the EU total arsenic standard of 10 µg l-1 – some by as much as three times. Eighty per cent of samples also failed to meet the US standard of 10 µg l-1 inorganic arsenic.
Of the samples of 'home-made' rice milk made by the researchers, all met US standards and only one failed to meet EU standards.
It is questionable, the researchers say, if rice milk counts as a water
substitute – where it would be regulated by these directives – or as a
food. But they believe that in this case the distinction between the
two should not be made. "Whether rice milk is a food or a drink is a
moot point," the researchers say in the paper. "…if rice milk is a
dietary constituent on a regular basis, then chronic arsenic exposure,
at levels deemed unsafe under the EU water drinking directive, will
The authors also note that currently no maximum permissible
concentration (MPC) for arsenic in food has been set by the Commission
of European Communities – meaning arsenic levels in food are
effectively unregulated in Europe and elsewhere. "Given that arsenic in
its inorganic form … is a chronic human carcinogen, it is surprising
that MPCs have not been set for this element," they say.
The new study
Andrew A. Meharg, Claire Deacon, Robert C. J. Campbell, Anne-Marie Carey, Paul N. Williams, Jörg Feldmann and Andrea Raab, Inorganic arsenic levels in rice milk exceed EU and US drinking water standards, J. Environ. Monit., 2008, DOI: 10.1039/b800981c