Arsenic in Rice

ENVIRONMENTAL SCIENCE

Arsenic levels in U.S. long-grain rice are the highest found in a recent survey of rice from different countries (Environ. Sci. Technol. 2005, 39, 5531). Nevertheless, this finding, which has received some media attention, should not alarm people, sources familiar with the study tell C&EN.

The survey--by Andrew A. Meharg and coworkers at the University of Aberdeen, Scotland--reports an average arsenic level in U.S. rice of 0.26 µg/g, based on seven samples. It means that a 120-lb person consuming 1 lb of U.S. rice grain per day would be exceeding the maximum daily intake of arsenic provisionally set by the World Health Organization.

The survey cannot represent national levels because its sample size is small, notes soil organic chemistry professor John M. Duxbury of Cornell University. David Coia, a spokesman for the USA Rice Federation, concurs: "To make global comparisons based on limited sample size is bad science."

Arsenic in U.S. rice is predominantly organic (58%), the survey also finds. By contrast, arsenic in rice from Europe, Bangladesh, and India is primarily inorganic (64%, 80%, and 81%, respectively). Inorganic arsenic is known to be far more toxic than organic species. The data indicate that arsenic in U.S. rice "is not a big problem for U.S. consumers," Duxbury says.

Richard H. Loeppert, a soil chemistry professor at Texas A&M University, agrees: "Rice is a minor contributor to the total arsenic intake by somebody in the U.S."

Meharg and coworkers suggest that arsenic in U.S. rice may be due to cultivation in areas where arsenic-based pesticides had been widely used. Loeppert disagrees: "Generally, U.S. rice is not growing in areas I consider to be high in arsenic."