测试美国大米中砷的含量

Preliminary results of a large study by the U.S. government and research by a non-profit organization show measurable amounts of arsenic in samples of rice and rice products for sale in U.S. markets. One form of the chemical, inorganic arsenic, is a known human carcinogen. While the private study cautions that people should limit their consumption of rice products, government scientists say they are making no recommendations until their study is complete, sometime next year.

Two hundred different types of rice and rice products tested by both the non-profit research group, Consumer Reports, and the U.S. Food and Drug Administration [FDA], contained varying levels of different forms of arsenic. Michael Taylor is the Deputy Commissioner for Foods at the FDA.

“Arsenic is a substance that nobody wants in food, but we are confident that at the levels that we are seeing, there is no immediate safety concern. People should continue eating rice,” said Taylor.

The U.S. government has standards for the amount of arsenic allowed in water for human consumption, but not for food. Taylor says the FDA is mainly concerned with cumulative lifetime exposure to arsenic.

“We don’ think, based on the preliminary information that we have, that we can recommend that consumers change their eating practices. Rice is an important staple of the diet. It’s a nutritious, healthy food," said Taylor. "I think we would want to be sure we have much more information before we make decisions about recommending changes in eating patterns.”

The FDA says it will complete its comprehensive study of 1,200 rice samples by the end of 2012, and will determine then whether to issue additional recommendations. Consumer Reports is less cautious, however. Its study reviewed only 200 rice samples, but concludes that to be safe, people - especially infants - should limit rice consumption.

Ami Gadhia, with Consumer Reports, said there is a heightened focus on this issue.

“From a public health standpoint, there is great deal of concern about what babies are ingesting. Very often the first solid food that babies are given is rice cereal, and to see arsenic in that product is obviously a problem," said Gadhia. "We also saw levels in rice milk, and sometimes if children are allergic to cow milk they are given rice milk.”

Consumer Reports and FDA officials agree the results in their separate studies are similar, but only the FDA can set national industry standards.

Arsenic, a known carcinogen, is a contaminant that comes in two forms: organic and inorganic. Organic arsenic occurs naturally in the soil and water. Inorganic arsenic comes mainly from commercial fertilizers and pesticides used in agriculture.

“Many of those pesticides were banned many years ago. Unfortunately, those pesticides and the arsenic in them remain in the soil, and so it is still getting into the rice plants," said Gadhia.

Gadhia said the highest levels of arsenic were found in samples of rice from the south-central U.S. The lowest arsenic levels were in rice from California, India and Thailand.

For now, the FDA recommends that consumers continue eating a balanced diet that includes a variety of grains. Consumer Reports recommends not only that people moderate their intake of rice, but also that they rinse it well and cook it with plenty of water.