A Consumer Reports investigation uncovered what it called worrisome levels of arsenic in rice and many rice products.
Consumer Reports lab-tested 32 rices and dozens of rice products like rice cakes, crackers, cereal and baby cereal and found all contained arsenic.
Lab tests showed many of the samples had troubling levels of inorganic arsenic, which is the most toxic form, according to Consumer Reports.
"Inorganic arsenic is a known human carcinogen that has been linked to skin, lung and bladder cancer," said Consumer Reports' Andrea Rock.
There are federal limits for the amount of arsenic allowed in drinking water, but none for most foods.
The investigation found there was often more arsenic in brown rice than in white rice.
"We aren't able to draw conclusions about specific brands because our tests are limited," Rock said. "But, the analysis we did of the government data shows that or Americans who eat rice, it is a significant source of arsenic exposure."
The USA Rice Federation responded: "There is no documented evidence off actual adverse health effects from exposure to arsenic in U.S.-grown rice."
"We already know that even low levels of arsenic exposure increase your risk of cancer and other health problems," Rock said. "We don't want to alarm people, but we do recommend that you limit the amount of rice you eat."
Research shows rinsing rice thoroughly and cooking it in plenty of water can reduce arsenic levels.
For babies, Consumer Reports recommends no more than a quarter cup of rice cereal per day.
While some arsenic occurs in nature, for years pesticides containing arsenic were used in agriculture. Most have been banned, but residues remain in the soil. Arsenic is still permitted in some pesticides, fertilizer and animal feed.
Consumer Reports' advocacy group is calling on the government to set limits on arsenic in food and ban its use in agriculture.
For the complete investigation: www.consumerreports.org/cro/arsenic1112