Last month, tests by Consumer Reports revealed significant levels of inorganic arsenic - a carcinogen - in about 10 percent of test samples of apple and grape juices commonly given to young children. Today, Dartmouth College researchers are reporting similarly worrisome levels of arsenic in infant formula and cereal bars, as well as energy bars and "energy shots" marketed for adults.

The apparent culprit: organic brown rice syrup, commonly used as a sweetener in place of high-fructose corn syrup. The study's authors stressed that babies "are especially vulnerable to arsenic's toxic effects," and urged them to check formula ingredients.

Citing an article by the Dartmouth researchers published today in the peer-reviewed Environmental Health Perspectives, Consumer Reports says:

• Two of 17 infant formulas tested listed organic brown rice syrup as the primary ingredient. One had a total arsenic concentration that was six times the federal limit of 10 parts per billion (ppb) for total arsenic in bottled or public drinking water. This is particularly worrisome for babies because they are especially vulnerable to arsenic’s toxic effects due to their small size and the corresponding arsenic consumption per pound of body weight.

• Twenty-two of 29 cereal bars or energy bars tested listed at least one of these four rice products—organic brown rice syrup, rice flour, rice grain or rice flakes - among the top five ingredients. The seven other bars were among the lowest in total arsenic, ranging from 8 to 27 ppb, while those containing syrup or other forms of rice ranged from 23 to 128 ppb.

• Tests of high-energy products known as “energy shots” that are used by endurance athletes and others showed that one of the three gel-like blocks contained 84 ppb of total arsenic, while the other two contained 171 ppb.

Previous Dartmouth studies, as well as other research, have suggested "that many people in the U.S. may be exposed to potentially harmful levels of arsenic through consumption of rice," Consumer Reports says. "Rice is among the plants that are unusually efficient at taking up arsenic from the soil, and much of the rice produced in the U.S. is grown on land formerly used to grow cotton, where arsenical pesticides were widely used for many years, just as they were in orchards and vineyards."

In an email this morning, CR quoted advice from Brian Jackson, lead author of the new study and a member of Dartmouth's Superfund Research Program: "In the absence of regulations for levels of arsenic in food, I would certainly advise parents who are concerned about their children's exposure to arsenic not to feed them formula where brown rice syrup is the main ingredient." It says Jackson noted "that infant formulas containing added rice starch did not appear to be a concern in terms of elevated arsenic."

CR says organic-farming methods offer no protection if the soil bears natural arsenic or arsenic from earlier contamination.  "That's because the rice takes up natural arsenic from the soil and when the rice is used to make brown rice syrup, much of that arsenic ends up there," Jackson told CR, published by Consumers Union. "We focused on organic brown rice syrup because this seems to be a sweetener of choice for some organic food products."

The study's authors conclude that "there is an urgent need for regulatory limits on As [arsenic] in food."