That sparked his interest in broader testing of packaged organic foods with and without brown rice syrup, purchased from local supermarket aisles in Hanover, N.H. The researchers tested infant formulas, cereal bars, energy bars and energy "shots," which are gels consumed by endurance athletes.
Arsenic occurs in several forms, some thought to be more dangerous than others. Organic forms of arsenic can be found naturally in the soil, along with arsenic-based pesticides used before the EPA banned them in 2009. Rice, Jackson noted, "takes up more arsenic than all the other grains."
Inorganic arsenic is considered much more toxic than organic arsenic, Jackson said. Brown rice is usually higher in total arsenic and inorganic arsenic than white rice because the outer layer that's removed in white rice contains the inorganic arsenic. However, another form of arsenic can be found inside the grain of both white and brown rice.
The EPA drinking water standard is 10 parts per billion for total arsenic, which combines inorganic and organic arsenic. Jackson's team tested one package of soy-based toddler formula made with organic brown rice syrup and found a total arsenic level of 60 ppb, including about 25 ppb of inorganic arsenic.
That kind of level is dangerous, given babies' small size and developing bodies, they said. Given the variety of formula brands available, he said, "I would choose one that wasn't based on organic brown rice syrup."
They also detected arsenic levels ranging from 23 to 128 ppb in cereal bars made with brown rice syrup; and levels of 84 to 171 ppb in three flavors of energy shots.
"I don't necessarily think eating a cereal bar every couple of days is a health risk," said Jackson, who collaborated on the study with researchers at Dartmouth's Children's Environmental Health and Disease Prevention Center, which is funded by the EPA and National Institute of Environmental Health Sciences. "But we don't have any guidelines for maximum allowable amounts in food or the cumulative amount of arsenic intake during the day."
"There's no perfect advice," Lovera said. "There's no one thing people can do." But she said, the surprising presence of arsenic in packaged foods give people a chance to ask themselves, "How many foods do I need to eat that are processed with ingredients I don't really know that much about?"