A rice-based ingredient that sometimes contains arsenic was found in infant formula, prompting researchers at Dartmouth College to say there is an “urgent need” for regulatory limits on the carcinogen in food. Two of 17 infant formulas tested listed organic brown rice syrup, which may contain arsenic, as the primary ingredient, and one had a total arsenic concentration level up to six times the U.S. federal limit of 10 parts per billion for drinking water, according to a study published today in the journal Environmental Health Perspectives.