Doctors at a major Boston hospital report they are seeing more hungry and dangerously thin young children in the emergency room than at any time in more than a decade of surveying families. Many families are unable to afford enough healthy food to feed their children, say the Boston Medical Center doctors. The resulting chronic hunger threatens to leave scores of infants and toddlers with lasting learning and developmental problems. Before the economy soured in 2007, 12% of youngsters age 3 and under whose families were randomly surveyed in the hospital's emergency department were significantly underweight. In 2010, that percentage jumped to 18%, and the tide does not appear to be abating, said Megan Sandel, MD, an associate professor of pediatrics and public health at BMC. "Food is costing more, and dollars don't stretch as far," Sandel said. "It's hard to maintain a diet that is healthy." The emergency room survey found a similarly striking increase in the percentage of families with children who reported they did not have enough food each month, from 18% in 2007 to 28% in 2010.