Weiner encourages parents to rotate rice cereal with barley cereal and oatmeal so that children don't consume too much of it.
"If an adult were to eat that amount of arsenic, it wouldn't necessarily be a problem, but for a baby's small body size, it adds up," he says.
Hays hopes that parents will refocus their good intentions for children's nutrition.
"My hope is that any parent that is going to be diligent to make sure their child doesn't get pesticides and hormones would be diligent that their child avoided obesity, because that effort would trump anything that we could do to avoid the side effects of additives," Hays says.
Saslow is a former Post staff writer.