Organic foods were also just as likely to contain heavy metals, since they occur naturally in soil and water.
"The effects of early exposure to heavy metals can have long-lasting impacts that may be impossible to reverse," said Victor Villarreal, an assistant professor in the department of educational psychology at the University of Texas at San Antonio, who has researched the effects of heavy metals on childhood development.
Heavy metal exposure, even in small amounts, may increase the risk of lower IQ and behavioral problems and have been linked to autism and attention deficit hyperactivity disorder, or ADHD.
"Babies and toddlers are particularly vulnerable due to their smaller size and developing brains and organ systems," said James E. Rogers, director of food safety research and testing at Consumer Reports. "They also absorb more of the heavy metals that get into their bodies than adults do."
While the test results are problematic, experts told Consumer Reports that parents should not panic.
James Dickerson, chief scientific officer at Consumer Reports, said these foods do not guarantee a child will develop health problems, but it does increase their risk. Other sources of heavy metals -- including lead paint and contaminated water -- also put children at risk.
"Just because you've been feeding your children these types of foods doesn't mean that they'll necessarily have a specific adverse response to eating them," Dickerson said. "If you've been feeding these foods to your children, reduce the amounts they are consuming per day or per week. And if you're really concerned about it, talk to your doctor."