Consumer Reports issued a warning Thursday that many foods made for young children contain dangerous levels of heavy metals such as arsenic and lead.

Consumer Reports tested 50 popular products typically fed to infants and toddlers, from cereals to pre-packaged entrees to cookies. Most came from baby food giants Beech-Nut and Gerber. About two-thirds of the products contained what Consumer Reports called "concerning levels" of heavy metals.

Long-term exposure to heavy metals increases the risk for serious health problems, including cancer and Type 2 diabetes.

"Children are going through development, particularly their neurological systems, and so those elements could adversely affect their proper development," said James Dickerson, Consumer Reports' chief scientific officer.

Snack foods and products made with rice fared worst in the tests.

"Certain plants, like rice, naturally uptake these heavy elements more so than other plants," Dickerson said.

Heavy metals occur naturally in soil and water, so buying organic doesn't help. Products labeled organic were just as likely to contain heavy metals as others.

To reduce the amounts of heavy metals children are exposed to, Consumer Reports recommends limiting the amount of infant rice cereal a child eats, limit packaged snacks and eat an array of healthful whole foods.

"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."