(CBS NEWS) – A consumer advocacy group is advising parents to limit the amount of rice cereal their children eat, with an analysis finding troublesome amounts of potentially toxic chemicals such as arsenic and lead.

Consumer Reports tested 50 baby and toddler foods purchased from different retailers across the country. Products made with rice fared the worst in tests, but all showed measurable levels of at least one of three toxic heavy metals: cadmium, inorganic arsenic and/or lead, the organization found.

Thirty-four of the products contained levels food safety experts at Consumer Reports believe warrant concern, while 15 would pose potential health risks to a child regularly eating one serving a day. More worrisome, organic foods are just as likely to contain heavy metals as conventional foods, the tests found.

READ ALSO: Weed-Killing Chemical Linked To Cancer Found In Some Children’s Breakfast Foods

Stressing that is findings represented a spot check of the market that should not be used to draw conclusions about specific brands, Consumer Reports devised a daily limit, or number a servings a child would need to eat to face potential health risks from exposure to the three metals.

For instance, it advised limiting to one serving a day Earth’s Best Organic Chicken & Brown Rice, Gerber Chicken & Rice and Sprout Organic Baby Food Garden Vegetables Brown Rice with Turkey. Little ones should only eat half a portion daily of Gerber Lil’ Meals White Turkey Stew With Rice & Vegetables, the group said.

Consumer Reports found less to be concerned about with an array of fruits and vegetable packaged for babies, setting no daily limits for products such as Beech-Nut Organic Peas, Green Peas, Green Beans and Avocado, or Gerber Organic Peas, Carrots & Beets. That said, it advised limiting both Beach-Nut Classics Sweet Potatoes and Earth’s Best Organic Sweet Potatoes, 1st Stage, to half a serving daily.

READ ALSO: California Suing Two Toddler Formula-Makers For High Lead Levels

Exposure to heavy metals can harm adults and children, but babies and toddlers are especially vulnerable given their smaller size and developing brains. “They also absorb more of the heavy metals that get into their bodies than adults do,” James Rogers, director of food safety research and test at Consumers Reports, said in a statement.

The issue is of particular concern in the United States, where children eat a lot of packaged baby food, annual sales of which exceed $53 billion, said Consumer Reports, citing numbers from Zion Market Research.

The Food and Drug Administration told Consumer Reports that it is working to finalize guidelines on inorganic arsenic in infant rice cereal by the end of the year, while food manufacturers all stressed the importance of food safety, and some noted that heavy metals can occur naturally, the advocacy group said.