A Dartmouth University study detected high levels of arsenic in some organic formula, cereal bars and high-energy foods.
Arsenic is a compound that may increase the risk of cancer.
The top ingredient in some organic toddler formula is organic brown rice syrup, a sweetener that is used as an alternative to high fructose corn syrup.
"Rice does take arsenic up from the soil easier than other grains so brown rice in particular will have more arsenic, but it was extremely concerning in high levels in foods meant for children," said Dr. Susan Buchanan, University of Illinois Hospital.
Dr. Buchanan, the director of UIC's Great Lakes Center for Children's Environmental Health, says high levels of arsenic over a period of time can affect every organ in the body.
"Chronic exposure can affect the neurologic system, affect the brain, cause skin rashes and several types of cancer, skin cancer, lung cancer, bladder, liver," Dr. Buchanan said.
The Dartmouth study did not name the specific brands of the products researchers tested. However, ABC News has learned Baby's Only Organic Dairy Toddler Formula and Baby's Only Organic Soy Toddler Formula made by Nature's One Inc. tested with the highest levels of arsenic. The company says its California based supplier of brown rice syrup uses an independent lab. In a statement, Nature's One says, "their testing results report undetectable amounts of arsenic at laboratory testing limits.''
Some parents who buy organic foods for their kids know organic doesn't always mean healthy.
"Look at when you brush teeth, do you use organic water, bottled water that is? No," said Kalemet Muhammad.
"Just because you shop at Whole Foods or are bringing organic, it doesn't mean it is the end all, be all, so if we can have the FDA take more time and effort into making sure everything is regulated, that would be great," said Tami Conway.
In a written statement, the Food and Drug Administration says for the past 20 years it has been monitoring the food supply for arsenic content. For many years, arsenic was used in pesticides which is why there are traces of it in soil. The FDA says it has expanded its surveillance in rice to make sure consumers are protected.