The increases in exposure come as more states have legalized the drug for medical or recreational use, the researchers noted. Marijuana exposure in young children generally comes from breathing or swallowing the drug.
"The high percentage of ingestions may be related to the popularity of marijuana brownies, cookies and other foods," study co-author Henry Spiller, director of the Central Ohio Poison Center at Nationwide Children's Hospital, said in a hospital news release.
"Very young children explore their environments by putting items in their mouths, and foods such as brownies and cookies are attractive," he added.
The study included information from the National Poison Database System and found that marijuana exposure among children aged 5 and younger rose more than 147 percent nationwide from 2006 through 2013.
Overall, almost 2,000 cases of marijuana exposure involving young children were reported to Poison Control Centers in the United States from 2000 through 2013.
The exposure rate increased nearly 610 percent among children in states that legalized marijuana for medical use before 2000.
Even in states that had not legalized marijuana by 2013, there was a 63 percent increase in marijuana exposure among young children from 2000 through 2013.
More than 75 percent of children exposed to marijuana were younger than 3. Most exposure involved swallowing marijuana, the researchers said.
Most of the children exposed to marijuana had only minor problems, but some suffered breathing problems, seizures and even comas. More than 18 percent of the young children exposed to marijuana were hospitalized, the study authors said.
The findings are cause for concern, said study senior author Dr. Gary Smith, director of the Center for Injury Research and Policy.
"Any state considering marijuana legalization needs to include child protections in its laws from the very beginning. Child safety must be part of the discussion when a state is considering legalization of marijuana," he said.