According to a study published Tuesday, the number of young children, particularly toddlers, who accidentally ate marijuana-laced treats increased dramatically over five years as marijuana became legal in more places across the United States.

Between 2017 and 2021, more than 7,000 confirmed cases of children under six eating marijuana edibles were reported to the nation's poison control centers, increasing from about 200 to more than 3,000 per year.

According to a new study published in the journal Pediatrics, nearly a quarter of the children were hospitalized, with some critically ill.

And those are just the reported cases, according to Dr.Marit Tweet, the study's lead author and a medical toxicologist at the Southern Illinois School of Medicine.

Cases of children consuming marijuana products such as candies, chocolate, and cookies have increased as more states legalize medical and recreational cannabis use. Currently, 37 states in the United States allow the use of marijuana for medical purposes, while 21 states regulate adult recreational use.

“When it’s in a candy form or cookies, people don’t think of it in the same way as household chemicals or other things a child could get into,” she said. “But people should really be thinking of it as a medication.”

Tweet and her colleagues analyzed reports to the National Poison Data System, which includes the nation’s 55 regional poison control centres. The study showed that more than half of the children were toddlers, ages 2 and 3. More than 90% got the edibles at home.

“They’re starting to explore and to get up and move around,” she said.

Researchers were able to track the outcomes of nearly 5,000 cases out of over 7,000 reports. They discovered that nearly 600 children, or approximately 8%, were admitted to critical care units, most often with impaired breathing or even coma. Almost 15% were admitted to non-critical care units, and nearly a third were seen in emergency rooms. The most common symptoms were drowsiness, breathing difficulties, a rapid heart rate, and vomiting.

According to Dr Brian Schultz, a pediatric emergency physician at Johns Hopkins Medicine in Baltimore, the findings are not surprising. He previously worked at Children's National Hospital in Washington, D.C., where he and his colleagues treated children who had consumed marijuana edibles "almost every day," he said.

During the last two years of the study, during the COVID-19 pandemic, reports and hospitalizations increased. More children were at home, which meant more opportunities to find pot treats, according to Tweet. She added that as marijuana became more widely legal, parents may have felt less stigma in seeking help from poison centers and health care providers.