As Colorado ushers in legalized pot, proponents of reform often cite a singular statistic: No one has ever died of a marijuana overdose. However, some say that’s setting the bar too high. A wider availability of marijuana may increase rates of accidental ingestions by children attracted to cookies and other candies laced with the drug.

On Tuesday, a two-year-old girl ingested marijuana accidentally by eating a cookie she’d found in front of her apartment building in Longmont, Colo. Aida Hernandez said that she told her daughter to throw away the cookie and didn’t realize anything was wrong until they’d gone out shopping. The girl later tested positive at the hospital for marijuana’s active ingredient, delta-9 tetrahydrocannabinol (THC). “She was sleepy, she was opening and closing her eyes, and she couldn’t walk very well,’ Hernandez told FOX31 Denver after police began investigating with social services on the case.

Detective Commander Jeff Satur said police had failed to find any signs of drug use after searching the family’s home. “At this point we believe the family,” Satur said.

The accidental dosing came just one day prior to the beginning of retail marijuana sales in the state, whose voters approved the drug law reform in a November referendum. Presently, marijuana is legal for prescription-based medical treatment in 18 states and the District of Columbia, whereas the drug has been legalized now for recreational purposes in Colorado and Washington.

In May, medical toxicologist George Sam Wang and his colleagues at the Rocky Mountain Poison and Drug Center in Denver published a study about pediatric marijuana poisonings. "We are seeing increases in exposure to marijuana in young pediatric patients, and they have more severe symptoms than we typically associate with marijuana," Wang said in a statement. "We hadn't seen these exposures before the big boom of the medical marijuana industry.”

The medical marijuana industry began in Colorado in 2009, before which such poisonings were much rarer. In the study, Wang and his colleagues compared the number of children treated in the emergency room of one local hospital for marijuana poisonings, before and after the law’s enactment.

At that hospital, nearly 14,000 children ages 12 and younger had been evaluated for accidental poisonings during the retrospective study group, running from January 2005 to the end of 2011. Of those pediatric cases, 790 occurred prior to the law’s change, while 588 occurred after Sept. 30, 2009 — showing a big jump. Moreover, Wang and his colleagues found that none of the earlier poisonings were attributed to marijuana.

Source: Wang, George Sam, Roosevelt, Genie, Heard, Kennon. Pediatric Marijuana Exposures In A Medical Marijuana State. JAMA Pediatrics. 2013.