The number of unintentional marijuana poisonings in children rose markedly in Colorado after medical marijuana was decriminalized in 2009, with visits to one emergency department climbing from zero to 2.4% of all poisoning cases in just 2 years, according to a report published online May 27 in JAMA Pediatrics.

The toxic effects in these children were more serious than those typically reported for marijuana exposures in the past, most likely because tetrahydrocannabinol concentrations are higher in today’s medical marijuana products than in the plant parts involved in most previous exposures. So now, even when the amount ingested is small, it still produces significant adverse effects in the pediatric population, including respiratory insufficiency requiring care in the pediatric intensive care unit (PICU), said Dr. George Sam Wang of Rocky Mountain Poison and Drug Center, Denver, and his associates.

The number of unintentional marijuana poisonings in children rose markedly in Colorado after medical marijuana was decriminalized in 2009, according to a report published online May 27 in JAMA Pediatrics.

In addition, medical marijuana is sold in a variety of forms that are more palatable to children than plant parts are, such as baked goods, soft drinks, and candies. So more children are attracted to eating the drug now, and they likely eat larger amounts than in the past.

"Physicians, especially in states that have decriminalized medical marijuana, need to be cognizant of the potential for marijuana exposures and be familiar with the symptoms of marijuana ingestion," the investigators said.

After Colorado decriminalized medical marijuana, both the number of dispensaries and the number of patients authorized to use the drug increased rapidly. As of 2010, more than 300 such dispensaries were licensed in Denver alone, "roughly twice the number of the city’s public schools," Dr. Wang and his colleagues noted.

They performed the first U.S. study to asses the impact of this legislation on pediatric poisonings: a retrospective cohort study at a tertiary children’s hospital that had approximately 65,000 annual visits to its emergency department. The researchers focused on children under age 12 who were evaluated for possible toxic exposures, comparing the 790 patients seen from 2005 to Sept. 30, 2009, before legalization with the 588 seen from Oct. 1, 2009, to the end of 2011 after medical marijuana was legalized.

There were no cases of marijuana poisoning during the first time period, compared with 14 in the second time period. The proportion of such visits in relation to all pediatric ED visits for toxic exposures thus rose from 0% to 2.4% after the drug was decriminalized.

Children as young as 8 months of age were exposed to marijuana. Most presented with central nervous system (CNS) effects such as lethargy or somnolence, and some displayed rigidity, ataxia, hypoxia, or respiratory insufficiency, the researchers reported (JAMA Ped. 2013 May 27 [doi: 10.1001/jamapediatrics.2013.140]).

Only two patients were known to have been exposed to marijuana on arrival at the ED; they underwent a urine toxicology screen. The rest underwent extensive workups to determine the cause of their symptoms, which included urine toxicology screens; blood work; CT and x-ray imaging of the head, spine, and abdomen; and lumbar punctures.

Only one patient, a 13-year-old girl with minimal symptoms, was discharged after being assessed. The rest were observed in the ED (5) or admitted for hospitalization (8), including 2 children who required admission to the PICU.

This 93% rate of hospitalization reinforces the hypothesis that current marijuana exposures induce more serious effects than past exposures did, because historically only 1.3% of marijuana poisoning cases required hospitalization, Dr. Wang and his associates said.

Eight of these 14 (57%) marijuana exposures were from food products that incorporated the drug. "Currently, there are no regulations on storing medical marijuana products in child-resistant containers, including labels with warnings or precautions, or providing counseling on safe storage practices," the investigators said.

As is the case with many accidental pediatric exposures to other medications, the source of the medical marijuana in several of the cases in this study was the child’s grandparent.

Dr. Wang and his colleagues added that proponents of legalizing marijuana often claim that it is "safer" than alcohol. However, only two patients under age 12 were evaluated for alcohol exposure at this ED since 2009. One, an 11-year-old, intentionally drank alcohol and only required observation for intoxication; the other, a 2-year-old who accidentally drank a household product containing ethanol, was discharged after failing to develop any symptoms.

In comparison, the symptoms, invasive assessments, and hospitalizations described in this study can hardly be considered "safer." These findings clearly demonstrate that "the consequences of marijuana exposure in children should be part of the ongoing debate on legalizing marijuana," the researchers said.

Seventeen states and Washington, D.C., have passed laws to decriminalize medical marijuana at the state level, even though marijuana is a schedule I drug under the Controlled Substances Act. "In November 2012, Colorado and Washington [State] passed amendments legalizing the recreational use of marijuana," Dr. Wang and his associates said.

No financial conflicts of interest were reported.

Striking rise in accidental marijuana poisonings