Colorado, like the other states with medical or recreational marijuana, has tried to keep the products away from children. It has ordered stores to sell them in child-resistant packages and bars labels designed to appeal to children. It requires manufacturers to list ingredients, serving sizes and expiration dates.

But critics say the regulations are not strict enough, especially for products that can contain 10 times as much psychoactive THC as the marijuana a casual user might take. (Because prices often depend on the amount of THC, one highly potent caramel chew can sell for $20 while a package of 10 less concentrated candies might be the same price.) And like flavored cigarettes or wine coolers, critics say, edible marijuana offers a dangerously easy on-ramp for younger users.

“They’re attractive to kids; they’re easily disguised,” said Gina Carbone of Smart Colorado, a group that opposes legalization. “They’re not being regulated properly at all to protect kids.”

One survey has found a small but growing number of children seeking treatment after accidentally consuming marijuana. Fourteen such children visited the emergency department of Children’s Hospital Colorado in the Denver area from October 2009 through December 2011, researchers reported last year in the journal JAMA Pediatrics. Before 2009, researchers reported no marijuana exposures.

The research took place after an explosion of medical-marijuana shops in Colorado, but before voters passed measures to legalize the sales and use of recreational marijuana to adults 21 and older. Dr. George Sam Wang, an author of the study and a clinical instructor in pediatrics at Children’s Hospital, said he had not seen any additional increases in children’s marijuana exposure since recreational sales began the first of this year.