A tray of tempting pastel-coloured candies sits on a countertop inside AmeriCanna's production facility. Although shaped like pot leaves and stamped with Colorado's universal symbol for the mind-altering ingredient in cannabis – a diamond containing the letters "THC" – the gummies would only provide a sugar high at this point.

Working with precision and speed, the kitchen supervisor uses a device to soak each candy with marijuana extract, so each piece contains exactly 10 milligrams of THC, a single dose under the state's regulations.

The entire process takes seconds, but it represents the culmination of a long regulatory journey for Colorado's edible marijuana industry – one that AmeriCanna owner Dan Anglin is urging Canada to learn from.

"I've heard it all. I know what they're going to say before they say it. 'What about kids who are at a party and somebody gives them weed candy?' OK, well, if you create a symbol like Colorado did ... it gives them an opportunity to educate the public," said Anglin. 

"It's very easy to have a government commercial that says, 'Here's what you're looking for, mom and dad, when you go through your teenager's backpack.' Or, 'Are you at a party? Did somebody hand you something? Well, if it has this (symbol) on it, then that's drugs.' "

Although many might assume inhaling hot smoke into your lungs would be the greater public health concern than marijuana candies, it was the edible industry that caused the greatest amount of debate after Colorado legalized pot in 2012. But today the state is a leader in packaging and dosage rules, and officials and businesses are urging Canada to take notes.

The Canadian government has said when marijuana becomes legal on July 1, 2018, sales will entail only fresh and dried cannabis, oils and seeds and plants for cultivation. Sales of edibles will come later, once regulations for production and sale can be developed.

When Colorado's first recreational pot dispensaries opened in January 2014, there were practically no restrictions on edibles. They were packaged in clear bags, said Anglin, and the cookies and brownies inside often looked identical to any other sugary treat. There was also no standardized dose, so a consumer who didn't pace themselves could accidentally ingest a whopping 100 milligrams of THC.

In 2014, the Rocky Mountain Poison and Drug Center received 87 marijuana exposure calls about children and youth under 18, nearly doubling the total for the previous year. A Wyoming college student jumped to his death from a balcony after eating infused cookies. And Maureen Dowd, the New York Times columnist, wrote about her harrowing trip after consuming too much of a pot-laced candy bar.

All of these incidents grabbed national headlines and sent industry and officials into a tailspin.

"When we first started, we really had no idea what the world of edibles would look like," said Dr. Larry Wolk, chief medical officer of the Colorado Department of Public Health and Environment. "We had to quickly consider all of that as we put those rules into place."

With input from business owners, including Anglin, the state developed packaging, labelling and potency restrictions that came into effect in 2015. Now, edibles must be contained in child-resistant packaging and be wrapped individually or demarcated in servings of 10 or fewer milligrams of THC.

The state has also banned cartoon characters on packaging, and edibles can't be shaped like humans, fruit or animals — so no more gummies in the shape of bears. It later required all edibles to be individually marked with the universal THC symbol.

"We were ahead of the curve on that," said Anglin, whose company began selling symbol-marked candies months before the rule came into force last October.

"A lot of companies that, say, were small mom-and-pop companies that didn't have millions of dollars behind them, who weren't paying attention to the news ... it was a surprise to them. They couldn't afford to continue to make that product."

Data from the Rocky Mountain Poison and Drug Center suggests child poisoning calls involving marijuana have started to come down. There were 82 calls about kids and youth under 18 in 2016, down from 111 the previous year.

"That pales in comparison to the thousands of calls we get when kids ingest alcohol, or when kids ingest over-the-counter medications or even prescription medications," added Wolk.

Wolk said the transformation of edible packaging and dosage rules in Colorado has been a success, largely due to co-operation between industry and government. He advised Canada to start small by allowing low-dose THC in predictable servings.

Inside the Cannabis Station dispensary in downtown Denver, manager Mike Koulouvaris shows off the store's wide variety of THC-infused candies, gummies and drinks. He carefully instructs how much to eat and how long to wait before nibbling on more.

Koulouvaris, a former edibles chef, said he believes the products shouldn't taste too good, so people aren't tempted to overeat. At the same time, he said he thinks the regulations have gone too far.

"It's kind of limiting creativity," he said. "It should be the responsibility of the parents to make sure that their stuff isn't lying around, rather than making it be in child-resistant containers. I don't think alcohol is in child-resistant containers."