High school graduation is supposed to be a time of celebration, to let loose and look forward to entering the real world.

But if some graduating students chose to experiment with drugs, B.C.'s provincial health officer says it could also end in tragedy.

"I think this is a riskier year than in the past," Perry Kendall wrote in an open letter to parents, urging them to talk to their children about the dangers of opioids.

"We know that a whole range of drugs — ecstasy, MDMA, speed — have become contaminated and therefore the drug supply is a lot more toxic than it has been in the past."

Kendall said this is the first summer the province thinks carfentanil — an opioid 100 times more powerful than the deadly drug fentanyl — might be present in some of the illegal drugs that people might be tempted to use.

He said that between November and January the overdose fatality rate doubled — a spike the province attributes to the presence of carfentanil.

According to the City of Vancouver, Vancouver Fire and Rescue responded to 667 overdose calls in the month of May.

As a result of overdoses, 27 people died over that same period.

'Be frank, open, non-judgmental'

Kendall sent out a similar warning after a spike of overdoses at musical festivals during the summer of 2015.

He said the number of overdoses was curbed the following summer after the province implemented a harm reduction program that included education programs, chilling tents and drug testing at festival sites.

In his most recent letter, Kendall advised parents to broach the topic directly and realistically.

"You start in a non-judgmental, non-accusatory way. You say you're aware of the dangers and that they're not exaggerated," he said.

"You don't want to accuse your child of using drugs, or assume they're not using drugs." 

He also told parents to drive home the message that anyone witnessing an overdose should immediately call 911, adding that many young people will hesitate out of fear that they will end up in trouble themselves.

"Young people aren't stupid and they have a good awareness of what's going on. If you can be frank, open and non-judgmental, there's a better chance of them listening."