The highly toxic opioid carfentanil has been detected for the first time in a drug overdose death in B.C., according to the provincial coroner.

Vancouver police said they were called to an East Vancouver home near Nanaimo and Dundas streets on Nov. 17 by an individual who was concerned for a colleague. He had failed to show up for work or respond to phone calls, which was out of character, police said.

With the help of the building manager, police were able to get into the man's suite and found the 39-year-old dead inside.

They found an unknown drug and drug paraphernalia inside the apartment and sent them to a Health Canada laboratory for testing, which confirmed the presence of carfentanil —  a deadly opioid 100 times more toxic than fentanyl.

Earlier this month, carfentanil was found for the first time in a drug seizure on the Downtown Eastside.

Vancouver police Staff Sgt. Randy Fincham said this is the first confirmed death linked to carfentanil in Vancouver.

"Unfortunately, we suspect this death won't be the last." 

However, the coroner said it's still not certain how the man died.

"Testing cannot currently confirm whether carfentanil was the cause of death for this individual," the coroner said in a statement. 

Carfentanil is used to tranquillize elephants and other large animals. It can be fatal to humans in an amount of 20 micrograms, which is less than a grain of salt.