Health Canada tests have confirmed the presence of dangerous substances laced into other illicit drugs in two B.C. communities.
The RCMP say pebble heroin seized in Surrey last December has come back positive for the chemical W-18, a drug developed as a potential painkiller.
The Mounties say cocaine seized by the West Shore detachment on Vancouver Island last May has also tested positive for the synthetic opioid fentanyl.
Health Canada has warned RCMP that this particular strain of fentanyl had not been seen in the area before.
At the time the cocaine was seized, police say there had been three overdoses in the area that authorities were called to.
RCMP assistant commissioner Jim Gresham says these results are a reminder to illicit-drug users that there are dangers no matter where they buy their drugs.
"Unfortunately, there is no way for you to know what is really being sold to you. Please take steps to avoid making a potentially lethal decision," he said.