A dangerous drug far more potent than fentanyl has been discovered in Metro Vancouver for the first time, police announced.

The update comes nearly two months after the largest fentanyl seizure in B.C. history, conducted by the Delta Police Department.

On Tuesday, police said the some of the products that were seized in the bust on March 17 have since tested positive for another drug called W-18, triggering a public warning to users.

Officers said users should be vigilant given the strength of the drug, which Health Canada has called 100 times more toxic than fentanyl.

"With fentanyl, the concern is with an amount about the size of a grain of salt is sufficient for a fatal overdose," Acting Sgt. Sarah Swallow told CTV News.

"W-18 is even more potent than that."

Because of its strength, addictions specialists worry that the designer drug will have a high mortality rate.

The province is already seeing a spike in illicit drug overdoses this year, and the introduction of extra-strong W-18 on the streets could cause the death toll to soar higher.

Although tests have only uncovered about 80 grams of the drug in the Vancouver area so far, police said as little as a cellphone-sized amount can be turned into a busload of counterfeit heroin.

As with fentanyl, unsuspecting users who think they're taking heroin are likely to overdose on the stronger substance.

“The street level use of drugs like W-18 is still in its infancy in Canada and it appears users are completely unaware of its presence in the drugs they are consuming,” Chief Const. Neil Dubord said in a release.

One group that’s aware of the deadly nature of W-18 is the traffickers, Dubord warned.

“In the seizures done by our investigators, the accused were carefully protecting themselves with respirators, gloves and goggles during the process and yet went on to knowingly sell this product to unsuspecting users. The motivation of these individuals to make money clearly supersedes their social responsibility in the equation,” Dubord said.

W-18 is a synthetic drug that was originally developed as a pain reliever in the 1980s. It was patented by scientists at the University of Alberta in Edmonton, but was never picked up by a pharmaceutical company.

In April, a forensic chemist told CTV Edmonton that the patent expired, and was recently resurrected in China.

Up until June 1, it was legal to produce, possess, import and export W-18 in Canada. The drug has now been added to Schedule 1 of the Controlled Drugs and Substances Act. 

The drug was banned as a result of research showing the drug had been used recreationally in Europe and Canada in the last two years.

Five people have been arrested in the Delta police investigation, including 35-year-old Scott Pipping of Surrey and 27-year-old Adam Summers of Delta. The pair is facing more than 20 charges and being held in custody.

Anyone who uses illegal drugs is urged to never use alone, and always start with a small amount, and not mix with other substances. Police also recommend people only use where help is easily available, and not be afraid to call 911 for help.

With a report from CTV Edmonton and CTV Vancouver's Michele Brunoro