The Middlesex London Health Unit’s warning to marijuana users that their drug of choice may be laced with fentanyl is being called into question.

The alert, sent out a week ago, explained urine drug screenings had found fentanyl in the urine of those who had reported only smoking pot.

“There are a multitude of reasons why people may not be honest about their other drug use because they may be afraid of being kicked out of these programs. You have to consider how honest people are being,” said Nick Boyce a spokesperson for the Ontario HIV and Substance Use Training Program. Tweet This

He says even if people are being honest there are other possible explanations for why fentanyl might show up in their urine.

“People could be exposed to trace amounts of fentanyl, that is, not amounts that could lead to intoxication or overdose. Simply hanging around with other people who are using drugs containing fentanyl, or perhaps the cannabis they’re consuming was put in another bag that previously held another drug in it,” said Boyce.

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Doctor Chris Mackie is standing by the claims, saying any possibility of contamination deserves a proper warning.

“Even if there’s a one per cent chance or a one-tenth of one per cent chance I want people to know,” said Mackie.

“Every study that’s ever been done of contamination of marijuana in Canada and the U.S has found between 15 and 30 per cent of samples are contaminated with one thing or another. There are serious risks here and people need to take them seriously,” said Mackie.

According to Boyce, financially and pharmacologically, putting fentanyl in pot is not worth the hassle.

“From a financial standpoint, it makes no sense for dealers or suppliers to actually put fentanyl, which is a high profit margin drug, into cannabis, which is a low profit margin drug. From a pharmacological standpoint it is actually very hard to get fentanyl in the right dosage into cannabis and stick it on that plant,” said Boyce. Tweet This

Mackie, on the other hand, believes it’s not just about fentanyl.

“The reality is there can be contamination with any number of things. Yes, fentanyl may be unlikely in some cases, but testing shows there are heavy metals that often contaminate marijuana, there’s often fungus or bacteria that can cause illness. It’s not a benign drug,” said Mackie.

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READ MORE: 5 drug overdoses in 2 days linked to bootleg fentanyl in South Eastern Ontario

On this, Boyce does not disagree with Mackie, but says they only tested the urine of someone who claimed to have only smoked marijuana. He says if you want to know for sure if fentanyl is in cannabis, you have to test cannabis, not urine.

“I’m concerned this alert may divert attention to other things that aren’t really a concern. For people that are using illicit substances, they may disregard this message because, in the context of the war on drugs and criminalization, they see this as sensational,” said Boyce.

Whether fentanyl has actually been found in marijuana still remains unclear, but Boyce and Mackie agree expanding access to naloxone and making sure opioid users understand they should never use illegal drugs alone, is a top priority.