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Irradiation 101: What Canadians Need to Know About Cannabis Irradiation

Published on July 8, 2019 · Last updated November 17, 2020
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Jesse Milns/Leafly

What’s Cannabis Irradiation?

If you answered, “I don’t know, but it sounds scary,” you’re not alone. A 2012 Angus Reid poll found that 57% of Canadians had not heard of food irradiation, although it’s common practice. Once participants were told that irradiation is “a method of preserving food by using a type of radiation energy,” 46% said they were unlikely to buy irradiated foods.Join the Leafly Canada CommunityDespite that reticence, it’s likely many Canadian shoppers are buying irradiated items, including cannabis, without even knowing it.

Patients should be informed as to whether or not cannabis has been irradiated so they can make the best choice for themselves and their medical needs.

Irradiation is approved for non-organic beef, potatoes, onions, dried spices, and certain wheat products. Although pre-packaged fully irradiated items must be labeled as such, foods containing less than 10% irradiated ingredients need not. In the States, the list of approved foods is much broader and includes most meats, seafood, fruits, vegetables, and spices.

Irradiating cannabis is also allowed—but not required—under Health Canada regulations. It has been estimated by some industry insiders that up to 80% of licensed producers irradiate their cannabis, but a media rep for Health Canada could not verify this number, and it’s not required for irradiated cannabis to be labeled as such.

So What Is Irradiation, Anyway?

Simply put, irradiation is the process of treating a product to radiation in order to prevent contamination. Gamma irradiation, which uses gamma rays, is the form of irradiation typically used on cannabis, with the intent of eliminating pathogens such as bacteria and mould by breaking their DNA.

Irradiation is a one-shot procedure and does not make your cannabis (or food) radioactive. A blog post by the licensed producer (LP) Emblem, likens it to walking through an airport security screening.

“Just as tossing your bag into a luggage scanner doesn’t make your purse or briefcase radioactive, nor will your medical cannabis become radioactive or be harmed when it’s irradiated.”

How Do People Feel About Irradiation?

We don’t have any surveys to tell us how cannabis consumers feel about irradiation, but throw the question to your puff buddies, or search ‘cannabis irradiation’ on Twitter, and you’ll likely encounter the same uncertainty that exists around the irradiation of food.

“Irradiation, in cannabis and otherwise, is one of the most maligned topics of our generation,” says Tantalus Labs founder Dan Sutton.

Sutton, who previously worked in nuclear technology, defends the practice, suggesting that people fear what they don’t understand. “I think you would be hard pressed to find someone outside of nuclear physics who can actually even define what ‘radiation’ means,” he says.

Is Irradiation Necessary for Cannabis?

Irradiation is not the only way for cannabis producers to deal with the threat of contamination. Avoiding it in the first place is a good strategy, but it requires diligence throughout growth and production cycles.

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“It’s really worth highlighting that aiming to limit irradiation isn’t about a single step,” says Sean Griffin, vice president of communications and public relations at Flowr. “We are intensely focused on every step involved in cultivation, harvesting, and curing to produce a clean product that is consistent and expresses the broadest possible spectrum of the terpene and cannabinoid profile.”

Although a few LPs have committed to never irradiating, most of the representatives who spoke to Leafly used words like ‘avoid’ or ‘limit,’ suggesting that irradiation is a useful tool of last resort, even for harvesters who’d rather avoid it. Above all else, irradiation is valued for its certainty.

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Jesse Milns/Leafly

Still, critics of the practice counter that its very effectiveness is the problem, with some calling it a crutch.

“Irradiation can be used to make a batch saleable that would otherwise not be able to be sold due to microbial contamination, but this doesn’t mean that the end result will be good cannabis,” says Nathan Woodworth, chief executive officer of JWC, an LP that does not irradiate.

What Are the Pros of Irradiating Cannabis?

Gamma irradiation of cannabis is safe enough to get Health Canada’s stamp of approval and provides assurance for immune-comprised patients.

“For medical patients, especially those with immunodeficiency, any level of microbial count in their day to day life could pose a threat, and irradiation works towards ensuring that doesn’t happen,” says Tamara Macgregor, vice president of communications and public affairs at Aphria.

What Are the Cons of Irradiating Cannabis?

In a study conducted by Dutch licensed producer Bedrocan, and published in the journal Frontiers in Pharmacology, researchers found that while irradiation did not alter cannabinoid content, it did reduce terpenes in varying degrees, thereby altering their overall ratio. Study authors noted that the terpene loss was comparable to what would happen if you were to stash your weed in a paper bag for a short time.

From a licensed producer perspective, the most compelling argument against irradiation may be that customers don’t like the sound of it. “Irradiation is not a process that consumers prefer, and therefore should be avoided,” says Woodworth.

Should Irradiation Inform Your Cannabis Purchasing Decisions?

Ashleigh Brown is CEO of patient advocacy group SheCann, and a strong proponent for personal choice.

“When it comes to patients, the more transparency they have around their medication, the more comfortable they feel,” she says. “We know very little about the actual impact of irradiation, other than the fact that it renders the flower less likely to have negative effects on immunocompromised patients. My personal feeling is that patients should be informed as to whether or not cannabis has been irradiated so they can make the best choice for themselves and their medical needs.”

Dan Sutton doesn’t factor irradiation into his consumption decisions, saying he hasn’t found a correlation with quality “either negative or positive,” while Sean Griffin says that consumers who care about aroma, taste, and overall experience should consider it relevant when an LP aims to avoid irradiation.

Whether or not you choose to buy irradiated products, it’s worth noting that Health Canada requires testing after processing and before sale. This means that the terpene information your LP offers has accounted for the effects of sterilization (but not for the natural degradation processes that continue after purchase.)

Oh, and just in case you’re wondering, irradiated cannabis will not be allowed in edible products when they become legal in late 2019, although edibles are permitted to include certain irradiated food ingredients, such as wheat flour mentioned above.

Which LPs Irradiate? Which LPs Don’t?

Here’s a chart! Note, the companies in the ‘yes’ category practice irradiation, but not necessarily on all their products. At the time of writing, companies in the ‘no’ category indicated that they either don’t irradiate or stringently avoid it. For the most up-to-date and product-specific information, call or email your LP directly.

CannTrustPeace Naturals

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Devon Scoble
Devon Scoble
Formerly a senior staff editor for Leafly Canada, Devon is a freelance writer, editor and content strategist focusing on health and lifestyle stories. Find her online at or at her local cannabis store, stocking up on mango haze flower and low-dose edibles.
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