The process of using gamma irradiation on food to prevent the spread of food-borne illnesses and preserve foods has long been controversial, despite the fact that many countries allow it. Now, to add to the controversy, medical marijuana producers in countries like Canada and The Netherlands use gamma irradiation to sterilize their cannabis.

Gamma irradiation is the process of exposing a substance to radiation via gamma rays. It has multiple different uses, including:

  • Sterilization: Irradiation, when done at the right levels, can sterilize objects. It can therefore be used to sterilize medical equipment as well as kill bacteria in food.
  • Medicine: Irradiation is used in diagnostic imaging, cancer therapy and blood transfusion.
  • Industrial chemistry: Irradiation is often used to cross-link plastics and improve the quality of precious stones like topaz. Exposing white topaz to irradiation, for example, turns it into blue topaz.
  • Agriculture: Irradiation can be used on seed and germplasm to essentially mix plant genes and breed crops with desirable characteristics. Irradiation is also used on food products like poultry, pork, and meat for preservation, to reduce the risk of foodborne illness and spread of invasive pests, and delay or eliminate sprouting or ripening.

The use of irradiation is extremely controversial. Activists, such as the Organic Consumers Associationand The Food Commission generally argue that irradiation damages the quality of food by breaking molecular chains and creating free radicals, which can then combine to create a variety of toxic substances. They also argue that irradiation can cause foods to lose up to 85% of vitamins as well as their natural digestive enzymes, making them harder to digest by humans.

Activists and spokespersons against irradiation also argue that there is insufficient evidence to suggest that a long-term diet of irradiated foods is safe for humans. Studies on animals fed irradiated foods have also shown increased tumors, reproductive failures and kidney damage, which do little to strengthen the argument in favor of this process.


Gamma irradiation is used to treat medical marijuana in a variety of countries, including The Netherlands and Canada.

For example, the irradiation process is used by several licensed producers under Health Canada’s Marihuana for Medical Purposes Regulations in order to ensure they adhere to the strict standards surrounding biological impurities in medical cannabis. In The Netherlands, medical cannabis producers like Bedrocan also use irradiation to adhere to their government’s safety standards.

Activists, skeptics, and regular cannabis users, however, tend to think differently. In general, they argue that gamma irradiation is unsafe and can potentially damage cannabis by ridding it of cannabinoids and terpenes. New research, however, suggests that isn’t the case.

Arno Hazekamp, Head of Research and Education at Bedrocan International BV, the main producer of medical-grade cannabis in The Netherlands, recently explored the effects of gamma irradiation on marijuana.

Hazekamp’s study looked 4 different strains of medical cannabis produced by Bedrocan both before and after the irradiation process. The study was particularly interested in changes to cannabinoids, terpenes, and moisture content. The strains were assessed visually and also underwent standard GC and HPLC cannabis potency testing.

The study found that there was no change to THC and CBD concentrations in any of the strains after irradiation. There was also no change to moisture content. The effect on terpenes is debatable; only a few terpenes were completely destroyed, while the exact ratio of terpenes in each strain only changed moderately.

The main terpenes affected were the monoterpenes myrcene, cis-ocimene and terpinolene, and the sesquiterpenes gamma-selinene and eudesma-3,7(11)-diene. Hazekamp noted that the terpenes were reduced but that no new compounds were formed in the cannabis due to irradiation, suggesting that the terpenes are evaporated during the process.


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