When it comes to post-harvest decontamination, X-rays outshine gamma rays in efficiency, safety, and simplicity.
Decontamination is an essential part of post-harvest cannabis processing. It helps eliminate mold and microbial contamination while ensuring overall sterilization. Decontamination is very common in Canada, where cannabis is legal and regulated at the federal level, as well as in some areas of the United States, where cannabis is regulated state by state.
Irradiation—the process of sterilizing cannabis through radiation technology—is one of the most effective ways to help ensure plant material and the products made from it are safe for consumption. Two irradiation methods, X-ray and gamma rays, are the most common. Although both have proved safe and effective for cannabis, X-ray technology offers significant advantages due to its ability to preserve the chemical makeup of the plant while maintaining operational safety and efficiency standards.
To understand the differences between X-ray and gamma-ray decontamination, it is essential to comprehend how they operate.
X-rays are produced during a process called electronic acceleration, which causes high-energy electrons to collide with a target material. The resulting X-ray photons penetrate almost everything in their path, damaging the DNA of organic tissue. This renders microorganisms unable to reproduce (sterile), eventually killing them. X-ray machines are encased in chambers lined with lead—which X-rays cannot penetrate—to keep the photons from escaping and damaging the DNA of unintended targets like nearby plants, animals, and humans.
Small-footprint X-ray machines are convenient in our industry because cannabis flower inside a sealed bag or jar can be loaded into a machine and sterilized. Keeping the flower inside its original, sealed container prevents recontamination after sterilization. X-ray sources can be turned on and off, and the X-ray machine’s operator controls the dosage level. Treatment has little effect on the product’s cannabinoid profile or terpenes, which is key to maintaining product quality.
On the other hand, gamma-ray irradiation typically employs cobalt-60, a radioactive isotope commonly used for sterilization. Gamma-ray equipment emits a constant stream of radiation that cannot be turned on and off. Exposure and sterilization levels are controlled by the distance between the product and the gamma-ray source, as well as the duration of exposure.
Gamma-ray decontamination machines also use lead insulation, but they add thick concrete walls to prevent external radiation exposure. The equipment functions by emitting high-energy photons that disrupt pathogens’ DNA, preventing them from functioning and reproducing. To decontaminate properly, gamma rays require time, a controlled distance from the target, and a suitable climate. Often, this method is used for sterilizing very large quantities of plant material.
For most uses in our industry, X-ray decontamination is the superior method. X-rays operate at lower energy levels (160–180kV) compared to gamma rays (about 1,250kV), making them able to penetrate through packaging to neutralize microbes without exposing the product to the air or altering its chemical makeup. This translates to maintaining cannabis’s flavor, fragrance, and other properties consumers enjoy.
In addition, X-ray systems are compact enough to be installed at cultivation or processing facilities, eliminating the need for off-site transportation. This not only reduces costs and logistical risks but also ensures full chain-of-custody control during processing. Gamma-ray systems use highly regulated radioactive isotopes. The equipment requires a lot of floor space and expensive safety and monitoring equipment. Gamma facilities are the size of a whole building, and products must be transported to the gamma site for treatment; X-ray equipment can occupy a single room.
Unlike gamma rays, which require regulatory oversight by the Department of Energy, X-rays utilize electrical power, a typical source for industrial equipment, and commonly found in most grow facilities. X-ray decontamination machines fall under standard safety protocols similar to dental or medical X-ray equipment. The machines can be registered with state programs, making them more accessible and manageable for most businesses.
Gamma-ray decontamination systems are accompanied by significant initial investments and ongoing costs associated with radioactive source replenishment and containment infrastructure. By contrast, X-ray decontamination systems are more affordable, with leasing and purchase options available that fit the budget of most medium to large-scale producers.
But X-ray solutions aren’t for everyone. While gamma-ray decontamination systems can process extremely large volumes (many hundreds of pounds per day), the highest-volume X-ray machines can handle just over 200 pounds per day. That is sufficient for many cannabis operators, but those who need to decontaminate large quantities of product on a regular basis may find X-ray solutions inefficient.
While both X-ray and gamma-ray technologies can decontaminate cannabis, X-rays can offer a superior edge to growers looking to prioritize quality, safety, operational simplicity, and legal compliance. By providing the ability to decontaminate on site, preserve the plant’s chemical properties, and avoid complexities in handling radioactive materials, X-ray machines offer a practical and cost-effective solution for most producers.
As founder and managing director at XRPure, Jeff Adams oversees a company propelling innovation in cannabis decontamination using X-ray energy. His thirty years of experience in industrial manufacturing operations spans process engineering, quality management, operations management, sales, and general management. Adams earned a master’s degree in mechanical engineering from MIT and an executive MBA from Brigham Young University.
Zap the Crap: Cannabis Decontamination Explained
Why is decontamination important in cannabis processing?
Decontamination ensures cannabis products are free from mold, microbes, and other contaminants, making them safe for consumption and compliant with regulatory standards.
What is the difference between X-ray and gamma-ray decontamination?
X-ray decontamination uses electronically generated radiation that can be turned on and off, offering precise, low-energy sterilization that preserves the cannabis plant’s chemical makeup. Gamma-ray systems use radioactive isotopes like cobalt-60, emit constant high-energy radiation, and are better suited for bulk sterilization but involve more regulatory oversight and infrastructure.
Is X-ray sterilization safe for cannabis products?
Yes. X-ray sterilization is considered safe and effective for cannabis, with minimal impact on cannabinoids and terpenes. It can be used on sealed packaging, reducing the risk of recontamination.
Can cannabis be decontaminated on-site?
Yes. Compact X-ray decontamination systems can be installed directly in cultivation or processing facilities, offering on-site sterilization without the need for transport to off-site gamma-ray facilities.
Which decontamination method is more cost-effective for cannabis operators?
X-ray systems are typically more affordable and accessible for small to mid-sized producers. Gamma-ray systems, while effective for high-volume processing, require significant investment and regulatory oversight.
