The state of Washington requires that all cannabis products sold in the state must be tested for harmful substances and potency. However, because cannabis is not legal federally, there are no federal laboratory quality standards or mandated testing methods, like those that exist for drinking water, soil, and similar products. This leaves cannabis producers, retailers, and consumers missing an extra layer of quality assurance.
The science of cannabis testing is still new and complex, as tests look to determine THC levels as well as cannabinoids, terpenes, residual solvents, pesticides, heavy metals, and microorganisms.
All states with legal cannabis programs have established labs to test cannabis products, but since there are no federal standards, there is often a lack of confidence in the results. Many scientists are looking to Canada for best practices, now that commerce barriers have been eliminated there nationally.
In Washington, the Cannabis Science Task Force was created in 2019. Since then, the CSTF has been working to recommend laboratory quality standards in preparation for a rulemaking change for cannabis-testing lab accreditation. The task force’s goal is to provide a solid framework for credible cannabis laboratory accreditation in the future.
Currently, to ensure consumers are purchasing products that meet required quality standards, the Washington Liquor and Cannabis Board and the Department of Health oversee the testing of cannabis products at accredited private cannabis laboratories.
Testing oversight will eventually transfer to the Department of Ecology, which was chosen by the Legislature because of its already robust accreditation reputation. It currently works with more than 500 laboratories across the state and other states, providing initial and continuing accreditation.
The task force, a group of professionals with expertise in chemistry, laboratory quality assurance and quality control, and state government policy, has been charged with providing a science-based framework for testing pesticides in cannabis plants and products.
Participants come from the Washington State departments of Agriculture, Health, and Ecology, as well as the Liquor and Cannabis Board and cannabis testing laboratories. These groups will continue to collaborate on standards through February 2022.
“When you want confidence and high-quality testing, it’s not simple,” said Annette Hoffmann, Ph.D., Environmental Assessment Program Manager for the DOE. “Think of a recipe for a cake: you have five cakes, all made with the same ingredients and the same instructions, but each cake is different. The only way to test accuracy is to be assured that each one has the same exact elements. Accurate testing tells you whether or not you got it right.”
She said federal barriers make national testing standards close to impossible.
“We cannot bring marijuana containing THC across state lines, which means we can only test hemp,” Hoffmann said. “Since THC can hide a pesticide, for example, testing for pesticides in hemp is not accurate.”
In June 2020, the task force made recommendations to the Legislature regarding the use of pesticides, which included:
• The use of existing agricultural method validation protocols and method performance measures developed by the U.S. Department of Agriculture, adapted to cannabis plants and products.
• The establishment of an interagency cooperative team staffed by WSLCB, WSDA, and DOH to maintain adopted protocols and provide technical assistance to cannabis laboratories.
• Regulatory updates which can facilitate the recommendations.
A second report, released December 2021, provided recommendations for additional laboratory quality standards covering potency, heavy metals, and residual solvents. Other recommendations address an Interagency Cooperative Team and its roles and responsibilities for initial and ongoing oversight and guidance for adopting laboratory quality standards and an in-state Cannabis Matrix Proficiency Testing Program.
Finally, robust recommendations for developing this Proficiency Testing Program, including the identification of critical cannabis matrix proficiency testing samples, was presented.
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