We speak with Heather Krug, State Marijuana Laboratory Sciences Program Manager, Colorado Department of Public Health and Environment (CDPHE) Laboratory Services Division, to find out more about the regulatory challenges of controlling pesticide use in cannabis.

How did you get involved in this field?

After Colorado legalized retail marijuana and sales began in 2014, the Colorado Department of Public Health and Environment (CDPHE) Laboratory Services Division, where I was employed, agreed to form an inspection program for the newly established private marijuana testing facilities in Colorado. My experience as a forensic toxicologist gave me an understanding of marijuana and related analytical techniques, so I was asked to run the program.

How would you describe the current regulatory landscape?

In my (perhaps biased) opinion, I believe regulators are working hard to establish appropriate requirements, despite the lack of information available regarding pesticide use in cannabis, but there are no simple answers. For example, Colorado regulators have taken a conservative approach by adopting the position that the detection of a banned pesticide is a threat to public health and safety because tolerance limits have not been established. This is certainly in the best interest of the patient or consumer, but it creates a secondary challenge in regard to regulatory testing requirements because analytical detection limits will vary from lab to lab.

What challenges are there?

The biggest challenges from a regulatory perspective are the absence of established tolerance limits for pesticides in cannabis and the lack of any approved registrations of any pesticides specifically allowing use on cannabis. Despite these challenges, Colorado has established a list of pesticides approved for use on marijuana, based on current knowledge. We have spent the past two years working with stakeholders and scientists to determine a list of banned pesticides that are most important to test for. We then conducted multi-laboratory studies using this list to determine the detection capabilities of the state’s analytical laboratories. Data from these studies were used to set regulatory limits, which became effective January 1, 2018.

What analytical techniques are you focusing on?

The CDPHE Marijuana Reference Laboratory is in the process of developing a method using a UHPLC combined with Q-Tof Mass Spectrometer, as well as exploring GC/MS analysis for some pesticide residues. In conjunction with this method development, we plan to experiment with different sample preparation, extraction, and clean-up techniques, including QuEChERS and dSPE, to determine best practice solutions for the cannabis industry at large. A number of cannabis testing laboratories nationwide are also conducting pesticide residue analysis utilizing an array of analytical techniques that encompass the sample extraction step all the way through instrumental analysis. While this is a relatively new field of analysis in the context of cannabis testing, it is one in which there has been a great amount of time and effort spent. The key moving forward will be to foster collaborative efforts between testing laboratories, regulators, and researchers to optimize the analytical techniques being used.

Who else do you work with?

My team and I work closely with scientists from Colorado’s licensed marijuana testing facilities and other marijuana industry stakeholders to understand and integrate various perspectives on testing requirements and advancements in the field. We actively expand upon our regulatory and scientific network by working with state government personnel from across the country who have similar roles and by participating in current standardization efforts led by national organizations such as ASTM and AOAC.

How do you see pesticide testing developing in future?

Major efforts are being made to standardize cannabis testing methods. As these develop, I hope we see superior analytical techniques come to light, which provide more consistency in results between laboratories. Regulation will adapt as research advances into pesticide pyrolysis and toxicity through various modes of exposure, providing regulators with data to make evidence-based policy decisions.