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Recent Workshop Emphasizes Why the Cannabis Industry Needs To Get Better at Measuring Heavy Metals

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If you attend cannabis science meetings, symposia, or conferences, have you ever wondered why there are never oral or poster presentations on heavy metals? Over the past six months, I’ve attended quite a few events and noted this absence again and again. I had been doing research for a new book I’m writing on the measurement of elemental contaminants in cannabis and hemp and was talking to lots of people in the industry and going to as many meetings as possible.

My research eventually connected me with Lori Dodson, deputy director of the Maryland Medical Cannabis Commission (MMCC), who was very enthusiastic to my suggestion of a 1-day workshop for the independent testing labs on the use of ICP-MS to measure heavy metals in cannabis. It took a couple of months to organize, but I’m glad to report that it came to fruition at a hotel in Columbia, Maryland on the 3rd of October. It was very exciting because it allowed me to tap into my 45 years of experience in trace element analysis and pull together an impressive list of speakers in the field, which would be the envy of any scientific symposia on plasma spectrochemistry. However, before I talk in greater detail about the workshop, allow me to give a brief explanation of why it’s critically important to be monitoring elemental contaminants in the cannabis plant and its many products.

There is no question that the lack of federal oversight with regard to heavy metals in medicinal cannabis products in the US has meant that it has been left to the individual states to regulate its use. Medical cannabis is legal in 34 states, while 12 states and the District of Columbia allow its use for adult recreational consumptionHowever, the cannabis plant is known to be a hyper-accumulator of heavy metals in the soil and growing medium, so it’s critical to monitor levels to ensure cannabis products are safe to use.

Unfortunately, there are many inconsistencies with heavy metal limits in different states where cannabis is legal. Most define four heavy metals (Lead, Arsenic, Cadmium, Mercury) while others specify up to nine. Some are based on limits directly in the cannabis plant, while others are based on human consumption per day. Others take into consideration the bodyweight of the consumer, while some states do not even have heavy metal limits. Some states only measure heavy metals in the cannabis plant/flower, while some give different limits for the delivery method such as oral, inhalation, or transdermal.

It was these regulatory inconsistencies, which led me to explore the possibility of writing a book on the topic. I had spent the last three years working on another book which focused on the measurement of elemental impurities in pharmaceuticals and was looking for a new project when one of my contacts suggested I take a look at the cannabis industry. It took me a few months of research and interviewing key players in the industry including cultivators, growers, processors, manufactures, state regulators, and testing labs to realize that heavy metals were not high on their priority list. One cultivator even accused me of being an investigative journalist, when I asked them if they knew what elemental contaminants were in their products.

Over the next few months, I started going to cannabis science meetings, conferences, and trade shows and noticed there were never any talks on heavy metals. When I began digging up information in the public domain about the hyper-accumulating properties of the cannabis plant, I realized that this was a topic that urgently needed to be addressed. My research eventually connected me with the MMCC which was responsible for regulating all sales of medical cannabis in the state of Maryland. As a result, I got a much better understanding of the extremely difficulty job that regulators had. They ensure that all cannabis-related products are safe for human consumption and that all the independent testing labs in the state of MD are generating high-quality data for all the critical analytes, including potency and contaminants such as residual solvents, pesticides, microbes, and heavy metals.

My interviews had also highlighted the inexperience and lack of knowledge of many of the testing labs that had sprung up in the past few years, because the industry was growing at such an alarming and chaotic pace. I felt that this was a great opportunity to make a difference and help the industry, so over the next few months I began to put together the agenda for a one-day educational workshop, the Optimization of ICP-MS for Measuring Heavy Metals in Cannabis, for the testing labs in the area that didn’t have a good understanding of working with the technique.

Fast forward to October 3rd, 2019 at the Sheraton Hotel in Columbia, Maryland, where we attracted an audience of over 50 people, made up of federal, state, private, and academic analytical testing lab personnel. The day was jam-packed with advice, tips, methods, guidance, troubleshooting, suggestions etc. on how to optimize the use of ICP-MS for the accurate and validated measurement of heavy metals in cannabis and cannabis-related products.

After Lori Dodson from MMCC had welcomed everyone, I kicked off the scientific part of the meeting, by talking about the early days of ICP-MS when I worked on the very first commercially-available instrument, the ELAN 250 in 1983 and the difficulty in generating sample ions in the plasma and the challenge of getting them into the mass spectrometer for separation and detection. I also talked about the fundamental principles and the most common application areas of the technique. We heard from:

  • Shimadzu’s Dr Andrew Fornadel who talked about the challenge of using ICP-MS to characterize the different kinds of cannabis-related samples.

  • Patti Atkins, from Spex CertiPrep, a manufacturer of standards and reference materials, talked about good laboratory practices and how to reduce and minimize sources of contamination in ICP-MS.

  • Laura Lawlor from Milestone, Inc., a manufacturer of microwave sample digestion systems, spoke on the selection of the optimum digestion approach for cannabis samples and the use of clean chemistry solutions to ensure clean blanks.

  • Dr Ryan Brennan and Justin Masone, of Glass Expansion, manufacturers of ICP-OES/ICP-MS sample introduction components, presented on maintenance procedures and ways to enhance sample throughput.

  • Dr Steven Pappas, from the Tobacco Inorganics Group of the Centers for Disease Control and Prevention (CDC), talked about testing electronic nicotine delivery (END) vaping devices for heavy metals and what he has learned about the corrosion of the metallic components inside the devices that could be applied to cannabis vaping pens.

  • Lawrence Neufeld, CEO of Spectron, Inc., a cone manufacturer, discussed ICP-MS cone maintenance and cleaning for enhanced instrument lifetime.

  • And finally, Dr Melissa Phillips, from the Chemical Sciences Division of the National Institute of Standards and Technology (NIST), spoke about the urgent need for quality assurance programs and Certified Reference Materials (CRM) to ensure robust validation protocols for the accurate measurement of all analytes in cannabinoids.

  • Outside of the agenda we also heard from Dr Nandu Sarma, the Director of Herbal Medicines at the United States Pharmacopeia (USP). Dr Sarma was in attendance and asked if he could say a few words about USP's position on standard methods for the analysis of cannabis and hemp.

It was a long day, but well worth it. The feedback we got from the attendees was very encouraging. There is no question that most of the audience left the workshop with a far greater appreciation of what it takes to get good data by ICP-MS. However, the industry will always be faced with the fact that typical operators only have a couple of years’ experience at most and some of them just a couple of months’. For that reason, it’s always going to be challenging for these operators who are not used to working in the ultra-trace environment but are also working in labs that in most cases were not designed for ultra-trace elemental analysis.

I have had requests to do similar workshops in other parts of the US, but as I did this one pro bono, there’s the issue of funding for future workshops. However, we recorded all the talks and linked them digitally to the PowerPoint slides so there might be opportunities to use them for training purposes. I’m firmly convinced that educating the industry is of critical importance. The people who are trying to raise the bar today will be rewarded when the federal regulators eventually come knocking on the door. As a result, I’m hoping to play a big part in helping the industry better understand the many sources and role of elemental contaminants in cannabis products, which will eventually lead to safer products for consumers.