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ASTM Workshop on Measurement of Elemental Contaminants in Cannabis/Hemp Consumer Products

By Robert Thomas

Published: Apr 22, 2021   
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m very pleased to be announcing the first ASTM International global Workshop on Measurement of Elemental Contaminants in Cannabis/Hemp Consumer Products, taking place virtually on June 28-30, 2021. I am extremely honored to be the technical program chair of this event, which has been approximately 6 months in the planning and has finally come to fruition with the posting of the technical program. So, allow me to give you a brief synopsis of events leading up to the announcement of the workshop.

Back in the fall of 2020, I was asked to serve on an ASTM D37 Cannabis subcommittee, initially to add my expertise to an ASTM ICP-MS method for measuring elemental contaminants in cannabis inflorescence. I soon discovered that we all had a common interest in understanding the sources of heavy metal contaminants in the cultivation and extraction processes and in particular, how many elemental contaminants should be monitored. So, we began to explore the possibility of a dedicated workshop on the topic. We had no idea where it would take us, but it soon became very clear that there was tremendous interest from the cannabis testing community, and what began as a half-day workshop would need to be expanded in both scope and duration. When we eventually put our stake in the ground to evaluate all the abstracts received, we ended up with a three-day event that included 20 high-quality technical presentations.

My involvement with the cannabis industry

So, before I specifically talk about the objectives of the workshop, I think it’s worth giving a little background about how I got involved in the cannabis industry. I first started getting an interest over two years ago when I researched the possibility of writing a book on heavy metals in cannabis and cannabinoid consumer products, having just finished one on elemental impurities in drug products and substances. I was the leader of the heavy metals task force on the ACS Reagent Chemicals Committee, which had worked very closely with the United States Pharmacopeia (USP) to expand and update the test for heavy metals from a colorimetric sulfide method to one using plasma spectrochemistry, which was described in USP Chapters 232/233 and ICH Step 3 Guidelines.

I was surprised to find that there was not a great deal known about the sources of heavy metals in cannabis consumer products, so I spent about three months just talking to as many people in the industry as possible including cultivators, growers, processors, manufacturers, regulators, and testing labs. I also went to a number of conferences and noticed there were never any talks on heavy metals. So, I decided to survey the symposium landscape and submitted abstracts on the topic to see if I could get the attention of conference organizers. Slowly I  started getting noticed. I was first invited to give a talk at an ACS regional meeting in Saratoga Springs in 2019, and also got an abstract accepted at the Pittsburgh Conference in Chicago in March 2020. Then I thought I’d hit the jackpot when I got accepted for a presentation at the Cannabis Science Conference East in Baltimore in April 2020. Unfortunately, COVID got in the way and it was postponed several times, until it eventually got rescheduled to later this year.

In the meantime, I was forging ahead writing my book and was looking for ways to increase its visibility when I found the online journal Analytical Cannabis. To cut a long story short, I proposed serializing a few chapters from the book. Much to my surprise, the Editorial Director, Jack Rudd was very enthusiastic and after I had convinced my publisher we would not infringe copyright, we published the first part of the 5-part series in the Spring of 2020. Fast forward 12 months and there have been numerous articles, and white papers as well as the publication of my new book, Measuring Heavy Metal Contaminants in Cannabis and Hemp, in October 2020. There is no question that the research I carried out over the past two years gave me the incentive for the ASTM workshop, as I realized that it was critically important to educate the industry on this topic. With that as a background, allow me to tell you about the objectives of the workshop and why it’s so important we use this forum to advance our understanding and knowledge of heavy metal contaminants in cannabis/hemp products to better protect consumer safety.

Heavy metal toxicity

Long-term exposure to heavy metals, irrespective of the source can have serious adverse effects on human health. They can interact with DNA and interrupt regular cellular functions causing cell mutations, carcinogenesis, and apoptosis (cell death).  Heavy metal toxicity affects virtually every system in the human body, and often occurs with no distinctive symptoms. It can damage the central nervous system, kidneys, and reproductive system and, at higher levels, can cause coma, convulsions, and even death. Many of them, such as lead and mercury are neurotoxins, which means they readily cross over the blood-brain barrier and affect the development and growth of brain neurons, so even at low levels they are associated with reduced brain development, lower intelligence, and learning disabilities.

Consumer safety

As a result, heavy metals are a known consumer safety hazard that are largely not being addressed by the cannabis/hemp industry. Currently, only four heavy metals (Pb, Cd, As, Hg) are required by the vast majority of the 36 states in the United States (and Canada) where consumption of cannabis/hemp consumer products for various purposes is legal. However, there is compelling evidence in the public domain that at least another ten elements could be of potential concern derived from the cultivation and growing environment including soil, grow medium, fertilizers, nutrients, water, and growth enhancers etc. Moreover, the production of various cannabinoid-based products can also lead to a further increase in these levels of elemental contaminants through the extraction, purification, concentration, and filtration processes as well as picking up additional elements from the manufacturing, packaging, and delivery equipment, which can represent significant safety risks to consumers.

In addition, it has been widely reported in the public domain that cannabis/hemp extracts and diluent oils used in electronic cannabis vaping delivery systems (ECDS) are corroding internal metallic components. Researchers are finding elements such as iron, chromium, nickel, aluminum, zinc, and lead in the vaping liquid, which are derived from a variety of alloys inside the vaping devices such as stainless steel, brass, nichrome, kanthal, solder and other metal-based materials. At vaping temperatures of 200-300°C, these metal particles are finding their way into the vaping aerosol and being delivered to the users’ respiratory pathways - potentially causing long term damage to the lungs.

Workshop objectives

This workshop will therefore provide a broad perspective and awareness of the current knowledge of elemental contaminants in cannabis/hemp consumer products, communicate their significance, and as a result, educate users, cultivators, processors, testing labs, and regulators within the cannabis/hemp community of their potential risk to human and environmental health.

Technical program

The following topics will be specifically addressed in the workshop:

  • The most current research detailing the mechanisms for metal uptake into a cannabis plant-based on growing conditions and soil chemistry.
  • Optimization of the analytical methodology used to measure heavy metals in cannabis/hemp consumer products.
  • Lessons learned from regulating heavy metals in drug products and using a scientifically risk-based approach to predict elemental impurities derived from the manufacturing process.
  • Toxicological impact of heavy metals and the industry’s responsibility for ensuring consumer health and safety.
  • The current state of the art research in phytoremediation and phytoextraction techniques.
  • The most recent research in characterizing elemental contaminants in vaping liquids and aerosols produced by electronic nicotine delivery systems (ENDS) and electronic cannabis delivery systems (ECDS).

To view the technical program, please click here.

As the program chair of the very first global workshop dedicated to the measurement of elemental contaminants in cannabis/hemp consumer products, it promises to be a truly groundbreaking event, so it should not be missed if you want to hear the latest cutting-edge research on this critically important topic.

Please follow this link to register. 

For technical questions, please feel free to contact me at robert.james.thomas@verizon.net 

Looking forward to seeing you all in June.

Robert Thomas, CSci, CChem, FRC

Technical Program Chair, ASTM Workshop on Measuring Elemental Contaminants in Cannabis/Hemp Consumer Products

Robert Thomas

Principal of Scientific Solutions

Rob is a heavy metals expert and has written for Analytical Cannabis on the subject since 2019. Through his consulting company Scientific Solutions, he has helped educate countless professionals in the cannabis testing community on heavy metal analysis. He is also an editor and frequent contributor of the Atomic Perspectives column in Spectroscopy magazine, and has authored five textbooks on the principles and applications of mass spectrometry. Rob has an Advanced Degree in Analytical Chemistry from the University of Wales, UK, and is a fellow of the Royal Society of Chemistry and a chartered chemist.


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