What is it about?
The pharmaceutical industry took over 20 years to change from monitoring a small group of heavy metals to finally arrive at regulations for twenty-four elemental impurities in drug products, classified by their permitted daily exposure limits and categorized by toxicological impact and method of administration. The entire premise was based on carrying out a comprehensive risk assessment study of their toxicity and the likelihood of finding them somewhere in the drug manufacturing process, which was fully documented in ICH Q3D guidelines for elemental impurities. The cannabis industry cannot move beyond regulating the big four heavy metals until this type of risk assessment study is carried out. This objective of this paper is offer guidance as to which elemental contaminants are worthy of consideration, based on likely sources derived from the manufacturing of cannabis and hemp consumer products and to explore how this well-established pharmaceutical risk assessment process could be adapted by the cannabis industry
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Why is it important?
The way to minimize heavy metals in cannabis and cannabis products is to first understand and characterize the cultivation process. Unfortunately, this is often very challenging, particularly if the plants are being grown outdoors. However, by carefully selecting the right cultivars, understanding the soil chemistry and the use of high purity fertilizers, nutrients and water, can all help to minimize the plants uptake of elemental contaminants. Moreover, by optimizing the extraction and purification method, processors have the ability to reduce levels of heavy metals in the final cannabinoid extracts. Very often there are many choices when selecting an extraction technology, depending on the desired extract or the products being made for a therapeutic outcome. It is clear that elemental contaminants can be minimized by optimizing the entire production process including extraction solvent, temperature/pressure conditions, and the other purification techniques including evaporation, distillation and filtration. However, this must also be extended to include the packaging and delivery systems, which are all important areas to characterize in order to ensure that cannabis consumer products are free of heavy metals and safe for human consumption.
Perspectives
The beginning of the journey to regulate elemental impurities in pharmaceuticals in the late 1990s can be compared to the production of cannabis and hemp derived products today, where the sources of elemental contaminants, the toxicological impacts of the contaminants and the methodology to perform the measurements were not fully understood or developed. In particular, the elemental toxicological guidelines to regulate the cannabis industry are being taken very loosely from a combination of methods and limits derived by the pharmaceutical, dietary supplements, food, environmental and cosmetics industries. Even though the process of manufacturing cannabinoids might be similar in some cases to drugs and herbal medicines derived from natural products, the consumers of cannabis and hemp products are using them very differently and in very different quantities, particularly compared to pharmaceuticals, which typically have a maximum daily dosage. The bottom line is that heavy metal toxicological data generated for pharmaceuticals over a number of decades cannot simply be transferred to cannabis, hemp, and their multitude of products. So, I take a detailed look at how the pharmaceutical industry approached bringing in comprehensive regulations using a risk assessment approach of those elements that are not only known to be toxic but also likely to be potentially found somewhere in the drug manufacturing process. I was personally involved in this process as the leader of heavy metals task force on the ACS (American Chemical Society) Reagent Chemicals Committee, that worked very closely with the United States Pharmacopeia (USP) to update its analytical procedure to include plasma spectrochemistry techniques (ICP-OES, ICP-MS).
ROBERT THOMAS
Scientific Solutions Inc
Read the Original
This page is a summary of: Understanding Sources of Heavy Metals in Cannabis and Hemp: Benefits of a Risk Assessment Strategy, Journal of Testing and Evaluation, January 2024, ASTM International,
DOI: 10.1520/jte20230603.
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