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The cannabis plant has multiple beneficial utilities – including soaking up heavy metals from the soil it is planted in. While this is good for the Earth, it is not ideal for crops that are grown for consumer consumption, as this contamination can have a detrimental impact on human health.
A new meta-analysis from Penn State University has highlighted that consumers of cannabis could be unknowingly exposed to harmful heavy metals.
The researchers show that strains that have been bred specifically for phytoremediation – because of their long stems, fast growth and high root and leaf surface area – can contain lead, mercury, cadmium and chromium which are all carcinogenic. Specifically, cadmium and chromium are capable of being transported and distributed up through the stalk and into the leaves and flowers and then exit through the trichomes.
Read more: High THC cannabis cultivation licence issued to Hilltop Leaf
This could have negative impacts on health, especially for people who are using the plant to manage symptoms of cancer or to manage a health condition.
The researchers propose a blueprint to support cultivators in avoiding this contamination of their crops, however, testing company Infinite Chemical Analysis Labs (InfinteCAL) believes there should also be extensive testing rules and regulations put in place to combat contamination.
Jayneil Kamdar, Ph.D., Lab Manager at InfiniteCAL, commented: “Cannabis plants have an exceptional ability to absorb heavy metals from the soil, which in fact, makes them promising candidates for remediating contaminated sites. However, from a consumer perspective, this means that extra precautions must be taken to grow cannabis in soil that is free of heavy metals.
“Heavy metals that have accumulated in the plant form may be inhaled by consumers. Even worse, heavy metals can concentrate in extracts by mass depending on the extraction technique. Another area of concern is heavy metals contamination in vape cartridges. If the cartridge hardware contains metal components, certain heavy metals (e.g. lead) can leach into the cannabis extract over time.
“InfiniteCAL often sees this with lower quality hardware. We encourage clients to do a heavy metal leaching test prior to filling any cartridges.
“Some of the health issues associated with heavy metals are kidney disease, neuropathy, anaemia, cancer, and developmental toxicity. Often, toxicity is incremental from chronic intake of heavy metals. Consumers, particularly for medical cannabis users, rely on having safe, clean products and must mitigate as much risk as possible.”
A 2019 YouGov survey demonstrated that around one million people in Britain – 2.8 per cent of the adult population – were using illicit cannabis for medical reasons. Contamination could be a huge problem for these patients that are using the plant from unregulated sources to manage their health conditions – as they do not know whether their medicine is contaminated.
Those using legal medical cannabis, however, can request for a certificate of analysis that will show any contaminant.
InfiniteCAL operates in California, and Kamdar highlights that in both California and Michigan, where there is a legal, regulated cannabis market, it is required that cannabis products are tested for heavy metals.
“We are also one of the few labs certified to test hemp for the state of Colorado which requires heavy metals testing as well. Arsenic, cadmium, lead, and mercury – often referred to as the “Big Four” of heavy metals testing – should be the minimum requirement, although Michigan also requires copper, nickel, and chromium.
“InfiniteCAL believes the more exhaustive the list required for testing the better it is for public health.”
For legitimate cannabis businesses providing products to consumers in these States, ensuring products are free of harmful contaminants is vital.
“According to regulations in California, product batches that have heavy metal concentrations greater than the allowed regulatory limits must be destroyed. Remediation is an option but removal of heavy metals is often not a trivial undertaking,” said Kamdar.
“The risk to any business is loss of product which is ultimately loss in revenue. This is why it is imperative that businesses mitigate their risk by performing R&D testing on their batches before advancing to the compliance level.
“Apart from diligent R&D testing of product batches, our suggestion is that manufacturers and producers stay vigilant of possible contamination sources from seed to sale. That may require testing the soil, water supply, hardware (e.g. vape cartridges), and even peripheral materials that are used in the cultivation or manufacturing process.
“Consumers should always ask to see a copy of the certificate of analysis to ensure that a product has been tested for heavy metals as well as microbials, mycotoxins, residual solvents and pesticides. The most commonly used methods are inductively coupled plasma coupled with mass spectrometry (ICP-MS) or inductively coupled plasma coupled with optical emission spectroscopy (ICP-OES).
“While each method has its advantages and disadvantages depending on the analytes being tested, ICP-MS in general is by far a much more sensitive and precise method. ICP-MS is often the preferred method when regulatory agencies assign low regulatory limits.”
The results from Penn State were published in Toxin Reviews, click here to read the results.
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