CBD might be good for you, but beware the toxic metal mix
Almost half of cannabis inhalation products tested in a South African laboratory study contained potentially dangerous levels of heavy metals.
Oral products, such as cannabidiol (CBD) drops, showed a relatively low contamination rate of 15%, made up of heavy metals including arsenic, lead and nickel, according to the study by a team from the National Analytical Forensic Services laboratory.
It is the first of its kind and raises questions about the monitoring of the fast-growing cannabis retail sector.
Another study by the same team, published in March, found that most cannabis products were far more potent than they are allowed to be.
High levels of tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, was found in most products, both prescribed and over-the-counter, despite stringent regulatory limits.
The metal contaminants study was based on 310 samples, including vape pens, CBD drops and raw leaves. Possible sources of heavy metal contamination include environmental pollution, water, pesticides and naturally occurring metals in soil and fertilisers, the team said.
“It is imperative to ensure regulation is enforced and the South African public is educated about the risks associated with using these products,” its report said. It also flagged the high level of nickel found in vape pens and their accessories, which heat cannabis oil to produce a vapour.
“Observations suggest that the metal housing showed characteristics of nickel plating,” it said.
“The small quantity of oil combined with the large surface area of the metal housing could leach enough nickel into products to cause detrimental health effects.”
Vape pens were only one of the product types that contained nickel. A huge majority (91%) of contaminants detected were class 1 residues, the most toxic variety.
The study authors said their data, while a cause for concern, was based on a small portion of samples on the market. “It is by no means a representative sample of the entire South African market, but inferences can be made nonetheless,” the authors said.
Contaminant levels are closely regulated in terms of international standards, while cannabis products must be registered by the South African Health Products Regulatory Authority. The authority did not respond to Sunday Times queries.
The laboratory’s study of THC levels found that most of the 840 samples exceeded the legal limit. In the case of extract samples, less than 1% adhered to the legal limit, with only slightly higher compliance (3%) for liquid products.
Study lead author Henrick Viviers said: “It would be a step in the right direction if pharmacy chains or any type of retailer required a certificate of analysis for the cannabis-based products currently on their shelves. This will at least protect the consumer somewhat with regards to label-claim potency and metal toxicity.”