In my previous two installments of this vape cart column, I primarily examined cannabinoid and terpene contents of vape carts and devices, as well as the various methods of extraction of those cannabinoids and terpenes.
Recently, I have been examining the metal components that vape cartridges and vape products are composed of, and the toxic metals that may leach from the cartridges or that are released by heating coils. In my research, I came across a June 2025 article from the University of California, Davis, titled “Disposable E-Cigarettes More Toxic Than Traditional Cigarettes.” The article shared findings from a study performed by UC Davis researchers that found the three tobacco vape products tested were unfit for human consumption, and many were basically poisons and dangerous.
This article prompted me to contact Mark Salazar, one of the researchers involved in the study. I inquired if it would be possible to re-perform the study utilizing cannabis vape products, given they are legal to possess and purchase in California. Salazar very rapidly replied that given that he did not possess a Drug Enforcement Administration (DEA) license authorizing him to study cannabis, he could not do so. Instead, he generously directed me to some recent studies that have examined heavy metals in cannabis products.
The main finding: Most vape products and accessories, for cannabis and nicotine, originate from the same source.
Research Recap
One study, published in August 2025 in the Scientific World Journal, titled “Heavy Metals in Cannabis Vapes and Their Health Implications – A Scoping Review,” found that cannabis vapes leached nickel, copper, cobalt, aluminum, lead, cadmium, and chromium. These contaminants were found in the vapor as tiny particles.
Researchers noted that “heavy metals beyond regulatory guidelines are released from [cannabis vapes] and have negative health consequences.” Additionally, they found that “the structural integrity of the device components, device age, operating temperature, vape liquid pH, and viscosity-cutting agents in the vape liquid caused metal dissolution,” meaning there was no single cause of this leaching.
The study authors concluded that further research is required to improve the design of cannabis vapes. A short-term solution the authors pitched as essential to preventing possible health risks is that cannabis vape companies disclose their devices’ contents on consumer-facing product packaging.
The study authors also (rightfully) noted that “the Cannabis sativa plant can be a metal source as it is a hyperaccumulator of metals which quickly absorbs them from the contaminated soil [...]. These naturally accumulated metals in cannabis may not entirely be removed through extraction and may be present in the final products derived from the plant.”
The authors also clarified that their findings (which were a result of a literature review) cannot be generalized to all cannabis vapes as the studies were primarily experimental.
Another study from researchers at Health Canada and the National Research Council Canada, and presented at a meeting of the American Chemical Society (ACS), saw 41 cannabis vape liquids – 20 legal, regulated samples from the Ontario Cannabis Store and 21 samples from the illicit market provided by the Ontario Provincial Police – tested for metal contamination.
Researchers found nano-sized toxic metal particles in cannabis vaping liquids even before they were heated with a vaping device, with the incidence worse in illicit products but still present in certain legally purchased products. In some cases, the contamination was more than 100 times above established tolerance limits.
Additionally, the metal contamination, which included cobalt, chromium, copper, nickel, lead, and vanadium, was found in the liquid of cannabis vapes that had never been used and were less than six months old.
“The evidence strongly suggests that metal contamination can come from the device when it's produced, and not from the heating of the coils,” said Zuzana Gajdosechova, a scientist at the Metrology Research Centre of the National Research Council of Canada, in an ACS release, adding that “depending on the quality of the device, the contamination may be increased by that heating.”
Andrew Waye, who manages the research program at the Office of Cannabis Science and Surveillance at Health Canada and presented the results of this study at an ACS event in 2024, said in the release that “different types of cannabis products present different risks. Our research doesn’t answer whether vaping is riskier than smoking, it just underlines that the risks may be different.”
My Perspective
The research done on cannabis vapes, and vapes more broadly, leads me to two conclusions:
- Regulatory guidelines are needed to prevent cannabis vape liquid contamination from accessories or packaging, including filling machines, and testing needs to include a broad range of metals – not just the “big four” (arsenic, lead, mercury, and cadmium).
- Additional testing is needed to determine how much of these metal particles get into the vapor that people inhale.
All vape products should be thoroughly vetted before they are allowed to be released to the consuming public. Also, all devices that come into contact with the cannabis oil used in vapes, such as filling machines, batteries, and cartridges, need to be tested to ensure they are not contaminating the oil with metals or other adulterants.
Contaminated vape cartridges pose a serious potential for health risks. I would think a strategic advantage going forward would be for cannabis vape manufacturers (and the companies supplying their equipment) to proactively test the metals and components their products are composed of, thus demonstrating to customers their desire to deliver a truly contaminant-free product.
Perhaps a standards organization could develop a distinct symbol to help these companies demonstrate that the product is demonstrably heavy metal-free, and state regulators should begin to test for more than a small number of possible heavy metal particulate contaminants.
