- Researchers found nano-sized toxic metal particles in cannabis vaping liquids, even before they were heated with a vaping device.
- Unregulated products tended to have higher amounts of these heavy metals, which included lead, nickel, zinc, and copper.
- Additional testing is needed to determine how much of these metal particles get into the vapor that people inhale.
Certain cannabis vape liquids may contain nano-sized toxic metal particles, even before the vaping device is heated, according to a new study.
This contamination is worse in products that were unregulated, researchers found.
“[Our] evidence strongly suggests that metal contamination can come from the device when it’s produced, and not from the heating of the coils,” study author Zuzana Gajdosechova, PhD, a scientist at the Metrology Research Centre of the National Research Council of Canada, said in a release.
However, “depending on the quality of the device, the contamination may be increased by that heating,” she said.
Researchers presented the study Mar. 19 at a meeting of the American Chemical Society. The results have not yet been published in a peer-reviewed journal, so should be viewed with caution.
Smoking cannabis flower (or tobacco) involves burning or combustion, which can produce
In contrast, vaping devices, or e-cigarettes, work by heating a liquid until it forms a vapor that can be inhaled. This is sometimes seen as safer than smoking cannabis.
However,
While many of these studies have been done in devices designed to vaporize nicotine-laced liquids, cannabis vape devices are
The results of the new study also suggest that metal particles may be present in vape liquid even before the vaping device is heated.
To determine this, researchers gathered 41 cannabis vape liquids samples — 20 legal, regulated samples from a licensed cannabis store; and 21 samples from the illegal market, which were provided by the police.
The study was carried out in Canada, where cannabis was legalized throughout the country in 2018.
Researchers used mass spectrometry to look for 12 metals in the vape liquids — from cartridges that had never been used and were less than six months old. They visually confirmed the presence of metal particles using techniques such as scanning electron microscopy.
In Canada, regulated cannabis products are routinely tested for heavy metals and other contaminants.
Based on this, researchers found that some metals in the vape liquids — including arsenic, mercury and cadmium — were below these accepted tolerance limits for cannabis products.
However, other metals exceeded these limits, sometimes by a large amount. For example, certain unregulated vape liquids contained 100 times more lead than regulated samples. High levels of nickel, zinc and copper were also found in some samples.
In addition, certain vape liquids from the same production lot contained different levels of metal particles, researchers found. This suggests that routine testing for contaminants may need to be done later in the manufacturing process.
“If contamination is happening when the device is assembled, you should be testing at that stage rather than earlier,” study author Andrew Waye, of the Office of Cannabis Science and Surveillance at Health Canada, said in the release.
Researchers also looked at the size of the metal particles.
They found that many of the particles were nano-sized, which Gajdosechova said are “highly reactive and potentially harmful.”
The study doesn’t show how much of the metal particles in the vape liquid end up on the aerosol, or vapor when the device is used. This is something the researchers hope to examine in the future.
It is the vapor that would reach the user’s lungs, so this information will be needed in order to understand the public health risks of cannabis vape devices.
“Different types of cannabis products present different risks,” said Waye, adding that many of these risks are still being identified through studies and testing.
“Our research doesn’t answer whether vaping is riskier than smoking, it just underlines that the risks may be different,” he said.
Irfan Rahman, PhD, a professor of environmental medicine at the University of Rochester Medicine in New York, said the presence of metals and other contaminants in vape devices is concerning.
Rahman was not involved in the study.
He pointed to a case report published in 2019, which described a 49-year-old woman who developed a lung condition called giant cell interstitial pneumonia.
Doctors found that her symptoms — which included shortness of breath on exertion, wheezing and coughing — were likely due to exposure to cobalt from a cannabis e-cigarette, which she had been using for 6 months.
In similar research as the new study, Rahman and his colleagues tested delta-8-tetrahydrocannabinol (Delta-8-THC) vaporizers, and found contamination with heavy metals such as magnesium, chromium, nickel, copper, zinc, mercury, lead and others.
“We tested at least 10 types of vape devices, and we saw that they have metal contaminants and some toxic chemicals,” he told Healthline.
The results were published in 2022 in
Delta-8-THC is a synthetic cannabinoid made from hemp-derived cannabidiol (CBD), an active compound found in cannabis plants. Rahman and his colleagues are now testing vape devices containing delta-9-THC, which is the main active component of cannabis plants.
Raman thinks one problem with vape devices in the United States is the lack of consistent regulation.
Marijuana remains illegal at the federal level, which leaves a patchwork of state regulations across the country, including testing requirements. In addition, as seen in Canada, some illegal, and entirely unregulated, products are sold on the market.
“So it will be a good thing when the government takes action after they realize there is currently little regulation of these products,” said Rahman.
Canadian researchers tested 41 cannabis vape liquid samples for 12 heavy metals, including regulated samples obtained from a licensed cannabis store and illegal samples provided by the police.
Certain metals were present in amounts that exceeded legal tolerance limits, including arsenic, mercury, and cadmium. Unregulated vape liquids tended to have higher amounts of certain heavy metals, compared to regulated products.
The study shows that these metal particles are present in products that have not been used and are less than 6 months old. Further research is needed to show how much of the metal particles get into the vapor that people inhale.