The great vaporizer-lung crisis of late 2019, in which at least 68 people died and 2,807 were sickened with “e-cigarette, or vaping product use associated lung injury,” or EVALI, as the Centers for Disease Control and Prevention classified the acute lung ailments developed after using cannabis or tobacco vaporizers, was great news for marijuana legalization.
Although “the exact causes of the outbreak… are likely to remain uncertain,” as esteemed medical journal The Lancet observed in 2020, the culprit most often blamed was vitamin E acetate, a viscous additive normally found in food that was discovered coating lung tissue in victims—used in this instance to dilute marijuana oil (in the same way someone might “cut” cocaine).
And although at least one dedicated anti-marijuana legalization group repeatedly claimed—very falsely, as it turned out—that several people were sickened with EVALI after using products purchased from legal cannabis dispensaries, nearly all reported cases came from states with no legal cannabis. Any problems stemming from cannabis vaporizer use, in other words, was an illicit market problem.
That may have been so with EVALI, but vaporizer pens are not risk-free. According to recently published research, the vaporizer devices themselves have the potential to poison users with heavy metals, leached into cannabis vapor during the heating process and inhaled directly into users’ lungs.
In legal states with testing requirements, cannabis oil is tested for impurities including microbial contamination as well as the “big four” of toxic heavy metals: arsenic, cadmium, mercury, and lead.
But the oil isn’t what end users are consuming—they breathe in a mixture of aerosols that can include elements of the vaporizer device itself, which can include of heavy metals including chromium and nickel.
Studies of e-cigarettes and nicotine-vaporizing devices have turned up higher levels of heavy metals in users’ blood than cigarette smokers, but so far, little research has been conducted to see if the same holds true for cannabis vaporizers.
And “[a]t the high voltage and temperature settings of standard [vaporizer] devices, dissolved metals or even fine metallic particles from the heating coil or the liquid could have the potential to be inhaled into the consumer’s lungs,” according to findings from a team of researchers at Medicine Creek Analytics, a licensed cannabis testing laboratory in Fife, Washington, recently published online ahead of a future print date in the peer reviewed journal Chemical Research in Toxicology.
“Results indicate that chromium, copper, nickel, as well as smaller amounts of lead, manganese, and tin migrate into the cannabis oil and inhaled vapor phase, resulting in a possible acute intake of an amount of inhaled metals above the regulatory standard of multiple governmental bodies,” they added, noting that smoke and vapor from cannabis flower and cannabis concentrate did not produce the same results, indicating that the vape pens’ heating devices were to blame.
The researchers obtained 13 different brands of vaporizer cartridges from a legal retailer in Washington state. Six were all “510-thread,” the most common size of vape pen on the market; another seven had “various styles of cartridge and battery systems.”
Researchers plugged the pens into a power source connected to a wall socket and used a “smoking machine” to mimic a human’s breathing action and draw out the resulting aerosols. A total of “50 puffs” worth of aerosol were drawn from each cartridge, and the aerosols were then analyzed using a plasma mass spectrometer.
Researchers reported detecting “measurable levels” of chromium, nickel and copper—three metals known to be in the heating elements and coils of vaporizer pens—in the resulting aerosols. Metals seemed to leach over time at ambient and elevated temperatures as well as during the heating process.
“The results suggest that the cartridge devices themselves are leaching metals and potentially at higher rates when the components are heated,” the researchers wrote, who noted that the cartridges “generally did not emit metals from the big four” of arsenic, cadmium, mercury, and lead.
That means that the still potentially harmful aerosol would pass all legal cannabis states’ testing regulations—which in turn means that states’ safety standards need to be re-assessed, the authors concluded.
Interestingly, adding terpenes—the chemical compounds found in plants that give cannabis strains their distinct taste and aroma—seemed to ameliorate the metal leaching.
Why that is, they did not say. Nor could they determine whether there was a level of added terpenes that seemed to be protective.
Since studies of e-cigarettes revealed heavy metal uptake, similar findings from structurally similar cannabis vaporizer devices shouldn’t be too surprising. And though government regulatory agencies have pulled vaporizer products from shelves for higher than allowed levels of lead found in vaporizer hardware and components, there aren’t yet reports of medical complications directly tied to heavy metal contamination in the literature.
Even so, the results suggest that cannabis vaporizers aren’t always the “safer” option their advocates often claim.