A breakdown of the extraction processes that produce vape extracts and the most common ingredients.

I wrote a column titled “What’s In Your Vape Cartridge?” for Cannabis Business Times' February 2019 issue. Later that year, there was an alarming number of lung injuries and deaths associated with the use of vaping products with, at first, no indication of what caused the illness.

There was a lot of speculation as to why people were getting sick from vaping, and products from both the illicit and legal market were considered. Theories ranged from problematic cartridges being those mixing nicotine with THC to those filled with propylene glycol or vegetable glycerin, which are mixed with oil to get a desired viscosity in cartridges, as well as speculating that THC or other cannabis derivatives were to blame. Both cannabis-derived compounds and non-cannabis fillers were named as possible culprits.

In the end it was determined that vitamin E acetate—used both as a cutting agent and a viscosity adjuster—was responsible for the illnesses, and it was dubbed “E-cigarette or Vaping Use-Associated Lung Injury” or EVALI by the Centers for Disease Control. In the end, the CDC indicated that more than 2,800 cases were reported and 68 people died. The agency pointed out that the outbreak was not caused by legal, regulated cannabis or tobacco products, but rather illegal products from illicit-market manufacturers were primarily to blame. However, the crisis damaged sales of safe, legal and legitimate vape products, resulting in millions in lost sales.

After the responsible chemical was identified and some illicit producers were arrested, the epidemic faded as quickly as it began, and another health crisis—the COVID-19 pandemic—dominated headlines.

That said, there are still products in the legal market facing scrutiny. In February 2022, Pennsylvania’s health department recalled more than 600 vape cartridges from small and large operators alike because some of the ingredients in the products have not been deemed safe for inhalation by the FDA. The state department published a list “of known additives contained in one or more products on the withdrawal list,” some of which are deemed “food safe,” but not for inhalation. The list includes compounds such as almond oil bitter, roman chamomile flower oil, cinnamon bark oil, eucalyptus oil, fir needle oil, ginger root oil, juniperberry oil, lavender oil, pepper oil, peppermint oil, as well as other terpene additives.

What remains unknown is what is the safe threshold of each of these chemicals to inhale when heated? And what is the FDA-safe threshold to inhale all of them combined?

Despite large recalls and the EVALI crisis, the legal vaping cartridge market has rebounded and remains a very robust segment of the cannabis industry today. According to the cannabis research firm Headset, vape cartridge market share has steadily increased. “In the U.S., market share has increased from 18.9% in April 2021 to 22.1% in April 2022,” which represents the second largest category behind the always-dominant flower, according to Headset. While the ramifications of the Pennsylvania recall remain to be seen, there are still questions surrounding what is in vape cartridges now?

The answer is not straightforward, and there are myriad cannabis oil extraction methods and associated extraction equipment.

Propylene glycol and vegetable glycerin are still utilized in both tobacco cartridges as well as a small segment of the cannabis cartridges available today, but that market is slowly dwindling because of a proliferation of products that only contain cannabis derivatives. Glycerin and glycol are sometimes utilized to dilute the viscosity of a cannabis distillate, which needs to be thinned to be able to be wicked into the heating element of a vape cartridge. Because distillation can remove delicate aromatic terpenes, some operators also utilize both cannabis- and non-cannabis derived terpenes or essential oils to their distillate to add back flavor.

Non-cannabis derived terpenes and/or essential oils are distilled or sourced from fruits and plants. They are typically steam distilled. Many of these terpenes and or essential oils are available for sale as additives to a cannabis or cannabinoid distillate and are utilized to attempt to mimic the flavor and odor of cannabis (a tall order considering it contains approximately 150 identified terpenes). Cannabis-derived terpenes are sourced via multiple methods in multiple forms, yet they are all derived from the cannabis plant only.

So how are THC and other cannabinoid and terpene vape cartridge ingredients manufactured and what equipment or method of extraction yields exactly what? Here is a breakdown of the most common extraction methods used in products on the market today:

Terpenes are essential oils that, when combined with sulfur-based thiols and other chemicals, are responsible for the aroma and flavor of cannabis. There are many classes of terpenes, the primary three being monoterpenes, diterpenes, and sesquiterpenes. Combined with other aromatic compounds, they create the plethora of aromatically diversified cultivars of cannabis.

As with cannabinoids, there are multiple methods of producing/ extracting cannabis terpenes:

Depending on the extraction method, the final vape cartridges can include these primary ingredients:

As I wrote in 2019, as we develop new products and formulations within this space, we will also have to wrestle with health and safety concerns. A lot of unknowns exist with cannabis. We still don’t know the acceptable thresholds for heated inhalation of single or combinations of concentrated terpenes, for example. Legal producers are doing their best with the information they have. What are acceptable levels for inhalation of these essential oils at an elevated temperature? I don’t suspect there will ever be an answer.

Kenneth Morrow is an author, consultant and owner of Trichome Technologies. Facebook: TrichomeTechnologies Instagram: Trichome Technologies k.trichometechnologies@gmail.com

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