Need for more research on the toxicity of cannabis vaporizing products

In a recent Toxicological Sciences studyScientists assess the challenges of cannabinoid vaping products while analyzing their effect on consumers’ respiratory health.

Study: Vaping cannabinoid products present new challenges in assessing respiratory health effects. Image Credit: Shannon L. Price/

Products for vaporizing cannabinoids

Some of the common cannabinoid vaping products include D9-tetrahydrocannabinol (D9-THC), D8-tetrahydrocannabinol (D8-THC), as well as cannabidiol (CBD) products.

Several studies involving e-cigarettes or vaping have shown the adverse effects, particularly in terms of their ability to cause lung damage, associated with cannabinoid vaping products. According to a February 2020 report by the US Centers for Disease Control and Prevention (CDC), 2,807 people were hospitalized and 68 died from the use of cannabinoid vaping products.

Several studies have found that among e-cigarette/vaping users with product use-associated lung injury (EVALI), 82% reported using THC vaping products, while only 16% reported using CBD vaping products.

Two of the main reasons associated with limited research on THC- and CBD-containing vape products are regulatory factors and the significant evolution of the cannabinoid market. For example, the US Drug Enforcement Agency Controlled Substances Act has classified THC under Schedule 1, which restricts the accessibility of THC-containing products for scientific research.

Previous studies have shown that both THC and CBD vaping products contain silicones, humectants, vitamins, flavors, terpenes, pesticides and metals. In addition, cannabinoid vaping products are typically characterized as concentrated “oils” and diluted “vape juice”. Pen-type devices are used for both types of products, using concentrated oils in concentrations from 700 to 1,200 mg/ml and vape juice from 15 to 50 mg/ml.

Since September 2019, D8-THC can be legally sold in many US states. Like D8-THC, D9-THC is highly analogous to marijuana use and produces perceptual, somatic and psychoactive effects. Compared to D8-THC, D9-THC has a less psychoactive effect.

According to a recent study by Google Trends, there has been a significant increase in searches related to D8-THC since August 2020. This compound is a minor component of hemp and can be easily extracted via acid-catalyzed intramolecular cyclization of CBD. The method for the isomerization of CBD to D8-THC is readily available online; however, an incorrect chemical reaction can lead to product contamination.

Users of cannabinoid vaping products

Researchers have pointed to a research gap related to the health effects of cannabinoid vaping products, particularly related to vaping and inhalation exposure. One of the reasons for this lack of data is that the cannabinoid market in the US is still relatively new. Interestingly, most of the data on the effect of cannabinoid vaping products is associated with adolescents.

According to a recent meta-analysis, lifetime use of THC vaping products among adolescents increased from 6.1% to 13.6% between 2013 and 2020. These studies reported that adolescents preferred THC vaping oil over cannabis flower.

Similar to this report, a US-based survey showed higher use of cannabinoid vaping products among adolescents and young adults. However, this study further reports that 26.1% of adult study participants used CBD, while 18.9% used CBD vaping oils.

Previous findings on the health effects of cannabinoid vaporization products in US adolescent participants identified an increased risk of multiple respiratory symptoms, including wheezing and dry cough. These products seem to affect not only the lungs, but also the brains and circulatory systems of users. In addition, prenatal studies of THC use have shown altered brain development.

Toxicological Assessment of Cannabinoid Vapor Products

In the current study, scientists performed toxicology profiles of cannabinoid vaping products. In it, they assessed the relevant dose-response patterns, the toxicity of additives and diluents, as well as inhalation exposures to inform federal policy.

In vitro experiments investigating the effect of exposure to CBD vaporization products on respiratory epithelial cells have revealed a high concentration of toxicity markers in exposed cells. Some of these markers include cellular reactive oxygen species, as well as those involved in cytotoxic processes and inflammation.

Recently, the US Cannabis Council investigated the chemical content of 16 commercially available D8-THC vaping cartridges. This study showed that all samples contained an elevated level of D9-THC compared to the federal limit of 0.3%. In addition, seven of the 16 samples contained high levels of chromium, nickel or copper.

Importantly, unknown cannabinoid-like compounds were also found in the samples. Previous studies have shown that consumption of synthetic cannabinoids causes psychosis, panic, dysphoria, anxiety and accidental death in users.


Scientists strongly recommend that more research be conducted to evaluate the lung toxicity of emerging cannabinoid vaping products, as these studies are essential to determine the effects of these products upon inhalation exposure. More studies are also needed to elucidate the cardiovascular and neurological toxicity of cannabinoid vaping products.

Reference magazine:

  • Love, AC, Schichlein, KD, Clapp, PW, et al† (2022). Vaping cannabinoid products present new challenges in assessing respiratory health effects. Toxicological Sciences 188(1);1-3. doi:10.1093/toxsci/kfac050.
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