Researchers have analyzed the chemical composition of the vapors released by butane hash oil - a cannabis extract commonly used in "dabbing," or vaporizing - and found carcinogenic substances.
In light of cannabis being legalized in several states across America, more and more people use marijuana recreationally.
The practice of "dabbing" has also gained popularity; users think that dabbing is safer and gets them a "cleaner high." In dabbing, consumers place a small amount, or a "dab," of concentrated cannabis on a hot surface (usually a nail) and inhale the resulting vapor.
But while dabbing cannabis extract is perceived as being less harmful than smoking it, new research suggests that the practice exposes users to various carcinogenic toxins.
The researchers - led by Dr. Robert Strongin, a professor of organic chemistry at Portland State University in Oregon - examined the composition of the vapor produced by butane hash oil.
Butane hash oil is the cannabis extract typically used in dabbing. The extract is made using the solvent butane to extract the tetrahydrocannabinol (THC) from the cannabis leaves and flowers.
The study focused on the chemistry of terpenes, or the oils that give cannabis its unique fragrance. Terpenes are ubiquitous; they are naturally found in plants, condiments, and the food we eat, but they can also be found in cosmetics and pharmaceuticals, due to their therapeutic effects.
Although "generally recognized as safe" by the Food and Drug Administration (FDA), terpenes can drastically enhance the psychoactive effect of cannabis in a phenomenon known as "the entourage effect."
This - along with the widespread presence of terpenes and the fact that they have recently been added to electronic cigarettes (e-cigarettes) - prompted the researchers to look at them more closely.
The first author of the new study is Jiries Meehan-Atrash, of Portland State University, and the findings were published in the journal ACS Omega.
Cancer-causing chemicals found
Dr. Strongin and his team simulated the conditions of dabbing in their laboratory. They monitored the cannabis-derived terpenes myrcene, limonene, linalool, and Fire OG.
The researchers identified chemical substances and assessed their levels using Nuclear Magnetic Resonance (NMR) spectroscopy. Additionally, they collected and analyzed dabbing vapor using other forms of spectrometry.
The experiments yielded high levels of benzene, which is a known cancer-causing chemical, and methacrolein, which is a noxious irritant.
Methacrolein, the authors write, is structurally very similar to another pulmonary irritant and "air pollutant of great concern" called acrolein. Acrolein is also a human carcinogen.
Although the safe environmental levels of methacrolein have yet to be determined, benzene has been studied intensively and it is known what is safe and what is not.
"Although benzene is a ubiquitous pollutant," write the authors, "the concentrations of benzene found in the dabbing terpenes at the highest [dabbing temperatures] are far greater than those found in ambient air."
The researchers comment on the significance of their findings, saying, "Given the widespread legalization of cannabis in the [United States], it is imperative to study the full toxicology of its consumption to guide future policy."
"The results [...] clearly indicate that dabbing, although considered a form of vaporization, may, in fact, deliver significant amounts of toxic degradation products."
Additionally, "the difficulty users find in controlling the nail temperature put[s] users at risk," the authors caution.
"This research also has significant implications for flavored e-cigarette products due to the extensive use of terpenes as flavorings," they add.
In the future, the researchers plan to further examine how terpenes and terpene-like substances contribute to the toxicity of e-cigarettes.