Although terpenes are ubiquitous in e-cigarettes, and are infused into many cannabis products, there has been very little research into the chemicals that are released upon their vaporization. Terpenes are espoused for enhancing the psychoactive and medicinal properties of cannabis in what is referred to as the entourage effect, as they interact with multiple cannabinoids to provide palliative effects. This has lead to an emphasis on terpenes in the cannabis industry. However, the assertions that terpenes are related to this effect are suspected but still not formally confirmed in peer reviewed literature.
A new study found in the American Chemical Society published on September 22, 2017 shows inconclusively that the terpenes released in dabbing concentrates could actually have harmful health effects. The study focused on the terpenes Myrcene, Limonene, Linalool and the byproducts Methacrolein and Benzene, which showed up in the highest concentrations. Methacrolein has been found to be a noxious irritant. It is chemically similar to acreolin, which is a powerful pulmonary irritant and has caused great concern as an air pollutant. Experiments with the effects on the respiratory system of mice shows it should not exceed .3 ppm. There is debate as to how much of this chemical is harmful and to what extent. On the other hand, there is very little debate as to the negative effects of Benzene. It has been found to be a strong carcinogen. It is the “largest single known cancer-risk air toxic (sic).”
Interestingly, as the chart below shows the amount of MC and Benzene present differs terpene by terpene. In fact, the terpene linalool shows very little Methocrolein and no Benzene at all.
This implies that carcinogenic effects due to high temperature degradation is terpene, thus strain, specific and with the proper amount of research could be avoided. The experiment only tested a small handful of possible terpenes so there is still much to be learned.
The other notable result of the experiment is that the ppm of MC and Benzene decreased along with lowered temperature. For each inhalation 338 ml of concentrate was used and tested over a 10 second duration. The results were as follows: “185 ± 11 ppb at Tm = 526 °C, 157 ± 2 ppb at Tm = 455 °C, 131 ± 9 ppb at Tm = 403 °C, and undetectable at Tm = 322 °C. Note Tm refers to median time.Benzene was not detected below the highest TR. Using the same rationale as above for MC emission, one dab of BHO delivers 17 ng of benzene. Represented as a concentration in the draw volume, this value is 15 ± 1.8 ppb.”
This experiment suggests that high heat dabbing could be potentially harmful, especially with longterm, repeated use. It also suggests that, with more testing, carcinogens released by terpenes could be better understood and avoided. Pressing at low heat is the beginning but dabbers beware: Keep those e-nail temps low! Your health may depend on it.