There’s this common misconception in the cannabis industry that more fire leads to a bigger rip. Sure, you can dab at super high temperatures, and you may see a big cloud of vapor and smoke, but the real question is what’s in the cloud?
Dr. Robert Strongin of Portland State University and his research team have been investigating this question and have unearthed some pretty interesting results. I spoke with Strongin in what I hope is just the first conversation of many. I was curious how he got involved in cannabis product safety research.
From E-Cigarettes to Cannabis
“I didn’t start out with cannabis research,” Strongin began. “I actually got into it via tobacco vaping research, and that was by accident. A colleague came to me with an NMR [nuclear magnetic resonance] spectrum of a collected aerosol from an e-cigarette. After seeing this data, I became interested in the chemistry and a few years ago, I became intrigued by cannabis vaping because a lot of younger people were interested in it. The product chemistry had evolved to much higher potencies.”
Because of Strongin’s experience with tobacco vaping research, it was an easier set up to move towards cannabis vaping. “It’s hard to break into the field, however, because of the Federal laws,” he explained, “so, it took a long time to be able to get permission to work with cannabinoids. For me, dabbing was of interest because it’s unique to cannabis. We are so far behind as a scientific community, so it’s an exciting time to be looking at these things!”
Strongin’s group focused on their own formulations of delta-9-tetrahydrocannabinol (THC) and terpenes. Because of their Drug Enforcement Agency (DEA) license, they can only work with the cannabinoid standards from vendors. These are shipped as 1 mg/mL ampules of a cannabinoid standard in a solvent like methanol.
“We can’t look at the plant material,” Strongin explained, “and we can’t buy products from a dispensary. We thought we may be able to get plant material from Ole Miss, but that hasn’t happened. We didn’t realize how hard it would be to get DEA approval. The DEA, however, has been very supportive and they’ve inspected our lab.”
What Happens on a Hot Nail
I was curious how Strongin’s team chose the temperatures used for dabbing. Typically, a scientist would consult the literature to see what’s been previously done, but with the cannabis industry, there’s so much that still hasn’t been explored.
“We looked in the literature, but didn’t really find any similar work on cannabinoids,” he answered, “so we had to go back to the 1970s to a series of papers out of the Netherlands. All they did was heat up cannabidiol and their temperatures were nowhere near what’s used for dabbing. So, we actually cite Reddit. By digging through social media, we can get a better information!”
Strongin got the idea for scoping out Reddit and other social media platforms from going to tobacco regulatory meetings. “That’s how they found out that Juul was advertising via social media,” Strongin added.
Strongin and his team are coming up with new ways to vaporize cannabinoids and terpenes. According to Strongin, they haven’t had much competition in this field. “We’re just crazy enough to try to stick it out,” he mused.
The interesting thing is that Strongin’s group didn’t know which molecules would produce toxins with heat. With vaping, because the formulations are simpler than the complexity of flower, they can better hone in on what molecules produce which toxicants. “We can trace back toxicants that form to specific ingredients and we can show how changing the formulations can affect the dosage,” Strongin explained. “If degradation products are forming, that means less of the main ingredients are getting into the aerosol.” (Which is ultimately a waste of money.)
In one of Strongin’s publications, both methacrolein and benzene formed from the degradation of myrcene, limonene, or linalool. [1] The concentrations of these health hazards increased with temperature. No methacrolein was detected at 322°C (612°F), but levels of methacrolein ranging from tens to hundreds of nanograms were found at 403°C (757°F), 455°C (851°F), and 526°C (979°F). I was curious how this compared to other products like e-cigs, cigarettes, or even baseline air levels.
“These levels are definitely above air levels, but they are really low,” Strongin answered. “There’s more acrolein in e-cigs than methacrolein. There are more toxicants formed from cannabis dabbing versus vaping. In every case, even at the highest power, and even during the dabbing conditions, we saw way less toxicant formation than you would from smoking cannabis. There’s fewer ingredients and less combustion.”
Terpenes: Problem or Protection?
When Strongin’s team creates their formulations, they’ve targeted myrcene concentrations like 5% or 9%. A vape oil had 14% myrcene. I was curious if these levels were used to provide representation of an upper limit?
“We’re trying to stay within real world products that we’ve seen range between 2% and 20% terpenes,” Strongin answered. “Products seem to be naturally closer to 5% or less, but distillates seem to have closer to 10% terpenes. We do, however, want to know a failure point by doing extremes. The last thing we want is for someone to think that this work is not representative of the market.”
Strongin’s team also has considered caryophyllene, which gives similar but different breakdown products. Looking at these volatile organic compounds, or VOCs, are only part of the story. There are also non-gaseous particulates from cannabinoid breakdown. Particle sizes are something that people are just beginning to consider. “When you vape, you’re getting aerosols (liquid drop in a gas), and there’s a partition between the gas and liquid droplet phase to varying degrees,” said Strongin. “Just like in air pollution, the size of the particles determines where the chemicals will be deposited in the lungs, and nanoparticles are being found.”
A second publication considered the effects of myrcene during dabbing and also during vaping. [2] There’s a line in the article that reads “THC and terpene transfer occur with less degradation as terpene % mass increases, and that the vaporizer operates with higher overall efficiency at the highest terpene % mass tested, 14%.” (Emphasis added by me.)
Some cannabis vape cart manufacturers are looking to reduce viscosity by using myrcene, a terpene that’s often diminished due to the drying and curing phases of harvest as well as processing the extracts. What’s interesting and paradoxical in this study is that this finding is in direct contrast with the dabbing experiments in the paper, where more degradation products were measured with increasing terpene concentrations.
“There’s definitely a moderation of viscosity,” Strongin explained. “More THC gets into the aerosol and this could be considered a type of entourage effect. It’s may not be as exciting as other methods of an entourage effect, but it’s still there! Another explanation that could be operative is that a lot of terpenes are antioxidants. So much of the chemistry that goes on regards heating under oxygen. Most reactions involve oxidation, so terpenes may prevent molecular breakdown.”
Advice for Consumers
So, what’s the overall take home message from the Strongin lab’s cannabis-themed research?
“We are so excited about these products to help palliative care, opioid addiction, pain — we’re really rooting for these products. Our big take home message, especially after the EVALI outbreak taught us all to be careful, is don’t get stuff off the street. We don’t understand what caused the outbreak. Smoking takes a lifetime for the bad effects to manifest. To see something that’s smoking related that happens within a week or a day is shocking!”
“Get your products from a licensed dispensary. We discovered pine resin in products! This was prevalent in Canada and pine resin creates the same fumes as solder fumes, which are a serious breathing hazard.” [3]
“Toxicant molecules are in lower levels compared to smoking, which is expected. Benzene is formed and carcinogens at any level above what’s in our air are obviously not good things to ingest. People who might be exposed over a longer period of time shouldn’t be using these products regularly. Be vigilant!”
Editor’s note, October 2026: This conversation, conducted by Jason S. Lupoi, Ph.D., was recorded in 2021. Dr. Robert Strongin is a professor of organic chemistry at Portland State University, where his research group studies the chemistry of vaping and dabbing; since this interview the group has published further work on what forms when cannabis concentrates are heated, including a 2025 review of cannabis concentrate vaping chemistry. Concentrates, cartridges and new semi-synthetic cannabinoids have only grown more common since 2021, which makes his core question — not how hot, but what is in the vapor — more relevant, not less. His answers above are kept exactly as given; the section that follows sets out what the research shows now.
What the Evidence Says Now
Strongin’s central point has held up well: the temperature of a dab or a vape decides what you inhale, and terpenes are part of that chemistry. His group’s later measurements put numbers on it — and confirmed the puzzle he describes in the interview, where terpenes seem to make things worse in one setting and better in another.
On a dab nail, terpenes add toxicants. The group’s 2017 study found that heating common cannabis terpenes — myrcene, limonene and linalool — under dabbing-like conditions produced methacrolein, benzene and other compounds of concern.[1] A 2019 follow-up dabbed pure THC and THC with about 10% terpenes on an e-nail at roughly 370°C. Adding terpenes raised the gas-phase toxicants sharply: methacrolein went from 2.7 to 12 micrograms per dab, benzene from 33 to 360 nanograms, and isoprene rose nearly fivefold.[4] For how the vaporization temperatures of these compounds compare, see our guide to terpene boiling points.
In a cartridge, terpenes can reduce them. The 2021 study Strongin mentions found the opposite pattern in a vape cartridge run at 10 watts: as myrcene content rose to 14%, more THC reached the aerosol (about 4 mg versus 1.6 mg with pure THC) and the overall delivery of harmful constituents fell. The authors attribute this to terpenes lowering the oil’s viscosity and boiling point. They also found most harmful constituents rose with power, and recommend the lowest practical setting.[2] The lesson is that “terpenes are harmful” and “terpenes are protective” are both too simple: the device and the temperature decide.
Relative risk. In the 2019 risk analysis, both dabbing and vaping produced far lower estimated hazard than smoking an equal dose of THC — though the authors measured only the gas phase and called their findings “not definitive.”[4] That matches Strongin’s own advice in the interview: lower than smoking is not the same as safe.
What’s new since 2021. The group has since shown that vaping cannabinoid acetates — semi-synthetic products such as THC-O acetate — produces ketene, a highly toxic gas, even in a single puff,[5] and has worked out how ketene forms during dabbing and vaping.[6] Their 2025 review of concentrate vaping chemistry adds that oxygen plays a key role in forming toxicants, and revisits additives such as the pine rosin Strongin warns about here.[3][7]
Storage matters too. Terpenes are also lost before anything is heated. In one storage study, terpene levels in flower fell by more than half within four months, far faster than cannabinoids; refrigeration helped.[8] For how extraction method shapes what ends up in a concentrate in the first place, see our guide to BHO extraction, how BHO and rosin compare chemically, and our guide to cannabis extracts. For the terpenes themselves, our terpene education hub has the map.
References
[1] Meehan-Atrash J, Luo W, Strongin RM. Toxicant formation in dabbing: The terpene story. ACS Omega. 2017;2(9):6112-6117. [journal impact factor = 3.512; times cited = 34] [2] Meehan-Atrash J, Luo W, McWhirter KJ, Dennis DG, Sarlah D, Jensen RP, Afreh IK, Jiang J, Barsanti KC, Ortiz AY, & Strongin RM. The influence of terpenes on the release of volatile organic compounds and active ingredients to cannabis vaping aerosols. RSC Advances. 2021;11:11714-11723. [journal impact factor = 3.36; times cited = 0] [3] Meehan-Atrash J, Strongin RM. Pine rosin identified as a toxic cannabis extract adulterant. Forensic Sci Int. 2020;312:110301. [journal impact factor = 2.395; times cited = 3] [4] Meehan-Atrash J, Luo W, McWhirter KJ, Strongin RM. Aerosol gas-phase components from cannabis e-cigarettes and dabbing: mechanistic insight and quantitative risk analysis. ACS Omega. 2019;4(14):16111-16120. doi:10.1021/acsomega.9b02301 [5] Munger KR, Jensen RP, Strongin RM. Vaping cannabinoid acetates leads to ketene formation. Chem Res Toxicol. 2022. doi:10.1021/acs.chemrestox.2c00170 [6] Munger KR, Anreise KM, Jensen RP, Peyton DH, Strongin RM. Mechanistic rationale for ketene formation during dabbing and vaping. JACS Au. 2024;4(6):2403-2410. [7] Munger KR, Anreise KM, Strongin RM. Cannabis concentrate vaping chemistry. Front Toxicol. 2025;7:1568207. doi:10.3389/ftox.2025.1568207 [8] Milay L, Berman P, Shapira A, Guberman O, Meiri D. Metabolic profiling of cannabis secondary metabolites for evaluation of optimal postharvest storage conditions. Front Plant Sci. 2020;11:583605. doi:10.3389/fpls.2020.583605Last updated October 2026 · Originally published November 5, 2021.
