By Ken Fry, Terps USA Research

SHORT ANSWER

There are two different questions hiding inside the terpene-spray debate. First: what happens when cannabis and its naturally occurring terpenes are heated or burned? Second: what additional chemistry is introduced by carriers or propellants that were not originally part of the flower? Keeping those questions separate produces a more useful safety discussion.

The risk already present in combustion

Burning organic plant material produces a complex mixture of thermal-degradation and combustion products. Terpenes are not exempt from that chemistry. Laboratory studies using high-temperature dabbing or vaporization conditions have identified compounds including methacrolein and, under some tested conditions, benzene from terpene degradation.

Those studies matter, but they do not by themselves establish the exposure from every joint, pre-roll, vaporizer, or enhanced-flower formulation. Temperature, oxygen, device conditions, terpene concentration, and the starting material all affect what is formed.

Added carriers are a separate question

Propylene glycol (PG) and polyethylene glycol (PEG) have legitimate uses in other product categories. That does not make food-use status an inhalation-safety determination. When heated, these materials can undergo thermal degradation and form carbonyl compounds; how much forms depends strongly on temperature and operating conditions.

That is the useful distinction for combustible flower: if a carrier is not necessary to the botanical material itself, adding it creates an exposure pathway that can be avoided through formulation choice.

Propellants belong in the same evidence-based conversation

Aerosol delivery systems may use compressed or liquefied gases to dispense a formulation. The relevant question is not whether every aerosol product is unsafe. It is whether the propellant and delivery system add anything necessary to the finished flower, and whether the manufacturer can document composition, application rate, and residual exposure. Mechanical atomization avoids making a chemical propellant part of that question.

What we can say — and what we cannot

We can say that cannabis combustion has intrinsic chemistry and that added carriers or propellants create additional formulation variables. We can also say that laboratory heating studies have demonstrated thermal degradation of PG, PEG, and terpenes under tested conditions.

We cannot honestly turn those findings into a universal claim that every use of PG or PEG produces the same toxicant dose, or that enhanced flower has been proven more or less harmful than otherwise comparable unenhanced flower. Those exposure comparisons have not been directly established.

The Terps USA position

Terps USA favors formulations that minimize unnecessary ingredients and application systems that make dosing measurable. That is a design choice: remove variables we do not need, disclose what remains, and avoid pretending that removing an additive eliminates the intrinsic chemistry of smoking cannabis.

FAQ

Does FDA GRAS status prove PG or PEG is safe to inhale or combust?

No. GRAS status concerns specified food uses and should not be treated as an FDA determination of inhalation or combustion safety. Heating chemistry and inhalation exposure require their own evidence.

Is terpene-enhanced flower proven to be more dangerous than unenhanced flower?

Current evidence does not establish that conclusion. High-temperature studies show that terpenes can form degradation products, but the total exposure from enhanced flower versus otherwise comparable unenhanced flower has not been directly established.

What is the practical difference between intrinsic and avoidable exposure?

Combustion products from the flower itself are intrinsic to smoking. Carriers or propellants added by formulation or packaging are additional exposures. Their presence is therefore a formulation choice rather than an unavoidable feature of cannabis flower.

Sources

Fry, K. (2026). The Transparency Standard: Safety, Combustion Chemistry, and the Case for Botanical Terpene Enhancement in Commercial Cannabis. Terps USA Research. DOI: 10.5281/zenodo.20767689.

Jensen, R. P., Luo, W., Pankow, J. F., Strongin, R. M., & Peyton, D. H. (2015). Hidden Formaldehyde in E-Cigarette Aerosols. New England Journal of Medicine, 372(4), 392–394.

Meehan-Atrash, J., Luo, W., & Strongin, R. M. (2017). Toxicant Formation in Dabbing: The Terpene Story. ACS Omega, 2(9), 6112–6117.

Munger, K. R., Anreise, K. M., & Strongin, R. M. (2025). Cannabis concentrate vaping chemistry. Frontiers in Toxicology, 7, 1568207.

This article is for informational and industry education purposes only. Terps USA products do not contain THC or CBD. These statements have not been evaluated by the FDA. Readers are encouraged to consult the cited primary sources directly.