Q&A: Uncovering how vaping additives injure lungs, impact breathing

Key takeaways:

• A study revealed that vitamin E, an additive in e-cigarettes, alters pulmonary surfactant functional properties.
• The CDC is against the use of vitamin E acetate in e-cigarettes.

Back in 2019, the CDC declared e-cigarette or vaping product use-associated lung injury an epidemic and later expressed confidence in the additive, vitamin E acetate, being strongly linked to this outbreak.

Over the years, there has been little understanding of how vitamin E acetate and vitamin E found in e-cigarettes damage the lungs, but new research published in Langmuir directly addresses this question.

According to a press release, Christine DeWolf, PhD, professor in the department of chemistry and biochemistry at Concordia University, and colleagues analyzed the impact of vitamin E in pulmonary surfactant model membranes and found functional property changes with the addition of this vitamin.

Healio spoke DeWolf with to learn more about vitamin E, the results of this study and future research efforts.

Healio: What does vitamin E (tocopherol) do to the lungs when inhaled via vaping? What about tocopherol acetate? Are there other known additives that harm the lungs?

DeWolf: Vitamin E acetate (a common synthetic formulation as it is more stable but readily oxidizes to form vitamin E) was a common diluent for cannabis vaping solutions. It was identified by the CDC as a chemical of concern due to its association with the 2019 outbreak of e-cigarette or vaping product use-associated lung injury (EVALI), wherein vitamin E acetate was found in significant proportions in the bronchoalveolar lavage samples from EVALI patients. The chemical structure of both vitamin E and its acetate form show it to be highly lipophilic. This, and its physical and chemical similarity to phospholipids, mean that these additives have a high likelihood to embed in and be retained in the pulmonary surfactant.

The pulmonary surfactant is the lipid-protein film that coats the surface of the alveoli and serves various roles including preventing the collapse of the alveoli and reducing the work of breathing. With its retention in the pulmonary surfactant, the vitamin E acetate alters the surface tension reduction capacity of the film (and consequently the work of breathing) and the respreadability of the film, enabling the film’s recovery to its initial state after each breathing cycle.

Alterations to the biophysical properties of this film can also impact oxygen-carbon dioxide gas exchange that occurs across this interface, although we have not explicitly measured this impact. In more physicochemical terms, the additives also alter the essential phase balance between the condensed phase (responsible for stability upon exhalation) and the fluid phase (responsible for the respreadability upon inhalation).

Healio: How did you conduct this study? What sets it apart from other studies evaluating e-cigarettes and their risks?

DeWolf: We use lipid monolayers, termed Langmuir monolayers, as model membranes to simulate the pulmonary surfactant and then look at the impact of additives at different scales. Specifically, we look at impacts on the surface tension reducing ability of the films and their stability through simulated inhalation-exhalation cycles (macroscopic), the morphology or phase balance between the condensed and fluid phases (microscopic) and changes to the molecular structure or organization of the film (molecular scale). All impacts were assessing using a range of biophysical characterization techniques, including surface X-ray scattering, imaging techniques such as Brewster angle microscopy and atomic force microscopy and surface tensiometry.

Our focus is on the potential direct and immediate impairment of the biophysical and functional properties of the pulmonary surfactant due to the entrapment and accumulation of the additives in this membrane, which serves as the first line of defense for species inhaled into the alveoli.

Healio: Why is the process of heating important to consider when studying vaping solutions?

DeWolf: Heating is important because vaping devices can reach internal temperatures up to 315°C, needed to generate the vaping aerosol. At these temperatures, chemical reactions can take place between components and lead to degradation. This means that the chemical components reaching your lungs may not in fact be those in your original vaping solution.

The concern is not only with additives, such as vitamin E acetate or flavorants, because this also applies to the matrix (a combination of vegetable glycerin and propylene glycol) and the active ingredients (nicotine, THC).

Much more work is needed to understand what chemical reactions take place at different power outputs, temperatures and temperature ramp rates so that we have a good understanding of what is being inhaled and its potential damage or inhibition of pulmonary functions.

Healio: What do you have planned for future research?

DeWolf: Our research will focus not only on the now banned/prohibited substances, but on identifying the chemical products of the vaping process and investigating their potential for impairment of the pulmonary surfactant functions. We hope that such research will influence government bodies on the regulation of vaping components for an improved safety.

Healio: Since vaping is popular among young adults, how can clinicians warn these patients about the dangers of these additives and vaping in general?

DeWolf: Vaping does not generate the particulate that traditional cigarettes produce; however, that does not make them inherently safe. The prevalence of flavors in combination with this lack of particulate make this particularly attractive to youth.

As the EVALI outbreak has demonstrated, there is much yet to be understood about the impacts (short term, long term) of inhaling the various components that make up a vaping solution and the reacted (and sometime reactive) products.

As the EVALI outbreak demonstrated, seemingly innocuous components (such as a vitamin) can have severe consequences and lead to lung injury and even death.

For more information:

Christine DeWolf, PhD, can be reached at christine.dewolf@concordia.ca.

References:

• Taktikakis P, et al. Langmuir. 2024;doi:10.1021/acs.langmuir.3c02952.
• Vaping additives harm a vital membrane in the lungs, according to new Concordia research. https://www.concordia.ca/news/stories/2024/04/04/vaping-additives-harm-a-vital-membrane-in-the-lungs-according-to-new-concordia-research.html. Published April 4, 2024. Accessed April 8, 2024.