Microscopic view of lung alveoli with highlighted vapor particles

Vaping Under the Microscope: New Study Reveals How E-Cigs Affect Your Lungs

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Mira Elwood in Health & Wellness December 2025 • 4 min read.

"Groundbreaking research uses radiolabeling to track e-cigarette aerosol deposition, offering insights into potential health risks."


Electronic cigarettes (e-cigs) have surged in popularity, particularly among younger adults, marketed as a safer alternative to traditional smoking. However, the long-term health effects of vaping remain largely unknown, sparking considerable debate and research. One significant challenge in assessing these effects is accurately measuring how e-cig aerosols deposit within the respiratory system.

Quantifying this deposition is crucial because it directly relates to the dosage of potentially harmful substances that lung tissues are exposed to. Traditional methods of assessing lung exposure have limitations, often failing to provide a clear picture of where and how much aerosol is deposited. This lack of precise data hinders our ability to fully understand the risks associated with vaping.

Now, a pioneering study has introduced a novel approach: radiolabeling e-cig aerosols to track their deposition in the lungs. This innovative technique promises to offer unprecedented insights into the behavior of e-cig aerosols, potentially reshaping our understanding of vaping's impact on respiratory health.

Breakthrough in Aerosol Tracking

Microscopic view of lung alveoli with highlighted vapor particles

Researchers at the University of North Carolina have successfully developed a method to radiolabel e-cigarette aerosols using technetium-99m-labeled carbon ultrafine particles (TCU). This technique involves introducing the radiolabeled TCU aerosol to a fourth-generation e-cig before the aerosol is even formed. By doing so, they ensure that the radioactive tracer is fully integrated with the e-cig vapor, allowing for precise tracking of its movement and deposition.

The study focused on a commercially available strawberry-flavored e-liquid containing 1.2% nicotine in a base of 55% propylene glycol and 45% vegetable glycerine. The e-cig was operated at a power setting of 100W. To validate their method, the scientists used a Sierra Cascade Impactor, which separates particles by size, allowing them to measure both the mass and radioactivity at each stage. The key to their success was demonstrating a strong correlation between the activity and mass deposition, confirming that the radiolabel accurately represented the aerosol's behavior.

To validate this technique, the researchers performed several critical steps:
  • Generated technetium-99m-labeled carbon ultrafine (TCU) aerosol.
  • Introduced TCU aerosol into a fourth-generation ECIG before aerosol formation.
  • Used a Sierra Cascade Impactor to measure mass and radioactivity at each stage.
  • Confirmed a strong positive correlation between activity and mass deposition (R² > 0.95).
The results were striking. The unlabeled e-cig aerosol had a mass median aerodynamic diameter (MMAD) of 0.85 µm. When radiolabeled with TCU, the e-cig aerosol maintained a consistent activity median aerodynamic diameter of 0.84 µm and an MMAD of 0.84 µm. Most importantly, there was a strong correlation between relative mass and radioactivity, with an average R² value of 0.973 (p<0.001). This high correlation confirmed that the TCU radiolabel effectively associated with the e-cig aerosol, accurately reflecting its behavior.

Implications for Future Studies

This breakthrough radiolabeling technique opens up new avenues for understanding e-cig aerosol deposition in both in vivo (living organisms) and in vitro (laboratory) settings. By accurately tracking where these aerosols deposit, researchers can gain valuable insights into potential health risks and develop more informed public health policies. The ability to quantify aerosol deposition will also enhance the accuracy of toxicology studies, leading to a better understanding of the long-term effects of vaping on respiratory health.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1089/jamp.2017.1442, Alternate LINK

Title: Radiolabeling An Electronic Cigarette Aerosol Using Technetium Carbon Ultrafine Particles

Subject: Pharmacology (medical)

Journal: Journal of Aerosol Medicine and Pulmonary Drug Delivery

Publisher: Mary Ann Liebert Inc

Authors: Landon T. Holbrook, Kirby L. Zeman, Alyssa Burke, Ilona Jaspers, William D. Bennett

Published: 2019-02-01

Everything You Need To Know

1

How did this study track the movement of e-cigarette aerosols in the lungs?

This novel research employed technetium-99m-labeled carbon ultrafine particles (TCU) to radiolabel e-cigarette aerosols. The TCU aerosol was introduced into a fourth-generation e-cig before the aerosol was formed. Scientists then tracked the deposition within the respiratory system, using a Sierra Cascade Impactor to validate the method, ensuring accurate representation of aerosol behavior. The strong correlation between activity and mass deposition confirmed the radiolabel's accuracy.

2

What specific e-liquid composition was used in the e-cigarette during this research, and why is it relevant?

The study used a commercially available strawberry-flavored e-liquid containing 1.2% nicotine in a base of 55% propylene glycol and 45% vegetable glycerine. This specific e-liquid was chosen to represent a common type of vaping product available on the market. The e-cig was operated at a power setting of 100W. It is important to note that the findings relate specifically to the characteristics of this particular formulation and power setting, and different e-liquids and devices may produce different results.

3

What were the key measurements and correlations observed when radiolabeling e-cig aerosols with technetium-99m-labeled carbon ultrafine particles (TCU)?

The study found that the unlabeled e-cig aerosol had a mass median aerodynamic diameter (MMAD) of 0.85 µm. When radiolabeled with technetium-99m-labeled carbon ultrafine particles (TCU), the e-cig aerosol maintained a consistent activity median aerodynamic diameter of 0.84 µm and an MMAD of 0.84 µm. A strong correlation between relative mass and radioactivity was observed, with an average R² value of 0.973 (p<0.001), confirming the TCU radiolabel accurately reflected the aerosol's behavior.

4

What are the broader implications of using this radiolabeling technique with technetium-99m-labeled carbon ultrafine particles (TCU) for understanding the health effects of vaping?

This radiolabeling technique, using technetium-99m-labeled carbon ultrafine particles (TCU), allows for accurate tracking of e-cig aerosol deposition in both in vivo and in vitro settings. Understanding where these aerosols deposit enables researchers to gain valuable insights into potential health risks. It also enhances the accuracy of toxicology studies, leading to a better understanding of the long-term effects of vaping on respiratory health, and can inform public health policies.

5

What important aspects related to health risks were not directly addressed in this research regarding e-cigarette aerosol deposition?

While this study offers valuable insights into the behavior of e-cigarette aerosols using technetium-99m-labeled carbon ultrafine particles (TCU), it doesn't directly assess long-term health outcomes or the specific toxicological effects of the deposited aerosols. Further research is needed to connect aerosol deposition patterns with the development of respiratory diseases or other health issues. Additionally, the study focused on a single e-liquid formulation and device setting, and more studies are needed to evaluate the broader range of vaping products and usage patterns.

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