Vaping vs. Smoking: The Heavy Metal Risk and 2025 Toxicity Data

The debate between vaping and smoking often centers on the absence of combustion, but new research suggests we are asking the wrong questions. In 2023, Mark Salazar, a Ph.D. candidate in pharmacology and toxicology at the University of California Davis, acted on a hunch. After seeing a friend use a disposable vape pod, he took the device into his lab to test it for metals. The initial results were so alarming that Salazar assumed his instrument was broken.

It wasn’t. Over the next two years, Salazar and his colleagues conducted a rigorous analysis of metal and metalloid content in popular disposable vapes. Their findings, published in July 2025, reveal that these devices leach lead, nickel, chromium, antimony, copper, and zinc at levels that exceed acceptable risk thresholds for cancer and non-cancerous conditions. While vaping skips the smoke, it introduces a new spectrum of metallic toxicity that experts are only beginning to quantify.

The Heavy Metal Leak: Inside the 2025 Salazar Study

Our analysis of the recent data highlights a disturbing trend in hardware safety. The disposable pods featured in Salazar’s study appear to emit significantly more toxins than earlier e-cigarette generations. This is particularly concerning because disposable pods are currently the most popular device type, especially among youth. Two of the three products Salazar tested rank among the top choices for young users.

The mechanism behind this toxicity lies in the device’s architecture. A vape consists of a battery, a reservoir of carrier liquid, a wick, and a metal heating element. When the device activates, the heating element warms the liquid to create an aerosol. However, the 2025 data indicates that this process also degrades the metal coil, shedding microscopic particles of heavy metals directly into the user’s lungs. Salazar’s team found that all three tested products leached metals at dangerous concentrations, challenging the narrative that vaping is a “clean” alternative.

The Myth of “Harmless Water Vapor”

Marketing campaigns frequently rely on the misconception that vaping produces simple water vapor. Science tells a different story. The output is technically an aerosol—a suspension of fine solid particles or liquid droplets in air. This aerosol contains dozens of chemicals, including volatile organic compounds (VOCs) such as formaldehyde and benzene.

Recent research (Kundu et al., 2025) links vaping to an increased risk for several acute and chronic conditions, alongside specific cancer-related biomarkers. While it is true that vape products contain fewer chemicals than the 6,500–7,000 found in conventional cigarettes (Margham, 2010), the chemicals that are present carry unique risks. For instance, the 2019 EVALI outbreak, which hospitalized thousands and caused at least 50 deaths, proved that unapproved additives like vitamin E acetate can turn these devices into lethal tools.

Comparison Matrix: Combustion vs. Aerosol Risks

To understand the trade-off, we must look at the specific physiological impacts of both delivery methods.

Risk Factor	Traditional Smoking	Electronic Vaping
Primary Toxin Source	Combustion (Burning organic matter)	Aerosolization (Heating chemical liquids)
Chemical Count	6,500 – 7,000 chemicals	Dozens (including VOCs and metals)
Addiction Pattern	Episodic (Smoke breaks)	“Grazing” (Continuous use)
Cardiovascular Impact	Heart disease via tar/CO	Increased heart rate & airway resistance
Specific Toxins	Tar, Carbon Monoxide	Lead, Nickel, Chromium, Formaldehyde

The “Grazing” Phenomenon and Addiction Potency

Interestingly enough, the way users consume nicotine has shifted dramatically. Traditional smoking is episodic; a smoker takes a break, smokes a cigarette, and stops. Vaping, however, allows for what researchers call “grazing.” Because the devices are stealthy and lack the lingering odor of smoke, users often puff continuously throughout the day.

This behavior, combined with the high nicotine potency of modern pods, leads to faster and more severe addiction responses (Singer et al., 2024; Camara-Medeiros et al., 2020). Furthermore, some unregulated products—even those labeled “nicotine-free”—contain synthetic nicotine analogs. These analogs can be more potent and toxic than tobacco-derived nicotine (Jordt et al., 2025), creating a higher baseline of physical dependency that is incredibly difficult to break.

The Knowns and The Unknowns

As Carl Sagan famously pointed out, “Absence of evidence is not evidence of absence.” Gaps in our knowledge regarding vaping are often filled with optimistic assumptions, but the data we do have is sobering.

• We Know: Vaping causes respiratory, cardiovascular, and cellular inflammation (Effah et al., 2025).
• We Know: Vaping increases heart rate, blood pressure, and airway resistance (Royal College of Physicians, 2024).
• We Don’t Know: The long-term cancer risk compared to smokers, or which specific chemicals drive the observed inflammation.
• We Don’t Know: The extent of third-hand exposure risks. While we know cigarette residue on furniture harms children, the impact of e-cigarette residue remains unquantified (Stracci et al., 2025).

Vaping as a Cessation Tool: Proceed with Caution

Is vaping an effective way to quit smoking? The evidence suggests it is “probably effective, maybe safe.” A review of trials found that nicotine e-cigarettes facilitated higher quit rates than chewing gum or patches (Lindson et al., 2024). However, the FDA has not approved e-cigarettes as a cessation method, and no manufacturers are currently seeking such approval.

For smokers who intend to use vapes to quit, the strategy must be precise to avoid the “Dual Use” trap. Continuing to smoke while vaping significantly increases the total toxic load on the body. Experts recommend a strict plan: no dual use, immediate titration, and a defined timeline to stop vaping entirely. The goal must be total abstinence, not permanent substitution.

FAQ

References

• Vahratian, A., Ph. D. ,. M. P. H., M. Briones, E., Ph. D., Jamal, A., M. B. B. S. ,. M. P. H., & L. Marynak, K., Ph. D. ,. M. P. P. (2025). Electronic cigarette use among adults in the United States, 2019–2023. In cdc.gov (No. 524). National Center for Health Statistics, Centers for Disease Control and Prevention. Retrieved January 3, 2026, from https://www.cdc.gov/nchs/data/databriefs/db524.pdf
• Effah, F., Sun, Y., Friedman, A., & Rahman, I. (2025). Emerging nicotine analog 6-methyl nicotine increases reactive oxygen species in aerosols and cytotoxicity in human bronchial epithelial cells. Toxicology Letters, 405, 9–15. https://doi.org/10.1016/j.toxlet.2025.01.007
• Tsai, M., Byun, M. K., Shin, J., & Alexander, L. E. C. (2020). Effects of e‐cigarettes and vaping devices on cardiac and pulmonary physiology. The Journal of Physiology, 598(22), 5039–5062. https://doi.org/10.1113/jp279754
• Margham, J., McAdam, K., Cunningham, A., Porter, A., Fiebelkorn, S., Mariner, D., Digard, H., & Proctor, C. (2021). The chemical complexity of e-Cigarette aerosols compared with the smoke from a tobacco burning cigarette. Frontiers in Chemistry, 9, 743060. https://doi.org/10.3389/fchem.2021.743060
• Royal College of Physicians. (2024). E-cigarettes and harm reduction: An evidence review. RCP.
• Stracci, J. M. A., Ganesan, A. P., Pitogo, P. G., & Smith, S. M. (2025). The Effects of Thirdhand Vape Residue from Nicotine and Non-Nicotine Vapes on Cells: A Systematic Review. International Journal of Environmental Research and Public Health, 22(4), 465. https://doi.org/10.3390/ijerph22040465
• Kundu, A., Sachdeva, K., Feore, A., Sanchez, S., Sutton, M., Seth, S., Schwartz, R., & Chaiton, M. (2025). Evidence update on the cancer risk of vaping e-cigarettes: A systematic review. Tobacco Induced Diseases, 23(January), 1–14. https://doi.org/10.18332/tid/192934
• Singer, J. M., Tackett, A. P., Alalwan, M. A., & Roberts, M. E. (2024). Nicotine dependence among undergraduates who use nicotine salt-based e-cigarettes. Journal of American College Health, 73(6), 2475–2481. https://doi.org/10.1080/07448481.2023.2299425
• Camara-Medeiros, A., Diemert, L., O’Connor, S., Schwartz, R., Eissenberg, T., & Cohen, J. E. (2020). Perceived addiction to vaping among youth and young adult regular vapers. Tobacco Control, 30(3), 273–278. https://doi.org/10.1136/tobaccocontrol-2019-055352
• Jordt, S., Caceres, A., Silinski, P., & Jabba, S. (2025). 6-methyl nicotine in Electronic cigarettes: Chemical analysis and toxicological Properties. American Journal of Respiratory and Critical Care Medicine, 211(Abstracts), A7552. https://doi.org/10.1164/ajrccm.2025.211.abstracts.a7552
• Lindson, N., Butler, A. R., McRobbie, H., Bullen, C., Hajek, P., Begh, R., Theodoulou, A., Notley, C., Rigotti, N. A., Turner, T., Livingstone-Banks, J., Morris, T., & Hartmann-Boyce, J. (2024). Electronic cigarettes for smoking cessation. Cochrane Database of Systematic Reviews, 2024(1), CD010216. https://doi.org/10.1002/14651858.cd010216.pub8
• National Institute on Drug Abuse. (2008). NIDA Notes: A collection of articles that address research on nicotine. U.S. Department of Health and Human Services, National Institutes of Health.
• American Lung Association. (n.d.). Tobacco trends brief: Overall tobacco trends brief. https://www.lung.org/research/trends-in-lung-disease/tobacco-trends-bri…
• M. Schmeck, H., Jr. (1976, June 16). Percentage of adults smoking cigarettes declining. New York Times.
• King, B. A., Patel, R., Nguyen, K. H., & Dube, S. R. (2014). Trends in awareness and use of electronic cigarettes among US adults, 2010-2013. Nicotine & Tobacco Research, 17(2), 219–227. https://doi.org/10.1093/ntr/ntu191