Nicotine Levels in E-Cigarettes for Tobacco-Related Cancer Prevention

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Ohio State University Comprehensive Cancer Center

Must not be taking: CYP2A6 inducers

Disqualifiers: Pregnancy, Lung disease, Cardiovascular, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 3 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 9

350 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to study how different types and levels of nicotine in e-cigarettes affect health risks and addiction potential. By examining these factors, researchers hope to identify the safest nicotine levels for e-cigarette users, potentially reducing tobacco-related cancer risks. The trial tests various e-liquids with different nicotine strengths and forms. It seeks participants who are either young adults using e-cigarettes exclusively for at least three months or older adults who smoke daily and are interested in trying e-cigarettes. Participants should not be trying to quit nicotine or tobacco and must refrain from using these products for at least 12 hours before visits. As an unphased trial, this study offers participants the chance to contribute to important research that could lead to safer e-cigarette use.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but you cannot participate if you are using medications that affect the CYP2A6 enzyme, like rifampicin or dexamethasone.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that e-cigarettes contain toxic substances, though usually in lower amounts than regular cigarettes. This suggests they might be less harmful but not completely safe. The FDA has found that some ingredients in e-cigarettes, such as propylene glycol (PG), are safe to ingest, but their safety when inhaled remains unclear.

E-cigarettes often release nicotine and other harmful substances in the vapor, affecting both users and those nearby. This study aims to determine the best nicotine levels, but it does not guarantee the safety of the e-liquids tested.

In this trial, researchers are examining different e-liquids with varying nicotine strengths and types. Since the trial is marked as "Not Applicable" for its phase, predicting how well the treatment will be tolerated is difficult. Considering potential risks before joining a study like this is always wise. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores the potential of manipulating nicotine levels in e-cigarettes to prevent tobacco-related cancer. Traditional treatments for tobacco-related cancer focus on interventions after cancer development, such as surgery, chemotherapy, or radiation. This trial stands out by investigating a preventative measure, potentially reducing cancer risk before it starts. It examines different nicotine concentrations and forms, offering insights into how various e-cigarette compositions might influence cancer prevention. By understanding these effects, researchers hope to develop strategies that could lead to more effective cancer prevention methods.

What evidence suggests that this trial's treatments could be effective for tobacco-related cancer prevention?

Research has shown that e-cigarettes release fewer harmful chemicals than traditional cigarettes, potentially lowering the cancer risk associated with tobacco use. Studies have found that e-cigarettes can aid smoking cessation when combined with counseling. However, e-cigarette use still poses health risks, such as DNA damage and inflammation, which are linked to cancer. This trial will examine how different nicotine levels in e-cigarettes impact addiction and health. Participants in the various treatment arms will vape e-liquids with varying nicotine concentrations, forms, and isomers. Early results suggest that e-cigarettes might be less harmful than regular cigarettes, but research continues. ^{1 6 7 8 9}

Who Is on the Research Team?

Theodore L. Wagener, PhD

Principal Investigator

Ohio State University Comprehensive Cancer Center

Are You a Good Fit for This Trial?

This trial is for individuals interested in the effects of e-cigarette nicotine on health. It's not specified who can't join, but typically participants should be healthy adults, possibly smokers or e-cigarette users.

Inclusion Criteria

I can avoid nicotine, tobacco, and marijuana for 12 hours before visits.

I am 21-24, use e-cigarettes only, and have smoked less than 10 cigarettes ever.

I am a smoker aged 25-65 and interested in trying an electronic cigarette.

Exclusion Criteria

I do not use tobacco products daily except for e-cigarettes or cigarettes.

Currently attempting to quit nicotine or tobacco products

I have not been diagnosed with new or worsening heart problems in the last 3 months.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Phase 1 (Study 1)

Participants are randomized to the order of 8 e-liquid combinations varying in nicotine concentration, form, and isomer. They participate in a 10-puff vaping session over 5 minutes followed by a 60-minute washout period and an ad libitum puffing session over 60 minutes at each lab visit.

8 lab visits, up to 4 hours each

8 visits (in-person)

Phase 2 (Study 2)

Participants are randomized to the order of 20 e-liquid combinations varying in concentration, FB fractions, and isomer. They take part in a 2-puff vaping session with each of the 20 study e-liquids with a 10-minute washout period between each session, grouped into two blocks of 10 separated by a 30-minute resting session.

1 lab visit, up to 6 hours

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Manipulating E-Cigarette Nicotine

Trial Overview The study investigates how manipulating nicotine levels in e-cigarettes affects addiction potential and health risks. Participants will undergo vaping sessions, provide biospecimens, have their carbon monoxide levels measured, and complete surveys.

How Is the Trial Designed?

Group I: Phase 2, Arm 9 (High, 45%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group II: Phase 2, Arm 8 (Low, 25%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group III: Phase 2, Arm 7 (Low, 25%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group IV: Phase 2, Arm 6 (High, 25%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group V: Phase 2, Arm 5 (High, 25%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group VI: Phase 2, Arm 4 (Low, 5%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group VII: Phase 2, Arm 3 (Low, 5%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group VIII: Phase 2, Arm 20 (Low, 85%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group IX: Phase 2, Arm 2 (High, 5%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group X: Phase 2, Arm 19 (Low, 85%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XI: Phase 2, Arm 18 (High, 85%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XII: Phase 2, Arm 17 (High, 85%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XIII: Phase 2, Arm 16 (Low, 65%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XIV: Phase 2, Arm 15 (Low, 65%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XV: Phase 2, Arm 14 (High , 65%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XVI: Phase 2, Arm 13 (High , 65%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XVII: Phase 2, Arm 12 (Low, 45%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XVIII: Phase 2, Arm 11 (Low, 45%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XIX: Phase 2, Arm 10 (High, 45%, R/S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XX: Phase 2, Arm 1 (High, 5%, S) Experimental Treatment 4 Interventions

Participants vape 20 different study e-liquids varying in concentration (low \[20 mg/g\] or high \[50 mg/g\]), freebase nicotine percentage (5%, 25%, 45%, 65%, or 85%), and isomer (S-nicotine or R/S nicotine) using the e-cig study device during two visits.

Group XXI: Phase 1, Arm 8 (Low, NicH+, R/S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXII: Phase 1, Arm 7 (Low, NicH+, S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXIII: Phase 1, Arm 6 (High, NicH+, R/S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXIV: Phase 1, Arm 5 (High, NicH+, S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXV: Phase 1, Arm 4 (Low, Nic, R/S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXVI: Phase 1, Arm 3 (Low, Nic, S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXVII: Phase 1, Arm 2 (High, Nic, R/S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Group XXVIII: Phase 1, Arm 1 (High, Nic, S) Experimental Treatment 4 Interventions

Participants are randomized to vape one out of the eight study e-liquids in a 10-puff vaping session over 5 minutes using the e-cig study device and then in an ad libitum puffing session over 60 minutes. The 8 e-liquids vary in nicotine concentration (low \[20 mg/g\] or high \[50 mg/g\]), form (Nic or NicH+), and isomer (S-nicotine or R/S nicotine).

Who Is Running the Clinical Trial?

Ohio State University Comprehensive Cancer Center

Lead Sponsor

Trials

350

Recruited

295,000+

Published Research Related to This Trial

Between 2012 and 2017, there was a nearly sixfold increase in calls to the British Columbia Poison Centre regarding exposures to electronic nicotine delivery systems (ENDS), primarily due to accidental ingestions in young children, particularly those aged 4 years or less.

Of the 186 unique exposures recorded, 46.8% resulted in reported symptoms, highlighting the need for regulatory measures to reduce children's access to ENDS and improve product safety through better labeling and packaging.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Electronic cigarette exposures reported to the British Columbia Drug and Poison Information Centre: an observational case series. Choi, A., Le, M., Rahim, T., et al.[2022]

E-cigarettes (ENDS) are considered a potential harm reduction tool for smoking cessation, as they do not produce harmful combustion products like traditional cigarettes, but they still deliver various harmful chemicals that raise concerns for cardiovascular and respiratory health.

There is a lack of long-term safety data on ENDS, and while they may help some adults quit smoking, their rising popularity among youth poses a risk of nicotine addiction, highlighting the need for careful regulation and clinician awareness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

E-Cigarettes Reexamined: Product Toxicity. Pipe, AL., Mir, H.[2022]

In a randomized trial involving 68 adult smokers, those using electronic nicotine delivery systems (ENDS) showed a significant reduction in cigarette smoking compared to a control group, indicating potential efficacy in smoking cessation.

Participants using the higher nicotine (24 mg) ENDS were more likely to continue using the product and make independent purchases, suggesting that higher nicotine delivery may enhance user engagement and support smoking reduction efforts.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A Naturalistic, Randomized Pilot Trial of E-Cigarettes: Uptake, Exposure, and Behavioral Effects. Carpenter, MJ., Heckman, BW., Wahlquist, AE., et al.[2018]

Electronic nicotine delivery systems (ENDS), like e-cigarettes, may help smokers quit by providing nicotine without the harmful combustion products found in traditional cigarettes, potentially exposing users to lower levels of toxicants.

However, the long-term safety of ENDS is still unknown, and there are concerns about their use among youth, which could limit their effectiveness as smoking cessation aids.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Clinical Pharmacology of Electronic Nicotine Delivery Systems (ENDS): Implications for Benefits and Risks in the Promotion of the Combusted Tobacco Endgame. Benowitz, NL., St Helen, G., Liakoni, E.[2023]

In a study of 2475 adult smokers transitioning to electronic nicotine delivery systems (ENDS), those who quit tobacco entirely showed significant reductions in various harmful biomarkers of tobacco exposure, including nicotine metabolites and tobacco-specific nitrosamines (TSNAs).

Smokers who became dual users of cigarettes and ENDS experienced some reductions in certain biomarkers, but these were less pronounced and depended on a significant reduction in cigarette consumption, indicating that complete cessation or exclusive ENDS use is more effective for reducing tobacco exposure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Changes in Biomarkers of Tobacco Exposure among Cigarette Smokers Transitioning to ENDS Use: The Population Assessment of Tobacco and Health Study, 2013-2015. Anic, GM., Rostron, BL., Hammad, HT., et al.[2023]

Many electronic nicotine delivery systems (ENDS) contain varying amounts of nicotine that do not match the concentrations labeled on the cartridges, indicating a lack of consistency and reliability in these products.

The presence of chemicals like propylene glycol and glycerol in ENDS raises safety concerns, as limited information is available about the actual contents, which could affect both recreational users and those attempting to quit smoking.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Electronic nicotine delivery systems: regulatory and safety challenges: Singapore perspective. Cheah, NP., Chong, NW., Tan, J., et al.[2022]

Electronic nicotine delivery systems (ENDS), like e-cigarettes, were introduced as a safer alternative for smokers, but their use has expanded to young people and non-smokers, raising concerns about unintended health risks.

The design and power of ENDS devices can significantly affect their safety, with higher power devices potentially being more hazardous, highlighting the need for ongoing research to understand the benefits and risks associated with these products.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Clearing the Haze: What Do We Still Need to Learn about Electronic Nicotine Delivery Systems? Fucito, LM., Malinosky, H., Baldassarri, SR., et al.[2023]

Over 1.5 years, there was a significant increase (156.4%) in the use of disposable devices with salt nicotine and no adjustable settings among frequent ENDS users, while the use of disposable pod/cartridges decreased by 15.2%.

Participants who switched from tank devices (which use freebase nicotine and have adjustable settings) to other device/liquid groupings reported higher nicotine concentrations and lower device power, indicating a trend towards stronger nicotine delivery with less powerful devices.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Transitions in device and liquid characteristic groupings among US adults frequently using electronic nicotine delivery systems (ENDS) over three timepoints, 2020-2021. Nian, Q., Hardesty, JJ., Crespi, E., et al.[2023]

Electronic cigarettes (e.cig.), or electronic nicotine delivery systems (ENDS), may help reduce smoking prevalence due to their ability to deliver nicotine effectively, potentially aiding smokers in quitting.

However, the current lack of regulations and established risk/benefit ratios for ENDS means that their safety and efficacy as smoking cessation aids remain uncertain, highlighting the need for evidence-based knowledge in public health discussions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Electronic cigarettes: A therapeutic tool, a social phenomenon or a business?]. Berlin, I.[2017]

Electronic nicotine delivery systems (ENDS), like e-cigarettes, are increasingly popular but their overall health impacts are still unclear, necessitating further research to understand their role in smoking cessation and potential risks, especially for youth.

The American Association for Cancer Research and the American Society of Clinical Oncology recommend strict regulations on ENDS, including ingredient transparency, childproof packaging, and restrictions on marketing to youth, to mitigate potential harms.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Electronic nicotine delivery systems: a policy statement from the American Association for Cancer Research and the American Society of Clinical Oncology. Brandon, TH., Goniewicz, ML., Hanna, NH., et al.[2022]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC4376316/

Electronic Nicotine Delivery Systems (“E-Cigarettes”) Compared to tobacco cigarettes, available evidence suggests that e-cigarettes are often substantially lower in toxic content, cytotoxicity, associated adverse ...

2. cancercontrol.cancer.gov cancercontrol.cancer.gov/brp/tcrb/electronic-nicotine-delivery-systems

Electronic Nicotine Delivery Systems (ENDS) Use NCI supports research to understand the potential impact of ENDS use on both individual and population health, as it relates to cancer control and prevention.

3. nejm.org nejm.org/doi/full/10.1056/NEJMoa2308815

Electronic Nicotine-Delivery Systems for Smoking Cessation The addition of e-cigarettes to standard smoking-cessation counseling resulted in greater abstinence from tobacco use among smokers than smoking ...

4. tobaccocontrol.bmj.com tobaccocontrol.bmj.com/content/early/2025/05/08/tc-2024-059019

Electronic cigarette use, related health outcomes and ... E-cigarette use is associated with several adverse acute health outcomes; there is currently insufficient longitudinal evidence to predict ...

5. aacrjournals.org aacrjournals.org/clincancerres/article/28/22/4861/710466/Electronic-Nicotine-Delivery-Systems-An-Updated

Electronic Nicotine Delivery Systems: An Updated Policy ... While ENDS emit fewer carcinogens than combustible tobacco, preliminary evidence links ENDS use to DNA damage and inflammation, key steps in cancer development.

6. sciencedirect.com sciencedirect.com/science/article/pii/S1043661823002414

Electronic nicotine delivery systems (ENDS) The FDA has classified PG as safe for oral intake, but the effects of its inhalation are still unknown. The cellular effects of direct contact are unclear, but ...

7. who.int who.int/news-room/questions-and-answers/item/tobacco-e-cigarettes

Tobacco: E-cigarettes E-cigarette emissions typically contain nicotine and other toxic substances that are harmful to both users and non-users who are exposed to the aerosols second- ...

8. fda.gov fda.gov/tobacco-products/products-ingredients-components/e-cigarettes-vapes-and-other-electronic-nicotine-delivery-systems-ends

E-Cigarettes, Vapes, and other Electronic Nicotine Delivery ... Get an overview of FDA regulation of e-cigarettes, vapes, and other electronic nicotine delivery systems. You can also find statistics about ...

9. tandfonline.com tandfonline.com/doi/full/10.1080/08958378.2025.2479518

The beginning of ENDS (electronic nicotine delivery systems) Electronic nicotine delivery systems (ENDS), commonly known as e-cigarettes, are battery-operated devices that produce aerosols by vaporizing e-liquids.