Vaping long term effects

Long-term use of e-cigarettes has been proven to be associated with various health risks, affecting multiple aspects such as the respiratory system, cardiovascular system, immune system, and even brain development. Although the harm may be less severe than that of traditional cigarettes in some respects, it is by no means harmless.

Respiratory system: Inflammation, damage, and disease risk
The evidence of damage to the respiratory system from long-term e-cigarette use is the most clear. A systematic review and meta-analysis found that compared with non-users, current e-cigarette non-smokers had a significantly higher risk of respiratory symptoms (such as wheezing, dry cough, and exercise-induced shortness of breath) (relative risk RR = 1.90). Additionally, there was "moderate" conclusive evidence that e-cigarette use was associated with a higher risk of chronic obstructive pulmonary disease (COPD), asthma, lung inflammation, and damage in non-smokers.

The underlying mechanisms include: e-cigarettes increase inflammation and oxidative stress, leading to airway barrier dysfunction. Specifically, the expression of inflammatory markers (such as IL-6, IL-8) increases. Long-term exposure may also lead to immune dysfunction and impaired mucosal ciliary function, thereby increasing susceptibility to infections. Moreover, there have been reports indicating that e-cigarette use is associated with some non-tumorigenic lung injuries, such as exogenous lipid pneumonia and diffuse alveolar hemorrhage.

Cardiovascular system: Blood pressure and vascular function impairment
E-cigarettes also have clear adverse effects on the cardiovascular system. Studies show that e-cigarette use leads to elevated blood pressure, impaired vascular function, and increased heart rate, all of which are known triggers of long-term cardiovascular diseases. A study led by the Johns Hopkins University School of Medicine and covering nearly 250,000 people further confirmed that "pure" e-cigarette use is associated with an increased risk of hypertension (especially in the 30-70-year-old adult subgroup), and is also associated with an increased risk of COPD.

Cancer risk: Biomarkers indicate potential carcinogenicity
Regarding the direct association between e-cigarettes and cancer, current research is still ongoing. A large-scale study of non-smokers found no significant risk of lung cancer or other types of cancer from e-cigarette use. However, evidence at the biomarker level suggests potential carcinogenicity. A meta-analysis including approximately 24,000 adults concluded that the levels of carcinogenic biomarkers in e-cigarette users were lower than those of traditional smokers but higher than those of non-smokers, indicating their presence of inflammation and potential carcinogenic effects. Mechanism studies have also proposed several possible carcinogenic pathways, including DNA damage, oxidative stress, and mitochondrial toxicity. More notably, the World Health Organization (WHO) under the International Agency for Research on Cancer (IARC) pointed out in a commentary that using e-cigarettes after quitting smoking may weaken the benefits of smoking cessation in reducing the risk of lung cancer and mortality.

Other systemic effects
Oral health: E-cigarette use is associated with various oral problems. Studies suggest that users may have a higher prevalence of dental caries (tooth decay) and increased risk of gingival inflammation, periodontal disease, and tooth sensitivity. The mechanism may involve e-cigarette aerosol inhibiting normal oral flora, promoting the growth of cariogenic bacteria.

Immune system: Long-term use of e-cigarettes disrupts the immune system. This may lead to chronic inflammatory diseases, increased risk of respiratory infections, and even the induction of autoimmune diseases. For individuals who started using e-cigarettes in their youth, the risk of such immune-related diseases seems to be higher.

Reproductive health: Preliminary studies show that e-cigarettes have potential toxicity to both male and female reproductive systems. In men, it may be associated with impaired testosterone synthesis, decreased sperm concentration and total count, and abnormal sperm motility and morphology. For women, it may interfere with follicular development, leading to hormonal imbalance and reduced fertility.

Brain development in teenagers: Nicotine poses particularly severe harm to the developing brain. As brain development continues until around the age of 25, exposure to nicotine by teenagers may cause long-lasting negative effects, including impairing attention, learning ability, emotional regulation, and impulse control, and increasing the risk of future nicotine addiction and other substance abuse.

Summary
Overall, the health risks associated with long-term use of e-cigarettes are real and multifaceted. Although compared to traditional cigarettes, it may have lower risks in some aspects (such as the concentration of carcinogens), it is by no means a "vapor" that is completely safe. There is sufficient evidence of its harm to the respiratory and cardiovascular systems, as well as clear potential threats to the immune system, oral health, reproductive system, and the brain development of teenagers. Regarding its long-term cancer risks, more research is needed to fully clarify the situation.