A study has found that the aerosols (vapor) inhaled from liquid-based e-cigarettes not only adversely affect the overall health of smokers and bystanders but also pollute the surrounding air. The researchers stated that nanoscale toxic substances, which are even finer than those in conventional cigarette smoke, penetrate deep into the lungs, blood vessels, and throughout the body.

Professor Byun Min-kwang of the Division of Pulmonology at Gangnam Severance Hospital, Yonsei University, announced on the 8th that, together with Professor Loren Wold of Ohio State University and an e-cigarette research group, they analyzed the effects of e-cigarettes and published the findings in the international journal ‘Annual Review of Pharmacology and Toxicology’. To comprehensively assess the hazards of liquid e-cigarettes with varying ingredient compositions and ratios, the team collected and analyzed around 140 key e-cigarette studies published worldwide over the past two decades.

Although e-cigarettes are often mistaken as relatively less harmful than combustible cigarettes, many studies have reached the common conclusion that aerosols and harmful substances from e-cigarettes negatively affect most human organs. The researchers explained that when components such as propylene glycol and glycerol, which constitute most of the e-liquid, are heated, they turn into aerosols at the nanoparticle (PM0.1) level, even finer than ultrafine particles (PM2.5), and are inhaled into the body together with nicotine and various heavy metals and toxic substances.

Pathological analyses of human impacts from e-cigarette exposure most commonly observed increases in oxidative stress and inflammatory responses. The team confirmed that e-cigarettes induce toxicity in nearly all organs, not only the lungs but also the brain, cardiovascular system, and metabolic system. Compared with non-smokers, e-cigarette users had up to 1.4 times higher risk of developing metabolic syndrome, and nanoparticles including nicotine were shown to damage vascular endothelial cells, leading to atherosclerosis, elevated blood pressure, and increased arterial stiffness.

It was also found that they disrupt the brain’s energy metabolism and directly trigger inflammation, impairing cognitive function, and that reduced cerebral glucose utilization exacerbates brain injury when a stroke occurs. In addition, they affect the male reproductive system, lowering sperm motility, concentration, and survival, and are linked to infertility.

Results were also presented showing that secondhand exposure from e-cigarettes can expose nearby non-smokers, including infants and young children, to toxic substances. After e-cigarette use, the average concentration of ultrafine particles rose from 6㎍/㎥ to 197㎍/㎥, peaking at up to 514㎍/㎥. Even with ventilation, aerosol particles suspended in the air were analyzed to adhere to wallpaper or furniture for months, causing third-hand exposure.

Professor Byun Min-kwang said, “This study has drawn a common conclusion in academia that e-cigarettes are not confined merely to lung health but induce toxicity across multiple organs throughout the body,” and added, “The dangers of e-cigarettes masked by sweet aromas need to be recognized by the general public, policymakers, and medical professionals alike.”