Electronic cigarettes are electronic transport systems used to generate aerosols for human inhalation and other purposes. Electronic cigarettes are powered by batteries to drive the atomizer, which then heats the liquid and inhales it in the form of gas by the human body, producing a smoking sensation and mist, but without any fireworks.
In 2003, Chinese pharmacist Han Li invented the world’s first electronic cigarette (such as a cigarette) to quit smoking, but unfortunately, it was acquired by Imperial Tobacco in 2013. Fortunately, there is a saying circulating in the electronic cigarette industry made in China: “Over 95% of global electronic cigarette production and products come from China, 70% of China comes from Shenzhen, and over 95% of Shenzhen comes from Bao’an.”. China is gradually transitioning from being the world’s largest e-cigarette manufacturer to the world’s largest e-cigarette brand exporter. The most common uses of electronic cigarettes can be divided into two points: ① smokers who want to replace traditional cigarettes with electronic cigarettes; ② Electronic cigarette players. Due to the strengthened regulation of smoking ban policies in various countries, people have a higher pursuit and greater concern for a healthy lifestyle, and the lack of freshness in traditional tobacco has led to the rapid growth of electronic cigarettes as a trendy single product.
Structure and classification of electronic cigarettes
Flavors of e-cigarettes
Electronic cigarettes attract many groups because of their unique flavor. This is because the flavor mixers use different essence to add to the electronic cigarette liquid to get consumer taste [2]. 3716 participants completed an online survey about their use of e-cigarettes and answered the following open-ended questions about their use of e-cigarette liquids: “What flavor do you like the most? What brand of flavoring liquid do you like?” The researchers used a three-step method to determine the flavor attributes present in electronic liquids through online search engines. The classification scheme for electronic liquids and the proportion of each category obtained are: tobacco (23.7%), menthol/menthol sugar (14.8%), fruit (20.3%), desserts/desserts (20.7%), alcohol (2.8%), nuts/spices (2.0%), candies (2.1%), coffee/tea (4.3%), beverages (3.1%), tasteless (0.4%), and unknown/other (5.8%), as shown in Figure 6; This is the most commonly used characteristic flavor classification method for experienced e-cigarette users in electronic cigarette liquids. Therefore, common electronic cigarette flavors abroad include tobacco, mint, fruit, sweets, nuts, candies, beverages, and other flavors. There are many reasons why electronic cigarettes are more attractive than traditional cigarettes, including cost, choice of different flavors, ease of use, use and influence of social media. Electronic cigarette users, including teenagers and adults, also have different opinions. Teenagers may use e-cigarettes due to the fashion sense brought by this new device, while adults may plan to quit traditional combustible cigarettes and switch to e-cigarettes. Electronic cigarettes require stronger regulations to prevent contact and use by teenagers.
Toxicology of e-cigarettes
A research report published in the international core journal Toxicology Reports suggests that when smokers switch to e-cigarettes or heat non combustible products, their chances of exposure to harmful substances are significantly reduced, and the harm reduction effect of e-cigarettes is better than that of heating non combustible products [6].
On May 26, 2021, the “China Smoking Health Hazards Report 2020” was released, indicating that:
(1) The smoke liquid contains low molecular weight aldehyde ketone compounds, which have a strong stimulating effect on the respiratory system. Formaldehyde, classified as Class 1 by the International Institute for Research on Cancer, and acetaldehyde, a Class 2B carcinogen; After being heated and inhaled by the human body, 2,3-butanedione may deposit and cause obstruction of the lungs and trachea, exacerbating respiratory inflammation and even forming popcorn lung.
(2) Nicotine is one of the main components of electronic cigarettes, and smokers are prone to developing dependence on it; For pregnant women who use electronic cigarettes during pregnancy, it can have adverse effects on fetal development and may lead to the occurrence of cardiovascular diseases. In addition, nicotine can have long-term adverse effects on the brain development of fetuses and adolescents who come into contact with it, which may lead to anxiety disorders and learning disabilities.
(3) Electronic smoke aerosols are nanoparticles, but toxic substances adhering to small nanoparticles may have a greater impact on health than adhering to larger submicron particles.
(4) Electronic cigarette seasoning agents, if used improperly, can increase the harm to users. The research results indicate that different electronic cigarette liquids and aerosols have cytotoxicity, and cells exposed to electronic cigarette smoke extract have a higher probability of DNA damage and death compared to cells not exposed.
(5) Smoking both electronic cigarettes and traditional tobacco at the same time can result in a combination of health hazards.
Therefore, the respiratory tract, cardiovascular system, and growth and development of individuals who consume electronic cigarettes for a long time or excessively may be damaged by the harmful components of electronic cigarettes and aerosols.
