Do you think that e-cigarettes are becoming more and more common in life? E-cigarette stores can often be seen on the streets of the downtown area, "lollipops" are placed on the shelves of convenience stores, and many smokers have more "accessories" around their necks...
Image credit: veer gallery
You're right, e-cigarettes are indeed becoming increasingly popular. But is this e-cigarette under the guise of "health" really harmless? The truth is not simple.
E-cigarettes that have attracted the attention of researchers
In fact, e-cigarettes are not a new thing, as early as 2003, Han Li, a pharmacist in Beijing, invented a nicotine aerosol generator. He dilutes nicotine with propylene glycol, and then heats the dilution with a resistance coil to release steam containing nicotine, and after people inhale, they can achieve an effect similar to smoking, which is the later electronic cigarette. In an interview with foreign media in 2016, Han Li recalled that he invented e-cigarettes to help him quit smoking. He himself started smoking at the age of eighteen, quit smoking 6 times without success, and did not want to get lung cancer like the father of the old smoker, so he had this idea.
The gimmick that e-cigarettes started with was indeed "helping to quit smoking" and "healthier than smoking." As we all know, smoking addiction is actually nicotine addiction, and the harmful gases and tar produced by the combustion of traditional cigarettes are by-products, and they are the most toxic to the human body. The e-cigarette produces a relatively pure nicotine vapor, which seems to be more "healthy", coupled with its cool shape and changeable taste, the e-cigarette market has become a hot gold rush track.
Searching for the two English names of e-cigarettes in search engines, "vaping" and "e-cigarette", you can see that since 2010, the internet popularity of e-cigarettes has skyrocketed, and there is no sign of cooling up until now.
Image source: Google search, author homemade
E-cigarettes have also attracted the attention of scientists. Search for "e-cigarette" on the biomedical dissertation site Pubmed and you'll find that the literature on e-cigarette has also grown rapidly since 2010, and scientists are still very close to the trend.
Image source: pubmed, the author made his own
More interestingly, words associated with e-cigarette include "lung," "teenage," "dependence," etc., and also hint at what scientists worried about the e-cigarette epidemic are worried about.
Below, let's take a look at e-cigarettes from a scientific point of view.
The "poison door hidden device" in e-cigarettes
Fans of e-cigarettes are often based on the logic that when it comes to the safety of e-cigarettes, don't compare with people who don't smoke at all, but with people who smoke cigarettes.
Admittedly, such a logic is not unreasonable, but as mentioned earlier, although e-cigarettes have eradicated the huge carcinogenic tar in principle. However, it will still release a variety of harmful substances.
Hazard one: heavy metal poisoning
The first is the metal heating coil. The vapor of the electronic cigarette requires the metal coil to be heated by electricity, and the metal coil itself is likely to release metal substances at high temperatures. In addition, the abundant chemical flavoring agents in e-cigarette liquids may help certain metal ions cross the body's barrier and enter key organs such as the brain and heart. For example, the commonly used fragrance substance maltol is easily combined with metal ions such as iron ions and aluminum ions to increase the body's absorption capacity of such metal substances, and inferior smoke liquid may also be the source of these metal substances.
A previous survey of 1139 U.S. smokers showed that Environ Pollut. 2019, 251, 970), smoking e-cigarettes, cigarettes, cigars, or a combination does not significantly alter the concentration of cadmium and lead in the blood. In terms of total mercury (Total Mercury) in the blood, e-cigarette users are even slightly ahead. This reflects the inability of people who smoke e-cigarettes to avoid the poisoning of heavy metal elements.
Effects of e-cigarettes, cigarettes and cigars on cadmium, lead and mercury levels in human blood
(Image source: Environ Pollut)
Hazard two: inhibition of immune cell function
In order to cater to the changing tastes of young people, the e-cigarette industry can be described as painstaking. According to researchers, there are actually 13 categories of 90 sub-categories of e-cigarette flavor options on the market. In the category of "alcoholic beverage flavors" alone, 11 flavors such as mojito, gin, and rum are subdivided, which are basically "attributed" to various chemical flavors.
Cinnamaldehyde is a typical representation of these flavors. Cinnamaldehyde is derived from the bark of cinnamon tree, with a special aroma, is a common spice in the food industry, and now the e-cigarette industry also uses it to mix a variety of flavors of tobacco liquid. Consuming and inhaling cinnamaldehyde in small amounts does not theoretically have a direct toxic effect on the human body. But the researchers also found that some e-cigarette fluids inhibit the function of immune cells in the human lungs, most likely due to the effects of cinnamaldehyde (Am J Physiol Lung Cell Mol Physiol. 2017, 313, L278–L292）。
From the perspective of organic chemistry, cinnamaldehyde belongs to the aromatic α, β-unsaturated aldehyde compounds. Children's shoes who have studied advanced organic chemistry are well aware that this is a class of organic matter with strong reactivity. Depending on the substrate, they can undergo electrophilic, nucleophilic, and conjugated additions, and it is not surprising that any reaction occurs in complex biological systems.
Hazard three: cause respiratory diseases
Creamy diacetyl is another e-cigarette flavoring. Diacetyl is also a food additive, especially common in popcorn, but nebulized diacetyl can cause respiratory diseases such as bronchiolitis obliterans. Popcorn workers need to be exposed to the diacetyl environment for a long time, and the probability of developing bronchiolitis obliterans is very high, which is also called "popcorn lung".
In 2019, CMAJ reported a case of bronchiolitis obliterans caused by suspected e-cigarettes (containing diacetyl), and the patient was a 17-year-old Canadian lad (CMAJ. 2019, 191, E1321）。 According to the article, the originally healthy young man developed symptoms such as stubborn cough and progressive dyspnea after smoking a large amount of flavored e-cigarettes and tetrahydrocannabinol, and after examination, he showed fever, tachycardia, hypoxemia and lung murmurs, combined with chest CT, and was finally diagnosed with acute bronchiolitis.
After ruling out the possibility of pathogen infection, doctors highly suspect that the cause is related to e-cigarettes and diacetyl. As his condition worsened, the young man even used ECMO, which was well controlled after using a lot of steroids. The patient was discharged home after 47 days in the hospital, but the physical mobility did not fully recover within several months.
The Canadian lad's chest CT on the first day of admission, his lungs are full of abnormal, small, branch-like fine lines, which are typical of diffuse bronchiolitis Image source: CMAJ
From live jumping around to ECMO rescue, it may be a matter of a few e-cigarettes.
Not only will it damage the lungs, the mouth, but it may also...
As the saying goes, "Open guns are easy to hide, dark arrows are difficult to defend", and the unknown is sometimes more frightening than the known dangers.
Through the joint efforts of the scientific community and public health departments, there is sufficient awareness and clinical evidence of the harm of cigarette smoke. There are more than 7,000 chemicals in cigarette smoke, of which at least 250 are harmful substances, 69 are known carcinogens, about 85% of lung cancers and 50% of bladder cancers are caused by smoking. It can be seen that cigarettes are a strong and clear enemy of public health, and through various risk education and policy constraints, global tobacco control has been effective in the past few decades.
However, e-cigarettes may be a seemingly weak enemy, but in fact more difficult to prevent. People who smoke e-cigarettes are not exposed to tar, so it is foreseeable that this group will have a lower probability of dying from lung cancer than people who smoke cigarettes. But who can guarantee that after decades of e-cigarette smoking, the probability of other types of diseases will not be higher? After all, there is already a lot of evidence that e-cigarette aerosols have toxic effects on the lungs, mouth, brain, immune system, cardiovascular system, etc.
The Canadian guys mentioned in the previous section are not isolated cases. The authors of the CMAJ article combed through the serious lung diseases associated with e-cigarettes reported as a "case reports" as of the end of October 2019, involving 18 diseases. Being able to act as a case report generally means that the illness is more serious, the lightest are hospitalized, and the heavy ones are directly into the ICU. In other larger cohort studies, e-cigarettes have seen as many as thousands of cases of lung disease (MMWR Morb Mortal Wkly Rep. 2019, 68, 860–864.）。
Some e-cigarette-related serious lung disease case reports
(Image source: CMAJ)
Compared with the lungs, the oral cavity is an earlier and more direct area of e-cigarette aerosol, and the harm will not be less. A recent study showed that e-cigarette users' oral cells undergo harmful biological changes regardless of whether they have smoked before or not (Sci rep. 2021, 11, 22773）。 Specifically, a variety of RNA expression levels changed, most of which were also found in cigarette smokers. A significant proportion of these altered genes are mitochondrial genes, and mitochondrial dysfunction can induce a variety of cardiovascular, respiratory, metabolic diseases, and cancers.
There are even more curious researchers who have given a more curious view: Men between the ages of 20 and 65 and have no history of cardiovascular disease, but men who use e-cigarettes every day are 2.4 times more likely to report impotence than men who do not use e-cigarettes (AJPM. 2022, 62, 26）。 On this kind of issue, no one should still say, "I am only compared to people who smoke cigarettes."
Teenage e-cigarette users
May let tobacco control "control a lonely"
Less toxic than cigarettes, cool looks, changeable tastes, peer-to-peer comparisons, social needs... There are too many reasons to attract minors and young people to smoke e-cigarettes. These children who are not deeply involved in the world and like to try new things may sneer at the cigarettes loved by their parents, but it is difficult to resist the temptation of e-cigarettes. In addition, in many countries, e-cigarettes have not been strictly controlled and sold like tobacco, and even sold as ordinary consumer goods, and minors can easily buy them.
According to the NIH report from the National Institutes of Health, 37% of high school students smoked e-cigarettes in 2018, compared to only 28% in 2017 (in fact, it is not very "only"... ）。 Globally, 1.3 million new e-cigarette teenage users were added in 2018. The percentage of high school students who smoke cigarettes has fallen from 22 percent 20 years ago to less than 4 percent.
Looking at the two sets of data together, we were surprised to find that the proportion of American high school students who smoked (cigarettes + e-cigarettes) 20 years ago was 22%, because there would be no e-cigarettes. In 2018, that percentage soared to 41 percent, much of which was contributed by e-cigarettes.
All those who did not smoke cigarettes went to smoke e-cigarettes, and even more, this smoke control, control a lonely. In view of the severe situation, the CDC of the US Centers for Disease Control and Prevention directly issued a document pointing out the risks of e-cigarettes to adolescents and young people:
E-cigarettes pose a health threat to children, adolescents and young adults;
Most e-cigarettes contain nicotine. Nicotine is highly addictive, can damage the brain development of adolescents, and the harm will continue until the age of 20;
In addition to nicotine, e-cigarettes have other harmful substances;
Young people who use e-cigarettes are more likely to smoke cigarettes in the future.
The reasons for this situation are manifold, in addition to the temptation of the e-cigarette itself mentioned earlier and the personality influence of adolescents, the lack of understanding of the harm of e-cigarettes, the lack of decisive clinical research, and the overall loose control of various countries have given the "green light" for the popularity of e-cigarettes.
epilogue
Of course, the situation is also changing in a good direction: in China, the "China Smoking Hazards Health Report 2020" put forward a warning that "e-cigarettes are not healthy", and the official ban on e-commerce platforms selling e-cigarettes; many states in the United States have also issued policies prohibiting the sale of non-tobacco flavored e-cigarettes and prohibiting e-commerce platforms from selling e-cigarettes to minors.
These measures show that the e-cigarette industry has experienced nearly 10 years of wild assault, and after barbaric growth, it is finally placed in the "cage" of stricter supervision. Of course, the government's strict management is on the one hand, everyone can not smoke e-cigarettes, do not smoke, can smoke less is the most critical.
Source: Science Compound