What is the harm of cigarettes to human health, nicotine or tar content?

This paper introduces the structure, properties and harm of harmful components produced in the process of smoking from the chemical point of view. There are more than 2540 kinds of components in cigarettes, and complex physical and chemical changes will occur after burning. There are more than 400 kinds of carcinogens, among which 10 can promote the development of cancer, among which nicotine, tar, carbon monoxide, cyanide and radioactive substances are the most harmful to human body. Nicotine, also known as nicotine, is a pyridine compound with the chemical formula of C 10H 14N2. The system name is N- methyl -2[α(β, γ)]-pyridyl tetrahydropyrrole. γ -nicotine is a kind of plant alkali existing in tobacco. It is a colorless oily or yellowish oily liquid with pungent taste and special smoke smell, and its boiling point is. Nicotine is a weak base, which can react with acid to form salt, and can also react with plant alkali reagent to produce color reaction. Nicotine has a strong stimulating and anesthetic effect on the central nervous system of human body, which makes people excited in a small amount and causes dizziness, vomiting and even poisoning death in a large amount. A cigarette contains enough nicotine to kill a mouse. Smoking a cigarette can generally inhale 0.2 ~ 0.5 mg, and adults can be fatal if they inhale 40 ~ 60 mg of nicotine at a time. Tar is produced by incomplete combustion of organic substances in cigarettes under anoxic conditions. Tar is a complex mixture of various hydrocarbons and oxides, sulfides and nitrides of hydrocarbons. 99.4% of the substances in flue gas tar are harmful, 0.2% are carcinogenic initiators and 0.4% are cancer synergists. At present, tar in smoke is considered as the most harmful substance, which is why tar content (high, medium and low) is marked on cigarette cases. The content of polycyclic aromatic hydrocarbons (PAHs) in tar is the most, and they all have strong carcinogenic effects, such as benzopyrene, diphenyl pyridine, diphenyl anthracene and so on. After these substances enter the human body, they can induce aromatic hydroxylase in human tissues, which can metabolize polycyclic aromatic hydrocarbons into carcinogens, which can combine with DNA molecules at a valence of * *. It is also found that some substances have the characteristics of auxiliary carcinogens, that is, so-called cancer promoters (synergists or cancer promoters). At present, it is considered that tar 3,4-benzopyrene is the strongest carcinogen. Its chemical formula is C20H 12, and its structural formula is 3,4-benzopyrene. Its boiling point is 179℃, and there is about 0.02 ~ 0. 10μ g in a cigarette. Carbon monoxide is a colorless, odorless and water-insoluble gas. Cigarette smoke contains a lot of carbon monoxide, and the binding capacity of carbon monoxide and hemoglobin is 240 ~ 300 times greater than that of oxygen. When inhaled in large quantities, it will combine with hemoglobin, seriously weakening the oxygen carrying capacity of red blood cells. Therefore, smoking accelerates blood coagulation and easily causes cardiovascular diseases such as myocardial infarction, stroke and myocardial hypoxia. Hydrogen cyanide is a colorless gas and the most toxic substance in cigarette smoke. It mainly comes from nitrogen-containing compounds in tobacco, such as nitrate, protein and nitrogen-containing heterocyclic compounds. Smoke contains radioactive polonium -2 10, which can produce radioactive ions and easily kill human cells, making them cancer cells. Experts estimate that smoking 30 cigarettes a day is equivalent to taking 300 X-rays every year. Smoking is harmful to health, and more importantly, smokers seriously hinder the health of others. The results show that a smoker does more harm to others than to himself. The death rate of lung cancer in women whose wives don't smoke and whose husbands smoke is 2.4 times that of their husbands. This kind of injury is the most serious for children. Children of smokers have a much higher risk of pneumonia, bronchitis, respiratory infection and other diseases than normal children. Because there is a long transition period between smoking and illness, its pathological changes appear even after 20 years, which leads some people to mistakenly think that smoking is harmful or harmless. In fact, there is no doubt that smoking is harmful to health. The harm of smoking to health has been recognized by more and more people. The World Health Organization lists smoking as a global epidemic and recognizes that tobacco is the biggest threat to human health at present. Governments and people all over the world have begun to take action and launched a massive anti-smoking campaign. Thirty-three countries in Europe decided to eliminate smoking by the year 2000. China has taken some measures, such as restricting cigarette production and banning smoking in public places and workplaces. However, the current situation is not optimistic. The number of smokers is increasing year by year, and smokers are younger, which should attract wide attention from all walks of life. Therefore, we should further strengthen the propaganda of quitting smoking and focus on teenagers, which will undoubtedly reduce the reserve team of smokers. Harm of smoking: Smoking is a bad habit that harms human health. Modern medicine has proved that tobacco will release more than 1000 compounds when burning, most of which are harmful to human body, and there are no less than 44 carcinogens. Such as tobacco tar, nicotine (such as nicotine), carbon monoxide, aldehydes (such as benzaldehyde), amines (such as benzidine) and so on. Recent research by Japanese scholars shows that smog also contains the most toxic compound "dioxin" among known substances. They can cause and aggravate various diseases, such as cancer, pneumonia, tracheitis, hypertension, hyperosteogeny, various cardiovascular and cerebrovascular diseases, asthma, infertility and so on. According to the information provided by the World Health Organization, about 654.38+0 billion people worldwide die of smoking-related diseases every year. Teenagers are in the period of growth and development, respiratory mucosa is easy to be damaged, and smoking is more harmful.