Smoking and cancer:what is the relationship

Smoking and cancer:what are the harmful substances in tobacco?

Smoking and cancer have a well-established and deeply concerning relationship. The smoke produced by cigarette combustion contains at least more than 3000 harmful components, including polycyclic aromatic benzopyrene, 1,2-benzoanthracene, nitrosamine, polonium-210, cadmium, arsenic β- Naphthylamine has carcinogenic effects, and the cancer promoting substances in cigarette smoke include cyanide, o-cresol, phenol, etc. When smoking, most of the cigarette smoke is inhaled into the lungs, and a small part enters the digestive tract together with saliva. Some harmful substances in smoke stay in the lungs, and some enter the blood circulation and flow to the whole body. Under the synergistic action of carcinogens and cancer promoters, normal cells are damaged and cancer is formed.

Harmful components in cigarette smoke include alkaloids such as carbon monoxide and nicotine, amines, nitriles, alcohols, phenols, alkanes, alkenes, carbonyl compounds, nitrogen oxides, polycyclic aromatic hydrocarbons, heterocyclic compounds, heavy metal elements, organic pesticides, etc.

They have a variety of biological roles, including:

• inflammatory stimuli to respiratory mucosa: such as aldehydes, nitrogen oxides, alkenes.
• toxic effects on cells: such as nitriles, amines, heavy metals.
• addictive effects: alkaloids such as nicotine.
• Carcinogenic to humans: Such as benzopyrene in polycyclic aromatic hydrocarbons, as well as cadmium, dimethylnitrosamine, and β-naphthylamine.”
• have cancer promoting effects on human body: such as phenolic compounds.
• make red blood cells lose oxygen carrying capacity: such as carbon monoxide.

The content of harmful substances in tobacco is usually evaluated by “smoke tar and carbon monoxide”. It is required that the smoke tar produced by each cigarette is less than 15 mg, and the actual smoke on the market is more than several times. According to 20 cigarettes a day, a quarter of which are inhaled into the body, the amount of smoke tar inhaled by smokers is about 120~200 mg per day. The joint effect of harmful substances in smoke tar is a major threat to human cancer.

Harmful components in cigarette smoke:

Nicotine (particulate) (smoking and cancer):

each cigarette contains about 1.5 mg, which makes smoking addictive. A small amount of nicotine plays an excitatory and stimulatory role, while a large amount of nicotine plays an inhibitory or paralytic role, with severe toxicity. The lethal dose is 40-60 mg. The bronchial mucosa is damaged and prone to inflammation and infection. It accelerates heart rate, increases blood pressure and arteriosclerosis, and promotes the occurrence of cardiovascular and cerebrovascular diseases.

Cigarette tar (particulate):

each cigarette contains 20-30 mg of carcinogens and cancer promoting substances. Cigarette tar is composed of phenol, aliphatic hydrocarbon, polycyclic aromatic hydrocarbons, acids, indole, pyridine and other concentrates. It often adheres to the throat, bronchus and alveoli and accumulates for many years, forming cancer.

Carbon monoxide (gas):

each cigarette can produce 20-30 ml of carbon monoxide, which destroys the oxygen carrying function of red blood cells, exacerbates hypoxia, and harms the cardiac and cerebral vascular systems. A series of organs of smokers will also produce pathological changes due to hypoxia. Promote the increase of cholesterol storage and accelerate atherosclerosis.

Radioactive substances (carcinogenic):

in tobacco fields, uranium rich phosphate fertilizer is applied, and uranium decomposes into radioactive needles, paving, atmosphere, etc. This radiation is harmful to human body and can lead to cancer. Radioactive needles are the most harmful, followed by radon, a derivative of pickaxes.

Direct carcinogens and others:

a cigarette contains about 100 nanograms of 3,4 benzopyrene and about 1-2 micrograms of cadmium, of which about 5% is absorbed by the human body, which has a strong carcinogenic effect. Other toxicants include hydrogen cyanide, acrolein, carbon monoxide, formic acid, etc.

Public policies and efforts to combat smoking In the United States

In the United States, public policies and efforts to combat smoking and encourage cessation have been significant and multifaceted. These initiatives have been driven by the recognition of the severe health consequences associated with smoking, including various types of cancer, cardiovascular diseases, and respiratory illnesses. Here are some key policies and their outcomes:

1. Tobacco Taxes: Increasing the price of tobacco products through taxation is a common strategy used to discourage smoking, especially among youth. States and the federal government have raised tobacco taxes over the years, leading to a decrease in smoking rates. For instance, a 10% increase in tobacco prices reduces cigarette consumption by about 4% in high-income countries.
2. Smoke-Free Laws: Implementing smoke-free laws that prohibit smoking in workplaces, restaurants, and bars has been effective in reducing exposure to secondhand smoke and encouraging smokers to quit. As of 2021, all 50 states and the District of Columbia have enacted laws prohibiting smoking in workplaces and public places.
3. The Family Smoking Prevention and Tobacco Control Act (2009): This federal law granted the U.S. Food and Drug Administration (FDA) the authority to regulate the manufacture, distribution, and marketing of tobacco products. It banned certain tobacco product marketing tactics, required larger and more prominent health warnings on packaging, and prohibited the sale of flavored cigarettes, except for menthol.
4. The National Tobacco Control Program: Established by the 1998 Master Settlement Agreement between the tobacco industry and 46 states, this program provides funding for comprehensive tobacco control and prevention efforts at the state and local levels. These efforts include mass media campaigns, school-based education, and cessation services.
5. Medicare Coverage for Smoking Cessation: In 2005, Medicare began covering smoking cessation counseling for beneficiaries, and in 2015, it expanded coverage to include all FDA-approved medications for smoking cessation.
6. The Great American Smokeout: Organized by the American Cancer Society, this annual event encourages smokers to make a plan to quit, or to plan in advance and then quit smoking for the day.

These policies and efforts have contributed to a decline in smoking rates in the U.S. According to the Centers for Disease Control and Prevention (CDC), the prevalence of smoking among adults in the U.S. has dropped from about 42% in 1965 to 12.5% in 2020. However, disparities exist, with lower-income individuals and those with less education continuing to have higher smoking rates. Ongoing efforts are focused on reducing these disparities and further lowering smoking rates across all segments of the population.