By now, everyone knows that tobacco smoke causes severe damage to the lungs and respiratory tract in general; however, not everyone knows what this damage actually is and by what substances it is caused.
A cigarette, in fact, does not only contain tobacco, but also contains other chemicals that can be extremely harmful to our body.
Cigarette smoke: what does it contain?
As mentioned, cigarettes contain not only tobacco, but also numerous other substances deriving from the processing of tobacco and the processing of the same cigarette.
Cigarette smoke is composed of a gas phase and a corpuscle phase, both of which contain oxygen free radicals and toxic substances.
So far, at least 4,000 different types of substances have been identified that derive from the incomplete combustion of the cigarette as a whole (therefore also deriving from the combustion of the paper that covers it). Of these 4,000 substances, at least 40 have been identified as certainly carcinogenic.
To simplify the matter, we can state that the substances that are inhaled when smoking a cigarette are:
- Nicotine, a stimulating alkaloid present in tobacco leaves and responsible for the onset of psychophysical addiction to tobacco smoke (smoking). Inhaled nicotine reaches the lungs and pulmonary alveoli, from here it passes to the bloodstream and finally reaches the nervous system where it binds to nicotinic receptors present in the brain, causing the classic sense of gratification felt by smokers. Nicotine also acts on the cardiovascular system, interfering with blood clotting and causing hypertension and increased heart rate.
- Carbon monoxide, a gas that is formed following the combustion of the cigarette. Carbon monoxide binds to "hemoglobin present in red blood cells, replacing oxygen molecules and giving rise to a complex called"carboxyhemoglobin". In doing so, blood levels of oxygen decrease and the body - in an attempt to compensate for the lack of oxygen - responds by increasing the heart rate.However, the heart is unable to make up for this lack of oxygenation and all this translates into an increased risk of developing both cardiovascular and respiratory diseases.
- Carcinogenic substances. These substances are mainly present in the tar contained in cigarettes and in the pesticides that are used during the cultivation of tobacco. Among the main carcinogenic substances present in cigarettes, we remember the polycyclic aromatic hydrocarbons (deriving from combustion), nitrosamines (deriving from the ammonia used in the manufacture of cigarettes), aromatic amines, heavy metals (such as nickel, cadmium, etc.) and even radioactive substances such as polonium 210 (Po-210) and lead-210 (Pb-210). The latter seem to derive from the fertilizers used to treat tobacco crops and are two extremely potent carcinogens. that these radioactive agents can be inhaled with both active and passive smoke.
- Irritants, such as formaldehyde, ammonia, hydrogen cyanide and acrolein. These substances are responsible for the onset of respiratory diseases, such as pulmonary emphysema, bronchial asthma and acute and chronic bronchitis. The irritants create a situation of constant inflammation in the tissues and mucous membranes with which they come into contact. Furthermore, they are able to modify and reduce the functionality of the cilia present in the respiratory epithelium, thus causing a stagnation of mucus which leads to the onset of cough (which in the long run can become chronic) and which increases the risk of contracting respiratory infections of various kinds.
Other components present in the cigarette are acetone, arsenic, urethane, nitric acid, benzene, DDT and methanol. Obviously, all of them are toxic, irritating or potentially carcinogenic.
Furthermore, it is good to clarify that the cigarette filter can limit the amount of harmful substances inhaled, but it certainly does not block them completely. Therefore, it is unthinkable to believe that the filter can constitute a sort of barrier capable of preventing the intake of these substances.
The respiratory system of a smoker
As mentioned above, smoke - and more precisely the irritants contained in it - is able to alter the functioning and cause the death of the hair cells present in the epithelium of the respiratory tract, thus causing a stagnation of mucus.
Mucus is normally produced by the respiratory epithelium to prevent foreign substances (such as pathogens, irritants, toxic substances, etc.) from entering the lungs. The cilia then, with their movement, push the mucus towards the pharynx to favor its swallowing, therefore, its elimination.
It is therefore clear that in smokers this balance between mucus activity and eyelash activity is altered. The lack of action of the eyelashes causes the mucus to stagnate, favoring the development of various kinds of infections, as well as promoting the onset of respiratory diseases. The organism tries to compensate for the lack of lash activity with the stimulus of cough, which often becomes chronic.
Cigarette smoke has a decidedly damaging action on the lungs as well.
First of all, smoke and the radical oxygen species it contains cause a state of chronic inflammation in the lungs, caused by a continuous accumulation of neutrophils, macrophages and other cells of the immune system.
This perennial inflammatory state can lead to the onset of chronic obstructive pulmonary disease (or COPD). The latter is a chronic and irreversible disease that affects the bronchi and lungs and is characterized by "obstruction of the airways and a reduction in pulmonary function. COPD is a disease that arises slowly and subtly, so much so that the symptoms (cough, dyspnea and sputum production) only manifest themselves when it is already in an advanced stage.
However, COPD is not the only risk to the health of smokers' lungs. In fact, the carcinogenic substances present in smoking also play their part in favoring the development of various types of lung cancer.
Numerous studies have been conducted on this subject and it has been concluded that within cigarette smoke there are two broad categories of carcinogenic substances:
- Direct acting carcinogens, such as polycyclic aromatic hydrocarbons. These compounds cause immediate lung damage.
- Carcinogenic substances with indirect action, such as aldehydes and polyphenols contained in cigarette paper. These compounds do not act immediately, but promote the onset of the tumor over time through slow modifications.
Tumors are very complex pathologies substantially caused by a series of genetic mutations within the cells from which the pathology then originates.
The genetic mutations that lead to the onset of lung cancer can be caused by factors of various kinds (including genetic predisposition) that contribute to each other in the development of the disease.
Therefore, smoking cannot be considered the only trigger for the onset of lung cancer. However, it has been estimated that the main causative factor of 80% of these neoplasms is tobacco smoking. This is a decidedly alarming fact, especially if we consider that smoking is one of the main AVOIDABLE causes of death in Italy.
Lung cancer and smoking: risk factors
Assuming that any smoker (heavy or not) is exposed to the risk of developing lung cancer, it can be said that the risks of developing this pathology increase as a function of:
- Amount of cigarettes smoked. In fact, there is a direct proportionality between the number of cigarettes smoked and the risk of developing lung cancer. In other words, the more cigarettes you smoke, the greater the likelihood of developing cancer.
- Age at which smoking addiction begins. Also in this case there is a direct proportionality between the age at which one begins to smoke and the probability of developing cancer: the younger one is, the greater the risks.
- Absence of filter in cigarettes. As mentioned, the filter can somehow limit the intake of harmful substances, even if it does not completely block them. Smoking unfiltered cigarettes, therefore, increases the amount of toxic substances inhaled.
- Duration of smoking addiction. The longer you smoke, the more likely you are to develop lung cancer.
It has been calculated that in people who quit smoking, the risk of developing lung cancer gradually decreases over the course of 10-15 years. After this period, ex-smokers run a risk of developing lung cancer equal to the risk of people who have never smoked.
However, it is important to point out that the passive smoke the risk of developing neoplastic lung diseases increases.
