By now, everyone knows that tobacco smoke causes serious damage to the lungs and the respiratory tract in general; however, not everyone knows what these damages actually are and what substances they are causing.
A cigarette, in fact, does not only contain tobacco, but 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 gaseous phase and a corpuscular phase, both containing oxygen free radicals and toxic substances.
Up to now, at least 4, 000 different types of substances have been identified which derive from the incomplete combustion of the cigarette in its entirety (thus also deriving from the burning 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 say 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 dependence on tobacco smoke (smoking). The inhaled nicotine reaches the lungs and the pulmonary alveoli, from here it passes to the blood circulation and finally reaches the nervous system where it binds to the nicotinic receptors present in the brain, causing the classic sense of gratification experienced by smokers. Nicotine also acts on the cardiovascular system, interfering with blood clotting and causing hypertension and an increase in heart rate.
- Carbon monoxide, a gas that is formed following the burning of the cigarette. Carbon monoxide binds to hemoglobin present in red blood cells, replacing oxygen molecules and giving rise to a complex called " carboxyhemoglobin ". By doing so, the blood oxygen levels decrease and the body - in an attempt to compensate for the lack of oxygen supply - responds by increasing the heart rate. However, the heart is unable to make up for this lack of oxygenation and all this results in an increased risk of onset of both cardiovascular and respiratory diseases.
- Carcinogens . These substances are present mainly in the tar contained in cigarettes and in the pesticides that are used during tobacco cultivation. Among the main carcinogenic substances found in cigarettes, we mention polycyclic aromatic hydrocarbons (deriving from combustion), nitrosamines (deriving from the ammonia used in cigarette processing), 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 powerful carcinogens. It should be emphasized that these radioactive agents can be inhaled with both active and passive smoking.
- 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 irritating substances create a situation of constant inflammation in the tissues and mucous membranes with which they come into contact. Moreover, they are able to modify and reduce the functionality of the eyelashes 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 toxic, irritating or potentially carcinogenic substances.
Furthermore, it should be clarified that the cigarette filter can limit the quantity of harmful substances inhaled, but it certainly does not completely stop them. Therefore, it is unthinkable to believe that the filter can constitute a sort of barrier able to prevent the intake of these substances.
The respiratory system of a smoker
As mentioned above, the smoke - and more precisely the irritating substances 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.
The mucus is normally produced by the respiratory epithelium to prevent the entry of foreign substances into the lungs (such as pathogens, irritants, toxic substances, etc.). The lashes then, with their movement, push the mucus towards the pharynx to favor the swallowing, therefore, the elimination.
It therefore appears 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 body tries to make up for the lack of hair loss activity with the cough stimulus, which often becomes chronic.
Cigarette smoking has a decidedly harmful action even at the lung level.
First of all, the smoke and the radical oxygen species contained in it, provoke a state of chronic inflammation in the lung, 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 affecting bronchi and lungs and is characterized by obstruction of the respiratory tract and a reduction in lung function. COPD is a disease that arises slowly and in a subtle manner, so that the symptoms (cough, dyspnea and sputum production) occur only when it is already at an advanced stage.
However, COPD is not the only risk to smokers' lung health. In fact, even the carcinogens present in the smoke play their part favoring the development of different types of lung cancer.
Numerous studies have been conducted on this and it has been concluded that within the cigarette smoke there are two major categories of carcinogens:
- Direct-acting carcinogens, such as polycyclic aromatic hydrocarbons. These compounds cause immediate lung damage.
- Carcinogens with indirect action, such as aldehydes and polyphenols contained in the cigarette paper. These compounds do not act immediately, but promote the onset of the tumor over time through slow modifications.
Tumors are very complex diseases caused substantially by a series of genetic mutations within the cells from which the pathology then originates.
Genetic mutations that lead to the onset of lung cancer can be caused by factors of various kinds (including genetic predisposition) that contribute to one another in the development of the disease.
Therefore, smoking cannot be considered the only cause that triggers the onset of lung tumors. However, it has been estimated that the main causative factor of 80% of these cancers is smoking tobacco. This is a decidedly alarming figure, especially if we consider that smoking is one of the main causes of death AVAILABLE in Italy.
Lung cancer and smoking: risk factors
Assuming that any smoker (avid or not) is exposed to the risk of developing lung cancer, it can be said that the risks of developing this disease increase in relation to:
- 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 more likely you are to develop cancer.
- Age in which smoking addiction begins . Also in this case there is a direct proportionality between the age at which we start smoking and the probability of developing cancer: the younger we are, 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 stop them. Smoking cigarettes without a filter therefore increases the amount of inhaled toxic substances.
- 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 are at risk of developing lung cancer equal to the risk of people who have never smoked.
However, it is important to underline the fact that passive smoking also increases the risk of developing neoplastic lung diseases.
