Carcinogenic substances. Based on the nature of their action, carcinogens are divided into three groups

Carcinogenic substances are chemical compounds that, when exposed to the human body, can cause cancer and other diseases (malignant tumors), as well as benign neoplasms.

Currently, carcinogenic refers to chemical, physical and biological agents of natural and anthropogenic origin that are capable of inducing cancer in animals and humans under certain conditions. The most widespread are carcinogenic substances of a chemical nature, acting in the form of homogeneous compounds or as part of more or less complex chemical products. They are very diverse in their origin, chemical structure, duration of exposure to humans and prevalence. Compounds classified as “naturally occurring” carcinogens, although numerous, have a limited distribution (for example, endemic areas with high content arsenic in soil and water) and, mainly, relatively low levels contents in environment.

The total oncogenic “load” on living organisms is determined by the background level of carcinogens. The background content of carcinogens consists of their natural content associated with the vital activity of organisms, abiogenic and anthropogenic pollution. Background is a regional concept; its fluctuations primarily depend on proximity to sources of environmental pollution associated with human economic activity. It is hardly possible to evaluate all the components that form the background.

Carcinogenicity - properties of some chemical, physical and biological factors alone or in combination with other factors, cause or promote the development of malignant neoplasms. Similar factors are called carcinogenic, and the process of tumor formation as a result of their exposure is called carcinogenesis. Vary carcinogenic factors direct action, which, with a certain dose-exposure effect, cause the development of malignant neoplasms, and so-called modifying factors, which do not have their own carcinogenic activity, but are capable of enhancing or weakening carcinogenesis. The number of modifying factors significantly exceeds the number of direct carcinogenic agents; their effects on the human body may vary in magnitude and direction.

Carcinogenic factors whose effects are associated with professional activity, are called occupational carcinogens or carcinogenic occupational factors (CPF). The role of industrial carcinogens was first described in English. researcher P. Pott (1714-1788) in 1775 using the example of the development of genital cancer among London chimney sweeps as a result of skin exposure to soot and high temperatures during work. In 1890, bladder cancer was reported among dye factory workers in Germany. Subsequently, the carcinogenic effects of several dozen chemical, physical and biological production factors on the worker’s body were studied and determined. Identification of CPF is based on epidemiological, clinical, experimental and other studies.

The International Agency for Research on Cancer (IARC) has developed a number of criteria for the degree of evidence of the level of carcinogenicity of various factors or agents, which made it possible to divide all carcinogens, including industrial ones, into classification groups.

Agent, complex of agents or external factors:

group 1 are carcinogenic to humans;

group 2a are probably carcinogenic to humans;

group 2 are possibly carcinogenic to humans;

group 3 are not classified as carcinogenic to humans;

group 4 are probably not carcinogenic to humans.

Currently, 22 chemical substances (not including pesticides and some drugs with carcinogenic properties) and a number of industries that use them, which are included in the 1st classification group, have been identified as chemical occupational carcinogens in accordance with this classification. These include 4-aminobiphenyl, asbestos, benzene, benzidine, beryllium, dichloromethyl ether, cadmium, chromium, nickel and their components, coal tar, ethylene oxide, mineral oils, wood dust, etc. These substances are used in rubber and woodworking industries, and also in the production of glass, metals, pesticides, insulating and filter materials, textiles, solvents, fuels, paints, laboratory reagents, construction and lubricants, etc.

The group of probably carcinogenic to humans (2a) includes 20 industrial chemical agents, including acrylonitrile, benzidine-based dyes, 1,3-butadiene, creosote, diethyl and dimethyl sulfate, formaldehyde, crystalline silicon, styrene oxide, tri- and tetrachlorethylene, vinyl bromide and vinyl chloride, as well as production associated with their use. The group of possibly carcinogenic industrial chemical agents (2b), the carcinogenicity of which has been proven mainly through experimental studies on animals, includes a large number of substances, including acetaldehyde, dichloromethane, inorganic lead compounds, chloroform, carbon tetrachloride, ceramic fibers, etc.

Physical CPFs include radioactive, ultraviolet, electrical and magnetic radiation; biological CPF - some viruses (for example, hepatitis A and C viruses), pathogens infectious diseases gastrointestinal tract, mycotoxins, especially aflatoxins.

Between exposure to CPF and the manifestations of cancer, 5-10 years or even 20-30 years may pass, during which the influence of other carcinogenic factors, including environmental, genetic, constitutional, etc., cannot be excluded. According to a number of researchers, the proportion of cancer diseases on the development which were mainly influenced by industrial carcinogens, in the overall structure of cancer incidence ranges from 4% to 40%. The generally accepted level of occupationally caused cancer incidence in developed countries is considered to be 2-8% of all registered cancer diseases.

Under working conditions that include exposure to any CPFs of groups 1, 2a and 2b, it is necessary to prevent cancer among workers in several areas: reducing exposure to CPFs by modernizing production, developing and implementing additional collective and individual protective measures; introduction of a system of restrictions on access to work with CPF, terms of work in this production; conducting continuous monitoring of the health status of workers in carcinogenically hazardous jobs and industries; taking measures to improve the health of workers and timely release them from work with the CPF.

Many researchers associate the current increase in the incidence of malignant neoplasms with an increase in the level of environmental pollution with various chemical and physical agents that have carcinogenic properties. It is generally accepted that up to 90% of all cancer cases are caused by exposure to environmental carcinogens. Of these, 70-80% are associated with exposure to chemical and 10% radiation factors. Environmental pollution with carcinogenic substances is global in nature. Carcinogens are found not only near emission sites, but also far beyond them. The ubiquitous presence of carcinogens raises doubts about practical possibility isolation of a person from them.

With the growth of industrialization, there has been a significant increase in environmental pollution with carcinogens such as polycyclic aromatic hydrocarbons (PAHs), which are formed as a result of the widespread combustion and pyrolytic processing of fuel and become permanent components of atmospheric air, water and soil. This group is very numerous. Its most famous representatives are benzo(a)pyrene, 7-12 dimethylbenz(a)-anthracene, dibenz(a,H)anthracene; 3,4-benzofluorethane, which has high carcinogenic activity. Benz(a)pyrene (BP) is one of the most active and widespread compounds in the environment, which gives reason to consider it as an indicator of the PAH group. The level of inorganic carcinogenic substances in the environment has also increased due to the widespread development of the mining industry and non-ferrous metallurgy, the use of some of them, for example, arsenic, as pesticides, etc.

Thus, a danger to public health from exposure to carcinogenic nitroso compounds can arise in the same way as with other chemical carcinogens, due to environmental pollution. However, it is still not clear whether amounts of NS found in the environment can cause malignant neoplasms in humans. It has been suggested that the carcinogenic effect may occur after many years of exposure to low doses, if other associated factors (promoters) were simultaneously influenced.

Carcinogenic substances can exert their influence directly on organs and tissues (primarily) or through the formation of products of their transformation in the body (secondary). Despite the variety of tumor reactions that can be caused by carcinogens in experimental animals and humans (under conditions occupational hazard) one can note the general features characteristic of their action.

Firstly, when exposed to carcinogenic substances, tumor development is not observed immediately, but after a more or less long period after the onset of action of the agent and, therefore, belongs to the category of long-term effects. The duration of the latent period depends on the species of animal and is proportional to the total life expectancy. For example, when using active carcinogens, the latent period in rodents (mice, rats) can be several months, in dogs - several years, in monkeys - 5-10 years. It is not a constant value for one type of animal: an increase in the activity of a carcinogen leads to its reduction, and a decrease in dose leads to an extension. Cancer can also develop long after the action of the carcinogen ceases, for example, in conditions of occupational hazard 20-40 years after contact with it.

Another feature of the action of carcinogens is related to the frequency of the effect. The experience of experimental oncology shows that only a few highly active carcinogenic compounds can induce tumors in almost 100% of animals. But even under such conditions there are individuals who are insensitive to their action. In humans, a high degree of damage can be observed in cases of prolonged continuous contact with such strong occupational carcinogens as coal tar pitch and aromatic amines. In most cases, the tumor reaction does not occur in all, but only in some representatives of the exposed population and is to a certain extent probabilistic in nature.

Among the many chemical compounds Polluting the environment, several hundred substances have been isolated that have demonstrated carcinogenic properties in experiments on animals. There are approximately two dozen chemical compounds that have been proven carcinogenic to humans.

Due to the fact that one of the main sources of the formation of carcinogenic substances is the industrial sector, a significant amount of research is devoted to the study of cancer incidence in certain industries and among various professional groups.

To date, extensive information has accumulated on the carcinogenicity for humans of a number of agents in the industrial environment, on the degree of risk of cancer development caused by contact with them, as well as on the approximate value of the latent period of such development. In industrial conditions, people come into contact with a wide variety of carcinogenic substances. Occupational carcinogens include agents of organic (aromatic hydrocarbons, alkylating agents, etc.) and inorganic (metals, fibers) nature, as well as physical factors (ionizing radiation).

2. STATE OF THE ATMOSPHERE AND TRANSPORT

Among all types of transport, automobiles cause the greatest damage to the environment. In Russia, about 64 million people live in areas of high air pollution; average annual concentrations of air pollutants exceed the maximum permissible levels in more than 600 Russian cities.

Carbon monoxide and nitrogen oxides, so intensely emitted by the seemingly innocent bluish smoke of a car muffler, are one of the main causes of headaches, fatigue, unmotivated irritation, and low productivity. Sulfur dioxide can affect the genetic apparatus, promoting infertility and congenital deformities, and all together these factors lead to stress, nervous manifestations, a desire for solitude, and indifference to those closest to you. In large cities, circulatory and respiratory diseases, heart attacks, hypertension and neoplasms are also more common. According to experts, the “contribution” road transport into the atmosphere is up to 90% carbon monoxide and 70% nitrogen oxide. The car also adds heavy metals and other harmful substances to the soil and air.

The main sources of air pollution in cars are exhaust gases from internal combustion engines, crankcase gases, and fuel fumes.

An internal combustion engine is a heat engine in which the chemical energy of a fuel is converted into mechanical work. Based on the type of fuel used, internal combustion engines are divided into engines running on gasoline, gas and diesel fuel. According to the ignition method, combustible mixtures of internal combustion engines are either compression ignition (diesels) or spark plug ignition.

Diesel fuel is a mixture of petroleum hydrocarbons with boiling points from 200 to 350 0 C. Diesel fuel must have a certain viscosity and self-ignition, be chemically stable, and have minimal smoke and toxicity during combustion. To improve these properties, additives, anti-smoke or multifunctional, are introduced into fuels.

Education toxic substances– products of incomplete combustion and nitrogen oxides in the engine cylinder during the combustion process occur fundamentally in various ways. The first group of toxic substances is associated with chemical reactions of fuel oxidation, occurring both in the pre-flame period and during the combustion process - expansion. The second group of toxic substances is formed by the combination of nitrogen and excess oxygen in combustion products. The reaction of formation of nitrogen oxides is thermal in nature and is not directly related to fuel oxidation reactions. Therefore, it is advisable to consider the mechanism of formation of these toxic substances separately.

The main toxic emissions from a car include: exhaust gases (EG), crankcase gases and fuel vapors. Exhaust gases emitted by the engine contain carbon monoxide (CO), hydrocarbons (C X H Y), nitrogen oxides (NO X), benzo(a)pyrene, aldehydes and soot. Crankcase gases are a mixture of part of the exhaust gases that penetrated through the leaks of the piston rings into the engine crankcase with engine oil vapors. Fuel vapors enter the environment from the engine power system: joints, hoses, etc. The distribution of the main emission components of a carburetor engine is as follows: exhaust gases contain 95% CO, 55% C X H Y and 98% NO X, crankcase gases contain 5% C X H Y, 2% NO X, and fuel vapors contain up to 40% C X H Y .

IN general case Engine exhaust gases may contain the following non-toxic and toxic components: O, O 2, O 3, C, CO, CO 2, CH 4, C n H m, C n H m O, NO, NO 2, N, N 2, NH 3, HNO 3, HCN, H, H 2, OH, H 2 O.

The main toxic substances - products of incomplete combustion - are soot, carbon monoxide, hydrocarbons, and aldehydes.

Table 1 – Content of toxic emissions in engine exhaust gases

Components	The share of the toxic component in the exhaust gas of internal combustion engines
	Carburetor		Diesel
	IN %	per 1000l of fuel, kg	V %	per 1000l of fuel, kg
	0,5-12,0	up to 200	0,01-0,5	up to 25
NO X	up to 0.8		up to 0.5
C X H Y	0,2 – 3,0		0,009-0,5
Benz(a)pyrene		up to 10 μg/m 3
Aldehydes	up to 0.2 mg/l		0.001-0.09 mg/l
Soot	up to 0.04 g/m 3		0.01-1.1 g/m 3

Harmful toxic emissions can be divided into regulated and unregulated. They act on the human body in different ways. Harmful toxic emissions: CO, NO X, C X H Y, R X CHO, SO 2, soot, smoke.

CO (carbon monoxide)- This gas is colorless and odorless, lighter than air. Formed on the surface of the piston and on the cylinder wall, in which activation does not occur due to intense heat removal from the wall, poor fuel atomization and dissociation of CO 2 into CO and O 2 at high temperatures.

During diesel operation, the CO concentration is insignificant (0.1...0.2%). In carburetor engines, when idling and at low loads, the CO content reaches 5...8% due to operation on enriched mixtures. This is achieved so that when bad conditions mixture formation to ensure the number of evaporated molecules required for ignition and combustion.

NO X (nitrogen oxides)– the most toxic exhaust gas.

N is an inert gas under normal conditions. Reacts actively with oxygen at high temperatures.

Exhaust gas emissions depend on the ambient temperature. The greater the engine load, the higher the temperature in the combustion chamber, and accordingly the emission of nitrogen oxides increases.

In addition, the temperature in the combustion zone (combustion chamber) largely depends on the composition of the mixture. A mixture that is too lean or rich during combustion releases less heat, the combustion process slows down and is accompanied by big losses heat in the wall, i.e. under such conditions, less NO x is released, and emissions increase when the mixture composition is close to stoichiometric (1 kg of fuel to 15 kg of air). For diesel engines, the NOx composition depends on the fuel injection advance angle and the fuel ignition delay period. As the fuel injection advance angle increases, the ignition delay period lengthens, the homogeneity of the air-fuel mixture improves, more fuel evaporates, and during combustion the temperature increases sharply (3 times), i.e. the amount of NO x increases.

In addition, with a decrease in the fuel injection advance angle, the emission of nitrogen oxides can be significantly reduced, but at the same time, power and economic performance are significantly deteriorated.

Hydrogens (C x H y)- ethane, methane, benzene, acetylene and other toxic elements. EG contains about 200 different hydrohydrogens.

In diesel engines, C x H y are formed in the combustion chamber due to a heterogeneous mixture, i.e. the flame goes out in a very rich mixture, where there is not enough air due to improper turbulence, low temperature, poor atomization. An internal combustion engine emits more C x H y when idling due to poor turbulence and reduced combustion rate.

Smoke- opaque gas. The smoke can be white, blue, black. The color depends on the state of the exhaust gas.

White and blue smoke- this is a mixture of a drop of fuel with a microscopic amount of steam; formed due to incomplete combustion and subsequent condensation.

White smoke forms when the engine is cold and then disappears due to heating. The difference between white smoke and blue smoke is determined by the size of the drop: if the diameter of the drop is greater than the wavelength of blue, then the eye perceives the smoke as white.

The factors that determine the occurrence of white and blue smoke, as well as its smell in the exhaust gas, include engine temperature, method of mixture formation, fuel characteristics (the color of the droplet depends on the temperature of its formation: as the fuel temperature increases, the smoke becomes Blue colour, i.e. droplet size decreases).

In addition, there is blue smoke from the oil.

The presence of smoke indicates that the temperature is not sufficient for complete combustion of the fuel.

Black smoke is made up of soot.

Smoke negatively affects the human body, animals and vegetation.

Soot- is a shapeless body without a crystal lattice; In the exhaust gas of a diesel engine, soot consists of undefined particles with sizes of 0.3... 100 microns.

The reason for the formation of soot is that the energy conditions in the cylinder of a diesel engine are sufficient for the fuel molecule to be completely destroyed. Lighter hydrogen atoms diffuse into the oxygen-rich layer, react with it and, as it were, isolate the hydrocarbon atoms from contact with oxygen.

Soot formation depends on temperature, combustion chamber pressure, fuel type, and fuel-air ratio.

The amount of soot depends on the temperature in the combustion zone.

There are other factors in the formation of soot - zones of rich mixture and zones of contact of fuel with a cold wall, as well as improper turbulence of the mixture.

The rate of soot combustion depends on the particle size, for example, soot is burned completely when the particle size is less than 0.01 microns.

SO2 (sulfur oxide)— formed during engine operation from fuel obtained from sulfurous oil (especially in diesel engines); these emissions irritate the eyes and respiratory organs.

SO 2 ,H 2 S are very dangerous for vegetation.

The main air pollutant lead in the Russian Federation is currently vehicles using leaded gasoline: from 70 to 87% of total lead emissions according to various estimates. PbO (lead oxides)- occur in the exhaust gases of carburetor engines when leaded gasoline is used to increase the octane number to reduce detonation (this is a very fast, explosive combustion of individual sections of the working mixture in the engine cylinders with a flame propagation speed of up to 3000 m/s, accompanied by a significant increase in gas pressure). When one ton of leaded gasoline is burned, approximately 0.5...0.85 kg of lead oxides are released into the atmosphere. According to preliminary data, the problem of lead pollution from vehicle emissions is becoming significant in cities with a population of over 100,000 people and for local areas along heavily trafficked highways. A radical method of combating lead pollution from road transport emissions is to stop using leaded gasoline. According to 1995 data. 9 out of 25 oil refineries in Russia switched to the production of unleaded gasoline. In 1997, the share of unleaded gasoline in total production was 68%. However, due to financial and organizational difficulties, the complete abandonment of the production of leaded gasoline in the country is delayed.

Aldehydes (R x CHO)- are formed when fuel is burned at low temperatures or the mixture is very lean, and also due to the oxidation of a thin layer of oil in the cylinder wall.

When fuel is burned at high temperatures, these aldehydes disappear.

Air pollution occurs through three channels: 1) exhaust gas emitted through the exhaust pipe (65%); 2) crankcase gases (20%); 3) hydrocarbons as a result of evaporation of fuel from the tank, carburetor and pipelines (15%).

Each car emits about 200 different components into the atmosphere with exhaust gases. The most large group compounds - hydrocarbons. The effect of falling concentrations of atmospheric pollutants, that is, approaching normal state, is associated not only with the dilution of exhaust gases with air, but also with the ability to self-purify the atmosphere. Self-purification is based on various physical, physico-chemical and chemical processes. The precipitation of heavy suspended particles (sedimentation) quickly clears the atmosphere only of coarse particles. The processes of neutralization and binding of gases in the atmosphere are much slower. Green vegetation plays a significant role in this, since intense gas exchange occurs between plants. The rate of gas exchange between the plant world is 25-30 times higher than the rate of gas exchange between humans and the environment per unit mass of actively functioning organs. The amount of precipitation has a strong influence on the recovery process. They dissolve gases, salts, adsorb and deposit dust particles on the earth's surface.

Automotive emissions spread and transform in the atmosphere according to certain patterns.

Thus, solid particles larger than 0.1 mm settle on underlying surfaces mainly due to the action of gravitational forces.

Particles whose size is less than 0.1 mm, as well as gaseous impurities in the form of CO, C X H Y, NO X, SO X, spread in the atmosphere under the influence of diffusion processes. They enter into processes of physical and chemical interaction with each other and with atmospheric components, and their action manifests itself in local areas within certain regions.

In this case, the dispersion of impurities in the atmosphere is an integral part of the pollution process and depends on many factors.

The degree of atmospheric air pollution by emissions from ATK facilities depends on the possibility of transporting the pollutants in question over significant distances, the level of their chemical activity, and meteorological conditions of distribution.

Components of harmful emissions with increased reactivity, entering the free atmosphere, interact with each other and the components of atmospheric air. In this case, physical, chemical and photochemical interactions are distinguished.

Examples of physical response: condensation of acid vapors in humid air to form an aerosol, reduction in the size of liquid droplets as a result of evaporation in dry warm air. Liquid and solid particles can combine, adsorb, or dissolve gaseous substances.

Reactions of synthesis and decomposition, oxidation and reduction are carried out between the gaseous components of pollutants and atmospheric air. Some processes of chemical transformations begin immediately from the moment emissions enter the atmosphere, others - when a favorable conditions— necessary reagents, solar radiation, and other factors.

When performing transport work, the emission of carbon compounds in the form of CO and C X H Y is significant.

Carbon monoxide in the atmosphere diffuses quickly and usually does not create high concentrations. It is intensively absorbed by soil microorganisms; in the atmosphere it can be oxidized to CO 2 in the presence of impurities - strong oxidizing agents (O, O3), peroxide compounds and free radicals.

Hydrocarbons in the atmosphere undergo various transformations (oxidation, polymerization), interacting with other atmospheric pollutants, primarily under the influence of solar radiation. As a result of these reactions, peroxides, free radicals, and compounds with nitrogen and sulfur oxides are formed.

In a free atmosphere, sulfur dioxide (SO2) after some time is oxidized to sulfur dioxide (SO3) or interacts with other compounds, in particular hydrocarbons. The oxidation of sulfur dioxide to sulfur dioxide occurs in a free atmosphere during photochemical and catalytic reactions. In both cases, the end product is an aerosol or solution of sulfuric acid in rainwater.

In dry air, oxidation of sulfur dioxide occurs extremely slowly. In the dark, SO 2 oxidation is not observed. In the presence of nitrogen oxides in the air, the rate of oxidation of sulfur dioxide increases regardless of air humidity.

Hydrogen sulfide and carbon disulfide, when interacting with other pollutants, undergo slow oxidation in a free atmosphere to sulfuric anhydride. Sulfur dioxide can be adsorbed on the surface of solid particles from metal oxides, hydroxides or carbonates and oxidized to sulfate.

Nitrogen compounds entering the atmosphere from ATK facilities are mainly represented by NO and NO 2 . Nitrogen monoxide released into the atmosphere under the influence of sunlight intensively oxidized by atmospheric oxygen to nitrogen dioxide. The kinetics of further transformations of nitrogen dioxide is determined by its ability to absorb ultraviolet rays and dissociate into nitrogen monoxide and atomic oxygen in the processes of photochemical smog.

Photochemical smog is a complex mixture formed upon exposure to sunlight from two main components of automobile engine emissions - NO and hydrocarbon compounds. Other substances (SO 2), particulate matter can also contribute to smog, but are not the main carriers high level oxidative activity characteristic of smog. Stable meteorological conditions favor the development of smog:

– urban emissions are retained in the atmosphere as a result of inversion;

– serving as a kind of lid on a vessel with reagents;

– increasing the duration of contact and reaction,

– preventing dissipation (new emissions and reactions are added to the original ones).

Rice. 1. Formation of photochemical smog

The formation of smog and the formation of oxidant usually stops when solar radiation ceases at night and the dispersion of reactants and reaction products ceases.

In Moscow at normal conditions the concentration of tropospheric ozone, which is a precursor to the formation of photochemical smog, is quite low. Estimates show that the generation of ozone from nitrogen oxides and hydrocarbon compounds due to the transfer of air masses and an increase in its concentration, and therefore, the adverse impact occurs at a distance of 300-500 km from Moscow (in the Nizhny Novgorod region).

In addition to the meteorological factors of atmospheric self-purification, some components of harmful emissions from road transport participate in processes of interaction with components of the air environment, which result in the emergence of new harmful substances (secondary atmospheric pollutants). Pollutants enter into physical, chemical and photochemical interactions with atmospheric air components.

The variety of exhaust products from automobile engines can be classified into groups that are similar in the nature of their effects on organisms or in their chemical structure and properties:

non-toxic substances: nitrogen, oxygen, hydrogen, water vapor and carbon dioxide, the content of which in the atmosphere under normal conditions does not reach a level harmful to humans;


2) carbon monoxide, the presence of which is characteristic of gasoline engine exhaust;


3) nitrogen oxides (~ 98% NO, ~ 2% NO 2), which combine with oxygen as they remain in the atmosphere;


4) hydrocarbons (alkaine, alkenes, alkadienes, cyclanes, aromatic compounds);


5) aldehydes;


6) soot;


7) lead compounds.


8) sulfur dioxide.


The sensitivity of the population to the effects of air pollution depends on a large number of factors, including age, gender, general health, nutrition, temperature and humidity, etc. Elderly people, children, sick people, smokers, sufferers chronic bronchitis, coronary insufficiency, asthma, are more vulnerable.


General scheme of the body’s response to exposure to environmental pollutants according to data World Organization health care (WHO) is as follows (Figure 2)





The problem of the composition of atmospheric air and its pollution from vehicle emissions is becoming increasingly urgent.


Among the direct action factors (everything except environmental pollution), air pollution certainly occupies the first place, since air is a product of continuous consumption by the body.


The human respiratory system has a number of mechanisms that help protect the body from exposure to air pollutants. Nasal hairs filter out large particles. The sticky mucous membrane at the top of the respiratory tract traps small particles and dissolves some gaseous pollutants. The mechanism of involuntary sneezing and coughing removes contaminated air and mucus when the respiratory system is irritated.


Fine particles pose the greatest risk to human health because they can pass through the natural protective membrane into the lungs. Inhaling ozone causes coughing, shortness of breath, damages lung tissue and weakens the immune system.


3. TASK


Environmental factors that have the greatest impact on the number of modern reptiles:
MAJOR DECISIONS TAKEN AT THE UN ENVIRONMENT CONFERENCE HELD IN RIO DE JANEIRO IN JUNE 1992 LIST THE BASIC PRINCIPLES OF ENVIRONMENTAL PROTECTION TECHNOGENIC SYSTEMS AND THEIR INTERACTION WITH THE ENVIRONMENT

Carcinogens are certain factors that, under the influence of which a person is more likely to develop malignant tumors. The rate of development of the pathological process depends on the state of people’s health, the duration of exposure to organic and inorganic substances or ionizing radiation. Carcinogens are found in small quantities in food and household chemicals; they are part of some pharmacological drugs. It will not be possible to completely protect yourself and your loved ones from compounds that cause cancer. But it is quite possible to reduce the amount of carcinogens in the environment, as well as minimize the consequences of contact with them.

Classification of carcinogens

The list of carcinogens includes several thousand substances of chemical and organic origin. Scientists were unable to collect them in one classification due to the lack of a unifying feature. Carcinogens were systematized as follows:

• according to the degree of effect on the human body: clearly carcinogenic, slightly carcinogenic, carcinogenic;
• according to the risk of developing oncology: compounds that are obtained at certain stages of technological processes with a high, medium and low probability of the formation of cancerous tumors, as well as substances whose carcinogenic properties are questioned;
• if possible, the formation of several tumors: under the influence of chemical compounds, a malignant neoplasm develops on a specific organ or in various parts of the human body;
• by time of tumor formation: carcinogens with local, remote-selective, systemic effects;
• by origin: carcinogenic substances that are produced in the human body or penetrated into it from the environment/

Chemical substances are also classified according to the nature of the pathological process they cause. One type of carcinogen changes the gene structure of the cell, others do not affect the body at the gene level and provoke tumor growth in other ways. Compounds that affect DNA are especially dangerous - the natural death of cells is disrupted, they begin to divide uncontrollably. If this pathological process affects healthy tissue, then the person is subsequently diagnosed with a benign tumor. But when defective, damaged cells divide, there is a high probability of a malignant tumor appearing.

Types of carcinogens

Carcinogenic substances are not only chemical compounds that are produced by various industries. They are found in food, plants, and are produced by viruses and bacteria.. Long-term exposure to substances hazardous to the body leads to the formation of tumors not only in humans, but also in animals.

Carcinogens are part of natural substances that, when consumed correctly, are very beneficial to health. But as soon as you exceed the dosage or treatment period recommended by the doctor, a favorable environment for division is immediately created cancer cells. Such compounds include the well-known birch tar, widely used in folk medicine.

To have a good understanding of the types of carcinogens, you should understand why these compounds are dangerous. First of all, you need to pay attention to food additives, medicines, insecticides and plant growth accelerators. That is, something without which it is difficult to imagine the life of a modern person.

Natural carcinogens

This term combines factors and hazardous substances that are always present in the environment. Their appearance was in no way influenced by man. The main cause of most diagnosed skin cancers is solar radiation, or ultraviolet radiation. Doctors never tire of warning about the dangers of tanning. In an effort to acquire a beautiful chocolate skin tone, women and men spend a lot of time on the beach or in the solarium. Under the influence of sunlight, a pathological process of cell division with an altered gene structure can begin in all layers of the epidermis.

Tan lovers are more likely to develop cancerous tumor 5-6 times higher. People with fair skin living in northern latitudes should be especially careful.

Radon is one of the most dangerous compounds for the human body.. It is an inert gas found in the earth's crust and building materials. The risk of developing cancer is higher in people who live on the first floors of high-rise buildings. Significant levels of radon have been noted by experts in houses located in rural areas. Such buildings have an underground floor or cellar, that is, there is no protection against inert gas. Radon is also found:

• in tap water that comes from an artesian well located on a piece of land with a high radon content;
• in natural gas burned for space heating or cooking.

If the house or apartment has poor sealing and no ventilation, then the concentration of radon in the surrounding area is high. This situation is typical for northern latitudes, where the heating season lasts most of the year.

Carcinogenic effects on the human body are caused by:

• hormones produced by the endocrine glands: prolactin and estrogens;
• tyrosine, tryptophan, bile acids, which are in the form of metabolites;
• polycyclic aromatic hydrocarbons contained in brown and hard coal or formed during the combustion of forests.

Experts include some viruses as biological compounds whose carcinogenic effects are still being studied. They cause the development of severe liver diseases - hepatitis B and C.

Bacterium Helicobacter pylori cannot directly influence the formation of a cancerous tumor. But it can provoke gastric and duodenal ulcers, erosive and chronic gastritis. Doctors classify these diseases as precancerous conditions.

Anthropogenic carcinogens

The appearance of this type of hazardous substances in the environment was the result of human actions. The following carcinogenic factors are included in this category:

• compounds that are part of carbon monoxide and exhaust, as well as those contained in household or industrial soot;
• polycyclic aromatic hydrocarbons released during the combustion of petroleum products, coal, and garbage;
• products remaining after wood or oil processing;
• formaldehyde resins that contain the smog of big cities.

Ionizing radiation is extremely dangerous for the human body.. Even in small doses, this carcinogenic factor causes radiation sickness in humans and causes radiation burns. Depending on their type, the rays penetrate various layers of the epidermis and provoke changes at the cellular level. Sources of ionizing radiation can enter the body through food or inhalation. Gamma rays are mortally dangerous to humans, from which only a thick layer of concrete or cement can protect.

Foods that cause cancer

Many people, when visiting stores, carefully read labels, trying to assess the carcinogenic effect of products. But manufacturers carefully hide food additives that can cause cancer. Incomprehensible capital letters with numerical designations remain a mystery to the average buyer. This is how compounds are encoded that increase the shelf life of products, improve their appearance and taste. The buyer, of course, realizes that natural milk cannot be stored for months. But finding a replacement for it on the supermarket counter is quite problematic - food additives are found in all dairy or fermented milk products.

A significant amount of nitrosamines is included in sausages and meat products. It is nitrites that give them an appetizing pink color and ensure a long shelf life. These chemical compounds, when directly exposed to the mucous membrane of the gastrointestinal tract, can provoke the formation of a cancerous tumor.

It should be kept in mind that, although unproven to be carcinogenic to humans, some food additives have been associated with cancer in animals. These are the well-known and frequently used saccharin and cyclamate. When purchasing, you should pay attention to the content of these sweeteners in curds and yoghurts.

Even healthy foods will become carcinogenic if they are fried in large quantities of any vegetable oil. Toxic compounds are found in the crispy, crispy crust:

• acrylamide;
• fatty acid metabolites;
• various aldehydes;
• benzopyrene

The effect of carcinogens on the human body is stronger, the longer the product is in the oil. This applies not only to ordinary fried potatoes. Toxic compounds contained:

• in pies and donuts;
• in potato chips;
• in meat baked on coal.

Some cafes and eateries neglect the norms established by law and do not change the oil before preparing the next portion of food. In such chebureks and pies the concentration of carcinogens is so high that it can cause serious harm to health.

Coffee, which many people cannot imagine their life without, contains the substance acrylamide. Experts could not confirm the likelihood of tumor formation when drinking coffee. But the presence of the carcinogen acrylamide in its composition does not allow us to refute this possibility. Therefore, you should limit the number of cups of coffee to 4-5 per day.

Carcinogens in food are found not only as food additives, they can form there over time. Aflatoxin is especially dangerous to the human body. It is produced by mold fungi, the spores of which can be found in cereals, bran, nuts and flour. Products containing aflatoxin can be easily identified by their unusual bitter taste. The carcinogen is not destroyed by heat treatment and in large doses often causes the death of animals. In humans, aflatoxin can cause a malignant liver tumor.

The most dangerous carcinogens

There are many compounds in the environment that have negative impact on the human body. But substances that people encounter in everyday life and at work pose a particular danger. Here is a list of carcinogens:

• Asbestos. A fine-fiber mineral from the silicate group is often used in construction work. If asbestos was used in the construction of residential premises, then the finest fibers may be present in their airspace. This carcinogen, after entering the body, causes the formation of malignant neoplasms of the lungs, larynx and stomach.
• Vinyl chloride. Contained in many types of plastic that are used in medicine. Consumer goods are made from it. Tumors of the lungs and liver are quite often diagnosed in workers of such enterprises.
• Benzene. The compound with prolonged contact provokes the formation of leukemia.
• Arsenic, nickel, chromium, cadmium. Derivatives of these compounds are found in exhaust gases. Carcinogens contribute to the development of prostate and bladder cancer.

Interesting fact: if potatoes are stored in a garage, they absorb carcinogens from exhaust gases. The medical literature describes cases of rectal cancer being diagnosed due to the use of pieces of newspaper as toilet paper.

How to get rid of carcinogens

Regular foods will help remove carcinogens from the body. They bind dangerous compounds using chemical reactions or simply absorb them on their surface. These products include:

• cabbage, carrots, beets and freshly squeezed juices from these vegetables;
• cereal porridges: buckwheat, oatmeal, rice;
• green tea, fermented milk products;
• dried fruits compote.

You should include cereals and vegetables in your daily diet. They are not only capable of removing carcinogens, but are also an excellent preventative against the formation of malignant tumors. You can cleanse the gastrointestinal tract of carcinogens accumulated on its mucous membrane using absorbents and enterosorbents (activated carbon, polysorb, smecta, lactofiltrum). A course of taking these pharmacological drugs will significantly reduce the negative impact of hazardous substances on the human body.

Chemical carcinogenic factors

In 1915, Japanese scientists Yamagiwa and Ishikawa induced small tumors by applying coal tar to the skin of a rabbit's ears, thus demonstrating for the first time that tumors can grow under the influence of a chemical substance.

The most common classification of chemical carcinogenic substances at present is their division into classes according to their chemical structure: 1) polycyclic aromatic hydrocarbons (PAHs) and heterocyclic compounds; 2) aromatic azo compounds; 3) aromatic amino compounds; 4) nitroso compounds and nitramines; 5) metals, metalloids and inorganic salts. Other chemicals may also have carcinogenic properties.

Accepted by origin highlight anthropogenic carcinogens, the appearance of which in the environment is associated with human activity, and natural, not related to production or other human activities.

Chemical carcinogens can also be divided into three groups depending on the nature of the action on the body:

1) substances that cause tumors mainly at the site of application (benz(a)pyrene and other PAHs);

2) substances of remote, predominantly selective action, inducing tumors not at the injection site, but selectively in one or another organ (2-naphthylamine, benzidine cause bladder tumors; p-dimethylaminoazobenzene induces liver tumors in animals; vinyl chloride causes the development of liver angiosarcomas in humans );

3) substances with multiple effects that cause tumors of various morphological structures in different organs and tissues (2-acetylaminofluorene, 3,3-dichlorobenzidine or o-tolidine induce breast tumors, sebaceous glands, liver and other organs in animals).

This division of carcinogenic agents is conditional, since depending on the method of introducing the substance into the body or the type

In an experimental animal, the localization of tumors and their morphology may vary depending on the characteristics of the metabolism of carcinogenic substances.

According to the degree of carcinogenic hazard For humans, blastomogenic substances are divided into 4 categories:

I. Chemicals whose carcinogenicity has been proven both in animal experiments and by data from population epidemiological studies.

II. Chemicals with proven strong carcinogenicity in experiments on several animal species and through various routes of administration. Despite the lack of data on carcinogenicity for humans, they should be considered potentially dangerous for him and the same strict preventive measures should be taken as for compounds of the first category.

III. Chemicals with weak carcinogenic activity that cause tumors in animals in 20-30% of cases in late dates experience, mainly towards the end of life.

IV. Chemicals with “doubtful” carcinogenic activity. This category includes chemical compounds whose carcinogenic activity is not always clearly detected in experiments.

A more specific classification of carcinogenic substances, based on the analysis of epidemiological and experimental data on 585 chemical substances, groups of compounds or technological processes, was developed by IARC in 1982. The division of all compounds studied for carcinogenicity proposed in this classification is of great practical importance, as it allows one to evaluate the actual the danger of chemicals to humans and set priorities in carrying out preventive measures.

They have the greatest carcinogenic activity PAH (7,12-dimethylbenz(a)anthracene, 20-methylcholanthrene, benzo(a)pyrene, etc.), heterocyclic compounds (9-methyl-3,4-benzacridine and 4-nitroquinoline-N-oxide). PAHs are found as products of incomplete combustion in the exhaust gases of motor vehicles, in the smoke of blast furnaces, in tobacco smoke, in smoking products, as well as in emissions from volcanoes.

Aromatic azo compounds(azo dyes) are used for coloring natural and synthetic fabrics, for color printing in printing, in cosmetics (monoazobenzene, N,N`-dimethyl-4-

aminoazobenzene). Tumors usually arise not at the site of administration of azo dyes, but in organs remote from the site of application (liver, bladder).

Aromatic amino compounds(2-naphthylamine, benzidine, 4-aminodiphenyl) cause tumors of various locations in animals: bladder, subcutaneous tissue, liver, mammary and sebaceous glands, intestines. Aromatic amino compounds are used in various industries (in the synthesis of organic dyes, medicines, insecticides, etc.).

Nitroso compounds and nitramines(N-methylnitrosourethane, methylnitrosourea) cause tumors in animals that vary in morphological structure and location. Currently, the possibility of endogenous synthesis of some nitroso compounds from precursors - secondary and tertiary amines, alkyl and arylamides and nitrosating agents - nitrites, nitrates, nitrogen oxides has been established. This process occurs in the human gastrointestinal tract when amines and nitrites (nitrates) are taken from food. In this regard, an important task is to reduce the content of nitrites and nitrates (used as preservatives) in food products.

Metals, metalloids, asbestos. It is known that a number of metals (nickel, chromium, arsenic, cobalt, lead, titanium, zinc, iron) have carcinogenic activity and many of them cause various sarcomas at the injection site histological structure. Asbestos and its varieties (white asbestos - chrysotile, amphibole and its variety - blue asbestos - crocidolite) play a significant role in the occurrence of occupational cancer in humans. It has been established that with prolonged contact, workers engaged in the extraction and processing of asbestos develop tumors of the lung, gastrointestinal tract, mesothelioma of the pleura and peritoneum. The blastomogenic activity of asbestos depends on the size of the fibers: the most active are fibers with a length of at least 7-10 microns and a thickness of no more than 2-3 microns.

Natural carcinogens. Currently, more than 20 carcinogens are known natural origin- waste products of plants, including lower plants - mold fungi. Aspergillus flavus produces aflatoxins B1, B2 and G1, G2; A. nodulans And A. versicolor - sterigmatocystin. Penicillium islandicum forms luteoskyrin, cyclochlorotene; P. griseofulvum-

griseofulvin; Strepromyces hepaticus- elaiomycin; Fusarium sporotrichum- fusariotoxin. Safrole, which is found in oil (an aromatic additive derived from cinnamon and nutmeg), is also a carcinogen. Carcinogens have also been isolated from higher plants: the Asteraceae family Senecio contains alkaloids in the structure of which a pyrrolizidine nucleus is identified; the main toxic metabolite and ultimate carcinogen is pyrrole ether. bracken (Pteridium aquilinum) When consumed, it causes tumors of the small intestine and bladder.

Endogenous carcinogens. May cause the development of certain types of malignant neoplasms in special conditions internal environment, in the presence of genetic, hormonal and metabolic disorders. They can be considered as endogenous factors that realize blastomogenic potential directly or indirectly. This was confirmed by experiments on the induction of tumors in animals by subcutaneous administration of benzene extracts from liver tissue of a person who died from stomach cancer. The effect of bile extracts has been studied, lung tissue, urine, and in all cases, as a rule, tumors occurred in the animals. Extracts isolated from organs of those who died from non-tumor diseases were low or inactive. It has also been established that during blastomogenesis, during the biotransformation of tryptophan in the body, some intermediate products of the orthoaminophenol structure are formed and accumulated: 3-hydroxykynurenine, 3-hydroxyanthranilic acid, 2-amino-3-hydroxyacetophenone. All these metabolites are also detected in small quantities in urine healthy people, however, with some neoplasms their number increases sharply (for example, 3-hydroxyanthranilic acid for bladder tumors). In addition, perverted tryptophan metabolism was found in patients with bladder tumors. In experiments devoted to the study of the carcinogenic properties of tryptophan metabolites, 3-hydroxyanthranilic acid turned out to be the most active, the administration of which induced leukemia and tumors in animals. It has also been shown that the administration of large quantities of tryptophan causes the development of dyshormonal tumors and that some metabolites of the cyclic amino acid tyrosine (paraoxyphenyllactic and paraoxyphenylpyruvic acids) have carcinogenic properties and cause tumors of the lungs, liver, and urinary tract.

bladder, uterus, ovaries, leukemia. Clinical observations indicate an increase in the content of parahydroxyphenyllactic acid in patients with leukemia and reticulosarcoma. All this indicates that the endogenous carcinogenic metabolites of tryptophan and tyrosine may be responsible for the development of some spontaneous tumors in humans.

General patterns of action of chemical carcinogens. All chemical carcinogenic compounds have a number of common features of action, regardless of their structure and physicochemical properties. First of all, carcinogens are characterized by a long latent period of action: true, or biological, and clinical latent periods. Tumor transformation does not begin immediately after contact of a carcinogen with a cell: first, the carcinogenic substance undergoes biotransformation, resulting in the formation of carcinogenic metabolites that penetrate the cell, changing its genetic apparatus, causing malignancy. The biological latent period is the time from the formation of a carcinogenic metabolite in the body until the onset of uncontrolled growth. The clinical latent period is longer and is calculated from the beginning of contact with a carcinogenic agent until the clinical detection of a tumor, and the beginning of contact with a carcinogen can be clearly defined, and the time of clinical detection of a tumor can vary widely.

The duration of the latent period can vary significantly. Thus, upon contact with arsenic, skin tumors can develop after 30-40 years, occupational bladder tumors in workers in contact with 2-naphthylamine or benzidine - within 3 to 30 years. The duration of the latent period depends on the carcinogenic activity of the substances, the intensity and duration of contact of the body with the carcinogenic agent. The manifestation of the oncogenic activity of a carcinogen depends on the type of animal, its genetic characteristics, gender, age, cocarcinogenic modifying influences. The carcinogenic activity of a substance is determined by the speed and intensity of metabolic transformations and, accordingly, the amount of final carcinogenic metabolites formed, as well as the dose of the administered carcinogen. In addition, promoters of carcinogenesis may be of no small importance.

One of the important features of the action of carcinogens is the dose-time-effect relationship. Correlation detected

between the dose (total and single), the latent period and the incidence of tumors. Moreover, the higher the single dose, the shorter the latent period and the higher the incidence of tumors. Strong carcinogens have a shorter latent period.

For most chemical carcinogens, it has been shown that the final effect depends not so much on a single dose as on the total dose. A single dose determines the time required for tumor induction. When splitting the dose, to obtain the same final effect, a longer administration of the carcinogen is necessary; in these cases, “time makes up for the dose.”

An important element environment that can have a significant impact on public health is housing.

Hygienists have long known the term “housing diseases”, i.e. diseases, the occurrence of which is largely determined by the nature of a person’s living conditions.

These included tuberculosis, rheumatism, some mental and cardiovascular diseases and so on.

In the specific conditions of the 21st century, characterized, in particular, by the active chemicalization of everyday life, the introduction of many hundreds and thousands of new compounds, the use of new building materials, etc., a list of diseases, the occurrence and development of which can be influenced by living conditions (in the broad sense of the word ), increases.

Air factor

There are serious reasons to believe that the quality of the internal environment of a modern home (primarily air) in some cases can also contribute to the occurrence of cancer in humans.

The point is not only that in non-industrial premises, in particular in the home, a person spends up to 7.0% of his time, which in itself makes it necessary to assess the possibility of the influence of the internal environment of the premises on the human body.

It is also important that the air quality in non-industrial premises is often worse quality outdoor air and even industrial air.

The air environment of a home is formed under the influence of a number of factors: products of incomplete combustion of gas formed when using gas stoves; substances arising during the cooking process; anthropotoxins released as a result of the vital activity of the human body; products of destruction of polymer materials from which household items, floors, wall coverings, etc. are made; compounds released from building structures (concrete products, etc.) and soil; smoking products; substances formed when using personal hygiene products, detergents and other household cosmetics; substances coming from atmospheric air.

This list alone of the sources of formation of the quality of the air environment of a home indicates a wide variety of compounds that can affect the human body (the number of toxic substances present in the air environment of residential premises ranges from 45 to 70). In rooms where people smoke, the number of air pollutants increases many times over.

Among this variety of chemicals, there are those that attract special attention from oncologists due to their potential carcinogenic hazard to humans.

Polycyclic aromatic hydrocarbons

One of the main sources polycyclic aromatic hydrocarbons (PAH) in the home is the combustion of gas in household appliances, as well as smoking and atmospheric air.

The “contribution” of atmospheric air to the aerogenic dose of PAHs in populated areas, near which coke-chemical, metallurgical, etc. enterprises are located. industry. Under normal conditions, the influence of atmospheric air is much less.

Radon

Radon (222Rn) and its decay products are intermediate decay products of uranium earth's crust. Their source can be the building structures of residential premises; radon can directly come from the ground into the basement, and then into residential premises.

Radon and thoron, inhaled in indoor air, are one of the main sources of radiation and account for more than half of the dose of natural radiation affecting people living in temperate climate zones. Epidemiological studies have shown the role of radon and its decay products in increasing the mortality of miners from lung cancer.

This allowed us to assume the existence of a real danger of radon for the population in their homes. Many studies provide data confirming this possibility, especially in cold climate zones where rooms are rarely ventilated.

At the same time, the possible role of radon and its products indoors in the occurrence of lung cancer is estimated at 2-10% of cases, and for smokers the likelihood of developing a tumor increases by more than 25 times.

The problem of radioactivity in the home is not new. Hygienists studied it 30-40 years ago. Even then, the main sources of radioactivity in the air of a home were known: building structures and the soil under the building, the total “contribution” of which to the formation of radon levels in a home is 78%.

It is from them that radon and thoron enter residential premises, where they can accumulate. Most building materials containing industrial waste (blast furnace and phosphate slag, fly ash, etc.) have increased radioactivity.

Of the rocks, granite and clay are the most radioactive. Radioactive substances can enter the air of apartments with gas combustion products. Moreover, the level of radioactivity in the air in kitchens can be approximately 5 times higher than the level of natural radioactivity in living rooms.

Formaldehyde

Formaldehyde (CH2O) has received particular attention in the last decade following studies showing its carcinogenicity in rats. According to experts International Agency for Research on Cancer (MAIR) Currently, there is sufficient evidence of the carcinogenicity of formaldehyde gas in experimental animals and limited evidence in humans for the occurrence of nasopharyngeal cancer. Formaldehyde has pronounced toxic and irritating properties to mucous membranes.

It is widely distributed in the environment and can be present in the air of residential premises, where it comes from particle boards made with formaldehyde adhesives, other glued wood products, foam insulation materials, carpets and textiles, etc. Urea, phenolic, polyacetate and other plastics and resins are made from formaldehyde. It is formed when smoking tobacco.

These data allow us to conclude that formaldehyde pollution in the air of residential and other premises has now become quite serious problem. To carry out preventive sanitary supervision over the use of polymer materials in construction, a average daily maximum permissible concentration of carcinogens(maximum concentration) formaldehyde for atmospheric air.

Nitrogen oxides

Nitrogen oxides (NOx)- compounds of both natural and anthropogenic origin that are widespread in the environment. In relation to the home, the main sources of nitrogen oxides are household heating devices operating on gas, smoking and atmospheric air. Nitrogen oxides are precursors N-nitroso compounds (NS).

NS themselves were also found in the air of residential premises, the main sources of which are smoking and frying food, and to a lesser extent - combustion products natural gas, atmospheric air, and poorly ventilated areas, the concentration of HC can reach relatively high values. The carcinogenic danger of NS is outlined above.

Asbestos

Asbestos is widely used in construction. It is used in the manufacture of more than 3 thousand products, including asbestos-cement sheets and pipes, insulation materials, flooring, ceilings, and gaskets. It is not surprising, therefore, that asbestos is often found in the air of different rooms.

According to some authors, indoor air pollution with asbestos may be associated with an oncological risk corresponding to 1 case of lung cancer per 100,000 population with an exposure duration of 20 years for adults and 10 years for children. Without going into a more detailed consideration of the issue, we emphasize that air pollution with asbestos can pose a real carcinogenic danger.

The list of carcinogenically hazardous household air pollutants is not limited to the compounds considered. Benzene, arsenic, halogen-containing organic compounds (chloroform, carbon tetrachloride, dichloromethane), etc. should also be mentioned here.

Overall, a rather serious picture emerges. Of course, it is impossible to imagine that almost the entire population is at risk. However, it can become quite real for people living in poorly ventilated gasified premises, in the construction of which asbestos-containing materials and building structures that are sources of radon were used.

From this point of view, the greatest interest is in studying the domestic environment in northern climatic zones, although quite serious situations can also arise in middle climatic zones.

Water factor

Different points of view are expressed about the degree of danger to the population from carcinogenic substances present in water. Without excluding the possibility of situations where the water factor can actually have a significant impact on the prevalence of malignant tumors among the population, nevertheless, in general, this effect appears to be relatively less significant than the effect, for example, of polluted atmospheric air.

When assessing the role of drinking water pollution in the formation of cancer incidence, it is probably necessary to do this very carefully, remembering that long-term exposure to even small (trace) amounts of carcinogens contained in drinking water can enhance the effect of carcinogenic substances entering the body in any other way .

Taking into account the above, data is provided below on the possible role of individual substances and groups of compounds that distribute by water, in the formation of cancer incidence.

Arsenic

Arsenic, recognized by IARC experts as unconditionally carcinogenic to humans, is so far, apparently, the only compound for which the role of waterborne distribution in the occurrence of human tumor diseases can be considered proven. Experts estimate that lifetime exposure to arsenic from drinking water at a concentration of 0.2 mg/l, gives a 5% risk of developing skin cancer.

Nitrates and nitrites

The study of the possible carcinogenic hazard associated with contamination of drinking water with nitrates and nitrites has not yet provided convincing data to determine their level from which the potential carcinogenic hazard for the population may increase.

In general, when assessing the problem of nitrate-nitrite water pollution from an oncohygienic point of view, it should be emphasized that the content of nitrates and nitrites in water bodies in most countries of the world continues to increase, and there are serious reasons to consider them potentially dangerous from a carcinogenic point of view for humans. Halogen-containing compounds (HCC)- water chlorination products. In the mid-70s of the 20th century, the first works appeared in the USA, which raised the question of the existence of a connection between the cancer incidence of the population and the presence of organochlorine compounds, formed during the chlorination of water. The most important among them are humic acids, tannins, quinones, phenols, etc.

The main localizations of tumors that are associated with the action of GSS are the bladder and colon, but it is not yet possible to draw a definitive conclusion. Apparently, a sober assessment of the real danger of HSS for humans is needed, based on new methodological approaches.

Asbestos

Asbestos enters water bodies mainly from asbestos-containing deposits, as well as with wastewater, although it can also enter from polluted atmospheric air. For drinking water, asbestos-cement pipes can also serve as a source of asbestos fibers.

Asbestos is undoubtedly carcinogenic to humans if it is inhaled into the body. Regarding asbestos-containing water, the vast majority of researchers are inclined to believe that asbestos in drinking water is not dangerous to human health.

Fluorine

The situation with the possible influence of fluoride on the cancer incidence of the population is even more unclear. Epidemiological studies to identify possible connection Studies between cancer and fluoride levels in water have been conducted for almost 30 years, but the question of the carcinogenic danger of water fluoridation remains open.

There are many other compounds present in water. According to American authors, drinking water can be polluted by more than 700 volatile organic compounds. Of all this variety of compounds, only a few are considered above, but they, however, according to modern ideas, can be considered among the most significant and studied.

It is obvious that as knowledge about the possible role of the water factor in the formation of cancer incidence increases, interest in this problem will increase.

Ecological aspects of the circulation of carcinogens

Human contact with various carcinogenic agents can occur in a variety of ways. As mentioned above, carcinogens enter the human body through air, water, food and medications, as well as through direct contact through the skin and mucous membranes.

The main source of air pollution is smoke emissions from enterprises, mainly the chemical industry, and exhaust gases from motor vehicles. At the same time, increased concentrations of PAHs, benzene, HC, vinyl chloride and other carcinogens are detected.

The air pollution index is the content of benzopyrene. From the atmospheric air, carcinogens enter the soil, plants, and water bodies. In addition, carcinogens enter the soil as a result of the use of mineral fertilizers and pesticides.

Nitrogen, potassium and phosphorus mineral fertilizers are used in agriculture. Potash fertilizers do not pose a carcinogenic risk. There is no convincing evidence of the carcinogenic effect of phosphorus-containing fertilizers.

Nitrogen-containing fertilizers are dangerous, the amount of which has recently doubled every 6-7 years. About 50% of the nitrogen introduced into the soil is absorbed by plants, the rest is washed out of the soil and increases the nitrate content in agricultural plants, surface water bodies and groundwater.

Many pesticides also have a carcinogenic effect, which are mainly chemically stable compounds that are highly soluble in fats, due to which they accumulate in plants, animal and human tissues. In addition, with rain and groundwater, carcinogens from the soil enter water sources.

IARC experts have recognized 22 pesticides as carcinogenic, which is due to their toxicity, as well as the presence of nitrosamines and their precursors in some of them.

In animal experiments, pesticides caused tumors of the liver, kidneys, lungs, skin, mammary glands and other organs. Contamination of plants used as livestock feed leads to the appearance of carcinogens in dairy and meat products.

The latter are also polluted by industrial and municipal waste. Compounds belonging to all groups of chemical carcinogens are found in contaminated water, which poses a potential danger to humans.

In residential premises main reason air pollution - smoking, and in kitchens - heat treatment of food. Asbestos filaments, radioactive polonium, radon are found in room dust in rooms with insufficient ventilation, and the concentration of cadmium and other metals is sometimes significantly higher than in the soil.

Uglyanitsa K.N., Lud N.G., Uglyanitsa N.K.

Malignant tumors have been known to mankind since ancient times. Hippocrates and other founders of medical science of the past clearly distinguished tumors from other diseases, but the causes of cancer remained a mystery. Tumors were found in Egyptian mummies; descriptions of processes resembling cancer are found in the works of ancient scientists who even tried to use surgical operations, sometimes very traumatic and ineffective.

Since knowledge was not sufficiently developed, there were no diagnostic methods, and surgical treatment was used quite rarely and did not always give at least some positive result, it is quite problematic to judge the prevalence of tumors even in the Middle Ages. Valuable information could have been provided by carefully conducted autopsies of the dead, but they were not widespread, and in a number of countries, due to religious and cultural characteristics, they were not carried out at all, so one can only guess how many tumors were hidden under the guise of “dropsy”, “jaundice” and similar causes of death.

For centuries, millions of people have been killed by various infections, being the main cause of mortality. The average life expectancy barely reached 35-40 years, and today it is known that Age plays an important role in the development of tumors.

By the age of 50, the risk of developing cancer is 50 times higher than 20, and more than half of tumors are found in people over 65 years of age.

It is not surprising that neoplasms did not frighten or worry our ancestors too much, because most of them simply did not live to that age.

With the deepening of knowledge in the field of the causes of various diseases, the advent of antibiotics, improvement of treatment methods, improvement of the sanitary-epidemiological situation and hygiene in general, infections lost their leading positions and by the twentieth century gave way to diseases of the cardiovascular system and tumors. This is how the science of oncology arose, the most important task of which was to unravel the essence and find out the causes of cancer development, as well as the development effective ways fight him.

Today, scientists of various profiles - geneticists, biochemists, oncologists, morphologists, immunologists - are working to determine the cause of cancer. Such interaction between specialists from different fields of science is bearing fruit, and it can be argued that the basic patterns of carcinogenesis have been studied quite well.

Tumor risk factors

A tumor is a pathological process characterized by rampant, uncontrolled, inadequate proliferation of cells endowed with specific characteristics that distinguish them from normal ones. The main feature of the neoplasm is its autonomy of growth, independence from the body as a whole and the ability to exist indefinitely in the presence of appropriate conditions.

As is known, Throughout life, cells are constantly formed that carry certain mutations. This happens because it is necessary to update the cellular composition of most organs and tissues, and it is impossible to avoid spontaneous mutations. Normally, antitumor immunity promptly destroys such cells and tumor development does not occur. With age defense mechanisms weaken, which creates the preconditions for the emergence of a malignant tumor. This partly explains more high risk cancer among older people.

According to WHO, in 90% of cases cancer appears due to exposure to external factors and only about 10% are associated with genetic abnormalities. However, this conclusion remains controversial, since with the development of modern cytogenetic research methods, new genetic disorders for various human tumors.

percentage of dominant factors in the development of cancer

Since the causes of cancer in most cases remain unclear, Malignant tumors are considered to be a multifactorial phenomenon.

Since it takes quite a long time for a tumor to form, it is quite problematic to reliably prove the role of a specific agent or external influence. Of all the possible external causes of malignant tumors, smoking is the most important. due to its widespread prevalence in the population, other carcinogens play a role in a relatively small number of cases.

• Elderly age;
• Family history and genetic disorders;
• The presence of bad habits and exposure to unfavorable environmental conditions;
• Chronic inflammatory processes of various localizations;
• Immunity disorders;
• Work in harmful conditions accompanied by contact with carcinogenic substances.

Psychological and spiritual reasons are becoming increasingly important, since the level of stress and stress on the psyche is constantly increasing, especially among residents of large cities.

While in adults, cancer most often occurs due to exposure to a number of external factors, Among the causes of cancer in children, the main place is given to genetic mutations and hereditary anomalies.

Cancer risk factors and their influence on the development of particular forms:

The longer a cell is exposed to unfavorable conditions, the higher the likelihood of mutations occurring in it and tumor growth subsequently, therefore the elderly, workers exposed to various carcinogens for a long time, and people suffering from disorders of the immune system should be under special control at doctors.

Video: What Causes Cancer?

What are carcinogens?

As mentioned above, a significant place among the main causes of cancer is given to carcinogens. These substances surround us everywhere, they are found in everyday life, get into food and water, and pollute the air. Modern man is forced to come into contact with a large number of different chemical compounds, not only when working with them, but also at home, but often most of us do not even think about possible danger one or another household chemical, food or medicine.

Carcinogens are substances, microorganisms or physical factors that are known to cause cancer. In other words, their role as a cause of malignant tumors has been proven through numerous studies and is beyond doubt.

The list of carcinogens is constantly expanding, and their spread is greatly facilitated by the development of industry (especially chemical, mining, metallurgical), the growth of large cities, as well as changes in the lifestyle of modern people.

The entire range of possible external factors that have carcinogenic properties can be divided into three main groups:

1. Chemical;
2. Physical;
3. Biological.

Carcinogens of chemical origin

Chemical carcinogenesis implies Negative influence substances entering the body from the outside, consumption of foods that have an unfavorable effect on the development of cancer, as well as the use of medications, vitamins and hormonal drugs (steroids, estrogens, etc.).

A large number of carcinogens enter the body from the external environment with emissions from industrial enterprises and vehicle exhaust gases, especially in major cities, agricultural waste.

Polycyclic hydrocarbons constitute a very large group of chemical carcinogens found not only in hazardous production conditions, but also in everyday life. Thus, building materials, pieces of furniture and even dust can carry such substances. The most common representatives of this group can be considered benzopyrene, dibenzanthracene, benzene, polyvinyl choride, etc.

Smoking is a very powerful carcinogen when inhaled along with tobacco smoke benzopyrene, dibenzanthracene and other very dangerous compounds. In addition, one should take into account the widespread prevalence of this bad habit among the population. different countries, and among the causes of malignant tumors of various localizations, smoking leaves behind all the others harmful effects taken together.

It is worth noting that the use of cigarettes with low content nicotine and various filters only slightly reduce the risk of cancer. In addition to the smokers themselves, cigarette smoke also has an adverse effect on family members, work colleagues and even passers-by on the streets, who may be forced to participate in the smoking process. The role of this bad habit has been proven not only in the development of lung cancer, but also of the larynx, esophagus, stomach, cervix and even bladder.

carcinogens and simply dangerous substances in cigarettes

Aromatic amines include, first of all, compounds such as naphthylamine and benzidine. Naphthylamine is often included in various paints and varnishes, and when it enters the body through inhalation of vapors, it turns into metabolites that are excreted by the kidneys. The accumulation of urine containing such secondary metabolic products in the bladder can provoke cancer of its mucosa.

Asbestos is a fairly commonly used substance in the production of vinyl wallpaper, cement, paper, and even in the textile and cosmetics industry (bedspreads, bed linen, deodorants with talc, etc.). Inhaling it with dust for a long time can lead to the development of lung cancer, larynx, and pleural mesothelioma.

The market of cosmetic products and household chemicals offers wide range a variety of products that help not only improve your appearance, but also make the lives of modern people much easier. All kinds of gels, shampoos, and soaps attract people with their smell, appearance and promises to make the skin smooth and velvety. Advertisements for home cleaning products offer to get rid of various problems in the kitchen or bathroom in minutes. However, almost all of them contain dangerous carcinogenic substances - parabens, phthalates, amines and others.

Hair dye, without which many not only women, but also men, cannot imagine life, can also be very toxic due to the toluidines contained in it, which can accumulate in the blood and have a carcinogenic effect. After examining the blood of hairdressers, scientists discovered a significant increase in the concentration of such substances. The more often the hairdresser dyed and permed his hair, the higher the concentration of toluidines in his blood was found.

Nutritional oncogenesis

It's no secret that the food consumed can contain a variety of harmful components that contribute to the development of malignant tumors. Products that cause cancer can be found in almost every home and on every table, and completely avoiding them in the modern world is quite problematic. The struggle for the food market leads to the use of a variety of chemical compounds that improve taste, appearance and extend shelf life. Confectionery products, smoked and fried meats, sausages, carbonated drinks, chips, etc. are especially rich in carcinogens. This list can be continued for quite a long time, but it is unlikely that such products will be completely eliminated from the diet.

Used as sweeteners cyclamates And saccharin can cause cancer in laboratory animals. The carcinogenic role for humans has not yet been proven, however, it is still worth keeping in mind the possible negative effect from their use.

Nitrosamines very widespread in the food industry and are used mainly in the production of meat products, sausages, ham, etc. These substances give a pink color and are good preservatives. Direct exposure to nitrites on the mucous membrane can cause cancer of the stomach and esophagus.

It is known that when various foods are fried in oil, a large number of harmful and toxic compounds are formed, including carcinogenic properties. So, in oil you can find aldehydes, acrylamide, free radicals, fatty acid derivatives and even benzopyrene. Especially dangerous are products that have been fried for a long time in oil at a temperature where it smokes.

Various pies, donuts, deep-fried foods, potato chips, and charcoal-grilled meats contain very toxic components, so it is best to avoid such products if possible. In addition, to reduce health risks, you need avoid overcooking and use oils with a high smoke point for cooking(refined sunflower, olive, rapeseed, corn, etc.). Often unscrupulous manufacturers food products use oil for frying several times, which significantly deteriorates the quality of the resulting food and can cause serious harm to health.

Disputes about the dangers or benefits of such a beloved drink as coffee continue to this day. Opinions have been expressed regarding the mutagenic effect of caffeine, but these assumptions have not been confirmed. It was later discovered in coffee acrylamide, formed during roasting of grains and having carcinogenic properties. Through numerous studies, scientists have not been able to reliably prove that there is a risk when drinking coffee, however, it is still not recommended to drink more than 5-6 cups of it per day.

In addition to harmful substances generated when preparing food at home or added to food products during their industrial production,microorganisms can pose a serious danger appearing when food storage standards are violated. Thus, the fungus Aspergillus flavus, which appears during improper storage of grain, nuts, dried fruits, and food, is capable of producing one of the most powerful carcinogens - aflatoxin. Once in the body, aflatoxin in high concentrations causes severe intoxication, and in smaller quantities, being metabolized in the liver, it can provoke liver cancer. Considering the likelihood of the presence of such mold in spoiled products, you should not risk your health, but it is better to immediately and completely throw away the poor-quality fruit or nut.

Many people are interested in the question of whether the use of meat products? As such, fresh meat good quality does not cause harm, but if the raw product may contain hormones or antibiotics, then improper heat treatment, frying or smoking results in very dangerous products.

All kinds of sausages, frankfurters, sausages, smoked briskets and balyks are saturated with preservatives and dyes (sodium nitrite and others), and it is also likely that benzopyrene– an aromatic hydrocarbon formed during smoking, and it does not matter whether it was produced in a natural way or using chemical components (“liquid” smoke). Scientists have calculated that 50 grams of modern sausage contains approximately the same amount of carcinogenic substances as can be obtained from one smoked cigarette.

When frying meat in a frying pan, cooking barbecue and barbecue, acrylamide, fatty acids, and transgenic fats are added to the list of harmful substances when using poor quality oils. It doesn’t matter what kind of meat you eat – whether it’s homemade pork or store-bought chicken.

The emergence of new food processing methods adds risk to people and health concerns on the part of doctors. Deep frying and grilling occupy leading positions in terms of the degree of harm caused. In an age when humanity is doing everything possible to save time, buying ready-made food from a deli seems like a great solution. In recent years, grilled chicken has become a frequent “guest” on many tables, and, meanwhile, this product is so dangerous that it is better to avoid eating it altogether, since this method of processing meat produces a huge number of carcinogens.

Video: carcinogens in food and why are they harmful?

Risk of cancer with medications and vitamins

It is worth mentioning vitamins separately. Modern people are so accustomed to using them that few people ask the question: are they really necessary and are they harmful? It has long been known that good nutrition And healthy image life is quite enough to receive all the necessary substances in natural form, and the times of scurvy and massive vitamin deficiencies are behind us. However, pharmacies are literally inundated with various dietary supplements and vitamin preparations, and the population considers it necessary to take them, at least in the spring, during epidemics of respiratory infections, as well as before and during pregnancy.

Since the end of the last century, the need for regular intake has been actively promoted. synthetic vitamins, opinions have been expressed about their anticancer effects, but studies recent years even scientists were shocked. It was found that with the systematic use of some of them (A, C, E, etc.), lung, prostate, and skin cancer occurs several tens of times more often. Today, more and more scientists and doctors are inclined to think that synthetic analogues natural vitamins Not only do they not provide significant benefit, but they may also have carcinogenic properties, so the use of such drugs should be limited and carried out only when necessary and as prescribed by a doctor.

The question of the rationality of the widespread use of Viferon and other analogues is still controversial, but their carcinogenic effect has not been proven. Of course, there is a certain risk of immune disorders with uncontrolled use of such drugs, but there is no reliable connection with malignant tumors.

If interferon preparations have a well-studied mechanism of action, then the effect of anaferon, consisting of antibodies to human interferon, may raise some doubts, however, its carcinogenic effect has not been proven. This kind of medication should be taken when it is appropriate. good reasons, indicated by the attending physician. Unfortunately, in many countries, self-medication and uncontrolled use of not only interferons, but also other similar drugs are widespread.

So-called hormone tumorigenesis implies the negative effect of hormones when, with their prolonged or uncontrolled use or metabolic disorders, there is a risk of malignant neoplasms. Ovulation disorders, taking synthetic female sex hormones, and ovarian tumors that produce hormones significantly increase the likelihood of uterine cancer (endometrial cancer in particular). Oral contraceptives with a high content of gestagens can lead to breast cancer, however modern drugs are considered safe in this regard.

Considering the rapid development of the pharmacological industry and the tendency of most people to medicinal treatment of anything, heated debates about the harm or benefit flash across the Internet every now and then various medications. One of these is Liv 52, a herbal preparation prescribed as a hepatoprotector and choleretic agent for diseases of the liver and gall bladder. Opponents of the use of this drug use as an argument the fact that its sale has been banned in Europe and the USA, but there is an opinion that this drug has been produced under a different name, but with the same composition. Still, given the possible risks of its use and the unproven positive effect, you should think carefully before using it for yourself or giving it to children.

Viral oncogenesis

It is reliably known about the existence of viruses that cause cancer, although this fact is constantly subject to doubt and controversy. So, Human immunodeficiency virus (HIV), herpes and hepatitis B have carcinogenic properties. There are probably few women who have not heard about the role of the human papillomavirus (HPV) in the genesis of cervical cancer.

Such information can be obtained at any antenatal clinic, and vaccinations against this type of cancer are done everywhere. Despite the contagiousness viral infection, it is impossible to catch cancer itself from such patients, since the condition is decisive in most cases immune system virus carrier.

Carcinogens of physical origin

Various types of radiation have pronounced carcinogenic properties.

Ionizing radiation in areas contaminated with radioisotopes can be one of the causes of blood cancer - leukemia. For example, the incidence of malignant tumors hematopoietic system increased tenfold after the accident Chernobyl nuclear power plant, among the surviving residents of Hiroshima and Nagasaki. Radionuclides can enter the body with water and food, and, given the long half-life (tens and even hundreds of years), the carcinogenic effect will be long-lasting.

Excess ultraviolet radiation as in natural conditions, and when using a solarium, can lead to skin cancer and melanoma, especially in predisposed fair-skinned individuals, with an abundance of moles, pigmentation disorders, etc.

X-ray radiation during radiation therapy can cause the growth of sarcomas subsequently. Its use for diagnostic purposes involves such a low dose of radiation that the risk of cancer is minimized, but pregnant women are still prohibited from using it due to the possibility of leukemia in the fetus.

In addition to the above reasons, the presence of genetic abnormalities, spontaneous mutations and disorders during embryonic development (brain cancer, etc.). Modern medicine has accumulated a large amount of information regarding genetic changes in certain types of cancer, which makes it possible to identify tumors by the presence of their markers even when the focus of malignant growth itself cannot be detected.

The psychological causes of cancer should also be considered separately. In ancient times, it was noticed that cheerful women were less likely to develop breast cancer, which was noted by Galen. Considering the ever-increasing level of stress and emotional stress, we can say for sure that these factors contribute to the emergence of malignant tumors. Chronic stress is especially dangerous when “unreacted” emotions accumulate in the body and a person is in constant tension and worry.

It is worth noting that the described harmful and dangerous carcinogenic factors are only a small part of what each of us can encounter every day. It is unlikely that you will be able to avoid contact with harmful substances, products containing carcinogens, or completely abandon household chemicals and cosmetics; however, you can significantly reduce their harmful effects on the body. Proper nutrition, careful monitoring of the quality of food consumed, medications, dietary supplements, etc., quitting smoking and alcohol abuse, as well as following the rules of a healthy lifestyle, good mood and adequate physical activity can help with this.

Video: causes and development of cancer

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