carcinogens. According to 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 means chemical, physical and biological agents of natural and anthropogenic origin, which are capable of inducing cancer in animals and humans under certain conditions. The most widespread carcinogenic substances of a chemical nature, acting in the form of homogeneous compounds or as part of more or less complex chemical products. In their origin, chemical structure, duration of exposure to humans and prevalence, they are very diverse. Compounds belonging to the category of "natural" carcinogens, although numerous, have a limited distribution (for example, endemic areas with high content arsenic in soil and water) and, in general, relatively low levels content in environment.

The total oncogenic "load" on living organisms is determined by the background level of carcinogens. The background content of carcinogens is composed of their natural (natural) content associated with the vital activity of organisms, abiogenic and anthropogenic pollution. The background is a regional concept, its fluctuations, first of all, depend on the proximity to sources of environmental pollution associated with human economic activity. It is hardly possible to estimate all terms forming 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 the occurrence of tumors as a result of their exposure is called carcinogenesis. Differ carcinogenic factors direct action, which, under a certain dose-exposure effect, cause the development of malignant neoplasms, and the so-called modifying factors that do not have their own carcinogenic activity, but are able to enhance or weaken carcinogenesis. The number of modifying factors significantly exceeds the number of direct carcinogenic agents, their impact on the human body can vary in magnitude and direction.

Carcinogenic factors, the impact of which is associated with professional activity, are called occupational carcinogens or carcinogenic production factors (CPFs). For the first time, the role of industrial carcinogens was described in English. researcher P. Pott (Pott; 1714-1788) in 1775 on the example of the development of cancer of the genital organs among London chimney sweeps as a result of exposure to the skin of soot and high temperatures during work. In 1890, oncological diseases of the bladder were reported in Germany among workers in a dye factory. 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 production ones, into classification groups.

Agent, complex of agents or factors of external influence:

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 chemicals (not including pesticides and some drugs with carcinogenic properties) and a number of industries using them, which are included in the 1st classification group, have been established as occupational chemical 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 filtering materials, textiles, solvents, fuels, paints, laboratory reagents, construction and lubricants, etc.

The group of probably carcinogenic to humans (2a) includes 20 manufacturing chemicals, 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 related industries. The group of possibly carcinogenic industrial chemical agents (2b), whose carcinogenicity has been proven mainly by 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; to biological KPF - some viruses (for example, hepatitis A and C viruses), pathogens infectious diseases gastrointestinal tract, mycotoxins, especially aflatoxins.

5-10 years or even 20-30 years can pass between exposure to CPF and manifestations of oncological disease, during which the impact of other carcinogenic factors, including environmental, genetic, constitutional, etc., can not be ruled out. which were mainly influenced by industrial carcinogens, in the general structure of oncological morbidity ranges from 4% to 40%. The generally accepted level of professionally caused oncological morbidity in developed countries is 2-8% of all registered oncological diseases.

Under working conditions that include exposure to any CPF groups 1, 2a and 2b, it is necessary to prevent oncological diseases among workers in several areas: reducing the exposure to CPF 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; carrying out continuous monitoring of the health status of workers in carcinogenic hazardous jobs and industries; taking measures to improve the health of workers and timely release them from work with 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 believed that up to 90% of all cancers 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 of a global nature. Carcinogens are found not only near release 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 by such carcinogens as polycyclic aromatic hydrocarbons (PAHs), which are formed as a result of the widespread distribution of combustion and pyrolytic fuel processing processes 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-benzofluoretane, which have high carcinogenic activity. Benz(a)pyrene (BP) is one of the most active and widespread compounds in the environment, which gave grounds to consider it as an indicator of the PAH group. The level of inorganic carcinogens in the environment has also increased due to the extensive development of the mining industry and non-ferrous metallurgy, the use of some of them, for example, arsenic, as pesticides, etc.

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

Carcinogenic substances can exercise 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) it is possible to 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 the agent's action and, therefore, belongs to the category of long-term effects. The duration of the latent period depends on the type of animal and is proportional to the total life span. For example, when using active carcinogens, the latent period in rodents (mice, rats) can be several months, in dogs - several years, 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 the dose leads to an elongation. Cancer can also develop after a long time after the termination of the action of the carcinogen, 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 manifestation of the effect. The experience of experimental oncology shows that only a few highly active carcinogenic compounds can induce neoplasms 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, aromatic amines. In most cases, the tumor reaction does not appear in everyone, 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 shown carcinogenic properties in animal experiments. 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 carcinogens is the manufacturing sector, a significant amount of research is devoted to the study of the incidence of cancer in certain industries and among various professional groups.

To date, extensive information has been accumulated on the carcinogenicity to humans of a number of agents in the working environment, on the degree of risk of developing cancer due to contact with them, as well as on the approximate value of the latent period of such development. Under production conditions, a person comes into contact with a wide variety of carcinogenic substances. Among occupational carcinogens, agents of organic (aromatic hydrocarbons, alkylating agents, etc.) and inorganic (metals, fibers) nature, as well as physical factors (ionizing radiation) are distinguished.

2. ATMOSPHERE AND TRANSPORT

Among all modes of transport, road transport causes the greatest damage to the environment. In Russia, about 64 million people live in places of high air pollution, the average annual concentrations of air pollutants exceed the maximum permissible in more than 600 cities of Russia.

Carbon monoxide and nitrogen oxides, so intensively released by the seemingly innocent bluish haze of a car muffler, are one of the main causes of headaches, fatigue, unmotivated irritation, and low work capacity. Sulfur dioxide can affect the genetic apparatus, contributing to infertility and congenital deformities, and all together these factors lead to stress, nervous manifestations, the desire for solitude, indifference to the closest people. In large cities, diseases of the circulatory and respiratory organs, heart attacks, hypertension and neoplasms are also more widespread. 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 of vehicles are the exhaust gases of internal combustion engines, crankcase gases, and fuel vapors.

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

Diesel fuel is a mixture of oil 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 combustion occurs fundamentally different ways. The first group of toxic substances is associated with chemical reactions of fuel oxidation, occurring both in the pre-flame period and in the process of combustion - expansion. The second group of toxic substances is formed by the combination of nitrogen and excess oxygen in the 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 vehicle emissions include: exhaust gases (EG), crankcase gases and fuel fumes. 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 have penetrated through the leakage of the piston rings into the crankcase of the engine, with engine oil vapor. Fuel vapors enter the environment from the engine power system: joints, hoses, etc. The distribution of the main components of emissions from a carburetor engine is as follows: exhaust gases contain 95% CO, 55% C X H Y and 98% NO X, crankcase gases each contain 5% C X H Y, 2% NO X, and fuel vapors up to 40% C X H Y .

IN general case The composition of the exhaust gases of engines 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, aldehydes.

Table 1 - The content of toxic emissions in the exhaust gases of engines

Components	The share of the toxic component in the ICE exhaust gas
	Carburetor		Diesel
	IN %	per 1000 liters of fuel, kg	V %	per 1000 liters 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		0.001-0.09mg/l
Soot	up to 0.04 g/m 3		0.01-1.1g/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. It is formed on the surface of the piston and on the cylinder wall, in which activation does not occur due to the intensive heat removal of the wall, poor atomization of the fuel and the dissociation of CO 2 into CO and O 2 at high temperatures.

During the operation of the diesel engine, the concentration of CO 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 in order to bad conditions mixture formation to provide the number of evaporated molecules required for ignition and combustion.

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

N is an inert gas under normal conditions. Actively reacts with oxygen at high temperatures.

The exhaust gas emission depends 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 heavy losses heat in the wall, i.e. under such conditions, less NO x is released, and emissions increase when the mixture is close to stoichiometric (1 kg of fuel to 15 kg of air). For diesel engines, the NO x composition depends on the fuel injection advance angle and the ignition delay period of the fuel. With an increase in the advance angle of fuel injection, the ignition delay period lengthens, the uniformity of the air-fuel mixture improves, a larger amount of fuel evaporates, and during combustion, the temperature increases sharply (by a factor of 3), i.e. the amount of NO x increases.

In addition, with a decrease in the advance angle of fuel injection, it is possible to significantly reduce the emission of nitrogen oxides, but at the same time, power and economic indicators deteriorate significantly.

Hydrohydrogens (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 incorrect turbulence, low temperature, poor atomization. The internal combustion engine emits more C x H y when it is idling due to poor turbulence and reduced combustion rate.

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

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

White smoke formed when the engine is cold, and then disappears due to heating. The difference between white smoke and blue smoke is determined by the droplet size: if the droplet diameter is greater than the blue wavelength, 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, the method of mixture formation, fuel characteristics (the color of the droplet depends on the temperature of its formation: with increasing fuel temperature, 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 insufficient for complete combustion of the fuel.

Black smoke is made up of soot.

Smoke adversely 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 to completely destroy the fuel molecule. The lighter hydrogen atoms diffuse into the oxygen-rich layer, react with it, and, as it were, isolate the hydrocarbon atoms from contact with oxygen.

The formation of soot depends on temperature, pressure in the combustion chamber, type of fuel, fuel-air ratio.

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

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

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

SO 2 (sulfur oxide)- is formed during engine operation from fuel obtained from sour oil (especially in diesel engines); these emissions irritate the eyes and respiratory organs.

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

The main air pollutant with lead in the Russian Federation is currently vehicles using leaded gasoline: from 70 to 87% of the total lead emission according to various estimates. PbO (lead oxides)- occur in the exhaust gas 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 burning one ton of leaded gasoline, approximately 0.5 ... 0.85 kg of lead oxides are emitted into the atmosphere. According to preliminary data, the problem of environmental pollution with lead from vehicle emissions becomes significant in cities with a population of over 100,000 people and for local areas along highways with heavy traffic. A radical method of combating environmental pollution with lead emissions from motor vehicles is the rejection of the use of leaded gasoline. According to 1995 data. 9 out of 25 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 phase-out of leaded gasoline production in the country is delayed.

Aldehydes (R x CHO)- are formed when the fuel is burned at low temperatures or the mixture is very poor, 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 goes through three channels: 1) exhaust gases emitted through the exhaust pipe (65%); 2) crankcase gases (20%); 3) hydrocarbons as a result of fuel evaporation 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 are hydrocarbons. The effect of falling concentrations of atmospheric pollution, that is, approaching normal state, is associated not only with the dilution of exhaust gases with air, but also with the ability of the atmosphere to self-purify. Self-purification is based on various physical, physico-chemical and chemical processes. The fallout of heavy suspended particles (sedimentation) quickly releases the atmosphere only from 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 intensive gas exchange takes place 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-like particles on the earth's surface.

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

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

Particles whose size is less than 0.1 mm, as well as gas 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 the processes of physical and chemical interaction between themselves and with the components of the atmosphere, and their action is manifested in local territories 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 ATC facilities depends on the possibility of transporting the considered pollutants over long distances, the level of their chemical activity, and meteorological conditions of distribution.

Components of harmful emissions with increased reactivity, getting into the free atmosphere, interact with each other and with the components of atmospheric air. At the same time, physical, chemical and photochemical interactions are distinguished.

Examples of physical response: condensation of acid vapors in moist air with the formation of 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.

The reactions of synthesis and decay, 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 favorable conditions- necessary reagents, solar radiation, other factors.

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

Carbon monoxide diffuses rapidly in the atmosphere and usually does not create a high concentration. 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, Oz), 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, compounds with oxides of nitrogen and sulfur 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 sulfurous anhydride to sulfuric anhydride 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, the oxidation of sulfur dioxide is extremely slow. In the dark, SO2 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 the 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 released into the atmosphere from ATC facilities are mainly represented by NO and NO 2 . Nitrogen monoxide released into the atmosphere under the influence of sunlight is rapidly 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 by exposure to sunlight from the two main components of automotive 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 dispersion (new emissions and reactions are added to the original ones).

Rice. 1. Formation of photochemical smog

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

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, an adverse effect occurs at a distance of 300-500 km from Moscow (in the Nizhny Novgorod region).

In addition to the meteorological factors of self-purification of the atmosphere, some components of harmful emissions from road transport are involved in the processes of interaction with the components of the air, resulting 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 their effects on organisms or 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 typical for the exhaust of gasoline engines;


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


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


5) aldehydes;


6) soot;


7) lead compounds.


8) sulfuric anhydride.


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


The general scheme of the body's response to the effects of environmental pollutants according to the data World Organization Health (WHO) has the following form (Figure 2)





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


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


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


Fine particles pose the greatest danger to human health, as they are able to pass through the natural protective membrane into the lungs. Inhalation of 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:
MAIN DECISIONS ADOPTED AT THE RIO JUNE 1992 UN ENVIRONMENT CONFERENCE LIST THE BASIC PRINCIPLES OF ENVIRONMENTAL PROTECTION MAN-MADE SYSTEMS AND THEIR INTERACTION WITH THE ENVIRONMENT

Carcinogens are certain factors that make a person more likely to develop malignant tumors. The rate of development of the pathological process depends on the state of health of people, the duration of exposure to organic and inorganic substances or ionizing radiation. Carcinogens are found in small amounts in food and household chemicals, they are part of some pharmacological preparations. It will not work to completely protect yourself and loved ones from compounds that provoke the development of cancer. But it is quite possible to reduce the amount of carcinogens in the environment, as well as to 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 action on the human body: clearly carcinogenic, slightly carcinogenic, carcinogenic;
• on the danger 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 on various parts of the human body;
• by the time of tumor formation: carcinogens with local, remotely selective, systemic effects;
• by origin: carcinogenic substances that have developed in the human body or penetrated into it from the surrounding space /

The classification of chemicals is also carried out according to the nature of the pathological process caused by them. One type of carcinogens changes the gene structure of the cell, while 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 tissues, then a benign tumor is subsequently diagnosed in a person. But with the division of defective, damaged cells, the likelihood of a malignant tumor is high.

Types of carcinogens

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

Carcinogens are natural substances that, when used properly, are very beneficial to health. But it is worth exceeding the dosage recommended by the doctor or the duration of treatment, as soon as a favorable environment for division is created. cancer cells. These compounds include the well-known birch tar, widely used in folk medicine.

In order to be well versed in the types of carcinogens, one 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 found in the environment. Their appearance was in no way influenced by humans. The main cause of most diagnosed cases of skin cancer is solar radiation, or ultraviolet radiation. Doctors do not get tired of warning about the dangers of sunburn. 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 in all layers of the epidermis, a pathological process of cell division with an altered gene structure can start.

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

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 cancerous tumors is higher in people who live on the first floors of high-rise buildings. A significant content of radon was noted by specialists in houses located in rural areas. In such buildings there is an underground or cellar, that is, there is no protection against inert gas. Radon is also located:

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

If the house or apartment is poorly sealed and there is no ventilation, then the concentration of radon in the surrounding space is high. This situation is typical for the northern latitudes, where the heating season lasts most of the year.

Carcinogenic effect on the human body is exerted 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.

To biological compounds, whose carcinogenic effects are still being studied, experts include some viruses. 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 stomach and duodenal ulcers, erosive and chronic gastritis. Doctors refer to 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 carcinogens are included in this category:

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

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

Cancer causing foods

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

A significant amount of nitrosamines is part of sausages and meat products. It is nitrites that give them an appetizing pink color, provide 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 borne in mind that, despite the unproven carcinogenicity to humans, some dietary supplements have caused malignant neoplasms in animals. These are the widely known and frequently used saccharin and cyclamate. When buying, you should pay attention to the content of these sweeteners in curds and yogurts.

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

• acrylamide;
• fatty acid metabolites;
• various aldehydes;
• benzapyrene.

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

• in pies and donuts;
• in potato chips;
• in charcoal grilled meat.

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

Coffee, without which many people cannot imagine their lives, 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 for the human body. It is produced by mold fungi, the spores of which can be found in cereals, bran, nuts and flour. Products with aflatoxin are 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 liver cancer.

The most dangerous carcinogens

There are many compounds in the environment that have negative impact on the human body. But substances that a person encounters in everyday life and at work are of 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 in their air space there may be the finest fibers. This carcinogen after penetration into the body causes the formation of malignant neoplasms of the lungs, larynx and stomach.
• Vinyl chloride. Contained in many varieties of plastic that are used in medicine. It is used to make consumer goods. Tumors of the lungs and liver are often diagnosed among employees 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 the potato is stored in the garage, then it absorbs carcinogens from exhaust gases. The medical literature describes cases of diagnosing rectal cancer due to the use of pieces of newspapers as toilet paper.

How to get rid of carcinogens

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

• cabbage, carrots, beets and freshly squeezed juices from these vegetables;
• cereal porridge: buckwheat, oatmeal, rice;
• green tea, dairy 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 prophylactic against the formation of malignant neoplasms. It is possible to clear the gastrointestinal tract from carcinogens accumulated on its mucous membrane with the help of absorbents and enterosorbents (activated carbon, polysorb, smecta, laktofiltrum). The course intake of these pharmacological preparations will significantly reduce the negative impact of hazardous substances on the human body.

Chemical carcinogenic factors

In 1915, Japanese scientists Yamagiva and Ishikawa induced small tumors by applying coal tar to the skin of rabbit ears, thus proving for the first time the possibility of neoplasm under the action of a chemical.

The most common classification of chemical carcinogens at present is their division into classes in accordance with the chemical structure: 1) polycyclic aromatic hydrocarbons (PAH) 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 be carcinogenic.

Accepted by origin allocate anthropogenic carcinogens, the appearance of which in the environment is associated with human activities, and natural, not related to industrial 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, mainly 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 of multiple action 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).

Such a division of carcinogenic agents is conditional, since, depending on the method of introducing a substance into the body or species

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 proven to be carcinogenic both in animal studies and in population epidemiological studies.

II. Chemicals with proven strong carcinogenicity in experiments on several species of animals with various routes of administration. Despite the lack of data on carcinogenicity to humans, they should be considered potentially dangerous to humans 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 experiences, especially towards the end of life.

IV. Chemicals with "doubtful" carcinogenic activity. This category includes chemical compounds, the carcinogenic activity of which is not always clearly detected in the experiment.

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

have the highest 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 motor vehicle exhaust, blast furnace smoke, tobacco smoke, smoking products, and volcanic emissions.

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

aminoazobenzene). Tumors usually occur not at the injection site 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 localization 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, drugs, insecticides, etc.).

Nitroso compounds and nitramines(N-methylnitrosourethane, methylnitrosourea) cause tumors in animals that are diverse in morphological structure and localization. At present, 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 is carried out in the human gastrointestinal tract when amines and nitrites (nitrates) are taken with 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 occupational cancer in a person. It has been established that with prolonged contact, workers involved 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 fibers are at least 7-10 microns long and no more than 2-3 microns thick.

natural carcinogens. More than 20 carcinogens are currently known natural origin- products of vital activity 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 luteoskirin, cyclochlorotin; P. griseofulvum-

griseofulvin; Strepromyces hepaticus- elaiomycin; Fusarium sporotrichum- Fusariotoxin. Safrole is also a carcinogen, which is found in oil (an aromatic additive obtained from cinnamon and nutmeg). Carcinogens have also been isolated from higher plants: the Compositae family Senecio contains alkaloids, in the structure of which a pyrrolizidine nucleus was detected; the main toxic metabolite and ultimate carcinogen is pyrrole ether. bracken fern (Pteridium aquilinum) When eaten, it causes tumors in 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 the blastomogenic potential directly or indirectly. This was confirmed by experiments on the induction of tumors in animals by subcutaneous administration of benzene extracts from the liver tissue of a person who died of stomach cancer. The effect of extracts from bile has been studied, lung tissue, urine, and in all cases, as a rule, tumors occurred in animals. Extracts isolated from the organs of those who died from non-tumor diseases were inactive or inactive. It has also been established that during blastomogenesis, in the process of tryptophan biotransformation, some intermediate products of the orthoaminophenol structure are formed and accumulated in the body: 3-hydroxykynurenine, 3-hydroxyanthranilic acid, 2-amino-3-hydroxyacetophenone. All these metabolites are also detected in small amounts in the urine. healthy people, however, with some neoplasms, their number increases sharply (for example, 3-hydroxyanthranilic acid in 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 introduction of which induced leukemia and tumors in animals. It has also been shown that the administration of large amounts of tryptophan causes the development of dyshormonal tumors and that some metabolites of the cyclic amino acid tyrosine (p-hydroxyphenyl-lactic and p-oxyphenyl-pyruvic 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 paraoxyphenyl lactic acid in patients with leukemia and reticulosarcoma. All this indicates that 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 the contact of the carcinogen with the cell: first, the carcinogen undergoes biotransformation, resulting in the formation of carcinogenic metabolites that penetrate into the cell, change its genetic apparatus, causing malignancy. The biological latent period is the time from the formation of a carcinogenic metabolite in the body to the onset of uncontrolled growth. The clinical latent period is longer and is calculated from the beginning of contact with a carcinogenic agent to the clinical detection of a tumor, and the onset 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 considerably. So, 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 substances, the intensity and duration of contact of the organism with a carcinogenic agent. The manifestation of oncogenic activity of a carcinogen depends on the type of animal, its genetic features, sex, age, cocarcinogenic modifying influences. The carcinogenic activity of a substance is determined by the rate 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 revealed

between the dose (total and single), the latent period and the incidence of tumors. 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 end 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 the living conditions of a person.

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

In the specific conditions of the 21st century, which are 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 whose occurrence and development can be influenced by housing 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 dwelling (primarily air) in some cases can also contribute to the occurrence of cancer in humans.

The point is not only that a person spends up to 7.0% of his time in non-production type premises, in particular in a dwelling, 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 of non-industrial premises is often worse quality outdoor air and even indoor air.

The air environment of the dwelling is formed under the influence of a number of factors: products of incomplete combustion of gas formed when using gas stoves; substances that occur during the cooking process; anthropotoxins released as a result of the vital activity of the human body; degradation products of polymeric 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 during the use of personal hygiene products, detergents and other household cosmetics; substances from the atmospheric air.

This list of sources for the formation of the quality of the air environment in a dwelling alone 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 of oncologists due to their potential carcinogenic hazard to humans.

Polycyclic aromatic hydrocarbons

One of the main sources polycyclic aromatic hydrocarbons (PAH) in the dwelling 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 settlements, near which there are enterprises of coke-chemical, metallurgical, etc. 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 building structures of residential premises, radon can directly come from the ground to the basement, and then to residential premises.

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

This made it possible to assume the existence of a real danger of radon for the population in their homes. Many works provide data confirming this possibility, especially in cold climatic 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 in 2-10% of cases, and for smokers, the likelihood of developing a tumor increases by more than 25 times.

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

It is from them that radon and thoron enter living quarters, where they can accumulate. The majority of building materials containing industrial wastes (blast-furnace and phosphate slags, 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 the products of gas combustion. At the same time, the level of radioactivity in the air of kitchens can be about 5 times higher than the level of natural radioactivity in living rooms.

Formaldehyde

Formaldehyde (CH2O) has attracted particular attention in the last decade after the appearance of works in which its carcinogenicity in rats was shown. According to experts international agency for research on cancerIARC) currently there is sufficient evidence of the carcinogenicity of gaseous formaldehyde in experimental animals and limited - for humans - in the occurrence of nasopharyngeal cancer. Formaldehyde has pronounced toxic and irritating properties on mucous membranes.

It is widely distributed in the environment and can be found in residential air from particle boards made with formaldehyde adhesives, other bonded wood products, foam insulation materials, carpets and textiles, etc. Based on formaldehyde, carbamide, phenolic, polyacetate and other plastics and resins are made. It is formed when smoking tobacco.

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

Nitrogen oxides

Nitrogen oxides (NOx)- Compounds of both natural and anthropogenic origin, widespread in the environment. In relation to housing, the main sources of nitrogen oxides are gas-fired household heaters, smoking and atmospheric air. Nitrogen oxides are precursors N-nitroso compounds (NS).

In the air of residential premises, NS themselves were also found, the main sources of which are smoking and frying food, and to a lesser extent, combustion products. natural gas, atmospheric air, and poorly ventilated rooms, the concentration of HC can reach relatively high values. The carcinogenic hazard of NS is described 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, insulating materials, flooring, ceilings, 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 can 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 hazard.

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

In general, a rather serious picture emerges. Of course, it cannot be imagined that practically 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 were used, which are sources of radon.

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

water factor

There are different points of view on the degree of danger to the population of carcinogenic substances present in water. Not excluding the possibility of situations where the water factor can really have a significant impact on the prevalence of malignant tumors among the population, nevertheless, on the whole, this effect seems to be relatively less significant than the effect, for example, of polluted atmospheric air.

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

In view of the foregoing, data are presented below on the possible role of individual substances and groups of compounds that spread by water, in the formation of oncological morbidity.

Arsenic

Arsenic, recognized by IARC experts as unconditionally carcinogenic to humans, is apparently the only compound for which the role of the aquatic pathway 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 the contamination of drinking water with nitrates and nitrites has not yet given convincing data in order to determine their level, from which the potential carcinogenic hazard to the population may increase.

In general, assessing the problem of nitrate-nitrite water pollution from an onco-hygienic point of view, it should be emphasized that the content of nitrates and nitrites in the water bodies of 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. Halogenated Compounds (HCC)- water chlorination products. In the mid-70s of the XX century, the first works appeared in the United States, which raised the question of the existence of a relationship between the oncological 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, colon, but it is not yet possible to make a final conclusion. Apparently, a sober assessment of the real danger of GSS 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. With regard to asbestos-containing water, the vast majority of researchers are inclined to believe that asbestos in drinking water is not dangerous to human health.

Fluorine

Even more unclear is the situation with the possible effect of fluoride on cancer incidence in the population. Epidemiological studies to identify possible connection between cancer and the content of fluorine in water have been carried out for almost 30 years, but the question of the carcinogenic danger of water fluoridation remains open.

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

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

Environmental aspects of the circulation of carcinogens

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

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

The air pollution index is the content of benzopyrene. From 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.

In agriculture, nitrogen, potash and phosphorus mineral fertilizers are used. Potash fertilizers do not pose a carcinogenic hazard. There is no convincing evidence of the carcinogenic effect of phosphorus-containing fertilizers.

Dangerous are nitrogen-containing fertilizers, 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 content of nitrates 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 the water sources.

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

In animal experiments, pesticides have caused tumors in the liver, kidneys, lungs, skin, breasts, 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. In polluted water, compounds belonging to all groups of chemical carcinogens are found, which poses a potential hazard to humans.

In living quarters main reason air pollution - smoking, and in kitchens - heat treatment of food. Asbestos threads, radioactive polonium, radon are found in the room dust of rooms with insufficient ventilation, and the concentration of cadmium and other metals is sometimes much 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 writings of ancient scientists who even tried to apply 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 rather problematic to judge the prevalence of tumors even in the Middle Ages. Carefully performed autopsies of the dead could provide valuable information, but they were not common, 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 mask of "dropsy", "jaundice" and similar causes of death.

For centuries, millions of people's lives have been claimed by various infections, being the main cause of death. 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 the tumors are found in people over 65 years of age.

It is not surprising that neoplasms did not frighten and care too much for our ancestors, because most of them simply did not live to such an age.

With the deepening of knowledge in the field of the causes of various diseases, the emergence of antibiotics, the improvement of treatment methods, the improvement of the sanitary and epidemiological situation and hygiene in general, infections lost their leading positions and by the 20th 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 elucidate the causes of cancer, as well as the development effective ways fight him.

Today, scientists of various profiles – genetics, biochemists, oncologists, morphologists, immunologists – are engaged in finding out the cause of cancer. Such interaction of specialists from different fields of science is bearing fruit, and it can be argued that the main patterns of carcinogenesis have been studied quite well.

Tumor Risk Factors

A tumor is a pathological process characterized by uncontrolled, uncontrolled, inadequate reproduction of cells endowed with specific features that distinguish them from normal ones. The main feature of the neoplasm is the autonomy of growth, independence from the body as a whole and the ability to exist indefinitely under the right 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 destroys such cells in a timely manner and tumor development does not occur. With age defense mechanisms weaken, which creates the prerequisites for the emergence of a malignant tumor. This partly explains more high risk cancer among the elderly.

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

percentage of dominant factors in the development of cancer

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

Since a sufficiently long time is needed for the formation of a tumor, it is rather problematic to reliably prove the role of a particular agent or external influence. Of all the possible external causes of malignant tumors, smoking is the most important. due to its wide distribution among the population, other carcinogens play a role in a relatively small number of cases.

• Elderly age;
• Burdened family history and genetic disorders;
• The presence of bad habits and the effect of adverse environmental conditions;
• Chronic inflammatory processes of various localization;
• Immunity disorders;
• Work during harmful conditions accompanied by contact with carcinogens.

Psychological and spiritual reasons are becoming increasingly important, as 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 private forms:

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

Video: what causes cancer?

What are carcinogens?

As mentioned above, a significant place among the main causes of cancer is assigned to carcinogens. These substances surround us everywhere, are found in everyday life, get into food and water, pollute the air. A modern person is forced to come into contact with a large number of various 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 product, food product or medicine.

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

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

The whole range of possible external factors with carcinogenic properties can be divided into three main groups:

1. Chemical;
2. physical;
3. Biological.

Chemical carcinogens

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

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

Polycyclic hydrocarbons make up a very large group of chemical carcinogens that are found not only in conditions of hazardous production, but also in everyday life. So, building materials, furniture and even dust can carry such substances. The most frequent representatives of this group are benzpyrene, dibenzanthracene, benzene, polyvinyl chloride, etc.

Smoking is a very powerful carcinogenic factor, in which inhalation occurs along with tobacco smoke benzpyrene, 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 should be noted that the use of cigarettes with low content nicotine and various filters only slightly reduces the risk of cancer. In addition to the smokers themselves, cigarette smoke also adversely affects family members, work colleagues and even passers-by on the streets, who may be forced participants in the smoking process. The role of this bad habit has been proven not only in the development of cancer of the lungs, but also of the larynx, esophagus, stomach, cervix and even the 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 the composition of various paint and varnish products, and when it enters the body by inhalation of vapors, it turns into metabolites excreted by the kidneys. Accumulation in the bladder of urine containing such secondary metabolic products can provoke cancer of its mucosa.

Asbestos is a fairly common substance in the production of vinyl wallpaper, cement, paper and even in the textile and cosmetic industries (spreads, bed linen, deodorants with talc, etc.). Inhaling it with dust for a long time can lead to the development of cancer of the lungs, larynx, pleural mesothelioma.

The market of cosmetic products and household chemicals offers wide range a variety of tools that help not only improve the appearance, but also greatly facilitate the life of modern people. All kinds of gels, shampoos, soaps attract with their smell, appearance and promises to make the skin smooth and velvety. Advertising for home cleaning products offers to get rid of various problems in the kitchen or bathroom in minutes. However, almost all of them contain dangerous carcinogens - 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 that can accumulate in the blood and have a carcinogenic effect. After conducting a study of the blood of hairdressers, scientists have identified a significant increase in the concentration of such substances. The more often the hairdresser dyed his hair and did a perm, the higher the concentration of toluidines in his blood was found.

Nutritional oncogenesis

It's no secret that the food you eat can contain a variety of harmful components that contribute to the development of malignant tumors. Cancer-causing foods 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 wide variety of chemical compounds that improve taste, appearance and extend shelf life. Confectionery, smoked and fried meat, sausages, carbonated drinks, chips, etc. are especially rich in carcinogens. This list can be continued for quite some time, and it is unlikely that such products can be completely excluded 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 bearing in mind the possible negative effect from their application.

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

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

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

Disputes about the dangers or benefits of such a favorite drink as coffee are ongoing to this day. Opinions were expressed regarding the mutagenic effect of caffeine, but these assumptions were not confirmed. Later found in coffee acrylamide, formed during the roasting of grains and has carcinogenic properties. Through numerous studies, scientists have not been able to reliably prove the risk of drinking coffee, however, it is still not recommended to drink more than 5-6 cups of it per day.

In addition to harmful substances formed during cooking at home or added to food products during their industrial production,micro-organisms can be a serious hazard, appearing in violation of food storage standards. So, the fungus Aspergillus flavus, which appears during improper storage of grains, nuts, dried fruits, 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 its cancer. Given the likelihood of the presence of such a mold in spoiled foods, you should not risk your health, but it is better to immediately and completely throw away a poor-quality fruit or nut.

Many 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 presence of hormones or antibiotics is possible in a raw product, then very dangerous products are obtained with improper heat treatment, frying or smoking.

All kinds of sausages, sausages, sausages, smoked brisket and balyk are saturated with preservatives and dyes (sodium nitrite and others), and it is also quite likely to detect benzpyrene- aromatic hydrocarbon formed during smoking, and it does not matter whether it was produced natural way or with the help of chemical constituents ("liquid" smoke). Scientists have calculated that 50 grams of modern sausage contains about the same amount of carcinogenic substances as they can be obtained from one smoked cigarette.

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

The advent of new ways of processing food adds risk to people and health concerns on the part of doctors. Deep-frying and grilling occupy a leading position in terms of the degree of harm caused. In an age when humanity is doing everything possible to save time, buying ready-made food in the culinary world seems like a great way out. Grilled chicken has become a frequent “guest” on many tables in recent years, and, meanwhile, this product is so dangerous that it is better to refuse to use it altogether, since a huge number of carcinogens are formed with this method of processing meat.

Video: carcinogens in food and why are they harmful?

Cancer risk with medications and vitamins

Separately, it is worth mentioning vitamins. Modern man is so accustomed to their use that few people ask themselves the question: are they really necessary and are they harmless? It has long been known that good nutrition And healthy lifestyle life is enough to get all the necessary substances in natural form, and the times of scurvy and massive beriberi are behind. However, pharmacies are literally overwhelmed 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 were expressed about their anticancer effect, but studies recent years shocked even scientists. It was found that with the systematic use of some of them (A, C, E, etc.), lung, prostate, 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 not carry significant benefits, but may also have carcinogenic properties, so the intake of such drugs should be limited and carried out only if necessary and as directed 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, and its carcinogenic effect has not been proven. This kind of medication should be taken when it is available. 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 oncogenesis implies a negative effect of hormones, when with their long-term or uncontrolled intake or metabolic disorders there is a risk of malignant neoplasms. Ovulation disorders, taking synthetic female sex hormones, hormone-producing ovarian tumors, greatly increase the likelihood of uterine cancer (endometrial, in particular). Oral contraceptives with a high content of gestagens can lead to breast cancer, however modern drugs considered safe in this respect.

Given the rapid development of the pharmacological industry and the propensity of most people to drug treatment of anything, heated debates about harm or benefit flicker on the Internet. various medicines. One of these is Liv 52, a herbal preparation prescribed as a hepatoprotector and choleretic agent for diseases of the liver and gallbladder. Opponents of the use of this drug use as an argument the fact that its sale was banned in Europe and the USA, however, it is believed that this drug began to be produced under a different name, but with the same composition. Nevertheless, given the possible risk of its use and the unproven positive effect, it is worth thinking 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 being questioned and disputed. So, human immunodeficiency virus (HIV), herpes and hepatitis B have carcinogenic properties. Perhaps there are 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 being contagious viral infection, it is impossible to catch cancer from such patients, since in most cases the condition is decisive 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 on 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.

Too much ultraviolet light vivo, 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 later. 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 fetal leukemia.

In addition to the above reasons, the presence of genetic abnormalities, spontaneous mutations and disturbances in the course of 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 cannot be detected.

Separately, it is worth considering the psychological causes of cancer. In ancient times, it was noticed that cheerful women are less prone to breast cancer, which Galen drew attention to. Given the ever-increasing level of stress and emotional stress, it can be accurately stated that these factors contribute to the appearance of malignant tumors. Of particular danger are chronic stresses, when “unreacted” emotions accumulate in the body and a person is in constant tension and worries.

It is worth noting that the described harmful and dangerous carcinogenic factors are only a small part of what each of us can face every day. Avoiding contact with harmful substances, products containing carcinogens, completely abandoning household chemicals and cosmetics is unlikely to succeed, however, it is possible to significantly reduce their harmful effects on the body. Proper nutrition, careful monitoring of the quality of food consumed, medicines, dietary supplements, etc., smoking cessation and alcohol abuse, as well as adherence to the rules of a healthy lifestyle, good mood and adequate physical activity can help in this.

Video: causes and development of cancer

The author selectively answers adequate questions from readers within his competence and only within the limits of the OncoLib.ru resource. Face-to-face consultations and assistance in organizing treatment, unfortunately, are not provided at the moment.