Carcinogenic factors of housing in oncology. Are they that scary?
Limiting work experience in a vibration-hazardous profession, as well as work schedules, is one of the forms of “time protection” - a method widely used for prevention harmful effects vibroacoustic factors.
4.8. Industrial carcinogens
A carcinogen is a factor under the influence of which the incidence of malignant neoplasms (cancer) increases or the time of their appearance decreases.
Industrial carcinogens(or carcinogenic production factors) are carcinogenic factors, the impact of which is caused by professional activity person.
Back in 1775 English doctor P. Then, for the first time, the role of an industrial carcinogen in the development of scrotal cancer from the action of stove soot - “chimney sweep disease” - was described. At the end of the 19th century. In Germany, bladder cancer was reported among dye factory workers exposed to aromatic amines. Subsequently, the carcinogenic effects of dozens of chemical, physical and biological factors in the working environment were described.
In 2001, experts from the International Agency for Research on Cancer (IARC) developed a ranking of factors according to the degree of evidence of carcinogenicity for humans (Table 4.6).
Table 4.6 |
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Ranking of carcinogenic factors | |||
Group of factors | Quantity |
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Carcinogenic to humans | |||
2A. Possibly carcinogenic to humans | |||
2B. Possibly carcinogenic to humans | |||
Not classified as carcinogenic | |||
for humans | |||
Probably not carcinogenic to humans | |||
Below is a list of carcinogenic factors (with proven carcinogenicity) included in the national List (GN 1.1.725-98).
Compounds and products produced and used in industry
4-amidophenyl Asbestos
Aflatoxins (B1, as well as a natural mixture of aflatoxins) Benzidine Benzene Benz(a)pyrene
Beryllium and its compounds Bichloromethyl and chloromethyl (technical) ethers Vinyl chloride Sulfur mustard
Cadmium and its compounds Coal and petroleum tars, pitches and their sublimations
Mineral oils (petroleum, shale), unrefined and incompletely purified Arsenic and its inorganic compounds
1-naphthylamine technical, containing more than 0.1% 2-naphthylamine 2-naphthylamine Nickel, its compounds and mixtures of nickel compounds
Woodworking and furniture production using phenol-formaldehyde and urea-formaldehyde resins in enclosed spaces Copper smelting (smelting process, converter stage, fire refining)
Industrial exposure to radon in the mining industry and work in mines.
Production of isopropyl alcohol Production of coke, processing of coal and shale tar, coal gasification Production of rubber and rubber products
Carbon black production
Production of coal and graphite products, anode and hearth masses using pitches, as well as baked anodes Production of cast iron and steel (sinter factories, blast furnace and steel foundries, hot rolling)
Electrolytic production of aluminum using self-sintering anodes Production processes associated with exposure to aerosols of strong
inorganic acids containing sulfuric acid
Household and natural factors
Alcoholic beverages Radon Domestic soot
Solar radiation Tobacco smoke
Tobacco products, smokeless (chewing snuff and tobacco mixture containing lime)
The first group includes factors that have unconditional evidence of carcinogenic danger. These include 87 names of factors chemical nature, industrial technological processes, bad habits, infections, drugs, etc. In group 2A - agents with a high degree of evidence for animals, but limited for the human body. Group 2B includes substances with probable carcinogenicity to humans and group 3 contains compounds that cannot be assessed accurately for their carcinogenicity (fluorine, selenium, sulfur dioxide, etc.).
TO Group 2A includes 20 industrial chemical compounds (acrylonitrile, benzidine-based dyes, 1, 3-butadiene, creosote, formaldehyde, crystalline silicon, tetrachlorethylene, etc.), group 2B includes a large number of substances, including acetaldehyde, dichloromethane, inorganic lead compounds, chloroform, ceramic fibers, etc.
TO industrial carcinogenic factors of a physical nature include ionizing and ultraviolet radiation, electric and magnetic fields, biological factors include some viruses (for example, hepatitis A and C viruses), microtoxins (for example, aflatoxins).
In the general structure oncological diseases industrial carcinogens as the root cause occupy from 4 to 40% (in developed countries from
Cancer prevention includes:
- reducing the impact of carcinogenic production factors by modernizing production, developing and implementing additional individual and collective protective measures;
- introduction of a scheme for restricting access to work with carcinogenic production factors;
- constant quality monitoring environment and the health status of workers are carcinogenic hazardous work and production;
- implementation of targeted programs for employee health improvement and their timely release from carcinogenically hazardous work based on the results of production control and certification of workplaces for working conditions.
4.9. Aeroionization of air in a production environment
The air ionization factor is an important criterion for its quality. The aeroionic composition of air belongs to the group of physical factors, the role and significance of which were especially intensively studied in the early and mid-20th century.
The priority of scientific research in this area belongs to the Soviet scientist Professor A.L. Chizhevsky, who in 1919 discovered the biological and physiological effects of unipolar air ions and then in subsequent years the comprehensive development of this discovery in relation to medicine, agriculture, industry, etc. For the first time in an experiment on animals, he established the effect of positive and negative unipolar air ions on the functional state of the nervous, cardiovascular, endocrine systems, on hematopoietic organs, on the morphology, physics and chemistry of blood (the quantity and quality of white and red blood), on body temperature, its plastic function,
metabolism, etc. In these studies, it turned out that air ions of negative polarity shift all functions in a favorable direction, and air ions of positive polarity often have an extremely unfavorable effect. These studies allowed A.L. Chizhevsky to penetrate deeply into a living cell and for the first time show the importance of positive and negative charges in its life. He called the air ions aeroions, the process of their occurrence - aeroionization, the artificial saturation of indoor air with them - aeroionification, treatment with them - aeroionotherapy. This terminology has become entrenched in world science and is now widely used in various aspects of both scientific and practical activity.
The physical basis of this phenomenon is that, under the influence of an ionizer, a gas molecule in the atmospheric air (most often oxygen) loses an electron from the outer shell of the atom, which can settle on another atom (molecule). As a result, two ions appear, each carrying one elementary charge - positive and negative. The addition of several neutral molecules to the resulting two ions gives rise to light air ions. Adsorption of ions on condensation nuclei (highly dispersed aerosol particles, including microorganisms) leads to the formation heavy air ions(or “pseudo-aeroions”).
Sources of air ionization (ionizers) are divided into natural and artificial. Natural ionization occurs everywhere and constantly over time as a result of exposure to various radiations (cosmic, ultraviolet, radioactive) and atmospheric electricity. Artificial ionization of air is created as a result of human activity and is either undesirable, as a product of certain technological processes (photoelectric effect, combustion process, etc.), or specially created for certain purposes, for example, using air ionizers - to compensate for aeroion deficiency . Despite the fact that ion formation is a continuous process, the number of ions does not grow indefinitely, since along with this process there is a continuous disappearance of air ions over time.
account of recombination, diffusion, adsorption on various filters and air purification systems. Due to the fact that ion formation and ion destruction are constantly taking place in the air, a state of equilibrium arises between the two processes and, depending on the ratio of their speeds, a certain state of ionization of the air environment is established as one of the most important aspects of air quality, a comfortable and “healthy” living environment in general. When hygienic characterizing the content of air ions, the so-called unipolarity coefficient– the ratio of the number of light ions with a negative charge to their number with a positive charge. Filtration of air through highly efficient filters leads to the loss of light ions, but the disturbed equilibrium state is restored in a few minutes due to the natural background radiation.
The normal course of neuroendocrine, physiological, metabolic and other processes in the body is largely determined by the presence of ions in the inhaled air. Long-term (and even more so chronic) deficiency of air ions can lead to serious violations health, in particular, to the widespread diseases among workers in modern office buildings associated with staying in buildings (Building - Related Illnesses, BRI).
It is advisable to carry out artificial ionization of indoor air for health-improving (preventive) purposes bipolarly, ensuring the presence of ions of both polarities in the air and maintaining the aeroionic background of the premises close to natural, when the biological effect of “active” negative ions will be harmoniously balanced by the action of positive ions. For modern office premises, it is advisable to solve the problem of normalizing the aeroionic composition of air using ionizers (bipolar) built into the supply air ducts of ventilation systems (near the air distribution grilles), then the distribution of aeroions throughout the room occurs evenly and the loss of generating ions is minimized.
The standardized values for the content of air ions are regulated by SanPiN 2.2.4.1294-03 “Hygienic requirements for the air ion composition of air in industrial and public buildings”, taking into account the following indicators of light ion concentrations per 1 cm3: minimum permissible concentration (positive - 400, negative - 600); optimal concentration (respectively, 1,500–3,000 and 3,000–5,000); maximum permissible concentration (50,000 for both signs).
IN under production conditions, a number of technological processes become leading in the generation of air ions. For example, during welding work (gas and electric arc welding), the number of heavy air ions in the worker’s breathing zone can reach 60,000 or more per 1 cm 3. Intense ion formation in industrial premises is facilitated by the use of laser and ultraviolet radiation, combustion processes, metal melting, grinding and sharpening of materials.
IN In some cases, artificial air ionization is used in production conditions to improve product quality and increase labor productivity. For example, in the textile industry - to remove electrostatic charge from threads of artificial (polymer) fiber. At the same time, in the breathing zone of workers, the number of negatively charged air ions during a shift can reach tens of thousands per 1 cm 3. And, on the contrary, in some cases, in the presence of electromagnetic fields and electrostatic electricity in rooms with personal computers, monitors, the concentration of air ions of both negative and positive polarities may not exceed 100 light ions per 1 cm3.
It is recommended to measure the aeroionic composition of air in work areas, the air environment of which is subject to special cleaning or conditioning; where there are sources of air ionization (UV emitters, melting and welding of metals), where the equipment is operated
And materials are used that can create electrostatic fields (VDT, synthetic materials, etc.), where air ionizers are used
And deionizers. Control and assessment of the factor is carried out in accordance with
SanPiN 2.2.4.1294-03 and methodological instructions MUK 4.3.1675-03 " General requirements to control the air ion composition." If the maximum permissible concentration and (or) non-compliance with the minimum required concentration of air ions and the unipolarity coefficient are exceeded, the working conditions of personnel for this factor, according to the hygienic classification, are classified as harmful (class 3.1).
4.10. The severity and tension of the labor process. Fatigue. Performance phases.
Work and rest modes
Factors in the labor process include the severity and intensity of labor.
The severity of labor is a characteristic of the labor process, reflecting the predominant load on musculoskeletal system And functional systems of the body (cardiovascular, respiratory, etc.), ensuring its activity.
Indicators of the labor process, characterizing the severity of labor.
1. Physical dynamic load, expressed in units of external mechanical work per shift, kg m:
a) with regional load; b) at total load;
c) when moving the load over a distance from 1 to 5 m; d) when moving the load over a distance of more than 5 m.
2. Mass of lifted and moved cargo, kg:
a) lifting and moving (one-time) heavy objects when alternating with other work;
b) lifting and moving (one-time) heavy objects constantly during the work shift;
c) the total mass of goods moved during each hour of the shift from the working surface and from the floor.
3. Stereotypical working movements, number per shift: a) with local load;
b) with regional load.
4. Static load, kg s: a) with one hand; b) with both hands;
c) with the participation of the muscles of the body and legs.
5. Working posture.
6. Body tilts, quantity per shift.
7. Movements in space caused by the technological process:
a) horizontally; b) vertically.
Assessment of the severity of physical labor is carried out based on taking into account all
indicators. In this case, a class is first established for each measured indicator, and the final assessment of the severity of work is established according to the most sensitive indicator, which received the highest degree of severity.
Labor intensity– a characteristic of the labor process, reflecting the load primarily on the central nervous system (CNS), sensory organs, and emotional sphere of the employee.
Indicators of the labor process characterizing labor intensity.
1. Intellectual load: a) content of work;
b) perception of signals (information) and their evaluation; c) distribution of functions according to the degree of complexity of the task; d) the nature of the work performed.
2. Sensory loads:
a) duration of concentrated observation (% of shift time); b) density of signals (light, sound) and messages on average
for 1 hour of work; c) the number of production facilities for simultaneous observation;
d) the size of the object of discrimination (with a distance from the eyes of the worker to the object of discrimination no more than 0.5 m) in millimeters for the duration of concentrated observation (% of the shift time);
e) work with optical instruments (microscopes, magnifying glasses, etc.) with the duration of concentrated observation (% of shift time);
f) monitoring the screens of video terminals (hours per shift); g) load on auditory analyzer; i) load on the vocal apparatus.
3. Emotional stress:
a) the degree of responsibility for the results of one’s own activities; b) degree of risk for own life; c) the degree of risk for the safety of other persons;
d) the number of conflict situations caused by professional activities per shift.
4. Monotonous loads:
a) the number of elements (techniques) necessary to implement a simple task or in repeated operations;
b) the duration of simple tasks or repetitive operations;
c) time active actions(in % of shift duration); d) monotony of the production environment (passive time
monitoring the progress of the technical process as a percentage of the shift time). 5. Operating mode:
a) the actual duration of the working day; b) shift work;
c) the presence of regulated breaks and their duration. For each of the indicators, its own class of working conditions is determined separately. In the event that any indicator is not presented based on the nature or characteristics of professional activity, then this indicator is assigned class 1 (optimal) - tension
light labor.
Fatigue is a condition accompanied by a feeling of fatigue, decreased performance, caused by intense or prolonged
activity, which is expressed in the deterioration of quantitative and qualitative indicators of work and stops after rest.
For a long time, physiologists have tried to answer the question about the essence and mechanisms of fatigue. Fatigue was seen as a consequence of "depletion" of muscle energy resources (mainly carbohydrate metabolism) or as a result of insufficient oxygen supply and impairment oxidative processes– theory of “strangulation”; was defined as a consequence of tissue contamination with metabolic products, i.e. “poisoning” with them.
According to one theory, the development of fatigue was associated with the accumulation of lactic acid in the muscles. All of these theories were humoral-localistic, defining fatigue as a process occurring only in the muscles, without taking into account the coordinating role of the central nervous system. The works of I.M. are devoted to studying the role of the central nervous system in the development of fatigue. Sechenova, I.P. Pavlova, N.E. Vvedensky, A.A. Ukhtomsky, M.I. Vinogradova.
So, I.M. Sechenov showed that fatigue does not arise in the working organ itself, not in the muscle, but in the central nervous system: “The source of the feeling of fatigue lies not in the muscle, but in the disruption of the activity of the nerve cells of the brain.” M.I. Vinogradov considered it necessary to distinguish between two types of fatigue: quickly occurring, due to central inhibition, and slowly developing, associated with a decrease in the levels of transmission of nerve impulses in the motor system itself.
According to I.P. Pavlova inhibition, which occurs during fatigue in the central nervous system, is protective in nature, limiting performance cortical centers brain, it protects nerve cells from overstrain and death. Until now, the most popular is the central nervous theory of fatigue. At the same time, the possibility of influence local processes, occurring in muscles and other working organs, on the formation of quenching processes (lack of oxygen, depletion of nutrients, accumulation of metabolites, etc.).
They can accelerate fatigue, and due to feedback– change the functional state of the central nervous system. Thus, with severe physical fatigue, mental work is unproductive, and, conversely, with mental
muscle performance is preserved in the event of fatigue. During mental activity, elements of muscle fatigue are constantly observed: prolonged stay in a certain static position leads to significant fatigue of the corresponding parts of the motor system.
With mental fatigue, more pronounced functional changes in the central nervous system are observed: attention disturbance, deterioration of memory and thinking, and decreased accuracy and coordination of movements. Resumption of work against the background of slowly developing fatigue leads to the fact that the remaining traces of fatigue accumulate and overwork sets in, and with it headache, a feeling of heaviness in the head, lethargy, absent-mindedness, decreased memory, attention, and sleep disturbance.
Performance phases
The effectiveness of a person’s work activity largely depends on two main factors: load and performance dynamics.
The total load is formed by the interaction of the following components: subject and tools of labor, organization of the workplace, hygienic factors of the production environment, technical and organizational measures. The effectiveness of matching these factors with human capabilities largely depends on the presence of a certain performance capacity.
Performance- the amount of functional capabilities of the body, which is characterized by the quantity and quality of work performed in a certain time, under the most intense stress.
The level of a person’s functional capabilities depends on working conditions, health, age, degree of training, motivation to work and other factors specific to each specific activity. During work activity, the functional ability of the body and labor productivity naturally change
throughout the working day. At the same time, the dynamics of performance has several phases or alternating states of a person (Fig. 4.1).
Rice. 4.1. Dynamics of human performance:
I, IV – periods of running-in; II, V – periods of high performance; III, VI – periods of decreased performance; VII – final impulse
Run-in phase. During this period, the volume of physiological processes accelerates and increases, the level of performance gradually increases compared to the initial one. Depending on the nature of the work and the individual characteristics of the person, this period lasts from several minutes to 1.5 hours, and for mental creative work – up to 2–2.5 hours.
Phase of high sustainable performance. It is characterized by a combination of high labor indicators with relative stability or even some reduction in the intensity of physiological functions. The duration of the period can be 2–2,5 h or more, depending on the degree neuro-emotional tension, physical heaviness and hygienic conditions labor.
Decreased performance phase. Decrease in performance
is accompanied by a decrease in the functional capabilities of the main working human organs. By the lunch break, the state of the cardiovascular system worsens, attention decreases, unnecessary movements and erroneous reactions appear, and the speed of problem solving slows down.
The dynamics of performance are repeated after the lunch break. At the same time, the start-up phase proceeds faster, and the stable performance phase is lower in level and shorter than before lunch. In the second half of the shift, a decrease in performance occurs earlier and develops faster due to deeper fatigue. Just before the end of work, a short-term increase in performance occurs, the so-called final or “finishing” rush.
Occurring deviations from the typical classical performance curve of greater or lesser severity indicate the presence of unfavorable external causes characteristic of specific types of activity, but the main task is to prolong the
requirements for sustainable performance.
Work and rest modes. When developing rational work and rest regimes, it is necessary to take into account the characteristics of professional activity. The current state of scientific and technological progress is characterized by a blurring of the lines between mental and physical labor and an increase in the share of the mental component. What are the features here?
Mental work combines work related to the reception and incomplete processing of information, requiring primary tension of the sensory apparatus, attention, memory, as well as activation of thinking processes and the emotional sphere. It is divided into operator, managerial, creative work, the work of medical workers, the work of teachers, students and students. These types of work differ in the organization of the labor process, uniformity of workload, and degree of emotional stress.
For example, managerial work - the work of heads of institutions, organizations, enterprises is characterized excessive growth volume of information, increasing lack of time for processing it, increased personal responsibility for decision making, possible conflict situations. The work of teachers is characterized by constant contact with people, increased responsibility, and often a lack of time and information to make the right decision, which leads to a high degree of neuro-emotional stress. For
Student work is characterized by tension in basic mental functions (memory, attention, perception), and the presence of stressful situations (exams, tests). Neuro-emotional stress is accompanied by increased activity of the cardiovascular system, breathing, energy metabolism, and increased muscle tone.
Optimization of mental work should be aimed at maintaining high level performance and to eliminate chronic neuro-emotional stress.
When developing rational work and rest regimes, it is necessary to take into account the fact that when mental load the brain is prone to inertia, to continuing mental activity in a given direction. At the end of mental work, the “working dominant” does not completely fade away, causing longer fatigue and exhaustion of the central nervous system than during physical work.
There are general basic physiological conditions for productive mental work.
1. You should get into work gradually. This ensures sequential switching physiological mechanisms, defining a high level of performance.
2. It is necessary to maintain a certain rhythm of work, which promotes the development of skills and slows down the development of fatigue.
3. You should adhere to the usual consistency and systematicity in your work, which ensures a longer preservation of the working dynamic stereotype.
4. Proper alternation of mental work with rest. Alternating mental and physical work prevents the development of fatigue and increases performance.
5. High performance is maintained with systematic activity that provides exercise and training. Optimizing mental activity, like any activity,
promotes a favorable attitude of society towards work, as well as a favorable psychological climate in the team.
The main task of scientifically based rational work and rest regimes is to reduce fatigue, achieve high labor productivity throughout the entire working day with lowest voltage physiological functions of a person and maintaining his health and long-term performance.
The maintenance of high, stable performance is facilitated by periodic alternation of work and rest, which is provided for by intra-shift work and rest regimes.
There are two forms of alternating periods of work and rest:
1) introduction of a lunch break in the middle of the working day, the optimal activity of which is determined taking into account the distance from workplaces sanitary facilities, canteens, and other places for eating;
2) introduction of short-term regulated breaks, the duration and number of which are determined based on monitoring the dynamics of performance, taking into account the severity and intensity of work. For work that requires a lot of nervous tension and attention, fast and precise hand movements, more frequent, but shorter, 5-10 minute breaks.
In addition to regulated breaks, there are also micro-breaks - breaks in work that ensure the maintenance of an optimal pace of work and a high level of performance. Depending on the nature and severity of the work, micro-breaks account for 9–10% of the working time.
In accordance with the daily cycle of performance, its highest level is observed in the morning and afternoon hours - from 8 to 12 o'clock in the first half of the day and from 14 to 17 o'clock in the second. In the evening hours, performance decreases, reaching its minimum at night. In the daytime, the lowest performance is between 12 and 14 o'clock, and at night - from 3 to 4 o'clock.
The alternation of periods of work and rest during the week should also be regulated taking into account the dynamics of performance. Thus, the highest performance occurs on the 2nd, 3rd and 4th days of work, and after
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 tumors of the mammary, 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 of 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 has a large practical significance, as it allows one to assess the actual 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 in animals of various locations: 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 involved in the extraction and processing of asbestos develop lung tumors, 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- products of plant life, including lower plants - molds. 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). 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. They may cause the development of certain types of malignant neoplasms in special conditions of the 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 extracts from bile, lung tissue, and urine was studied, and in all cases, as a rule, tumors appeared in 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 the urine of healthy people, but with some neoplasms their amount 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 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 effects of chemical carcinogens. All chemical carcinogenic compounds have a number of common features actions 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, and 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.”
CARCINOGENIC SUBSTANCES
(carcinogens, oncogenic substances), chemical. compounds, increasing the incidence of malignancies. tumors. Among K. v. conventionally distinguish between direct and non-direct agents direct action. The first include highly reactive compounds. (and its derivatives, etc.), capable of directly reacting with biopolymers (DNA, RNA,). Indirect K. v. themselves are inert and turn into active compounds. with the participation of cell enzymes - for example, monooxygenases, which catalyze the inclusion of one oxygen atom in the substrate molecule. As a result, substances are formed that react with biopolymers. Yes, metabolic. activation of indirect K. v. N-nitrosodimethylamine (NDMA), which causes tumors in many. species of animals, is carried out according to the scheme:
The resulting diazohydroxide is capable of alkylating cells, including nucleophiles. DNA base centers. It is assumed that in this case the max. important target - alkylation of which at the O atom in position 6 leads to the appearance mutations(see also Art. Mutagens).
Mutations arise in the process of DNA repair (restoration) if the damaged area cut out by endonucleases is restored with errors (for example, as a result of changes in the original nucleotide sequence), which are copied during replication (self-reproduction of DNA) and, having thus been fixed, are transmitted in a number of cellular generations. If such structural changes occur in a proto-oncogene (a DNA nucleotide sequence that causes malignant cell transformation), this leads to its transformation into an oncogene and the synthesis of mutant regulatory proteins that carry out individual stages of malignancy. cell transformation. The same thing can happen as a result of caused by K. v. changes in the location of genes in the genome (for example, during gene translocation S-tus in the region of actively transcribed immunoglobulin genes in Burkitt lymphoma). The occurrence of oncogenic mutations is the stage of initiation of carcinogenesis (the transformation of a normal cell into a tumor one), and the agents that cause carcinogenesis are called. carcinogen initiators. Further changes in the cell on the path to malignancy. transformations cause carcinogenesis, which cause disturbances in intercellular interactions and cellular metabolism, leading the cell to a state of phenotypically expressed tumor transformation and to the development of a tumor. The primary tumor node progresses to the main stage. as a result of cellular selection, changing their properties depending on the decomposition. influences (hormonal, chemotherapeutic) most often in the direction of dedifferentiation and reducing dependence on the regulatory influences of the body. Naib. The studied promoters of skin carcinogenesis are certain derivatives of diterpenes, hepatic -phenobarbital (5-phenyl-5-ethyl-2,4,6-pyrimidinetrione) and certain chlororg. conn., in the large intestine - bile acids. The vast majority of K. c. has both initiating and promoting activity and belongs to the “full” K. century. Mn. K.v. have pronounced organotropy (the ability to induce tumors in certain organs), edges may. due to the distribution of K. century. in the body and the characteristics of their metabolism in the cells of different organs. Thus, for example, 2-naphthylamine causes bladder cancer in humans, angiosarcomas of the liver, and asbestos causes mesotheliomas of the pleura and peritoneum. In the experiment, skin tumors are caused by polycyclic. aromatic (for example, 1,2-benzopyrene, 9,10-dimethyl-1,2-benzoanthracene), liver tumors - fluorene derivatives (for example, 2-acetylaminofluorene, type I): certain (for example, 3 -methyl-4"-dimethylaminoazobenzene), (for example, aflatoxin B 1), intestinal tumors - hydrazine derivatives (for example,). The species specificity of the action of many K. v. is noted. Thus, 2-acetylamicofluorene - K. v. for in rats, but not in guinea pigs, aflatoxin B 1 is found to be high in rats and rainbow trout, but has low activity in mice. 
According to the International Agency for Research on Cancer (IARC), in 1985 there were 9 production facilities. processes and 30 compounds, products or groups of compounds that are certainly capable of causing tumors in humans. Another 13 substances are considered as agents with a very high probability of carcinogenic risk for humans. To unconditional K. v. include:, or imuran (see. Immunomodulatory agents);
antitumor agents (some of them are not currently used) - (II), chlorobutin (III), mileran CH 3 S(O 2)O(CH 2) 4 OS(O 2)CH 3, melphalan L -p-[(ClCH 2 CH 2) 2 N]C 6 H 4 CH 2 CH(NH 2)COOH; a combination of antitumor drugs, including procarbazine n-[(CH 3) 2 CHNHC(O)]C 6 H 4 CH 2 NHNHCH 3 .HCl, nitrogenous, vincristine (an alkaloid contained in the pink periwinkle plant) and (IV); painkillers containing phenacetin P- C 2 H 5 OC 6 H 4 NHC(O)CH 3 ; a mixture of estrogens [piperazinium and Na-salt of estrone (V) and Na-salt of equilin (VI)]; vinyl chloride; diethylstilbestrol [p-NOS 6 H 4 C (C 2 H 5) =] 2; mustard gas; methoxazolene (VII) in combination with UV irradiation; ; 2-naphthylamine; N,N- bis-(2-chloroethyl)-2-naphthylamine; threosulphine 2; 1,1"-dichlorodimethyl ether; benzidine; 4-aminobiphenyl; and its compounds; and some of its compounds; coal tar; pitch obtained from this tar; shale oils; asbestos; tobacco smoke; chewing gum containing betel and tobacco leaves; chewing tobacco. Conventional toxicants for humans include: certain aflatoxins, 1,2-benzopyrene and its compounds, dimethyl and diethyl sulfate and some of its compounds, procarbazine, o-toluidine, phenacetin, nitrogen mustards, creosote and hydroxymethalone (VIII).An increased incidence of malignant tumors is observed in enterprises for coal gasification, nickel refining, auramine production (diarylmethane dye), and in underground mining of hematite (red iron ore) in mines polluted with radon; in the rubber, furniture and shoe industries; in the production of coke and isopropyl alcohol using H 2 SO 4. In everyday life, chlorine compounds enter the human body with the products of tobacco smoking, which cause cancer of many localizations (primarily lung cancer), with internal engine exhaust. combustion, smoke emissions will heat. systems and industrial enterprises, mycotoxins that contaminate food when stored improperly, etc. The possibility of synthesizing carcinogenic nitrosamines from secondary nitrosamines and nitrites in the human stomach has been shown. Endogenous K. v. are formed in the body when the metabolism of certain amino acids is disrupted, in particular tryptophan and tyrosine, which can be converted accordingly. into carcinogenic 3-hydroxykynurenine and 3-hydroxyanthranilic (2-amino-3-hydroxybenzoic) compounds. Action K. v. can be significantly weakened with the help of vitamins (riboflavin, ascorbic acid, vitamin E), b-carotene (carotenoid), trace elements (Se and Zn salts), and a number of other chemicals. conn. (eg, teturama, certain steroids). Lit.: Shabad L. M., Evolution of the concepts of blastomogenesis, M., 1979; Results of science and technology. Ser. Oncology, v. 15. Chemical carcinogenesis. M., VINITI, 1986; IARC monographs on the evaluation of the carcinogenic risk of chemicals to humans. Suppl., v. 4 Chemicals, industrial processes and industries associated with cancer in humans, Lyon, 1982 (IARC Monographs, v. 1 to 29); Valinio H., "Carcmogenesis", 1985, v. 6, no. 11, p. 1653-65. G. A. Belitsky.
Chemical encyclopedia. - M.: Soviet Encyclopedia. Ed. I. L. Knunyants. 1988 .
See what "CARCINOGENIC SUBSTANCES" are in other dictionaries:
- (from lat. cancer cancer and...gene) chemical substances, the effect of which on the body under certain conditions causes cancer and other tumors. Carcinogenic substances include representatives of various classes of chemical compounds: polycyclic... ... Big Encyclopedic Dictionary
Carcinogens- chemical compounds that, when exposed to the human body, can cause cancer and other diseases ( malignant tumors), as well as benign neoplasms. See also Carcinogenicity... Russian encyclopedia of labor protection
- (from lat. cancer cancer and...gene), a chemical substance, the effect of which on the body under certain conditions causes cancer and other tumors. Carcinogenic substances include representatives of various classes of chemical compounds: ... ... encyclopedic Dictionary
- (from Latin cancer cancer and Greek genes giving birth, born) blastomogenic substances, carcinogens, carcinogens, chemical compounds that, when exposed to the body, can cause cancer and other malignant tumors, as well as benign... ... Great Soviet Encyclopedia
- (cancer + Greek genes generating) m. Oncogenic substances ... Large medical dictionary
- (from lat. cancer cancer and...gene), chemical. in va, the effect on the body at a certain level. conditions causes cancer and other tumors. To K. v. include representatives of various chemical classes compounds: polycyclic hydrocarbons, azo dyes, aromatics. amines... ... Natural science. encyclopedic Dictionary
- (syn.: blastimogenic substances, carcinogenic substances, carcinogens) substances that have the ability to cause the development of tumors. Oncogenic substances are exogenous O. v., entered the body from the environment. Oncogenic substances endogenous O... Medical encyclopedia
- (syn.: blastomogenic substances, carcinogenic substances, carcinogens) substances that have the ability to cause the development of tumors ... Large medical dictionary
Occupational carcinogenic factors
Occupational carcinogenic factors include physical and chemical factors whose impact on the human body in the process of work leads to the development of occupational tumors. These tumors cannot be distinguished by qualitative characteristics from neoplasms caused by other causes; the main criterion in resolving this issue is quantitative indicators - earlier and more frequent development of tumors in workers in certain production conditions. Establishing a connection between a tumor and the influence of industrial factors makes it difficult to establish a long latent period for the occurrence of tumors. By the time a tumor forms, a person can already stop working in contact with carcinogenic factors. Therefore, it is very important to correctly collect anamnesis and establish an occupational route, as well as take into account the intensity of industrial exposure.
The most common occupational tumors are those associated with direct contact of the body with a carcinogenic factor (skin tumors in chimney sweeps, lung tumors in dust workers, etc.), or on the paths of concentration (liver) and excretion of a carcinogenic substance (bladder). Of great importance is the high sensitivity of tissues (hematopoietic tissue) to the blastomogenic effects of radiation.
Epidemiological and experimental methods are used to identify occupational carcinogenic factors. The epidemiological method alone does not provide sufficient information, since the effect of any factor at work and at home cannot be isolated. With the help of experiments, the blastomogenic properties of a number of chemical substances were revealed, and this gave rise to a new scientific direction - oncohygiene. Of the inorganic substances, the carcinogenic effect of metals (nickel, chromium, beryllium, cadmium), as well as fibrous materials (asbestos), which cause a carcinogenic effect mainly at the site of application, has been best studied. The main carcinogenic factors of physical nature are ionizing radiation and UV rays. Under general irradiation with penetrating radiation (gamma rays, hard X-rays, protons, neutrons), neoplasms are induced in almost any organ. Under the influence of non-penetrating ionizing radiation (soft x-rays, α- and β-particles) tumors develop at the site of the primary and longest contact of tissue with radiation. Among organic substances, 3,4-benzo(a)pyrene, halogenated hydrocarbons, aromatic amines, resins, mineral oils, etc. have a carcinogenic effect.
The initial phase of any type of carcinogenesis is the initiation-induction of genetically altered cells. The next phase, promotion, the period before tumor detection, is associated with the selection of initiated cells and the manifestation of their transformed phenotype. A necessary link in both stages of carcinogenesis is cell proliferation. Most carcinogens have an initiating effect, and only for some of them the main effect is a promoting effect. Such carcinogens, called conditional (carbon tetrachloride, some metals, possibly asbestos), lead to an increase in tumors, apparently as a result of stimulation of cell proliferation initiated by other agents, most likely endogenous. Carcinogenesis is influenced by many factors called modifying factors. An important place among them is occupied by nonspecific tissue damage (mechanical, thermal, chemical), leading to stimulation of the process, which is referred to as the “carcinogenic effect.”
The occurrence of tumors largely depends on the individual sensitivity of the body, in particular the genetically determined level of activity of metabolic systems and enzymes that perform DNA repair.
Thus, the carcinogenic danger is determined not only by the nature of the carcinogen, but also by various exo- and endogenous factors.
According to the classification of the International Agency for Research on Cancer (IARC, 1982), chemical substances according to their carcinogenic hazard to humans are divided into 2 large groups:
Group I - substances with proven carcinogenicity for humans; 4-amidophenyl; arsenic and its compounds; asbestos, benzene; benzidine; bis (chloromethyl) and chloromethyl ether (technical grade); chromium and some of its compounds; sulfur mustard; 2-naphthylamine; soots, resins and mineral oils; vinyl chloride
Group II - substances with probable carcinogenicity for humans (divided into 2 subgroups): IIa - for which this probability is high, and subgroup IIb, for which the degree of probability is low.
Subgroup IIa includes: acrylonitrile, benzo(a)pyrene, beryllium and its compounds, diethyl sulfate, dimethyl sulfate, nickel and its compounds, o-toluidine.
Subgroup IIb includes: amitrol, auramines (technical grade); benzotrichloride; cadmium and its compounds; carbon tetrachloride; chloroform; chlorophenols (industrial exposure); DDT; 3,3-trichlorobenzidine; 3,3-dimethoxybenzidine (orthodianizidine); dimethylcarbamoyl chloride; 1,4-diaxin; straight black 38 (technical purity); direct mini 6 (technical purity); epichlorohydrin; ethylene oxide; ethylene thiourea; formaldehyde (gas); hydrazine; herbicides; derivatives of phenoxyacetic acid (industrial exposure); polychlorinated biphenyls; tetrachlorodibenzo-n-dioxin-2,4,6-trichlorophenol.
Most substances in both groups are carcinogenic to animals.
Regarding group IIb, epidemiological data are contradictory.
The carcinogenic effect of chemical factors depends on their structure.
Ways to prevent cancer at work: There are 2 main ways to prevent cancer: primary prevention, aimed at eliminating etiological factors, and secondary prevention, based on early detection and treatment of precancerous diseases. In this case, production, technical, sanitary, hygienic and medical preventive measures are used.
Production activities include a variety of engineering, technical, legal and organizational decisions carried out at the stage of design and reconstruction of production. They consist of sealing equipment and automation of technological processes, changing technology, decarcinogenization of industrial products by cleaning them from carcinogenic impurities or destroying carcinogens, prohibiting the use of certain types of raw materials and materials, etc.
Sanitary and hygienic measures are aimed mainly at identifying industrial carcinogenic factors using experimental and epidemiological studies, as well as identifying contamination of the working environment with carcinogens. To quickly select (screen) substances suspected of having carcinogenic properties, rapid tests for mutagenicity are used (a correlation has been identified between the mutagenicity and carcinogenicity of chemicals).
In relation to the most dangerous carcinogenic compounds, the main remedy is to limit their production and use. For carcinogens that are ubiquitous, hygienic regulation is necessary based on the dose-effect relationship in animals, identification of the minimum effective dose and further extrapolation of the data obtained to humans.
When standardizing, the results of epidemiological studies are also taken into account.
The goals of prevention are compliance with personal hygiene and safety rules (in particular, regular and correct use of personal protective equipment), which is facilitated by well-organized sanitary education work and timely instruction.
Medical prevention includes preliminary pre-employment and periodic medical examinations workers, as well as clinical examination of the population aimed at identifying and treating background and precancerous diseases.
Given the long latent period of cancer, people at least 40-45 years old should be employed in cancer-hazardous industries.
Thanks to preventive measures, the incidence of occupational cancer in the coke-chemical, shale processing, oil refining, aniline paint and other industries has been reduced.
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 (e.g. endemic areas with high levels of arsenic in soil and water) and are generally relatively low levels content in the 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 economic activity person. It is hardly possible to evaluate all the components that form the background.
Carcinogenicity is the property of some chemical, physical and biological factors, alone or in combination with other factors, to 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. There are direct-acting carcinogenic factors, 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, the impact of which is associated with professional activities, are called occupational carcinogens or carcinogenic occupational factors (COP). 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 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 have been identified as chemical occupational carcinogens in accordance with this classification. chemicals(not including pesticides and some medicines that have carcinogenic properties) and a number of industries that use them, which are included in the 1st classification group. 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. To the group of possibly carcinogenic industrial chemical agents (2b), the carcinogenicity of which has been proven mainly by experimental research 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 CPFs include some viruses (for example, hepatitis A and C viruses), causative agents of infectious diseases of the 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 that pollute the environment, several hundred substances have been identified 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 the closest people. In large cities, circulatory and respiratory diseases, heart attacks, hypertension and neoplasms are also more common. According to experts, the “contribution” of road transport to the atmosphere is up to 90% for carbon monoxide and 70% for 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.
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, 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, N2, NH3, HNO3, HCN, H, H2, OH, H2O.
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, under poor mixing conditions, the number of evaporated molecules required for ignition and combustion is ensured.
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 enriched during combustion releases less heat, the combustion process slows down and is accompanied by large heat losses 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. With an increase in the fuel injection advance angle, the ignition delay period lengthens, the homogeneity of the air-fuel mixture improves, large quantity the 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 of 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 vehicle 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 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 largest group of compounds is hydrocarbons. The effect of falling concentrations of atmospheric pollution, that is, approaching the normal state, is associated not only with the dilution of exhaust gases with air, but also with the ability of self-purification of 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 favorable conditions for this appear - the 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 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, O3), peroxide compounds and free radicals.
Hydrocarbons in the atmosphere undergo various transformations (oxidation, polymerization), interacting with other atmospheric pollution, 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 participate in smog, but are not the main carriers of the high level of 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, under 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 are involved 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 suffering from chronic bronchitis, coronary insufficiency, asthma are more vulnerable.
The general scheme of the body’s response to exposure to environmental pollutants according to the World Health Organization (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. Inhalation of ozone causes coughing, shortness of breath, damage 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
