The toxic effects of various substances are examples. Classification of hazardous chemicals. Toxicological classification of hazardous substances

Classification of harmful substances. Performance different types Geological exploration (drilling of bore holes, blasting, loading, unloading and transportation of rock mass) is accompanied by the release of harmful substances into the air.

A harmful substance is a substance that, in the event of a violation of safety requirements, can cause industrial injuries, occupational diseases or deviations in the state of health that are detected both during work and in the long-term life of present and future generations.

From the point of view of the Belarusian Railways, when assessing the state of the air environment, the following is of greatest importance: 1) the gas composition of the air; 2) the level of its atmospheric pressure; 3) the presence of mechanical and toxic impurities in the air.

1. Gas composition of air. The most favorable for breathing is atmospheric air containing (% by volume) nitrogen - 78.08, oxygen - 20.95, inert gases - 0.93, carbon dioxide - 0.03, other gases - 0.01.

Harmful substances released into the air of the working area change its composition, as a result of which it can differ significantly from the composition of atmospheric air.

Of the chemical components of the air for the human body, the oxygen content in the air is important. The main sources of oxygen release are the planktonic film of the ocean and flora. Its decrease to 17% leads to a deterioration in the human condition, a further decrease causes death. The high oxygen content dramatically increases the explosion and fire hazard of the environment.

In unventilated mine workings, the oxygen content only due to oxidative processes can drop to 3%. Entering such workings is life-threatening. The oxygen content in existing workings must be at least 20%.

Methane is released from coal seams. It is a colorless and odorless gas and is the main constituent of firedamp. In coal, methane is at a pressure of 20-30 atmospheres, and during the development of the seam, due to the pressure difference, it is released into the atmosphere of the workings. With significant accumulations of methane in the bottomhole, it is possible to displace oxygen and create conditions for the occurrence of asphyxia in workers (asphyxia - asphyxiation). The main danger of methane release is the ability to form a mixture with oxygen, which explodes in the presence of sources of high temperature. The explosion has maximum force when the air contains 9.5% methane.

A large amount of poisonous gases are released during blasting operations, the operation of machines with internal combustion engines in case of fires. The gaseous decay products of radioactive substances (emanations) - radon, toren and actinon - are very dangerous admixtures of mine air. They are found in mines developing uranium and thorium deposits. All emanations are isotopes that have different half-lives. Thus, radon has a half-life of 3.825 days and is capable of spreading over considerable distances from the source.

2. Level of atmospheric air pressure. The level of atmospheric air pressure depends on the altitude of the area and the air temperature. Normal air pressure is 101 kPa. But in the same area, the air pressure changes during the day. For human safety, it is not the pressure itself that is important, but the rate of its decrease or increase (73-126 kPa). About 23% of the population with a change in pressure complain of headache and weakness, especially those suffering from cardiovascular diseases. When climbing to a height and working in high altitude conditions, the pressure decreases (at an altitude of 5.5 km, the pressure drops by a factor of 2). The thin air causes oxygen starvation in humans. When working in mountainous areas, a person needs to adapt to these conditions within 3-4 weeks. Increased pressure in the workplace can be when working in mines, or in a caisson (fr. Box). When people are under pressure higher than atmospheric pressure, human blood and tissues absorb nitrogen. This causes decompression sickness (ear pain, dizziness, etc.). To prevent this disease, it is necessary to follow the Safety Rules for the production of caisson work (under compressed air).
3. The presence of mechanical and toxic impurities in the air. When carrying out various technological processes, solid and liquid particles, as well as vapors and gases, are released into the air. Vapors and gases form mixtures with air, and solid and liquid particles - aerodispersed systems - form aerosols. Aerosols are air or gas containing suspended solid or liquid particles. Aerosols are usually divided into smoke and fog. Fumes are systems consisting of air or gas and particles of solid matter distributed in them, and mists are systems formed by air or gas and particles of a liquid.

Dust is the main occupational hazard in the mining industry. Disintegration aerosols are generated during the crushing of any solid substance, for example, in disintegrators, crushers, mills, during drilling and other processes.

For the hygienic assessment of dust, an important feature is the degree of its dispersion (size of dusty particles). The particle size of the dust particles is greater than 1 µm, and the particle size of the smoke is less than this value. Distinguish between coarse (particle size more than 50 microns), medium (from 10 to 50 microns) and fine (particle size less than 10 microns) dust. The most dangerous for humans are particles ranging in size from 0.2 to 5 microns. They enter the lungs when breathing, linger in them and, accumulating, can cause disease.

The biological activity of dust depends on its chemical composition. The fibrogenicity of dust is determined by the content of free silicon dioxide (SiO2). Iron ore dust contains up to 30% free SiO2. The higher the content of free silica in the dust, the more aggressive it is.

There are various classifications of harmful substances based on their effect on the human body. In accordance with the most common (according to E.Ya. Yudin and S.V. Belov) classification, harmful substances are divided into six groups: general toxic, irritating, sensitizing, carcinogenic, mutagenic, affecting the reproductive (fertile) function of the human body.

General toxic substances cause poisoning of the whole organism. These are carbon monoxide, lead, mercury, arsenic and its compounds, benzene, etc.

Irritating substances irritate the respiratory tract and mucous membranes of the human body. These substances include: chlorine, ammonia, acetone vapor, nitrogen oxides, ozone and a number of other substances.

Sensitizing substances act as allergens, i.e. lead to allergies in humans. This property is possessed by formaldehyde, various nitro compounds, picotinamide, hexachlorane, etc. (Sensitization is an increase in the reactive sensitivity of cells and tissues of the human body).

The impact of carcinogenic substances on the human body leads to the emergence and development of malignant tumors (cancerous diseases). Chromium oxides, 3,4-benzpyrene, beryllium and its compounds, asbestos, etc. are carcinogenic.

Mutagenic substances, when exposed to the body, cause a change in hereditary information. it radioactive substances, manganese, lead, etc.

Among the substances that affect the reproductive function of the human body, one should first of all name mercury, lead, styrene, manganese, a number of radioactive substances, etc.

The nature of the action of harmful substances on the human body. The penetration of harmful substances into the human body occurs through the respiratory tract (the main route), as well as through the skin, with food, if a person takes it while at the workplace. The action of these substances should be considered as exposure to hazardous or harmful production factors, since they have a negative (toxic) effect on the human body. As a result of exposure to these substances, poisoning occurs in a person - a painful condition, the severity of which depends on the duration of exposure, concentration and type of harmful substance. Dust, getting into the human body, has a fibrogenic effect, consisting in irritation of the mucous membranes of the respiratory tract. Dust settles in the lungs and lingers in them. With prolonged inhalation of dust, occupational lung diseases occur - pneumoconiosis. When dust containing free silicon dioxide (SiO2) is inhaled, the most common form of pneumoconiosis, silicosis, develops.

For the air of the working area of industrial premises and open areas, in accordance with GOST 12.1.005-88, maximum permissible concentrations (MPC) of harmful substances are established. MPCs are expressed in milligrams (mg) of a harmful substance per 1 cubic meter of air, i.e. mg / m3. In accordance with the above-mentioned GOST, MPCs have been established for more than 1300 hazardous substances. Approximately 500 additional hazardous substances have tentative safe exposure levels (OSL).

According to GOST 12.1.005-88, all harmful substances according to the degree of impact on the human body are divided into the following classes:

1 - extremely dangerous (MPC less than 0.1 mg / m3),
2 - highly hazardous (MPC 0.1 to 1 mg / m3),
3 - moderately hazardous (MPC 1 to 10 mg / m3),
· 4 - low-hazard (MPC more than 10 mg / m3).

For example, metal mercury, lead, chlorine compounds, etc., low-hazardous ones with an MPC of more than 10 mg / m3 - ammonia, gasoline, kerosene, ethyl alcohol, etc., are extremely dangerous with an MPC less than 0.1 mg / m3.

The danger is established depending on the MPC value, the average lethal dose and the zone of acute or chronic action. If the air contains a harmful substance, then its concentration should not exceed the MPC value. Examples of maximum permissible concentrations of various substances are presented in table. 5.

Table 5

Maximum permissible concentrations of some harmful substances

Substance name	Chemical formula		Hazard Class	State of aggregation
Benzopiren Beryllium and its connections (in terms of for beryllium)		0,00015 0,001		Spray can
Sulphuric acid Hydrogen chloride
Nitrogen dioxide Methyl alcohol
Carbon monoxide Fuel gasoline	СНзСОСНз

With the simultaneous presence in air environment several harmful substances with a unidirectional effect, the following condition must be met:

where С1 С2 Сз, ..., Сn - actual concentrations of harmful substances in the air of the working area, mg / m3;

MPC1, MPC2, MPC3 ... .., MPCn - the maximum permissible concentration of these substances in the air of the working area.

Improvement of the air environment. The improvement of the air environment is achieved by reducing the content of harmful substances in it to safe values (not exceeding the MPC for a given substance), as well as maintaining the required microclimate parameters in the production area.

Preventive measures related to human exposure to dust can be divided into three groups: 1) technological and technical; 2) sanitary-technical; 3) medical and prophylactic.

It is possible to reduce the content of harmful substances in the air of the working area using technological processes and equipment in which harmful substances are either not formed or do not enter the air of the working area. For example, the conversion of various thermal installations and furnaces from liquid fuel, the combustion of which produces a significant amount of harmful substances, to a cleaner gaseous fuel, and even better - the use of electric heating.

Reliable sealing of equipment is of great importance, for example, devices for the transport of dusty materials, which exclude the ingress of various harmful substances into the air of the working area or significantly reduce their concentration in it.

Use of wetted bulk materials. The most commonly used hydro-irrigation using fine spray nozzles. To maintain a safe concentration of harmful substances in the air, use various systems ventilation.

If the listed activities do not give the expected results, it is recommended to automate production or switch to remote control of technological processes.

In some cases, to protect against the effects of harmful substances in the air of the working area, it is recommended to use personal protective equipment for workers (respirators, gas masks), but it should be borne in mind that this significantly reduces the productivity of personnel.

Consider the main personal protective equipment designed to protect the human respiratory system from harmful substances in the air of the working area. The specified means of protection are divided into filtering and insulating.

In filtering devices, polluted air inhaled by a person is pre-filtered, and in insulating devices, clean air is supplied through special hoses to the respiratory organs of a person from autonomous sources. Filtering devices (respirators and gas masks) are used with a low content of harmful substances in the air of the working area (no more than 0.5% by volume) and with an oxygen content in the air of at least 18%. One of the most common domestic respirators - the valveless respirator ШБ-1 "Lepestok" - is designed to protect against the effects of fine and medium-sized dust. Various modifications of the "Petal" are used to protect against dust, if its concentration in the air of the working area is 5-200 times higher than the MPC value. Industrial filtering gas masks are designed to protect the respiratory system from various gases and vapors. They consist of a half mask, to which a hose with a mouthpiece is connected, connected to the filter boxes. They are filled with absorbers of harmful gases or vapors. Each box, depending on the absorbed substance, is colored in a certain color (Table 6).

Table 6

Characteristics of filter boxes for industrial gas masks

Isolating gas masks are used in cases where the oxygen content in the air is less than 18%, and the content of harmful substances is more than 2%. Distinguish between self-contained and hose gas masks. The self-contained gas mask consists of a knapsack filled with air or oxygen, the hose from which is connected to the face mask. In hose insulating gas masks, clean air is supplied through a hose to the face mask from a fan, and the length of the hose can reach several tens of meters.

Various methods (filtration, sedimentation, electrical), etc. can be used to control the dust content of the air in the working area. New methods for measuring the concentration of dust in the air of the working area using laser technology are very promising. In our country, the most common direct weight (gravimetric) method for measuring the concentration of dust in the air of the working area. It consists in the selection of all dust in the breathing zone for special aerosol filters of the AFA VP type. Sampling is carried out using various aspirators. Determination of the concentration of harmful substances present in the air in the form of vapors and gases can also be carried out by various methods, for example, using portable gas analyzers such as UG-1 or UG-2.

Questions for self-control

1. What are aerosols?
2. What are the main ways of penetration of harmful substances into the human body?
3. How do harmful substances work on the human body?
4. Provide the classification of hazardous substances.
5. What is the fibrogenic effect of dust on the human body?
6. Give a definition of the concept of "maximum permissible concentration" (MPC).
7. How to ensure the maintenance of a safe concentration of harmful substances in the air?
8. List personal protective equipment against exposure to harmful substances.
9. How is the control over the content of harmful substances in the air of working ash carried out?
10. How are filtering and isolating gas masks arranged? What is their scope?
11. How are the filter boxes of domestic filtering gas masks marked and painted?

The rapid development of the chemical industry and the chemicalization of the entire national economy led to a significant expansion of production and the use in industry of various chemical substances; the range of these substances has also significantly expanded: many new chemical compounds have been obtained, such as monomers and polymers, dyes and solvents, fertilizers and pesticides, flammable substances, etc. on workers or inside their bodies, they can adversely affect the health or normal functioning of the body. These chemicals are called harmful. The latter, depending on the nature of their action, are divided into irritating substances, toxic (or poisons), sensitizing (or allergens), carcinogenic, etc. Many of them have several harmful properties at the same time, and primarily toxic to one degree or another, therefore the concept “ harmful substances "is often identified with" toxic substances "," poisons "regardless of the presence of other properties in them.

Poisoning and diseases resulting from exposure to harmful substances in the process of performing work in production are called occupational poisoning and diseases.

Causes and sources of emission of harmful substances. Harmful substances in industry can be included in the composition of raw materials, end products, by-products or intermediate products of a particular production. They can be of three types: solid, liquid and gaseous. The formation of dust of these substances, vapors and gases is possible.

Toxic dusts are generated for the same reasons as ordinary dusts described in the previous section (grinding, incineration, evaporation followed by condensation), and are released into the air through open openings, leaks of dusting equipment or when they are poured in an open way.

Liquid harmful substances most often seep through leaks in equipment, communications, are sprayed when they are openly drained from one container to another. At the same time, they can get directly on the skin of workers and have a corresponding adverse effect, and in addition, contaminate the surrounding external surfaces of equipment and fences, which become open sources of their evaporation. With such pollution, large areas of evaporation of harmful substances are created, which leads to a rapid saturation of the air with vapors and the formation of high concentrations. The most common reasons for the leakage of liquids from equipment and communications are corrosion of gaskets in flange joints, loosely lapped taps and valves, insufficiently sealed glands, metal corrosion, etc.

If liquid substances are in open containers, evaporation and penetration of the resulting vapors into the air of working rooms also occur from their surface; the larger the exposed surface of the liquid, the more it evaporates.

In the case when the liquid partially fills a closed container, the resulting vapors saturate the empty space of this container to the limit, creating very high concentrations in it. If there are leaks in this container, concentrated vapors can penetrate into the workshop atmosphere and pollute it. The vapor yield increases when the container is pressurized. Massive vapor emissions also occur when the container is filled with liquid, when the liquid being poured displaces accumulated concentrated vapors from the container, which enter the workshop through the open part or leaks (if the closed container is not equipped with a special air outlet outside the workshop). The release of vapors from closed containers with harmful liquids occurs when opening covers or hatches to monitor the progress of the process, stirring or loading additional materials, taking samples, etc.

If gaseous harmful substances are used as raw materials or are obtained as finished or intermediate products, they, as a rule, are released into the air of working rooms only through accidental leaks in communications and equipment (since if they are present in the apparatus, the latter cannot be opened even for a short time ).

As a result of adsorption, gases can settle on the surface of dust grains and be carried away along with them to certain distances. In such cases, places of dust emission can simultaneously become places of gas emission.

The source of emission of harmful substances of all three types (aerosol, vapor and gas) is often various heating devices: dryers, heating, roasting and melting furnaces, etc. Harmful substances in them are formed as a result of combustion and thermal decomposition of some products. They are released into the air through the working openings of these furnaces and dryers, the leaks of their masonry (burnouts) and from the heated material removed from them (molten slag or metal, dried products or fired material, etc.).

A frequent cause of massive emissions of harmful substances is the repair or cleaning of equipment and communications containing toxic substances, with their opening and even more so dismantling.

Some vaporous and gaseous substances, released into the air and polluting it, are sorbed (absorbed) by individual building materials, such as wood, plaster, brick, etc. Over time, such building materials are saturated with these substances and under certain conditions (temperature changes, etc.) ) themselves become sources of their release into the air - desorption; therefore, sometimes, even with the complete elimination of all other sources of hazardous emissions, their increased concentrations in the air can remain for a long time.

Ways of entry and distribution of harmful substances in the body. The main routes of entry of harmful substances into the body are the respiratory tract, digestive tract and skin.

Their entry through the respiratory system is of the greatest importance. Toxic dusts, vapors and gases released into the indoor air are inhaled by workers and penetrate into the lungs. Through the branched surface of the bronchioles and alveoli, they are absorbed into the blood. Inhaled poisons have an adverse effect almost throughout the entire time of work in a polluted atmosphere, and sometimes even after the end of work, since they are still being absorbed. The poisons that enter the bloodstream through the respiratory system are spread throughout the body, as a result of which their toxic effect can affect the most various bodies and fabrics.

Harmful substances enter the digestive organs by ingesting toxic dusts that have settled on the mucous membranes of the oral cavity, or by bringing them there with contaminated hands.

The poisons that enter the digestive tract are absorbed through the mucous membranes into the blood throughout the entire path. Absorption mainly occurs in the stomach and intestines. The poisons that enter the digestive organs are sent to the liver by the blood, where some of them are retained and partially neutralized, because the liver is a barrier to substances entering through the digestive tract. Only after passing through this barrier, poisons enter the general bloodstream and are carried by them throughout the body.

Toxic substances with the ability to dissolve or dissolve in fats and lipoids can penetrate the skin when the latter is contaminated with these substances, and sometimes when they are present in the air (to a lesser extent). The poisons that penetrate the skin immediately enter the general bloodstream and are carried throughout the body.

Poisons that have entered the body in one way or another can be relatively evenly distributed over all organs and tissues, exerting a toxic effect on them. Some of them accumulate mainly in some of the tissues and organs: in the liver, bones, etc. Such places of predominant accumulation of toxic substances are called a depot of poison in the body. Many substances are characterized by certain types of tissues and organs, where they are deposited. The delay of poisons in the depot can be both short-term and longer - up to several days and weeks. Gradually leaving the depot into the general bloodstream, they can also have a certain, usually mild toxic effect. Some unusual phenomena (alcohol intake, specific food, illness, injury, etc.) can cause more rapid elimination of poisons from the depot, as a result of which their toxic effect is more pronounced.

The excretion of poisons from the body occurs mainly through the kidneys and intestines; the most volatile substances are also excreted through the lungs with exhaled air.

Physical and chemical properties of harmful substances. The physicochemical properties of harmful substances in the form of dust are the same as those of ordinary dust.

If solid, but soluble hazardous substances are used in production in the form of solutions, their physicochemical properties will in many respects be similar to those of liquid substances.

When harmful substances get on the skin and mucous membranes, the surface tension of the liquid or solution, the consistency of the substance, the chemical affinity for fats and lipoids that cover the skin, and the ability to dissolve fats and lipoids are of the greatest hygienic importance from the physical and chemical properties.

Substances of a liquid consistency and liquids with a low surface tension when in contact with the skin or mucous membranes wet them well and contaminate a larger area, and, conversely, liquids with a high surface tension, thick consistency (oily) and solids, getting on the skin, more often remain on it in the form of droplets (if they are not rubbed) or dust particles (solids), in contact with the skin in a limited area. Thus, substances with a low surface tension and a liquid consistency are more dangerous than solids or substances with a thick consistency and with a high surface tension.

Substances that are close in their chemical composition to fats and lipoids, upon contact with the skin, relatively quickly dissolve in fats and lipoids of the skin and together with them pass through the skin into the body (through its pores, ducts of the sebaceous and sweat glands). Many liquids have the ability to dissolve fats and lipoids on their own and, as a result, also penetrate the skin relatively quickly. Consequently, substances with these properties are more dangerous than others with opposite physical and chemical properties (all other things being equal).

With regard to pollution with harmful vapors or gases of the air environment, the volatility of the substance, the pressure of its vapor, the boiling point, specific gravity, and chemical composition are of hygienic importance.

The volatility of a substance is the ability to evaporate a certain amount of it per unit of time at a given temperature. The volatility of all substances is compared with the volatility of ether under the same conditions, taken as a unit. Substances with low volatility saturate the air more slowly than substances with high volatility, which can evaporate relatively quickly, creating high concentrations in the air. Consequently, substances with increased volatility are more dangerous than those with low ones. With an increase in the temperature of a substance, its volatility also increases.

The elasticity or vapor pressure of the toxic liquid is of great hygienic importance, i.e. the limit of its saturation of air at a certain temperature. This indicator, like air pressure, is expressed in millimeters of mercury. For each liquid, the vapor pressure at certain temperatures is a constant value. The degree of possible saturation of the air with its vapors depends on this value. The higher the vapor pressure, the greater the saturation and the higher the concentrations can be created when this liquid evaporates. As the temperature rises, the vapor pressure also increases. This property is especially important to take into account during prolonged evaporation of toxic substances, when vapors are released until the air is completely saturated with them, which is often observed in closed, poorly ventilated rooms.

The boiling point, which is a constant value for each substance, also determines the relative hazard of this substance, since volatility depends on it under the usual temperature conditions of the shop. It is known that the most intense vaporization, i.e. evaporation occurs during boiling when the temperature of the liquid rises to this constant value. However, a gradual increase in the volatility of a liquid occurs as its temperature approaches the boiling point. Consequently, the lower the boiling point of a substance, the smaller the difference between the last and normal shop temperatures, the closer the temperature of this substance (if it is not additionally cooled or heated) to its boiling point, therefore, its volatility is higher. Thus, substances with a low boiling point are more dangerous than high boiling ones.

The density of a substance is one of the factors that determine the distribution of vapors of this substance in the air. Vapors of substances with a density less than the density of air under the same temperature conditions rise to the upper zone, therefore, passing through a relatively thick layer of air (when vapors are released in the lower zone), they quickly mix with it, polluting large areas and creating the highest concentrations in the upper zone (if there is no mechanical or natural extraction from there). When the density of substances is higher than the density of air, the emitted vapors accumulate mainly in the lower zone, creating the highest concentrations there. However, it should be noted that this last regularity is often violated when heat release takes place or the vapors themselves are released in a heated form. In these cases, despite the high density, the vapors are entrained in the upper zone by convection currents of heated air and also pollute the air. All these patterns must be taken into account when placing workplaces at different levels of the workshop and when equipping exhaust ventilation.

Some of the above physical properties of substances are significantly influenced by the state of the external environment, and above all by meteorological conditions. So, for example, an increase in the mobility of air increases the volatility of liquids, an increase in temperature increases the vapor pressure and enhances the volatility, the latter also contributes to the rarefaction of air.

The most essential hygienic value is the chemical composition of hazardous substances. The chemical composition of a substance determines its main toxic properties: different substances in their chemical composition have different toxic effects on the body, both in nature and in strength. A strictly defined and consistent relationship between the chemical composition of a substance and its toxic properties has not been established, however, some connection between them can still be established. So, in particular, substances of one chemical group, as a rule, are in many respects similar in the nature of their toxicity (benzene and its homologues, a group of chlorinated hydrocarbons, etc.). This sometimes makes it possible, by the similarity of the chemical composition, to roughly judge the nature of the toxic effect of some new substance. Within individual groups, similar in chemical composition of substances, some regularity was also revealed in the change in the degree of their toxicity, and sometimes in the change in the nature of the toxic effect.

For example, in the same group of chlorinated or other halogenated hydrocarbons, as the number of hydrogen atoms replaced by halogens increases, the degree of toxicity of substances increases. Tetrachloroethane is more toxic than dichloroethane, and the latter is more toxic than ethyl chloride. The addition of nitro or amino groups to aromatic hydrocarbons (benzene, toluene, xylene) instead of a hydrogen atom gives them completely different toxic properties.

Revealed some relationships between the chemical composition of substances and their toxic properties made it possible to approach an approximate assessment of the degree of toxicity of new substances based on their chemical composition.

The effect of harmful substances on the body. Harmful substances can have local and general effects on the body. Local action most often manifests itself in the form of irritation or chemical burns of the place of direct contact with the poison; usually it is the skin or mucous membranes of the eyes, upper respiratory tract and mouth. It is a consequence of the chemical effect of an irritating or toxic substance on living cells of the skin and mucous membranes. In a mild form, it manifests itself in the form of redness of the skin or mucous membranes, sometimes in their swelling, itching or burning sensation; in more severe cases, the painful phenomena are more pronounced, and changes in the skin or mucous membranes can be up to their ulceration.

The general effect of the poison occurs when it penetrates the bloodstream and spreads throughout the body. Some poisons are specific, i.e. selective action on certain organs and systems (blood, liver, nervous tissue, etc.). In these cases, penetrating the body in any way, the poison affects only a specific organ or system. Most of the poisons have a general toxic effect or effect on several organs or systems at the same time.

The toxic effect of poisons can manifest itself in the form of acute or chronic poisoning - intoxication.

Acute poisoning occurs as a result of a relatively short exposure to a significant amount of a harmful substance (high concentrations) and is characterized, as a rule, by the rapid development of painful phenomena - symptoms of intoxication.

Prevention of occupational poisoning and diseases. Measures to prevent occupational poisoning and diseases should be aimed, first of all, at the maximum elimination of harmful substances from production by replacing them with non-toxic or at least less toxic products. It is also necessary to eliminate or minimize toxic impurities in chemical products, for which it is advisable to indicate the limits of possible impurities in the approved standards for these products, i.e. carry out their hygienic standardization.

In the presence of several types of raw materials or technological processes to obtain the same product, it is necessary to give preference to those materials that contain less toxic substances or the existing substances have the least toxicity, as well as those processes in which toxic substances are not emitted or the latter have the least toxicity.

Particular attention should be paid to the use in production of new chemicals, the toxic properties of which have not yet been studied. Among such substances, there may be highly toxic ones, therefore, if appropriate precautions are not taken, the possibility of occupational poisoning is not excluded. To avoid this, all newly developed technological processes and newly obtained chemical substances should be simultaneously studied from a hygienic standpoint: to assess the hazard of hazardous emissions and the toxicity of new substances. All innovations and envisaged preventive measures must be coordinated with local authorities sanitary supervision.

Technological processes with the use or the possibility of the formation of toxic substances should be as continuous as possible in order to eliminate or reduce to a minimum the release of harmful substances at the intermediate stages of the technological process. For the same purpose, it is necessary to use the most sealed technological equipment and communications, which may contain toxic substances. Particular attention should be paid to maintaining tightness in flange connections (use resistant to this substance gaskets), in closing hatches and other working openings, stuffing box seals, samplers. If a leak or knocking out of vapors and gases from the equipment is found, urgent measures must be taken to eliminate the existing leaks in the equipment or communications. For loading raw materials, as well as unloading finished products or by-products containing toxic substances, sealed feeders or closed pipelines should be used so that these operations can be performed without opening equipment or communications.

The air displaced during the loading of containers with toxic substances must be discharged by special pipelines (air vents) outside the workshop (as a rule, to the upper zone), and in some cases, when especially toxic substances are displaced, it must be subjected to preliminary cleaning from harmful substances or their neutralization, disposal, and so on. Further.

It is advisable to maintain the technological mode of operation of equipment with the content of toxic substances in it so that it does not contribute to the increase in the emission of harmful substances. The greatest effect in this regard is provided by the maintenance of a certain vacuum in the apparatus and communications, in which even in the event of a leakage, the air from the workshop will be sucked into these apparatus and communications and prevent the release of toxic substances from them. It is especially important to maintain the vacuum in equipment and devices that have permanently open or non-hermetically closed working openings (ovens, dryers, etc.). At the same time, practice shows that in cases where, according to the conditions of technology, it is required to maintain especially high pressure inside the apparatus and in communications, knocking out of such apparatus and communications is either not observed at all, or it is very negligible. This is due to the fact that with significant leaks and knocking out, high pressure drops sharply and disrupts the technological process, i.e. it is impossible to work without proper tightness.

Technological processes associated with the possibility of harmful emissions should be mechanized and automated as much as possible, with remote control. This will eliminate the danger of direct contact of workers with toxic substances (contamination of the skin, overalls) and remove workplaces from the most dangerous zone of the location of the main technological equipment.

Timely scheduled preventive maintenance and cleaning of equipment and communications are of essential hygienic importance.

Cleaning of technological equipment containing toxic substances should be carried out mainly without opening and dismantling it, or at least with minimal opening in terms of volume and time (blowing, flushing, cleaning through stuffing box seals, etc.). It is advisable to repair such equipment on special stands isolated from the general room and equipped with enhanced exhaust ventilation. Before dismantling the equipment, both for delivery to the repair stand and for on-site repairs, it is necessary to empty it completely from the contents, then blow or rinse well until the residues of toxic substances are completely removed.

If it is impossible to completely eliminate the release of harmful substances into the air, it is necessary to use measures sanitary engineering and in particular ventilation. The most expedient and giving a greater hygienic effect is local exhaust ventilation, which removes harmful substances directly from the source of their release and does not allow their spread throughout the room. In order to increase the efficiency of local exhaust ventilation, it is necessary to cover the sources of hazardous emissions as much as possible and produce an exhaust from under these shelters.

Experience shows that in order to prevent the knocking out of harmful substances, it is necessary that the hood ensure that air is sucked in through open openings or leaks in this shelter at least 0.2 m / s; for extremely and especially dangerous and highly volatile substances, for a greater guarantee, the minimum suction rate increases to 1 m / s, and sometimes even more.

General exchange ventilation is used in cases where there are scattered sources of harmful emissions, which are practically difficult to completely equip with local suction units, or when local exhaust ventilation, for some reason, does not provide complete trapping and removal of the released harmful substances. It is usually equipped in the form of suction from areas of maximum accumulation of hazards with compensation of the removed air by an inflow of outside air, supplied, as a rule, to the working area. This type of ventilation is designed to dilute the harmful substances emitted into the air of working rooms to safe concentrations.

To combat toxic dust, in addition to the general technological and sanitary measures described above, the anti-dust measures described above are also used.

The layout of industrial buildings in which harmful emissions are possible, their architectural and construction design and the placement of technological and sanitary equipment should, first of all, ensure the preferential flow of fresh air both naturally and artificially to the main workplaces, to the service areas. For this, it is advisable to place such production facilities in low-span buildings with opening window openings for the natural flow of outside air into the workshop and with the location of service areas and stationary workplaces mainly near the outer walls. In cases of possible release of especially toxic substances, workplaces are located in closed control panels or isolated control corridors, and sometimes the most dangerous equipment in terms of gas emissions is isolated cabins. In order to exclude the danger of the combined action of several toxic substances on the workers, it is necessary to isolate production areas with various hazards as much as possible from each other, as well as from areas where there are no harmful emissions at all. At the same time, the distribution of the inflow and exhaust of ventilation air should provide for a stable backwater in clean or less polluted rooms with harmful emissions and discharge in more gassed ones.

For interior cladding of floors, walls and other surfaces of working rooms, such Construction Materials and coatings that do not absorb airborne toxic vapors or gases and are not permeable to liquid toxic substances. In relation to many toxic substances, oil and perchlorovinyl paints, glazed and metlakh tiles, linoleum and plastic coatings, reinforced concrete, etc. have such properties.

The above are only general principles of improving working conditions when working with hazardous substances; depending on the hazard class of the latter, their use in each specific case may be different, and in some of them a number of additional or special measures are recommended.

For example, sanitary standards the design of industrial enterprises when working with hazardous substances of 1 and 2 hazard classes, it is required to place technological equipment that can emit these substances in isolated cabins with remote control from consoles or operator zones. In the presence of substances of the 4th hazard class, air can be sucked into adjacent rooms and even partially recirculated if the concentration of these substances does not exceed 30% of the MPC; in the presence of substances of 1 and 2 hazard classes, air recirculation is prohibited even during non-working hours and the blocking of local exhaust ventilation with the operation of technological equipment is provided.

All of the above measures are mainly aimed at preventing air pollution of working premises with toxic substances. The criterion for the effectiveness of these measures is to reduce the concentration of toxic substances in the air of working rooms to their maximum permissible values (MPC) and below. For each substance, these values are different and depend on their toxic and physicochemical properties. Their establishment is based on the principle that a toxic substance at the level of its maximum permissible concentration should not have any adverse effect on workers, detected modern methods diagnostics, with an unlimited period of contact with him. In this case, a certain safety factor is usually provided, which increases for more toxic substances.

To control the state of the air environment, organize measures to eliminate detected hygienic deficiencies and, if necessary, provide first aid in case of poisoning, special gas rescue stations have been created at large chemical, metallurgical and other enterprises.

For a number of hazardous substances, especially hazard classes 1 and 2, automatic gas analyzers are used, which can be interlocked with a recording device that records concentrations throughout the shift, day, etc., as well as with a sound and light signal that notifies of exceeding the MPC. with the inclusion of emergency ventilation.

If it is necessary to carry out any work with concentrations of toxic substances exceeding their maximum permissible values, such as: liquidation of accidents, repair and dismantling of equipment, etc., it is necessary to use personal protective equipment.

To protect the skin of the hands, rubber or plastic gloves are usually used. Arms and aprons are made of the same materials to prevent overalls from getting wet with toxic liquids. In some cases, the skin of the hands can be protected from toxic fluids with special protective ointments and pastes, with which the hands are lubricated before work, as well as so-called biological gloves. The latter are a thin layer of a film formed during the drying of highly volatile non-irritating special compositions such as collodion. Eyes are protected from splashes and dust of irritating and toxic substances by means of special glasses with tight-fitting soft frames to the face.

If potent substances get on the skin or mucous membranes of the eyes, oral cavity, they must be immediately washed off with water, and sometimes (in case of contact with caustic alkali or strong acids) and rendered harmless by additional wiping with a neutralizing solution (for example, acid is a weak base, and alkali is weak acid).

When the skin is contaminated with difficult to remove or dyes, they cannot be washed off with various solvents used in industry, since most of them contain toxic substances in their composition, so they themselves can irritate the skin or even penetrate through it causing a general toxic effect. For this purpose, special detergents should be used. At the end of the shift, workers should take a warm shower and change into clean home clothes; in the presence of substances that are especially toxic and permeate clothing, everything should be changed, including underwear.

In those industries where, after carrying out and strict adherence to all preventive measures, there is still a certain danger of possible exposure to toxic substances, workers are provided with benefits and compensations that are provided for by the norms, depending on the nature of production.

When entering a job where there is a danger of contact with toxic substances, workers undergo a preliminary medical examination, and while working with substances of chronic action - a periodic medical examination.

A harmful substance is a substance that, in the event of a violation of safety requirements, can cause industrial injuries, occupational diseases, deviations in the state of health, found both in the process of work and in the long-term life of present and future generations.

Harmful substances released into the air of the working area change its composition, as a result of which it can differ significantly from the composition of atmospheric air.

There are various classifications of harmful substances based on their effect on the human body. In this regard, harmful substances are divided into 6 groups:

· General toxic;

· Annoying;

· Sensitizing;

· Carcinogenic;

· Mutagenic;

Affecting human reproductive function

General toxic substances cause poisoning of the whole organism. These are carbon monoxide, lead, mercury, arsenic.

Annoying substances cause irritation of the respiratory tract and mucous membranes of the human body. These include: chlorine, ammonia, acetone vapor, ozone.

Sensitizing substances(sensitization - increasing the reactive sensitivity of cells and tissues of the human body) act as allergens. This property is possessed by formaldehyde, various nitro compounds.

Impact carcinogenic substances on the human body leads to the emergence and development of malignant tumors. Carcinogenic are: chromium oxides, beryllium and its compounds, asbestos.

Mutagenic substances when exposed to the body, they cause a change in hereditary information. These are radioactive substances, manganese, lead.

Among substances that affect the reproductive function of the human body, one should first of all name mercury, lead, manganese, a number of radioactive substances, etc.

Currently, about 7 million chemicals and compounds are known, of which 60 thousand are used in human activities: 5500 - in the form of food additives, 4000 - drugs, 1500 - household chemicals.

All chemicals, depending on their practical use, are classified into:

· Industrial poisons used in production - organic solvents, fuel (uranium, butane), dyes (aniline);

· Pesticides used in agriculture (pesticides);

· Medicines (aspirin);

· Household chemicals used in the form of food additives (vinegar), sanitation, personal hygiene, cosmetics;

· Biological plant and animal poisons, which are found in plants, mushrooms, animals and insects;

· Toxic substances - sarin, mustard gas, phosgene.

Industrial chemicals can enter the body through the respiratory tract, gastrointestinal tract and intact skin. But the main route of admission is the lungs.

Domestic poisoning most often occurs when a poison enters the gastrointestinal tract.

The distribution of toxic substances in the body obeys certain patterns. First, there is a dynamic distribution of the substance, determined by the intensity of blood circulation. Then the absorption capacity of tissues begins to play the main role. A number of metals (silver, manganese, chromium, vanadium, cadmium) are characterized by rapid excretion from the blood and accumulation in the liver and kidneys. Compounds of barium, beryllium and lead form strong compounds with calcium and phosphorus and accumulate in bone tissue.

The toxic effect of harmful substances is the result of the interaction of the body, the harmful substance and the OS.

It is customary to refer to poisons only those that have their own harmful action develop under normal conditions and in relatively small quantities.

Industrial poisons include a large group of industrial substances and compounds that are in the form of raw materials, intermediate or finished products are found in production.

The general toxicological classification of poisons includes the following types effects on living organisms:

Nerve-paralytic (convulsions, paralysis);

· Local inflammation in combination with general toxic phenomena (vinegar essence);

General toxic (coma, cerebral edema, convulsions), for example, alcohol and its substitute, carbon monoxide;

· Lachrymal and irritating, for example, vapors of strong acids and alkalis;

· Psychotropic - drugs, atropine.

Poisons can also have selective toxicity, i.e. can pose a danger to a specific organ system or a specific organ.

They are divided into:

Cardiac with a predominant cardiotoxic effect ( medications, vegetable poisons, metal salts);

• nervous, causing impaired mental activity (carbon monoxide, alcohol, drugs, sleeping pills);

Liver (hydrocarbons, poisonous mushrooms, phenols and aldehydes);

Renal (connections heavy metals, oxalic acid);

· Blood - analyne, nitrites, arsenous hydrogen;

· Pulmonary - nitric oxide, ozone.

Industrial and chemical substances can enter the body through the respiratory system, gastrointestinal tract and damaged skin.

Toxic substances are present in a person's life and surround him every day. Such compounds have different structures, but they are always harmful to health. The aggregate state of substances is different, the effect on the human body is manifested immediately or after some time. What are the most dangerous toxic substances? How to reduce harm from them?

What is it

Toxic substances are compounds that are dangerous and are used in various areas of life. They pollute the atmosphere and negatively affect the health of living organisms. Toxic elements are the most common food contaminants.

They enter the body through food and liquid. Infection is possible through objects. Harmful compounds are in the form of gases, liquids and solid. Gaseous substances are spread by the wind and can penetrate through walls and open windows.

Toxic compounds in liquid form enter the body along with drinking, are present in the liquid immediately, or are formed during any chemical reactions.

The simultaneous action of several poisons on the body enhances the adverse effect or leads to its weakening.

Classification of toxic compounds

The number of toxic compounds is large, so there is a need to divide all substances into several groups according to certain symptoms. Such a classification allows you to timely determine the characteristics of the poison and provide assistance to the affected people.

What is toxicity? Harmful substances affect life, disrupting its normal course. Occupational poisoning is common. Such intoxications are acute - a single action of the toxin in a large volume - and chronic, when the poison enters the body in small portions, but constantly.

All poisons are divided according to the physiological effects of chemicals on humans. Which substance is the most toxic?

Groups:

Nerve paralytic. This group includes compounds that cause disruption of the nervous system. When ingested, they provoke vision problems, a strong flow of tears, painful sensations in the chest, and heart failure. The respiratory system is especially affected, the presence of spasmodic manifestations is noted. A lethal outcome is possible with serious poisoning in the first minutes of the penetration of the toxin inside. Such substances include VX, herd, soman. These toxins are the most dangerous and prohibited for use.
Skin blisters. Substances included in this list penetrate into the body through the upper layer of the epidermis, disrupting its integrity. The first signs of such intoxication appear gradually, after a while. A person's body temperature rises, he feels weakness, apathy. Gradually, the skin becomes irritated, redness, blisters, itching and pain are noted. Substances that enter the bloodstream are spread throughout the body and cause poisoning. Lewisite is also referred to as such compounds.
Commonly poisonous. Toxic compounds negatively affect the functioning of the brain, heart system, and other organs. In case of poisoning, there is nausea, dizziness, discomfort in the heart, problems with the respiratory system. With severe intoxications, convulsive manifestations, shortness of breath, respiratory failure, cardiac arrest are diagnosed.
Suffocating. Such compounds primarily affect the respiratory system. At the initial stages, damage to the mucous membranes of the upper respiratory tract develops, later bronchitis and pneumonia develop. Serious overdose leads to pulmonary edema. The victim has an increase in temperature, he does not have enough air, blood pressure is greatly reduced. The cause of death is pulmonary edema and respiratory failure.
Irritating substances. They enter the body through the respiratory tract. Provoke Negative influence on the mucous membranes of the nerve endings. The victim has severe painful sensations, tears flow, sneezing, intense coughing is present. Soreness disappears after a short period of time. Negative consequences - diseases of the eyes, lungs, severe bronchitis.
Psychochemical. Compounds of this group have a strong effect on the mental state of a person. The poisoned person has an increased desire to sleep, performance is impaired. The heart rate becomes more frequent, dryness of the epidermis and mucous membranes is noted. Lethargy gradually manifests itself, the person is not able to speak clearly. The duration of action of such substances is close to four days. Substances from this group are prohibited for use.

The effect of toxic compounds manifests itself individually for each person. For some, they can be poisonous, others will not do any harm. Toxic products are also classified according to the type of chemical elements.

Views:

Carcinogenic compounds cause malignant tumors and stimulate the spread of metastases.
Mutagenic ones have a negative effect on the genetic level, accumulate in the body and lead to the development of genetic mutations.
Sensitizing compounds negatively affect the immune system, increase the body's sensitivity to allergens.
Chemicals provoke various disturbances in the work of all body systems, adversely affect the reproductive system.

All toxic substances adversely affect the work of internal systems. Often, poisons lead to the destruction of cells, which provokes a complete organ failure.

Hazard classes can cause toxins

Toxic compounds have different effects on the body. According to regulatory documents substances are assigned a certain hazard class depending on its signs and degree of damage.

Separation:

The first class includes extremely dangerous toxic elements. The group includes plutonium, beryllium. All elements are dangerous, have carcinogenic effects, and lead to the development of oncology and radiation sickness.
The second class is represented by highly toxic substances. These include: arsenic, lead, chlorine. When ingested, they cause serious disturbances in the functioning of organs, cause painful sensations, and negatively affect the nervous system and the brain. They often cause death.
The third class includes moderately hazardous toxic substances. These are phosphates, nickel,. Toxins have a negative effect on the nervous system, disrupt metabolism, provoke allergic reactions and mental disorders.
The fourth class is represented by low-toxic compounds. This group includes chlorides and sulfates.

Thus, all toxins have their own hazard class. This allows you to accurately determine the possible consequences of poisoning.

Action on the body

How do they affect the body toxic substances? Toxic compounds have different effects on humans.

Influence:

Disruption of the nervous system, the occurrence of seizures and nervous excitement.
Negative effect on the organs of hematopoiesis.
Irritation of mucous membranes and respiratory tract.
They cause allergic reactions, increase the sensitivity of the skin.
They provoke the development of oncological diseases.
They have a harmful effect on the reproductive system, provoke miscarriages and infertility.
Cause a mutation at the gene level.

As a result of exposure to toxins in humans, the risk of developing serious diseases, the transition of diseases to a chronic form, increases. In case of serious poisoning, a lethal outcome is not excluded.

In everyday life, a person often uses various toxic substances. Careful and careful handling is required.

Scroll:

Antifreeze. They disrupt the work of the nervous system, provoke vomiting, lethargy, and the development of convulsive phenomena.
Poisons for rodents. The presence of nausea, lethargy, apathy, rarely diarrhea, bleeding from the gums is noted.
Psychoactive drugs. They disrupt the work of the cardiac system, there is dryness of the mucous membranes, an epileptic state.
Solvents. They cause painful sensations in the abdomen, vomiting, bowel upset, kidney and liver disorders.
Cleaning products. A person has vomiting, coughing, heart failure, irritation on the skin.
Grinding agents. An overdose is manifested by nausea, vomiting, impaired respiratory activity, the presence of blood in the urine.
Medicines. Pain in the stomach and intestines, nausea, dizziness, impaired breathing, vision.

Irritation, a feeling of grit in the eyes, redness are just minor inconveniences with impaired vision. Scientists have proven that a decrease in vision in 92% of cases ends in blindness.

Crystal Eyes is the best way to restore vision at any age.

Even drugs become poisonous if taken incorrectly. It is not uncommon for people to suffer from paint removers, fungicides, and other toxins. In everyday life, storage of such substances is required in inaccessible places.

How toxic substances enter the body

They can penetrate inside in different ways, which depend on the state of aggregation of the substance.

Ways and impact:

Most often, intake occurs through the respiratory tract. In such situations, the poison quickly enters the circulatory system and spreads throughout the body. First of all, the nervous system suffers. Poisonous vapors and gases act on all organs much faster than substances in another state.
In second place are poisoning as a result of ingestion of the toxin, getting it into the stomach. Harmful compounds are liquid or solid. Such intoxications are less dangerous, because there is time to provide first aid to a person. Toxins are absorbed slowly, symptoms develop after a while.
Penetration through the skin occurs only if the toxin has a destructive effect on the epidermis. The poison is absorbed internally and spreads throughout the body.
Mucous membranes cannot retain harmful compounds, therefore penetration occurs rapidly, and poisoning occurs.
Open wounds let toxins pass easily, and harmful products are rapidly absorbed into the bloodstream. Burns and frostbite slow down this process.

Any toxin poses a danger to humans, regardless of the possibility of entering the body. It is recommended to be more careful about poisonous products.

Ways of excretion entering the body

Toxic compounds are excreted from the body in several ways. Possible withdrawal through the intestines, respiratory organs, epidermis and with the help of the kidneys. When withdrawing, the poison continues to have a negative effect, therefore, these organs often suffer no less than others.

Toxic substances surround a person everywhere. Compliance with safety precautions and storage rules will help to avoid poisoning and negative consequences.

Video: what are toxins and their effect

Under harmful means a substance that, upon contact with the human body, causes industrial injuries, occupational diseases or abnormalities in the state of health.

Sources of emission of harmful substances in various industries can be leaking equipment, insufficiently mechanized (automated) operations of loading raw materials and unloading finished products, renovation work... Harmful substances can enter production premises and through supply ventilation systems in cases where the atmospheric air is contaminated with chemical products that are emissions from this production.

The direct sources of the release of harmful substances during poor storage can be preparatory operations: grinding and screening of materials, transportation of raw materials, pickling, and drying.

For example, the following substances and compounds can be dangerous at communication enterprises during installation, commissioning, operation: sealing wax, stamp paint, kerosene, gasoline, alcohol, acids (sulfuric, hydrochloric, boric), alkalis, lead, tin, fluxes, hydrogen, Sentabic (instead of bleach), antiseptics (uralite, triolite, sodium fluoride, creosote and anthracene oil) for impregnating poles and supports, waste gases in generator and diesel installations.

By chemical structure, harmful substances can be divided into the following groups:

* organic compounds (aldehydes, alcohols, ketones);
* elementary organic compounds (organophosphorus, organochlorine);
* inorganic (lead, mercury).

According to the state of aggregation, harmful substances are divided into gases, vapors, aerosols and their mixtures.

According to the effect on the human body, harmful substances are subdivided: a) into toxic- interacting with the human body, causing various deviations in the health status of the worker.

Conventionally, according to the physiological effect on humans, toxic substances can be divided into four groups:

* annoying- acting on the respiratory tract and the mucous membrane of the eyes (sulfur dioxide, chlorine, ammonia, hydrogen fluoride and chloride, formaldehyde, nitrogen oxides);
* suffocating- violating the process of assimilation of oxygen by tissues: carbon monoxide, chlorine, hydrogen sulfide, etc.;
* narcotic- nitrogen under pressure, trichlorethylene, benzyl, dichloroethane, acytene, acetone, phenol, carbon tetrachloride;
* somatic- causing disruption of the body or its individual systems: lead, mercury, benzene, arsenic and its compounds, methyl alcohol;
b) sensitizing- causing neuroendocrine disorders, accompanied by nesting baldness, skin depigmentation;
v) carcinogenic- causing growth cancer cells(from the Greek "carcero" - a crab, in the form of which cancerous tumors were presented);
G) generative-- gonadotropic(acting on the genital area), embryotropic(acting on embryos), mutagenic(acting on heredity);
e) allergens- causing various allergic reactions.

According to the degree of danger to the human body, all harmful substances are divided into four hazard classes (GOST 12.1.007-76): 1st class - extremely dangerous; 2nd class - highly hazardous; 3rd class - moderately dangerous; 4th class - low-hazard.

For the air of the working area of industrial premises, the maximum permissible concentration (MPC) of harmful substances, aerosols and dust, which is the mass of the harmful substance contained in 1 m 3 of air (mg / m 3), is established.

MPC- concentration, which, during daily work for 8 hours (40 hours per week) during the entire working experience, cannot cause diseases or deviations in the state of health, detected by modern methods of medical research, in the process of work or in certain periods of life of the present and subsequent generations.

The degree and nature of disturbances in the normal functioning of the body caused by a harmful substance depend on the route of entry into the body, dose, exposure time, concentration of the substance, its solubility, the state of the receiving tissue and the body as a whole, atmospheric pressure, temperature and other characteristics of the environment.

The effect of harmful substances on the body can be anatomical damage, permanent or temporary disorders and combined consequences. Many potent harmful substances in the body cause a disorder of normal physiological activity without noticeable anatomical damage, effects on the functioning of the nervous and cardiovascular systems, on the general metabolism, etc.

Harmful substances enter the body through the respiratory system, gastrointestinal tract and through the skin. The most likely penetration into the body of substances in the form of gas, vapor and dust through the respiratory system (about 95% of all poisonings).

The release of harmful substances into the air is possible during technological processes and work related to the use, storage, transportation of chemicals and materials, their extraction and manufacture.

The greatest harm to the human body is caused by poisons.

Poisons- substances that, entering the body in small quantities, enter into chemical or physicochemical interactions with tissues and, under certain conditions, cause health problems. Although almost all substances can exhibit toxic properties, even such as table salt in large doses or oxygen at elevated pressure, it is customary to refer to poisons only those that exhibit their harmful effects under normal conditions and in relatively small quantities.

Production (industrial) poisons are called, that affect a person in working conditions and cause deterioration in working capacity or health problems - occupational or industrial poisoning.

Household poisons are called substances that affect a person in everyday life. These are substances contained in household chemicals and cosmetics.

The action of poisons can be general or local. The general action develops as a result of the absorption of poisons into the blood. At the same time, relative selectivity is often observed, which is expressed in the fact that certain organs and systems are mainly affected, for example, the nervous system in case of manganese poisoning, hematopoietic organs - in case of benzene poisoning. With local action, tissue damage prevails at the site of their contact with poison: the phenomenon of irritation, inflammation, burns of the skin and mucous membranes - most often in contact with alkaline and acid solutions and vapors. Local action, as a rule, is accompanied by general phenomena due to the absorption of tissue decay products and reflex reactions as a result of irritation of the nerve endings.

Industrial poisoning occurs in acute, subacute and chronic forms.

Acute poisoning more often group and arise in case of accidents.

These poisonings are characterized by:

* the short duration of the action of the poison - no more than during one shift;
* intake of poison in the body in relatively large quantities;
* at high concentrations in the air, mistaken ingestion, severe contamination of the skin;
* bright clinical manifestations immediately at the time of the action of the poison or after a relatively short - usually several hours - latent (latent) period.

In the development of acute poisoning, as a rule, there are two phases: the first is nonspecific manifestations (headache, weakness, nausea) and the second is specific (for example, pulmonary edema in case of poisoning with nitrogen oxides).

Chronic poisoning arise gradually, with prolonged action of poisons that penetrate into the body in relatively small quantities. They develop as a result of the accumulation of the poison itself in the body or the changes it causes. Affected organs and systems in the body in chronic and acute poisoning with the same poison may differ. For example, in acute poisoning with benzene, the nervous system is mainly affected and a narcotic effect is observed, in chronic poisoning - the hematopoietic system.

Along with acute and chronic poisoning, they emit subacute forms, which, although similar in terms of the conditions of occurrence and manifestation with acute poisoning, develop more slowly and have a more protracted course.

Industrial poisons can cause not only specific, acute, subacute and chronic poisoning but also other negative consequences. They can reduce the body's immunobiological resistance, promote the development of diseases such as catarrh of the upper respiratory tract, tuberculosis, kidney disease, cardiovascular system, HIV infection, etc. There are industrial poisons that cause allergic diseases (bronchial asthma, eczema, etc.) and a number of individual consequences. For example, some poisons affect the generative function, affecting the gonads, having an embryotoxic effect, causing the development of deformities. Among the poisons are those that promote the development of tumors - the so-called carcinogens, which include aromatic amines, polycyclic carbohydrates.

The body's response to poison depends on:

* from gender, age, individual sensitivity;
* chemical structure and physical properties of the poison;
* the amount of the ingested substance, the duration and continuity of its intake;
* environment - noise, vibration, temperature, relative humidity of the room, dust.

Dust, along with poisons, also causes great harm to the human body.

Dust is the most common adverse factor working environment... Numerous technological processes and operations in industry, transport, agriculture accompanied by the formation and emission of dust. Large contingents of workers can be exposed to it.

Dust are finely dispersed particles that are formed during various production processes - crushing, grinding and processing solids, when sieving and transporting bulk materials, etc. Dusts suspended in the air are called aerosols accumulation of settled dust - aerogels.

Industrial dust happens organic(wood, peat, coal) and inorganic(metal, mineral).

According to the degree of toxicity, dust is divided into poisonous and non-poisonous. The harmfulness of exposure depends on the amount of dust inhaled, the degree of its dispersion, on the chemical composition and solubility.

Dust particles ranging in size from 1 to 10 microns penetrate deep into the lungs. Smaller ones are exhaled back, while larger ones are retained in the nasopharynx. In addition, non-toxic dusts can adsorb toxic and radioactive substances, acquire an electric charge, which increases their harmful effect.

In some cases, the deposition process depends on the electrical properties of dust particles, and, consequently, the time spent in the air. With a different charge, the dust grains are attracted to each other and quickly settle. With the same charge, dust particles, pushing off one another, can stay in the air for a long time.

Dust can be a carrier of microbes, ticks, helminth eggs, etc. The basis for taking measures to combat harmful substances is hygienic regulation, that is, limiting the content of harmful substances in the air of the working area to maximum permissible concentrations. MPCs for harmful substances in the air of the working area are established by GOST 12.1.005-88.

A decrease in the level of exposure to harmful substances on working and its complete elimination is achieved by carrying out organizational, technological, technical, sanitary and hygienic measures and the use of means individual protection.

TO organizational activities include preliminary and periodic medical examinations, shorter working hours, provision of additional vacations, accounting and registration occupational diseases and poisoning, a ban on working with harmful substances for adolescents and women.

TO technological measures include such as the introduction of continuous technologies, automation and mechanization of production processes, remote control, replacement of hazardous technological processes and operations with less hazardous and safe ones.

Technical activities: installation of ventilation and air conditioning systems, equipment sealing, alarms, etc.

When organizational, technological and technical measures do not exclude the presence of harmful substances in the air, sanitary and hygienic activities: breathing exercises, provision of therapeutic and prophylactic nutrition and milk, etc.

Along with protective measures, personal protective equipment is also used (filtering and insulating gas masks, respirators, goggles, special clothing).