The general toxic effect of harmful chemicals is manifested in. Harmful substances. A hazardous substance is a substance that, if safety requirements are violated, can cause work-related injuries. General toxic chemicals

Substances used and formed in technological processes at enterprises, due to improper organization of work and non-compliance with certain preventive measures, which have a harmful effect on the health of workers, leading to acute or chronic poisoning and occupational diseases, are called harmful substances(industrial poisons).

Poisoning that workers can get can be acute or chronic.

Harmful substances can enter the human body through the respiratory system (vapors, gases, dust), skin (liquid, oily, solid substances), and the gastrointestinal tract (liquid, solid, and gases). Most often, harmful substances enter the human body through the respiratory system and quickly penetrate into the vital important centers person.

In addition to the general effect on the human body, harmful substances can also have a local effect. This is how acids, alkalis, some salts and gases (chlorine, sulfur dioxide, hydrogen chloride, etc.) act. Chemicals can cause three degrees of burns.

Poisons may enter the gastrointestinal tract if personal hygiene rules are not followed. Toxic substances, cyanides can be absorbed already in the oral cavity, entering the blood.

Classification of toxic substances

In terms of toxic (harmful) effect on the human body chemical substances divided into general toxic, irritant, sensitizing, carcinogenic, mutagenic, affecting reproductive function.

Generally toxic chemicals(hydrocarbons, hydrogen sulfide, hydrocyanic acid, tetraethyl lead) cause disorders nervous system, muscle cramps, affect the hematopoietic organs, interact with blood hemoglobin.

Irritants(chlorine, ammonia, nitric oxide, phosgene, sulfur dioxide) affect the mucous membranes and respiratory tract.

Sensitizing substances(antibiotics, nickel compounds, formaldehyde, dust, etc.) increase the body’s sensitivity to chemicals, and in industrial conditions lead to allergic diseases.

Carcinogens(benzopyrene, asbestos, nickel and its compounds, chromium oxides) cause the development of all types of cancer.

Chemical substances, affecting human reproductive function (boric acid, ammonia, many chemicals in large quantities), cause congenital malformations and deviations from normal development in the offspring, affect the intrauterine and postnatal development of the offspring.

Mutagenic substances(lead and mercury compounds) affect non-reproductive (somatic) cells that are part of all human organs and tissues, as well as germ cells. Mutagenic substances cause changes (mutations) in the genotype of a person in contact with these substances. The number of mutations increases with the dose, and once a mutation has occurred, it is stable and is passed on from generation to generation unchanged. Such chemically induced mutations are non-directional. Their load joins the general load of spontaneous and previously accumulated mutations. Genetic effects from mutagenic factors are delayed and long-lasting. When exposed to germ cells, the mutagenic effect affects subsequent generations, sometimes in very distant periods.

Rice. 1. Classification of harmful substances

The last three types of harmful substances (mutagenic, carcinogenic and affecting reproductive ability) are characterized by long-term consequences of their influence on the body. Their effect manifests itself not during the period of exposure and not immediately after its end, but in distant periods, years and even decades later.

The above classification of harmful substances by the nature of their impact does not take into account a large group of substances - aerosols (dust) that do not have pronounced toxicity. These substances are characterized fibrogenic effect effects on the body. Aerosols of coal, coke, soot, diamonds, dust of animal and plant origin, silicate and silicon-containing dust, metal aerosols, when entering the respiratory system, cause damage to the mucous membrane of the upper respiratory tract and, when retained in the lungs, cause inflammation (fibrosis) of the lung tissue. Occupational diseases associated with exposure to aerosols are pneumoconiosis.

Pneumoconiosis is classified into:

  • silicosis - develops under the influence of free silicon dioxide dust;
  • silicates - develop under the influence of aerosols of silicic acid salts;
  • types of silicosis: asbestosis (asbestos dust), cementosis (cement dust), talcosis (talc dust);
  • mstalloconiosis - develops when inhaling metal dust, such as beryllium dust (berylliosis);
  • carboconiosis, for example anthranosis, which occurs when inhaling coal dust.

The result of human inhalation of dust is pneumosclerosis, chronic dust bronchitis, pneumonia, tuberculosis, and lung cancer.

The presence of a fibrogenic effect in aerosols does not exclude their general toxic effects. Toxic dusts include aerosols of DDT, lead, beryllium, arsenic, etc. When they enter the respiratory system, in addition to changes in the upper respiratory tract and lungs, acute and chronic poisoning develops.

In production, work is usually carried out with several chemicals. In this case, the employee may be exposed to negative factors of a different nature (physical - noise, vibration, electromagnetic and ionizing radiation). This creates the effect combined(with the simultaneous action of negative factors of different nature) or combined(with the simultaneous action of several chemicals) the effects of chemicals.

Combined action- this is the simultaneous or sequential effect on the body of several substances through the same route of entry into the body. There are several types of combined action depending on the toxicity effects:

  • summation (additive action, additivity) - the total effect of the mixture equal to the sum effects of the components included in the mixture. Summation is typical for substances of unidirectional action, when substances have the same effect on the same body systems (for example, mixtures of hydrocarbons);
  • potentiation (synergistic effect, synergism) - substances act in such a way that one substance enhances the effect of another. The synergistic effect is more additive. For example, nickel increases its toxicity in the presence of cuprous waste by 10 times, alcohol significantly increases the risk of aniline poisoning;
  • antagonism (antagonistic action) - the effect is less than additive. One substance weakens the effect of another. For example, eserine significantly reduces the effect of antropine and is its antidote;
  • independence (independent action) - the effect does not differ from the isolated action of each of the substances. Independence is characteristic of substances with multidirectional effects, when substances have different effects on the body and affect different organs. For example, benzene and irritating gases, mixtures of combustion products and dust act independently.

Along with the combined effect of substances, it is necessary to highlight complex action. With complex action, harmful substances enter the body simultaneously, but in different ways (through the respiratory organs and skin, respiratory organs and gastrointestinal tract, etc.).

Maximum permissible concentration of harmful substances

The harmful biological effects of chemicals begin at a certain threshold concentration. To quantify harmful effects per person of a chemical substance, indicators are used that characterize the degree of its toxicity. These indicators include:

  • average lethal concentration of a substance in the air (LC50);
  • average lethal dose (LD50);
  • average lethal dose when applied to the skin (LDK50);
  • acute action threshold (APT);
  • threshold of chronic action (TCT);
  • acute action zone (AZZ);
  • zone of chronic action (ZAD);
  • maximum permissible concentration.

Hygienic regulation, i.e. limiting the content of harmful substances to maximum permissible concentrations (MACs), is used to limit the adverse effects of harmful substances. Due to the fact that the requirement for the complete absence of industrial poisons in the breathing zone of workers is often impossible, hygienic regulation of the content of harmful substances in the air of the working area (GN 2.2.5.1313-03 “Maximum permissible concentrations of harmful substances in the air of the working area”, GN) acquires particular importance 2.2.5.1314-03 “Indicative safe exposure levels”).

Harmful substance in the air of a working area (HSA) - a concentration of a substance that, during daily (except weekends) work for 8 hours or another duration, but not more than 40 hours a week during the entire work experience, cannot cause diseases or abnormalities health detected modern methods research in the process of work or long-term life spans of the present and subsequent generations.

MPCZ, as a rule, is set at a level 2-3 times lower than the threshold for chronic action. When the specific nature of the action of a substance is revealed (mutagenic, carcinogenic, sensitizing), the maximum permissible limit is reduced by 10 times or more.

A harmful substance is a substance that, in case of violation of safety requirements, can cause occupational injuries, occupational diseases, and health problems detected both during work and in the long-term life of present and subsequent generations.

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

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

· general toxic;

· irritating;

· sensitizing;

· carcinogenic;

· mutagenic;

affecting human reproductive function

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

Annoying substances cause irritation of the respiratory tract and mucous membranes 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. Formaldehyde and various nitro compounds have this property.

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 changes hereditary information. These are radioactive substances, manganese, lead.

Among substances affecting the reproductive function of the human body, we should first of all mention mercury, lead, manganese, a number of radioactive substances, etc.

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

All chemicals depending on their practical use 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), sanitary products, personal hygiene products, cosmetics;

· biological plant and animal poisons that are found in plants, mushrooms, animals and insects;



· toxic substances – sarin, mustard gas, phosgene.

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

Household poisoning most often occurs when poison enters the gastrointestinal tract.

The distribution of toxic substances in the body follows certain patterns. First, a dynamic distribution of the substance occurs, determined by the intensity of blood circulation. Then the absorption capacity of the tissues begins to play a major role. A number of metals (silver, manganese, chromium, vanadium, cadmium) are characterized by rapid removal 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 environment.

Poisons are usually classified as only those that exhibit their harmful effects under normal conditions and in relatively small quantities.

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

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

Nervous (convulsions, paralysis);

· local inflammation in combination with general toxic phenomena (acetic essence);

· general toxic (coma, cerebral edema, convulsions), for example, alcohol and its surrogate, carbon monoxide;

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

· psychotropic – drugs, atropine.

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

They are divided into:

· cardiac with a predominant cardiotoxic effect (medicines, plant poisons, metal salts);

· nervous, causing disturbances in mental activity (carbon monoxide, alcohol, drugs, sleeping pills);

· hepatic (hydrocarbons, poisonous mushrooms, phenols and aldehydes);

· renal (heavy metal compounds, oxalic acid);

· blood – analine, nitrites, arsenic hydrogen;

· pulmonary – nitric oxide, ozone.

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

Industrial poison- a harmful chemical substance to which a person may be exposed during industrial activities.

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

By the nature of the effect on the body substances are divided into:

  • - general toxic- causing poisoning of the entire body or damaging separate systems(central nervous system, hematopoietic system), as well as those causing pathological changes in the liver and kidneys (carbon monoxide, lead, mercury, benzene);
  • - annoying- causing irritation of the mucous membranes of the respiratory tract, eyes, lungs, skin (chlorine, ammonia, sulfur and nitrogen oxides, ozone);
  • - sensitizing- acting as allergens (formaldehyde, solvents);
  • - mutagenic- leading to violation genetic code, changes in hereditary information (lead, manganese, radioactive isotopes);
  • - carcinogenic- causing malignant neoplasms ( aromatic hydrocarbons, chromium, nickel, asbestos);
  • - influencing reproductive function (mercury, lead, styrene).

Mutagenic, carcinogenic, effects on reproductive function, as well as acceleration of aging, are classified as long-term consequences influence chemical compounds on the body. This is a specific action that manifests itself years and even decades later.

This classification does not take into account state of aggregation substances, while for a large group of aerosols that do not have pronounced toxicity, it is necessary to distinguish fibrogenic effect effects on the body. These include aerosols of coke, diamonds, dust of animal and plant origin, and silicate-containing dust. Once in the respiratory system, substances of this group damage the mucous membrane of the upper respiratory tract, and when retained in the lungs, they lead to the development of connective tissue in the air exchange zone and scarring (fibrosis) of the lungs. The presence of a fibrogenic effect does not exclude the general toxic effects of aerosols.

The effect of poison on tissue is accompanied by various changes. The action of the poison is called local if changes are observed at the point of contact of the poison with the body, without noticeable general reaction the last one. The local effect of the poison is often short-lived and can be considered as First stage general process. When absorbed (resorption), toxic substances in toxic doses exhibit general action.

Local(irritant, cauterizing) effect on the skin and mucous membranes is exerted by many different substances chemical structure- corrosive gases and vapors (for example, chlorine, bromine, iodine, ammonia), corrosive acids and alkalis, a number organic matter(acids - acetic, oxalic, phenols, aldehydes).

The effect of caustic poisons is not limited to local damage; Depending on their nature, concentration, duration of exposure and place of application in the body, functional disorders arise, varying in clinical manifestation, intensity and outcome. Caustic gases and vapors cause severe irritation of the mucous membranes of the upper respiratory tract, and if these substances penetrate into the lungs, severe lesions (edema) develop in them.

General action poisons largely depends on the chemical structure of a particular substance.

The classification of chemicals according to basic toxicological criteria is shown in the figure.

General classification of chemicals

General toxic substances cause poisoning of the body (pesticides, mineral fertilizers, exhaust gases, hydrocyanic acid, etc.).

Irritants cause irritation of the mucous membranes and upper respiratory tract (runny nose, lacrimation, cough): these are acids, alkalis, chlorine, ammonia, sulfur, fluorine, etc.

Carcinogens lead to the growth of cancer cells (asbestos, arsenic, benzopyrene, etc.).

Mutagenic substances lead to changes in heredity (lead, manganese, mercury).

Sensitizing substances cause allergic reactions (mercury, varnishes and paints, nickel).

Chemicals can enter the human body through the respiratory system, gastrointestinal tract, skin and mucous membranes, as well as directly into the blood (when administered intravenously).

As a result of exposure to a toxic substance, a person may develop the following conditions:

  • poisoning develops in acute, subacute and chronic forms:

    • acute poisoning , as a rule, group, occur as a result of accidents, equipment breakdowns and gross violations of labor safety requirements; characterized by the short duration of action of toxic substances, the entry of harmful substances into the body in relatively large quantities - at high concentrations in the air; erroneous ingestion; severe contamination of the skin, etc.;
    • chronic poisoning arise gradually: with a long-term intake of poison into the body in relatively small quantities, a mass of harmful substances cumulates (accumulates) in the body, which can subsequently cause negative health effects and diseases;
  • sensitization - state hypersensitivity the body to the influence of a foreign substance, causing an allergic reaction when this substance re-enters the body;
  • addictive – weakening of the effects of exposure to a harmful substance during repeated exposure. To develop addiction to the chronic effects of a harmful substance, its concentration (dose) must be sufficient to form an adaptive response, but not excessive, so as not to lead to rapid and serious damage to the body. In this regard, possible developments should be taken into account tolerance - increased resistance to some substances after exposure to others.

The result of exposure to chemicals on humans is shown in the figure.

Chemicals have general and selective toxicity. According to selective toxicity (predominant action), poisons are distinguished:

  • cardiac;
  • neurotoxic;
  • hepatotropic (liver);
  • renal (renal);
  • hemic (blood);
  • pulmonary, etc.

In the classification according to the toxic (harmful) effect on the human body, chemical substances are divided into general toxic, irritating, sensitizing, carcinogenic, mutagenic, and affecting reproductive function.

Generally toxic chemicals(hydrocarbons, hydrogen sulfide, hydrocyanic acid, tetraethyl lead) cause disorders of the nervous system, muscle cramps, affect the hematopoietic organs, and interact with blood hemoglobin.

Irritants(chlorine, ammonia, nitric oxide, phosgene, sulfur dioxide) affect the mucous membranes and respiratory tract.

Sensitizing substances(antibiotics, nickel compounds, formaldehyde, dust, etc.) increase the body’s sensitivity to chemicals, and in industrial conditions lead to allergic diseases.

Carcinogens(benzopyrene, asbestos, nickel and its compounds, chromium oxides) cause the development of all types of cancer.

Chemical substances, affecting human reproductive function (boric acid, ammonia, many chemicals in large quantities), cause congenital malformations and deviations from normal development in the offspring, affect the intrauterine and postnatal development of the offspring.

Mutagenic substances(lead and mercury compounds) affect non-reproductive (somatic) cells that are part of all human organs and tissues, as well as germ cells. Mutagenic substances cause changes (mutations) in the genotype of a person in contact with these substances. The number of mutations increases with the dose, and once a mutation has occurred, it is stable and is passed on from generation to generation unchanged. Such chemically induced mutations are non-directional. Their load joins the general load of spontaneous and previously accumulated mutations. Genetic effects from mutagenic factors are delayed and long-lasting. When exposed to germ cells, the mutagenic effect affects subsequent generations, sometimes in very distant periods.

The harmful biological effects of chemicals begin at a certain threshold concentration. To quantify the harmful effects of a chemical on humans, indicators characterizing the degree of its toxicity are used. These indicators include the average lethal concentration of a substance in the air (LC50); average lethal dose (LD50); average lethal dose when applied to the skin (LDK50); acute action threshold (LimО.Д); threshold of chronic action (LimХ.Д); zone of acute action (ZО.Д); zone of chronic action (Z Х.Д), maximum permissible concentration.


Hygienic regulation, i.e. limiting the content of harmful substances in the air of the working area to maximum permissible concentrations (MPC), is used to limit the adverse effects of harmful substances. Due to the fact that the requirement for the complete absence of industrial poisons in the breathing zone of workers is often impossible, hygienic regulation of the content of harmful substances in the air of the working area (GN 2.2.5.1313-03 “Maximum permissible concentrations of harmful substances in the air of the working area”, GN) acquires particular importance 2.2.5.1314-03 “Indicative safe exposure levels”).

Maximum permissible concentration of a harmful substance in the air of a working area (MPCL) - a concentration of a substance that, during daily (except for weekends) work for 8 hours or another duration, but not more than 40 hours a week during the entire work experience, cannot cause illness or deviations in health status detected by modern research methods in the process of work or long-term life spans of the present and subsequent generations.

MPCZ is usually set at a level 2–3 times lower than the threshold for chronic action. When the specific nature of the action of a substance is revealed (mutagenic, carcinogenic, sensitizing), the maximum permissible limit is reduced by 10 times or more.