Toxicity factor definition. The toxic effect of drugs and methods for its elimination

Pathological(from Greek patos - pain, sickness) a condition that develops as a result of the interaction of a harmful substance (poison) with the body is called intoxication or poisoning.

Intoxication (toxicosis)- a pathological condition associated with a violation of chemical homeostasis due to the interaction of various biochemical structures of the body with toxic substances of exogenous or endogenous (formed inside the body) origin.

The term "intoxication" refers to the entire process of development of toxicosis from its very initial symptoms to the full clinical picture of the disease, the content of which depends on the physiological role of the main toxicity receptors, i.e. certain biochemical structures with which this toxicant (poison) selectively interacts.

In accordance with the terminology adopted in Russia, exogenous intoxications caused by xenobiotics are usually called poisoning, in contrast to endogenous intoxications associated with the accumulation in the body of toxic substances of its own metabolism (autointoxication).

Toxicity - property of a substance that causes a violation of biochemical processes and physiological functions of the body.

Toxicity is characterized by the amount of a substance that causes a damaging effect, and the nature of the toxic effect on the human or animal body. The nature of the toxic action means:

• 1. The mechanism of toxic action.
• 2. The nature of pathophysiological processes and the main symptoms of the lesion that arose after the defeat of the biotarget.
• 3. Dynamics of development of toxic action in time.
• 4. Other aspects of the toxic effect of the substance on the body.

There are three concepts of toxic dose:

• 1. Therapeutic therapeutic dose - the dose of a substance that produces a specific therapeutic effect.
• 2. Toxic dose - a dose of a substance that causes pathological changes in the body that do not lead to death.
• 3. Lethal (lethal) dose - the dose of a substance that causes the death of an organism.

Toxicity is characterized by the dose of a substance that causes a certain degree of poisoning. If a person of mass G(kg) inhales air with a concentration of C (mg / l) in it of a harmful substance (poison) over time t(min) at the intensity of breathing V(l / min), then the specific absorbed dose of a harmful substance (the amount of a harmful substance that has entered the body), Dya(mg/kg), will be equal to

The German chemist F. Gaber proposed to simplify this expression. He made the assumption that for people or a particular species of animals that are in the same conditions, the ratio V/G constantly, thus it can be excluded when characterizing the inhalation toxicity of a substance, and received the expression T=Ct(mgh min/l).

Work Ct Haber called the indicator (coefficient) of toxicity and took it as a constant value (see Chap. 3.7).

For inhalation poisoning, the dose D = ct, where C is the concentration of vapor or aerosol in mg / m 3, t- inhalation time in min.

If affected by other routes (through the gastrointestinal tract, skin, intravenously, intramuscularly, etc.), the dose D is estimated by the amount of substance in mg per 1 kg of live weight (in case of skin damage - in mg / cm 2).

Distinguish toxicity parameters:

• 1. Average lethal (average lethal) doses, causing the death of 50% of experimental animals with a certain method of administration:
  • a) CZ, 5 o (JlK 5 o) - with inhalation poisoning;
  • b) /) 1 5 o (LD 5 o) - with other types of exposure (inside, on the skin, etc., except for inhalation).
• 2. Absolute lethal (lethal) doses, causing the death of 100% of experimental animals:
  • a) CLioo(JIKioo) - in case of inhalation poisoning;
  • b) DGyuoShDyuo) - with other types of exposure.

All those substances in which the LD is low are considered toxic. Yes, at

classic poisons - potassium cyanide and strychnine LD io is 10 and 0.5 mg / kg. The LD is much lower for chemical warfare agents (sarin, zaman, etc.) and some natural plant toxins (toxins of curare, botulism, and diphtheria).

• 3. Threshold doses, causing obvious, but reversible changes in the vital signs of the body:
  • a) RSyu (PKyu) - in case of inhalation poisoning;
  • b) Rdo(PDyu) - for other types of exposure.

The number in the index (0) shows the probability (in%) of the appearance of signs of poisoning. Threshold doses are determined in rabbits (during inhalation), rats (by changing the blood picture) and humans (by smell, effect on the bioelectric activity of the brain). The harmful effects of chemicals on humans always begin at a threshold concentration.

Toxodose- amount of toxic substance. Toxicity \u003d 1 / tox-sodose.

With for the purpose of quantifying toxicity in toxicology, certain categories of toxic doses are used (Table 2.1)

Table 2.1

To quantify the toxicity of substances, the values ​​are used median effective toxodosis(ED 50), causing certain effects in 50% of experimental animals (affected). AU 50 - first letters of words Effective dose- effective dose. In the case of lethal substances, when the "effect" is estimated by the death of animals, the values ​​are used LD 50 and IC/50 (L from the word letholis- lethal), and when assessing the incapacitation - the magnitude Yu 50 and ICts o (I from the word Incapacitating- disabling), etc. (see Table 2.1).

LD 5 o and LCt 5 o - is the value of the average dose, after which it enters the stomach, abdominal cavity, on the skin within three days, the death of 50% of the experimental animals occurs. Sometimes to determine LD 50 and LCtso experimental animals are observed for not three, but 14 days.

Median Effective doses are statistically more significant compared to other categories of toxodosis ( ED 5 , ED 95, etc.) and in this respect it is more correct to indicate, for example, a dose equal to 2ED 50 , how EDm.

When determining EDso(LDso) the dependences of the effect-dose on experimental data are studied, which are analyzed using statistical methods, as a rule, using probit analysis.

The use of the probit method is based on two assumptions:

• 1. The probabilities of the distribution of bioresponses in toxicological and pharmacological experiments usually follow the law of a log-normal distribution.
• 2. Probabilities of bioresponses are estimated using probit values ​​(rather than percentages, as is often done in the practical work of toxicologists); pierced (from English, probability units) are the probabilistic quantities proposed by Bliss and Gaddem (hence the name: the probit method). The use of probits allows one to analyze the dependences of bioresponses on the logarithms of doses in a linear form:

pierced = a + big D in a wide range of bioresponses from 0.1 to 99.9% (see tables 2.2 and 2.3).

Coefficients of the equation "a" and "b", essentially characterize the sensitivity of animals to a given substance in a given type of application. The probit values ​​for the bioresponses observed in the experiment are found from tables or calculated analytically.

Statistical processing of experimental data is carried out on computers using special programs (Finney and others). In this case, mean square errors and confidence intervals are calculated EDsq(LD 5Q) and other categories of toxodosis. The values ​​of the tangents of the slope angles of the probit lines ( b), in essence, determine the relationship of various categories of toxodosis.

Table 2.2

Converting interest to punched

Table 2.3

Coefficient valuesa, b andP in the fatal injury formula

Thus, the values ​​of the slope angle tangents of probit lines, which reflect changes in the probability of effects with changes in toxodose values ​​(logarithm of toxodose), along with median toxodose, are important in assessing the toxic effect of a substance.

For example, in the event of an accident at a chemically hazardous facility, the degree of damage to people is obtained using a probabilistic approach to determining the damaging factor R then by probit function Rg as

where a, b and P- constants for each specific OHV (Table 2.3.), t - time of exposure to a hazardous chemical, min; C - concentration of OHV at a specific point of the infection zone, ppm, related to the concentration of the substance in mg / l by the ratio

where Сppt, Сmg/l - the concentration of a hazardous chemical, expressed in ppm and mg/l, respectively; t- air temperature, °С; M- molecular weight of the hazardous chemical, kg/kmol; R - air pressure, mm Hg Art.

TOXICITY

(from the Greek. toxikon-poison), the ability of the island to cause violations of the fiziol. functions of the body, resulting in symptoms of intoxication (disease), and in severe lesions, its death.

The degree of T. in-va is characterized by the amount of toxic. dose-count in-va (usually referred to a unit mass of an animal or person), causing a certain toxic. Effect. The less toxic , the higher T.

There are medium lethal doses (median lethal, abbreviated as LD 50 or LD 50), absolutely lethal (LD 90-100, LD 90-100), minimally lethal (LD 0-10, LD 0-10), medium effective (median effective, ED 50 )-causing certain toxic. effects, threshold (PD 50, RD 50), etc. (the numbers in the index are the probability in % of the occurrence of a certain toxic effect-death, threshold action, etc.).

Naib. often use the values ​​​​of LD 50, PD 50 and ED 50, to-rye are statistically more reliable than others.

The degree of T. in-va is also characterized by the maximum permissible concentration (MAC) -max. number of in-va per unit volume of air or water, a cut with daily exposure to the body for a long time. time does not cause pathological in it. changes, and also does not interfere with the normal life of a person.

Values ​​of toxic. doses (concentrations) characterize the degree of danger in-in with certain routes of entry into the body. There are different classifications in-in, taking into account the degree of their danger. In the prom. toxicology naib. spread, providing for 4 classes of harmful substances (see table; sometimes the term "toxic" is used instead of the term "dangerous").

When determining toxic doses investigate (experimentally) the dependence of the effect-dose, to-ruyu then analyze using statistical. methods (probit analysis, etc.). The amount of toxic the dose depends on the method of administration of the substance or the ways it enters the body, on the type of animal, age, sex and individual differences, as well as on the specific conditions of exposure to the substance.

With intravenous, intramuscular, subcutaneous and oral (through the mouth) administration, as well as with cutaneous application of toxic. doses have dimensions: mg / kg, mcg / kg, mol / kg, etc. Often also used toxic. doses related to the unit of pov-sti of the body, i.e., having the dimensions: mg / m 2, g / m 2, etc. This is due to the fact that similar doses of nek-ry in-in for different lab. animals and humans differ to a lesser extent than doses per unit mass. This is used in some cases to analyze species sensitivity and transfer data from the lab. animals per person.

Recalculation of doses from the unit of mg / m 2 to mg / kg is carried out using special. tables and nomograms or according to the f-le, for example: ED 50 (mg / m 2) \u003d

Chemical encyclopedia. - M.: Soviet Encyclopedia. Ed. I. L. Knunyants. 1988 .

See what "TOXICITY" is in other dictionaries:

Toxicity Dictionary of Russian synonyms. toxicity see toxicity Dictionary of synonyms of the Russian language. Practical guide. M.: Russian language. Z. E. Alexandrova. 2011 ... Synonym dictionary

TOXICITY- 1) the property of a substance or organism to have a harmful effect on other organisms; 2) toxicometric indicator, calculated as the reciprocal of the absolute value of the average lethal dose (l/DL50) or concentration (1/CL50). According to N. S. ... ... Ecological dictionary

Toxicity- the degree of manifestation of the harmful effects of various chemical compounds and their mixtures. Toxicity is one of the important factors that determine the quality of the environment, quite informative, significantly complementing our understanding of the degree ... ... Official terminology

toxicity- and, well. toxic. The property is toxic. gas toxicity. ALS 1. Toxicity of mixtures used in the fight against agricultural pests using aircraft. 1925. Weigelin Sl. avia. Lex. SIS 1937: toxicity/value... Historical Dictionary of Gallicisms of the Russian Language

- (toxicity), the ability of chemical compounds and substances of biological nature to have a harmful effect on the human body, animals and plants ... Modern Encyclopedia

The ability of certain chemical compounds and substances of biological nature to have a harmful effect on the human body, animals and plants ... Big Encyclopedic Dictionary

Explosives (from Greek toxikon poison * a. toxicity of explosives; n. Toxizitat der Sprengstoffe, Toxizitat der Explosivstoffe; f. toxite des explosifs; i. toxicidad de explosivos, toxicidad de sustancias explosives, toxicidad de materias ... Geological Encyclopedia

TOXICITY, toxicity, pl. no, female (special, medical). distraction noun to toxic. Explanatory Dictionary of Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov

TOXIC, oh, oh; chen, chna. Containing toxins, toxic. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

Stimulus in Gram and some other bacteria release endotoxin during the decay and cause in a person or animal a symptom complex characteristic of this type of toxins. T. is determined by administering to laboratory animals (usually mice) different doses of heated fish. ... ... Dictionary of microbiology

The most important characteristic of toxic and other toxic substances, which determines their ability to cause pathological changes in the body, which lead to the loss of combat capability of personnel or the death of the affected. It is characterized by toxic ... ... Marine Dictionary

Books

• Toxicity of modern cars. Methods and means of reducing harmful emissions into the atmosphere
• Toxicity of modern cars (methods and means of reducing harmful emissions into the atmosphere). Textbook, V. I. Erokhov. The environmental problems of the development of road transport are outlined. The sources of formation and emission of harmful substances (HM) by motor vehicles are considered. Analyzed features...

Modern medicines help to cure many diseases. Some - as independent means, others - as part of complex therapy. Some of them are used for preventive purposes. However, each group of drugs in most cases has not only a therapeutic effect, but often causes side reactions.

The toxic effect of drugs is due to the presence in their composition of chemical components that exhibit toxic properties at certain concentrations and conditions of administration.

Depending on the organ or system on which the impact is carried out, there are:

• hemotoxicity - effect on the blood;
• hepatotoxicity - the main blow falls on the liver;
• ulcerogenic effect - damage to the organs of the digestive system with the formation of ulcers and erosions of the mucous membrane.

Therefore, each intake of any drug must be justified. Treatment should be carried out after prior consultation with a doctor.

Depending on the principle of pathological influence, there are:

• teratogenic - the ability to provoke anatomical defects up to deformities during the intrauterine development of the fetus;
• embryotoxic - a negative impact that is indirectly related to violations of the formation of the internal organs of the fetus in the first trimester of pregnancy;
• fetotoxic - manifests itself in the form of developmental anomalies after the end of the formation of the main internal systems;
• mutagenic - leads to damage to cells, genetic DNA chains;
• carcinogenic - a trigger for the formation and subsequent growth of tumors of various etiologies.

By the nature of the effects differentiate:

• primary - a direct result of the pharmacological action of drugs;
• secondary - adverse effects arising indirectly.

There is also a division into allergic and non-allergic reactions.

There is a classification of toxic reactions by type:

• A - depending on the dosage of drugs, account for about 75% of the total number of adverse reactions;
• B - dose-independent, or immunoallergic, making up 25%;
• C - due to long-term use, including withdrawal syndrome, drug tolerance, dependence;
• D - reactions, the manifestation of which is carried out with a delay (carcinogenicity, mutagenicity, teratogenicity).

According to the degree of danger, several groups of consequences of the toxic effects of drugs are distinguished:

• causing short-term deterioration of health;
• requiring one-time medical care (administration of injections, use of droppers to neutralize side effects);
• eliminated only in a hospital (specific treatment to stabilize the physical condition);
• requiring emergency resuscitation;
• life-threatening, poorly or not at all amenable to medical correction.

With untimely qualified assistance, the pathological (critical) state of the body often ends in death.

Fetotoxic action

The medical term refers to the toxic effect of drugs on the condition of the fetus, the degree of maturity of which corresponds to 12 weeks of intrauterine development. As a rule, it entails serious consequences regarding:

• general development (insufficient weight, body length);
• violations of the functions of physiological systems (hematopoietic, auditory, bone, etc.).

For example, the fetotoxic effect of anticoagulants leads to a decrease in fetal blood coagulation, the use of antibiotics of the tetracycline group provokes a delay in the development of bone tissue, and the use of aminoglycosides contributes to damage to the hearing aid.

To avoid the development of congenital pathologies, the expectant mother should take care of her health during the period of bearing a child. In the presence of any diseases, only a doctor should prescribe treatment.

Embryotoxic reactions

Formed in the first weeks after conception. Due to the negative effect of active substances in the composition of pharmaceuticals on:

• zygote;
• blastocyst.

Substances that can provoke cellular damage, destruction of the blastocyst include:

• hormones - progesterone, estrogen, deoxycorticosterone acetate, growth hormone;
• inhibitors of protein (actinomycin), carbohydrate (iodine acetate) metabolism;
• antimetabolites - Cytarabine, Mercaptopurine, others;
• barbiturates;
• salicylates;
• antimitotic (colchicine);
• nicotine-containing;
• fluorine-containing substances.

There are 3 groups of drugs depending on the level of danger to the fetus:

1. Contraindicated for pregnant women - Contergan, androgens, antifolic, contraceptives, Diethylstilbestrol.
2. Assign in the case when the benefits outweigh the possible risks: anti-epileptic drugs; medicines taken for diabetes mellitus, malignant neoplasms.
3. Pharmaceuticals that can cause congenital anomalies under certain conditions - antibiotics (chloramphenicol, tetracycline, neuroleptics, anti-tuberculosis, diuretics, vitamin K antagonists).

The toxic effect of teratogenic drugs develops between 4 and 8 weeks of pregnancy, causing various anomalies and malformations of intrauterine development.

Teratogenic reactions

They are directly dependent on the duration of the period of use, dosage. For example, most drugs taken before 2 weeks of gestation are more likely to lead to its termination than to the development of intrauterine pathologies. Further, depending on the time of admission, anomalies may occur:

• 15-25 days after conception - damage to the nervous system;
• 20-40 - cardiovascular;
• 24-45 - violation of the normal formation of limbs.

There are 3 groups of drugs that have a pronounced teratogenic effect on the human embryo. Among them:

• steroid hormonal preparations of the androgenic type;
• Thalidomide;
• antimetabolites.

Carcinogenicity

Substances that, under certain conditions, can provoke the growth of malignant cells are called carcinogenic. These include:

• Azathioprine;
• analgesics with phenacetin;
• oral cyclic, combined contraceptives;
• cyclosporins;
• Melphalan;
• Estrogens used as hormone replacement therapy.

There are 3 stages in the formation of a malignant tumor:

• initiation;
• promotion;
• progression.

At the first stage, an almost irreversible transformation of the cellular structure occurs, which becomes the beginning of the pathological process.

Mutagenic action

Mutagenicity is characterized by the ability to damage the hereditary apparatus of cells - chromosomes, genes. As a result of deformation, a change in the genotype of hereditary structures occurs. The predominant majority of anticancer drugs have a mutagenic property.

Allergy and dysbiosis

Dysbiosis, or dysbacteriosis, is a violation of the natural microflora of the mucous membranes, characterized by the replacement of beneficial bacteria by fungal and other pathogenic microorganisms. As a rule, it develops as a result of treatment with antibiotics, some groups of hormones.

An allergic response is formed as a result of the body's identification of active components as antigens. There are 4 types of allergic response:

• immediate (after a few hours);
• cytotoxic;
• delayed;
• immunocomplex.

With the development of allergic reactions, the dose, frequency of use of the pharmaceutical preparation does not really matter. The severity of allergic manifestations depends on the individual characteristics of the body. Signs can include skin rash and anaphylactic shock.

Adverse reactions of a non-allergic nature

Depending on pathogenetic signs, several types of body reactions are distinguished:

• caused by activation of receptors of certain organs, tissues;
• cytotoxic type;
• enzymatic type;
• provoked by metabolic disorders;
• associated with the mass destruction of pathogens of various diseases, changes in saprophytic microflora;
• due to genetic predisposition.

These reactions may occur as a result of drug dependence, local irritant effects, incompatibility of pharmacological agents.

Causes

The toxic effect of drugs is promoted by:

• physical and chemical composition of the agent;
• age factor (up to 18, after 60 years);
• weakening of the protective functions of the body;
• overdose, incorrect use of medications;
• a combination of incompatible substances;
• individual intolerance to the components;
• the use of drugs in the presence of contraindications.

Toxic effects in most clinical cases are directed to specific organs and systems. As a rule, the liver and kidneys suffer more than others. In the acute stage, irreversible processes can start, affecting several directions simultaneously.

Precautionary measures

To avoid harm from drugs that have a toxic effect on the body, you should take any medication according to the instructions, after prior consultation with a specialist. Before the doctor prescribes this or that medicine, it is necessary to inform him of the presence of a tendency to allergic manifestations, individual intolerance to certain substances.

With drug treatment, one must strictly adhere to the recommended dosage, therapeutic regimen in order to prevent undesirable effects from taking the chemical. Particular care should be taken by pregnant women and the elderly.

Almost any drug treatment is accompanied by the development of undesirable toxic effects associated with the body's reaction to the intake of certain chemicals. Increases the risk of negative effects of overdose and violation of instructions for use. To minimize harm, drugs should be used only for their intended purpose, and potent, specific drugs should be used only under medical supervision.

Concentration of toxicants in biota components, due to its analytical accessibility and the possibility of a simple quantitative expression of the effect, it is often considered as an ecotoxicological response to environmental pollution. However, the fate of a biological system is ultimately determined not by the levels of its contamination, but by how pronounced the deviations of the main population and biocenotic characteristics are due to the toxic load.

Despite the fact that until now a single concept " population"does not exist, we will adhere to the opinion that as such one should consider a stable group of individuals united territorially, having a single life cycle, and in relation to organisms with cross-fertilization - a single gene pool, to some extent reproductively isolated from other similar groups and having the ability to homeostasis under changing environmental conditions.As an ecotoxicological reaction of population-level systems, we consider the effects of direct toxic effects and effects mediated (modified) by population mechanisms and the natural environment.

Direct toxic effects. Obviously, the signs of damage caused by the accumulation of toxicants in mammalian organisms and considered in detail within the framework of toxicology should occur not only in mammals from natural populations, but also with certain specificity in other objects of the biota. To the greatest extent, such effects of direct toxic effects can be distinguished at the molecular and cellular-tissue levels of the functioning of biological systems. This is due to the fact that in the presence of powerful endogenous homeostatic mechanisms, suborganismal indicators are the least affected by changing living conditions. It is also important that at present there are well-developed quantitative methods for diagnosing such deviations.

One of the clearest indicators direct toxic effect are biochemical changes that are most specific to the effects of specific toxicants. It is known from toxicology that the intake of many xenobiotics into the organisms of warm-blooded animals stimulates the generation of reactive oxygen species. In case of violation or overload of the molecular mechanisms of inactivation of these radicals, it is possible to enhance the processes of free radical oxidation and the accumulation of products of lipid peroxidation.

The blocking of these processes is carried out due to endogenous antioxidants- vitamins A and E. The accumulation of products of lipid peroxidation by warm-blooded animals under conditions of toxic environmental pollution is associated with this depletion of endogenous protector resources. The consequence of this is a violation of the structure of biomembranes and enzymatic systems of xenobiotic metabolism, i.e. manifestation of signs of intoxication. Most clearly, biochemical disorders can be diagnosed in animals that constantly live in conditions of toxic exposure.

It has been shown, for example, that in the liver of great tit chicks in the contaminated zones, the intensity lipid peroxidation almost twice as high as in clean areas. A similar picture is in the pied flycatcher. The noted levels correlate well with the accumulation of lead, zinc, copper in the skeleton of the chicks. For the same species, a significant, almost two-fold decrease in the levels of vitamins E and A in the liver of chicks in contaminated areas was noted. The latter indicators also correlate with the content of heavy metals in organisms.

Evaluating such direct toxic effects, it must be borne in mind that the discussed indicators are recorded in organisms living in natural conditions. This means that individual individuals with the maximum manifestation of signs of intoxication, which for this reason do not meet the stringent requirements of the habitat, can be eliminated from the population. In contrast to laboratory or vivarium experiments, the analyzed samples in this case reflect the result of selection determined both by intrapopulation mechanisms and by the quality of the habitat. In this regard, the cited data are most successful for nestlings, since the mentioned selection factors in the nesting period in birds are expressed to the least extent.

There are numerous information obtained, among other things, on other objects, according to which it is possible to diagnose a wide variety of signs of damage (biochemical, physiological, functional, etc.) caused by direct toxic effects. However, in any case, the natural environment acts as a kind of filter that corrects these indicators. That is why, in contrast to laboratory experiments in natural conditions, at equal levels of toxic load, determined by the content of toxic substances in environmental objects, it is often not possible to diagnose the presence of specific direct toxic signs in animals.

Let's take another example illustrating what has been said. It is known that most pollutants of the natural environment lead to the manifestation in animals of clearly expressed signs of damage to both the peripheral and the central nervous system. Neurotoxic manifestations are observed, as a rule, at low levels of exposure, preceding other clinical signs. The certain neuropsychic shifts that manifest themselves in this case, expressed in a change in the rate of reaction to an external stimulus and in the behavior of animals, lead not only to a change in the zoosocial status of the animal, but also to an inadequate reaction of animals to danger. This was shown in deer hamsters, when animals poisoned with dieldrin sharply reduced their reaction to the appearing shadow of a predator. For this reason, such animals should be predominantly eliminated from the population.

Despite the obvious in these cases direct conditionality of toxic effects the intake of pollutants into animal organisms, the discussed indicators cannot be considered as effects of the supraorganismal level, i.e. strictly speaking, ecotoxicological effects. Rather different. The ecotoxicological response of the system will be determined not so much by the severity of biochemical or other deviations, but by the changes in the structure of the population caused by them due, for example, to a decrease in the number of groups of organisms most sensitive to toxicants.

A toxic process is the formation and development of reactions of a biosystem to the action of a toxicant, leading to its damage (i.e., violation of its functions, viability) or death is called a toxic process.

The mechanisms of formation and development of the toxic process, its qualitative and quantitative characteristics, are primarily determined by the structure of the substance and its effective dose. However, the forms in which the toxic process manifests itself undoubtedly also depend on the type of biological object and its properties.

Manifestations of a toxic process are primarily determined by the level of organization of a biological object, on which the toxicity of a substance (or the consequences of its toxic action) is studied:

Cellular;

Organ;

Organismic;

Population.

The forms of the toxic process detected at the level of the whole organism can be classified as follows:

INTOXICATIONS - diseases of chemical etiology;

TRANSITOR TOXIC REACTIONS - quickly passing, not threatening health conditions, accompanied by a temporary disability (for example, irritation of the mucous membranes);

ALLOBIOTIC STATES - a change in the body's sensitivity to infectious, chemical, radiation, other physical influences and psychogenic stresses occurring under the influence of a chemical factor (immunosuppression, allergization, tolerance to a substance, asthenia, etc.);

SPECIAL TOXIC PROCESSES - non-threshold processes with a long latent period that develop in a part of the exposed population under the action of chemicals, as a rule, in combination with additional factors (for example, carcinogenesis).

Depending on the duration of the interaction between the chemical and the organism, intoxications can be acute, subacute and chronic.

Acute intoxication is called intoxication, which develops as a result of a single or repeated action of substances for a limited period of time (usually up to several days).

Subacute is called intoxication, which develops as a result of continuous or intermittent (intermittent) action of a toxicant lasting up to 90 days.

Chronic intoxication is called intoxication, which develops as a result of prolonged (sometimes years) action of a toxicant.

The concept of acute, subacute, chronic intoxication should not be confused with the acute, subacute, chronic course of a disease that has developed as a result of contact with a substance. Acute intoxication with certain substances (mustard gas, lewisite, dioxins, halogenated benzofurans, paraquat, etc.) may be accompanied by the development of a long-term (chronic) pathological process

The essence and doctrine of the LEO system.

The system of medical evacuation support adopted by the disaster medicine service is called the system of staged treatment of the injured and sick with their evacuation according to their destination.

The essence of this system is the consistent and successive provision of medical care to the affected (sick) in the lesion and at the stages of medical evacuation in combination with evacuation to a medical institution that provides comprehensive medical care in accordance with the existing lesion (disease).

For the effective functioning of the system of staged treatment of the affected (patients) with evacuation according to the destination, it is necessary to comply with a number of requirements. The main ones are the following:

1. The leading role of the provisions of a unified medical doctrine, which includes common views of all medical personnel of the service on the etiopathogenesis of lesions and diseases of the population in emergencies and the principles of the staged provision of medical care and treatment of the injured and sick during the elimination of the medical and sanitary consequences of emergencies.

2. Availability of 13 medical institutions with a sufficient number of specialized (profiled) hospital beds in each evacuation direction.

3. The presence of a concise, clear, unified system of medical documentation that ensures consistency and continuity in medical and evacuation activities.