Hydrocyanic acid, which in the chemical industry is called hcn acid, is classified as a highly toxic substance with a toxic spectrum of action. The main consequence of this poison entering the body is oxygen starvation.

In some cases, the accumulation of acid in the human body is fatal if its distribution throughout the body is not blocked in time. This information is also confirmed by the fact that in the past some states used it as a poisonous substance in concentration camps.

General information

Many people know that the smell of hydrocyanic acid has a characteristically pronounced aroma of bitter almonds. In this case, the substance has no color, representing a liquid with good volatility. Sometimes such a poison is also called hydrocyanic, which served as the basis for the name of its salts cyanides.

The substance, entering the body, completely blocks the normal functioning of enzymes, which leads to the rapid development of oxygen starvation of cells. The central nervous system immediately falls under the scope, and later the effect of toxins extends to the cardiovascular system, and also affects the respiratory function.

To prevent the destructive action of the poison, experts recommend avoiding dangerous places where it can be found (for example, in chemical plants). But even if we discard the fact of its presence in laboratories and other specialized departments of chemical production, you can find it even in everyday life.

Some ordinary people do not even suspect that it is contained in:

• in the fruits of the stone fruit family;
• bitter almonds;
• cigarette smoke;
• agents for the control of insects and rodents.

At the same time, the acid itself is not in the almond. There are glycosides. After a certain effect is made on them, they split, releasing the very poison that is dangerous for living organisms.

But production still appears in the ranking of the most common causes of poisoning. Salts of this substance are actively used to obtain metals from ore rocks. Often they are involved in the production of plastics, rubber, and organic glass.

It is also not difficult to meet this substance in the composition of herbicides or growth activators for various crops. Adopted a toxic substance and experts from the pharmaceutical industry.

At the same time, acid traditionally has relatively unstable compounds, which leads to rapid decomposition, followed by the release of poison upon contact with both moisture and air. Especially often such a transformation can be found in enterprises engaged in the extraction of coal.

In everyday life, there is an opinion that it overtakes all those who are used to eating bones along with fruits. In fact, this is not entirely true, because one fruit does not contain a lethal dose of amygdalin. It is from it that, through certain conditions, toxins are released.

According to the medical summary, the average pits/seeds of certain dangerous berries and fruits contain the following doses of amygdalin:

• almonds - up to 3%;
• peach - up to 3%;
• apricot - about 1.5%.

The remaining seasonal fruits received an indicator of less than one percent. This list included:

• Apple,
• cherries and cherries
• plum.

Doctors advise avoiding the use of fruits with seeds in preservation. If their presence is minimal, then the destructive properties of cyanides can be “killed” by huge portions of sugar. The only exception is grapes and wine. In all other cases, the berries should not contain seeds.

Negative influence

The impact of hydrocyanic acid on humans has been studied by specialists for a long time. Experts say that one of the most pronounced signs is tissue oppression, which very quickly leads to an acute shortage of energy resources. Such an influence guarantees the failure of the normal functioning of the brain.

The nervous system has to face no less serious consequences, as its cells begin to rapidly change structure. The most dangerous thing is the fact that these changes are recognized as irreversible.

The main feature of the effect of acid on tissues is that even a sufficient oxygen content in the blood does not become a guarantee of successful transfer of intoxication. The problem is that the poison blocks the entry of oxygen into the reactions where it is vital. As a result, the toxin accumulates in the blood.

Pathologists note that those who died from poisoning with this substance have characteristic external and internal signs:

• bright scarlet color of the skin;
• red mucous membranes.

In addition to the listed systems of the body, the spleen suffers from the effects of hydrocyanic acid on a person. The reason is that the body “thinks” that it really does not have enough oxygen and begins a rescue operation to restore its amount to normal. In search of a solution to the problem of homeostasis, there is an active release of blood cells from the spleen.

But the effect on the liver, heart and some other organs is not so pronounced.

When should you sound the alarm?

Signs of hydrocyanic acid damage may differ depending on how the toxin entered the blood. It can be:

• inhalation of toxic fumes;
• direct ingestion of acid;
• upon contact with exposed skin.

Depending on how the acid entered the body, the rate of its spread and the manifestation of the first symptoms will depend. If a person has suffered from inhalation of vapors, then this can make itself felt in a couple of minutes. In some cases, if the concentration was several times higher than normal, death occurs within ten minutes.

Hydrocyanic acid has a slightly different effect on the digestive system, which reacts much more slowly to its toxins. The substance acts even more slowly through the skin if the temperature in the room remains within the room temperature and the person is not in the stage of physical activity. As a result, the patient begins to sweat profusely, and the main symptoms appear in about an hour and a half.

The main symptoms of departure are called:

• characteristic pink color of the skin and mucous membranes;
• the victim smells of almonds with bitter notes;
• sore throat, as well as a sensation of a metallic taste;
• profuse salivation;
• constant urge to go to the toilet;
• nausea, which flows into vomiting;
• rapid pulse, which may continue with tachycardia;
• oppressive pain in the chest;
• violation of the respiratory rhythm;
• dizziness and/or headache;
• dilated pupils and impaired speech.

How to help the patient?

Hydrocyanic acid occurs in several stages, which include:

• removing the patient from the area of ​​​​impact of the poison (laboratory, workshop, home) and removing clothes from him in order to get rid of traces of toxic exposure.
• promptly call an ambulance.
• if the toxin entered the body through the digestive system, it should immediately be artificial. To do this, give the victim plenty of drink (ordinary warm boiled water with a weak solution of potassium permanganate) and irritate the root of the tongue. You can resort to this method only if the poisoned person is still conscious. Otherwise, a person will choke either with water poured into him through force, or with outgoing vomit.
• taking activated charcoal according to the standard scheme: one tablet for approximately 10 kg of weight.
• provide the patient with maximum rest in a warm place until the arrival of doctors.
• if the victim is unconscious, then he is laid on his side so that the vomit does not block the airways.
• in case of clinical death, resuscitation procedures should be urgently carried out.

A weak solution of potassium permanganate with activated charcoal is the best antidote that almost everyone can find in their home or industrial medicine cabinet.

If hydrogen cyanide gets on the skin, it must be promptly washed off with soapy water, after removing clothing. At the same time, it is strictly forbidden to smear the trapped substance so as not to increase the affected area.

Other well-known and relatively common antidote options include:

• baking soda,
• camphor,
• sugar,
• acetic fumes.

After the ambulance arrives at the scene, the doctors immediately begin the standard procedure for therapeutic measures. The specialist on duty immediately needs to report what you have already done before his arrival. Next, health workers produce antidote therapy based on inhalers and intravenous injections, followed by oxygen inhalation.

If blood pressure falls below normal, then adrenaline or replacement therapy is performed. If necessary, stimulants are introduced to normalize the functioning of the respiratory system. Almost immediately, the patient receives a vitamin solution, after which he is transported to the toxicological department for further measures.

Prevention measures

Having dealt with the fact that the degree of danger of hydrocyanic acid can reach a lethal mark, you must not forget about a few simple preventive rules.

So, for example, you should not ignore the safety regulations at enterprises that dictate the mandatory wearing of a special suit or gas mask to protect the respiratory system from toxic fumes. According to the same principle, a set of measures is carried out aimed at the destruction of rodents or harmful insects. After deratization, the room should be constantly ventilated.

Doctors also insist that:

• control at hazardous industries was carried out on an ongoing basis;
• employees of dangerous departments knew the rules of first aid;
• engineers monitored the health of the equipment;
• if possible, all dangerous stages of production were moved to a mechanical mode;
• workers for hazardous industries underwent regular medical control.

Also, doctors recommend refraining from independent experiments involving the use of hydrocyanic acid at home. Otherwise, not only you, but also unsuspecting people around you may suffer.

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Hydrocyanic acid, with its cyanide derivatives, is the fastest acting poison known to mankind. Its use for executions and suicides, by the French army in 1916 as a chemical warfare agent, by the German Nazis in concentration camps claimed hundreds of thousands of lives. However, often poisonings are not intentional, but accidental with the excessive use of certain products.

What effect does hydrocyanic acid have on a person? What are the symptoms of poisoning? How to help the victim? You will find the answer to these and other questions in our article.

Where is hydrocyanic acid found

Acid can enter the stomach with products containing it, as well as with those products that are obtained from plants that have been treated with pesticides containing cyanides.

Hydrocyanic acid is not found in pure form in nuts and seeds., and in the composition of amygdalin glycoside, it is he who gives a bitter taste and a specific aroma. Once in the body, amygdalin decomposes into 3 components: benzaldehyde, glucose and hydrocyanic acid. Bitter almonds are especially rich in amygdalin, so its excessive consumption is dangerous, and it is generally not recommended for children, even in small quantities.

Also very dangerous are wines made with fruits with stones (cherry and apricot tinctures, plum brandy and others). But jam and compotes from fruits with stones are not dangerous, because when heated to 80 ° C, the acid decomposes.

How many foods can be poisonous

The amount of food containing amygdalin that can cause poisoning depends on age, body weight, and health status. However, their average numbers have been determined.

30 bitter almonds can cause intoxication, 50-60 apricot, 70 plum and cherry and pits. A dangerous amount of small seeds (apples, cherries) is 30-40 grams, which is equivalent to 100-120 grains.

Severe poisoning and deaths occur at a dose of 1 mg amygdalin per 1 kg of body weight. This amount is contained in 40 bitter almond kernels, 100 plum or apricot pits, 60-80 cherry or cherry pits, 200 apple seeds.

Almond lovers should remember that it is better to buy it in a peeled form, in a package with all the manufacturer's barcodes. Those who prefer natural almonds should be aware that even unripe sweet almonds contain this acid. Bitter almonds are now used only in the perfume and cosmetic industries.

Symptoms of hydrocyanic acid poisoning

The acid, getting into the blood, forms a compound with the oxygen of erythrocytes, blocking its cleavage and return to the tissues. As a result, the concentration of oxygen sharply increases in the blood, and it does not enter the tissues and organs, their hypoxia develops.

The most delicate organ, the brain, suffers first and foremost. All its vital centers are oppressed, which leads to oppression of organs and systems, the whole organism quickly fails. External signs of hydrocyanic acid poisoning:

• Intense pink coloration of the skin and mucous membranes;
• Dizziness, headache, loss of balance, numbness of the lips, dilated pupils;
• Increased heart rate, retrosternal pain;
• Increased breathing, lack of air;
• Nausea, vomiting;
• Bitterness in the mouth and taste of metal, increased urge to defecate.

From the victim of hydrocyanic acid poisoning, a characteristic smell of bitter almonds is felt during breathing.

In severe cases of poisoning, tachycardia is replaced by a slowing of the pulse, loss of consciousness quickly occurs, paralysis of the respiratory center, convulsions develop. If no help is provided, death occurs within 2-3 minutes.

First aid for poisoning, how to remove poison from the body

The victim must immediately call an "ambulance" and immediately begin to provide first aid, which consists in the possible rapid removal of poison from the body.

It is necessary to immediately rinse the stomach with a soda solution - 1 tablespoon per 1 liter of water, you can give 2-3 glasses of this solution to drink.

After washing, you need to give one of the antidotes, which are: sugar (2-3 tablespoons per 500 ml of water) or pharmacy glucose solution, strong black sweet coffee, you must also give a double dose of any sorbent.

The antidote for hydrocyanic acid, which is available at home, is a solution of methylene blue. It is necessary to dissolve a few drops in a glass of warm water and let the patient drink. It is also necessary to provide him with access to fresh air, it is convenient to lay down, unfasten tight clothes, turn his head to one side. It is good to let the ammonia vapors inhale, bringing the moistened cotton wool to the nose for 3-4 seconds. Ammonia has an alkaline reaction, and, getting into the blood, will neutralize the acid.

Respiratory tract, with food or water. The poison blocks the ability of red blood cells to carry oxygen.

Organs do not receive it from the blood and refuse to work. Interestingly, the Swedish chemist Karl Scheele synthesized in 1782 hydrocyanic acid to become medicine.

But, it was rejected due to the discovery of toxic properties. But, the substance was useful to the military.

As a chemical weapon hydrocyanic acid first used in 1916. On July 1 of this year, a battle took place on the Somme River.

The opposing sides are the Germans and the French. The latter, and used poison instead of bayonets.

Where else, except in military companies, can it come in handy and what properties does it have? Answers, next.

Properties of hydrocyanic acid

Hydrocyanic acid is a substance liquid, colorless, with the aroma of bitter almonds.

It is interesting that in a real nut there is also a compound, more precisely, there are about 2 percent of amygdalin glycoside.

In the body, it is broken down by the enzyme emulsin, turning it into hydrocyanic acid. Underwire amygdalin can be more than 3 percent.

In this case, eating nuts is dangerous. So, buy almonds only from trusted sellers.

Amygdalin is also found in the bones of several other foods. It might turn out cherry hydrocyanic acid.

Therefore, you should not swallow the seeds of berries, especially chew them. Amygdalin is also present in the cores of apricots, apples, plums and pears.

There is evidence that hydrocyanic acid is synthesized in the stomach and when eating caviar. The delicacy is forbidden.

You get a couple of hundred grams, nothing will happen. But, if you eat about one and a half kilograms of black caviar at a time, you will get poisoned.

Some will ironize that this is a desired death. However, it is better not to go further than jokes.

If the poison enters the stomach, the symptoms of poisoning may not appear for 1-2 hours, but then it will not seem enough.

Hydrocyanic acid poisoning manifests itself quickly if you inhale the vapors. However, their density in air is less than 1 percent.

To produce the desired effect, the pairs must be heavier. That is why the French operation on the Somme was not successful.

The German soldiers felt only a slight malaise. Attempts to weight the vapors with trichloride and chloroform also failed.

Therefore, in the 21st century, the compound as a poison is mixed with food, not air.

In case of poisoning hydrocyanic acid acts on mucous membranes. They blush. The skin begins to smell like almonds.

It tickles in the throat, salivation increases, the taste of bitterness is felt. The oral cavity is partially numb. Can vomit, want to go to the toilet.

The pulse quickens. The chest begins to press. Then, the pulse, on the contrary, slows down. The rhythm of breathing and the ability to speak are disturbed.

Starts to wobble. Dizzy. In general, a fatal outcome is not excluded, especially in the absence of timely assistance.

Symptoms of hydrocyanic acid poisoning appear faster in heat. The liquid has a low boiling bar - only 25.7 degrees Celsius.

In the excited state, the connection is more active. At 13 degrees, hydrocyanic freezes.

If the substance has gone into steam, most porous substances will absorb it. The only unsuitable absorber is activated.

According to the chemical composition, hydrocyanic acid is a compound, and. Therefore, the substance is called hydrogen cyanide.

It easily reacts with alkalis. The result of any of the interactions with them - hydrocyanic acid salt.

Notable examples are cyanide and cyanide. Their toxicity is slightly inferior to the fundamental principle.

Hydrocyanic acid also reacts with halogens, that is, elements of the 17th group.

Therefore, the result of the reaction can be cyanogen bromide, cyanogen chloride, iodocyan. It turns out that halogens are replaced by a hydrogen atom.

Poison detoxification can be carried out by netons and aldehydes. When interacting with them, non-toxic rhodomides and cyanhydrides are formed.

It is also necessary to take into account the fact that hydrogen cyanide is a strong poison, but a weak acid. It is displaced from it by other acids, all without exception.

Extraction of hydrocyanic acid

On an industrial scale, the reagent is obtained by catalytic oxidation of methane.

The formation of acid is based on the endothermic method, that is, the absorption of heat. Hydrogen must be burned at the same time.

Then, the oxidation of ammonia and methane is incomplete, which speeds up the reaction.

Accelerates it and the presence of a catalyst. Usually, he is, but plates from other metals are also suitable.

Process formation of hydrocyanic acid from methane and ammonia, it proceeds with an intermediate product - nitroxide.

However, this is just a hypothesis. The exact process has not been studied. It is possible that instead of nitro acid, separate atoms and radicals are formed - a consequence of the decomposition of the reagents.

First, oxygen is absorbed on the catalyst. In this case, surface compounds of the active class are formed.

Then, molecules of methane and ammonia interact with the obtained compounds. As a result, new radicals and biradicals are formed on the catalyst.

They again contact with ammonia and methane. It turns out methylamine. It oxidizes with air. So hydrocyanic acid is ready. What for? We will devote a separate chapter to this issue.

The use of hydrocyanic acid

The action of hydrocyanic acid in small doses is not dangerous. This is used in the aromatic industry.

The smell of almonds comes in handy in perfumes, creams, sprays for the home. Contains hydrocyanic acid and in acrylonitrile, more precisely, it serves as a raw material for its creation.

Acrylonitrile, in turn, is the basis for some. Therefore, the "derivatives" of hydrogen cyanide can be roller skate wheels, and from, and substrates for corridor rugs.

Methyl methacrylate and adiponitrile are also made using hydrocyanic acid. These are two more raw materials for synthetic.

Plastics are close to them, therefore, they also contain hydrogen cyanide derivatives. It is also used in the agricultural industry.

The first role of acid is obvious - a herbicide for pests. But, cyanide can also be a growth stimulant, the main thing is not to overdo it with proportions.

Hydrocyanic acid compounds needed by farmers are called cyclones. The most popular is Cyclone B. The product is aimed at insects.

But, cyanide is also used as a poison for rodents. In this capacity, hydrocyanic acid was popular in the last century.

Organic manufacturing is another area of ​​application for hydrogen cyanide. For ceramics, it is also needed.

But, the bulk of the reagent is spent on the extraction of metals from ores.

They do not react with acid, and other components of the rock, as a rule, are disposed to interact.

Consequently, all excess goes into solution, and noble elements are deposited.

Hydrocyanic acid solutions sometimes act as disinfectants. Although, more often in this field, mixtures come in handy.

Karl Scheele's intentions to use hydrogen cyanide as a medicine did not fail 100%.

Sometimes, doctors prescribe hydrocyanic acid to patients in the form of mandelic or cherry laurel waters.

Both are able to dull the excitability of the mucous membrane of the larynx. This relaxes her, relieving people from coughing. That is, the recommendation for the use of the compound is the pathology of the respiratory tract.

Leveling the contractions of the respiratory tract, hydrogen cyanide is also able to reduce the peristalsis of the gastrointestinal tract.

The medicine partially paralyzes him. For some diagnoses, this is necessary. So, hydrocyanic acid can not only cripple, but also heal, although it is rarely prescribed, in extreme cases.

The price of hydrocyanic acid

Not easy to find deals buy hydrocyanic acid, as calls to purchase sensors that determine the amount of its vapor in the air.

Devices, as a rule, are portable, cost from 13,000 rubles. There are models for 150,000. The latter are designed for large enterprises.

It is these people who order the reagent, which is transported in tank cars of model 1515-56. A set of rules is written, there are orders. However, their cost is not mentioned.

In interest, where and for how much you can buy hydrocyanic acid is puzzling.

Users ask why such a strong poison was needed and suggest finding less toxic reagents.

So, the cost of hydrocyanic acid for a private trader is a secret behind 7 seals. They do not disclose the price of derivatives, for example, potassium cyanide.

On those who advertise for sale, they are asked to fill out an order form. The price tag is reported in a personal telephone conversation, after checking the buyer's data.

Of the open offers, there is an announcement by CJSC Yuventa. The powder is shipped in bulk in bags of 50 kilograms. For every 1000 grams they ask for 450 rubles.

Hydrocyanic acid is a potent toxic substance, the poisoning of which can lead to death. This colorless liquid, which quickly turns into a gaseous state, is very toxic at high concentrations. Therefore, in the past, some countries used it as a chemical warfare agent, and the Nazis - in concentration camps.

Let's take a closer look at the sources of poisoning with this poison, how hydrocyanic acid is dangerous, what signs of intoxication can be, how to help the victim.

A little about hydrocyanic acid

This substance is a volatile liquid without color. It has the smell of bitter almonds. Hydrocyanic acid is also called hydrocyanic acid, and its salts are called cyanides.

In the human body, these substances block the activity of enzymes, especially cellular cytochrome oxidase, which contributes to the development of tissue hypoxia (oxygen starvation). This is the reason for the toxic effect of hydrocyanic acid on humans. First of all, the nervous system suffers, especially the central one. The poison affects the cardiovascular system, and the respiratory function. Characteristic changes appear in the bloodstream.

Where is hydrocyanic acid found

To prevent poisoning, you need to know where hydrocyanic acid is contained. She is present:

• in the bones of some fruits and berries (cherries, plums, apricots and peaches), as well as in bitter almonds, glycosides are contained, during the splitting of which hydrocyanic acid is released (with some exposure);
• in tobacco smoke;
• in insecticides (insecticides) and rodents;
• it is used in production.

Hydrocyanic (hydrocyanic) acid poisoning is more common in manufacturing, where its salts are used to extract precious metals from ore, make plastics, plant growth activators, organic glass, herbicides, aromatics, and rubber. Salts are used in the pharmaceutical industry. These compounds are unstable: upon contact with air and moisture, they quickly decompose with the formation of poison. Hydrocyanic acid is released with the gas formed during the production of coal.

Symptoms of hydrocyanic acid poisoning

Signs of hydrocyanic acid poisoning can be observed when the poison is ingested, when its vapors are inhaled, and when it comes into contact with the skin. The speed of its action and the appearance of clinical symptoms depend on the way in which the toxic substance entered the body. Severe poisoning occurs when vapors enter the respiratory system. In this case, symptoms of hydrocyanic acid poisoning may appear in the first minutes after contact. If the concentration of the poisonous substance is very high, then a lethal outcome can be observed in a matter of minutes.

In the digestive system, hydrocyanic acid can spend some time inactive. The slowest intoxication develops when acid enters through the skin. This process proceeds more actively with an increase in the temperature in the room, during physical activity, which leads to intense sweating. In this case, the hidden period can be up to 90 minutes.

The main signs of hydrocyanic acid poisoning are as follows.

First aid for hydrocyanic acid damage

In case of damage by hydrocyanic acid, first aid includes a number of measures:

1. Stop further exposure to the poisonous substance on the body: take the victim out of the poisoned atmosphere, remove clothing on which toxic substances can settle.
2. Call an ambulance immediately.
3. When poison enters the digestive system, the first thing to do is to get rid of the contents of the stomach - to induce vomiting on your own. For gastric lavage, a weak solution of potassium permanganate or with 1% hydrogen peroxide is suitable. You can use a solution of sodium thiosulfate (5%) and sodium bicarbonate (2%). Such events are allowed to be carried out by a person who is conscious.
4. You can give a laxative (salt) and activated charcoal.
5. To create rest for the victim and it is necessary to ensure that he stays warm.
6. If the person is unconscious, it must be laid on its side so that the vomit does not enter the respiratory tract.
7. If there are signs of clinical death, resuscitation is carried out.

In case of poisoning with hydrocyanic acid, first aid can be provided by someone who was next to the victim. Arriving at the place of doctors will carry out further treatment.

Basic therapeutic measures

All victims are transported by ambulance to the toxicology department.

After acute poisoning, neurological disorders may progress in the future. At the same time, parkinsonism and cerebellar disorders develop.

Preventive actions

In order not to be exposed to hydrocyanic acid and to avoid the severe consequences of its exposure, it is necessary:

• strictly follow the safety requirements, if necessary, use a gas mask;
• regularly ventilate the room after working with toxic substances (deratization, disinsection);
• constant monitoring of the level of harmful substances on the territory of the enterprise;
• where possible, use mechanized labor when working with hazardous substances;
• monitor the health of the equipment;
• personal hygiene;
• strict selection of employees for health reasons at enterprises with harmful working conditions.

Every person who is going to work in conditions of likely exposure to cyanide must be informed what first aid should be for a victim of hydrocyanic acid damage. The life of the person himself and the people who work next to him depends on this.

At home, the independent use of products containing hydrocyanic acid and its salts is very dangerous. This can hurt you and your loved ones.

Hydrocyanic acid and its compounds

Hydrocyanic acid (hydrocyanic acid) was first synthesized by the Swedish scientist Karl Scheele in 1782. Hydrocyanic acid was first used as a poisonous substance on July 1, 1916 on the river. Somme by French troops against German troops. It was not possible to obtain a pronounced combat effect, since the relative density of HCN vapor in the air is less than 1. Attempts to make hydrocyanic acid vapor heavier by adding arsenic trichloride, tin chloride and chloroform also did not lead to the creation of combat concentrations of toxic vapors in the atmosphere.

The acid itself and its salts are widely used in agriculture (as pest control agents for fruit trees), in industry (for extracting gold and silver from ores), in the chemical synthesis of nitrile rubber, synthetic fibers, plastics, etc.

As an OV, it is unlikely to be used. It is possible to use hydrocyanic acid derivatives as diversion agents.

Currently, various groups of chemical compounds are known that contain a CN group in the molecule.

250. Boiling point of hydrocyanic acid

Among them: nitriles - hydrocyanic acid, cyanide, potassium cyanide, cyanogen chloride - CI-CN, propionitrile - C3H7-CN, etc.); isonitriles - phenylisonitrile chloride; cyanates - phenyl cyanate; isocyanates - methyl isocyanate, phenyl isocyanate; thiopianates - thiocyanate potassium; isothiocyanates - methylisothiocyanate. The least toxic (LD50 over 500 mg/kg) are representatives of cyanates and thiocyanates. Isocyanates and isothiocyanates are irritating and asphyxiant. A general toxic effect (due to the elimination of the CN- ion from the parent substance in the body) is exhibited by nitriles and, to a lesser extent, isonitriles. In addition to hydrocyanic acid itself and its salts, cyanogen chloride, cyanogen bromide, as well as propionitrile, which is only 3-4 times inferior in toxicity to potassium cyanide, is distinguished by high toxicity.

Hydrocyanic acid occurs in plants in the form of heteroglycosides. About 2000 plant species contain CN-containing glycosides. For example, in the form of amygdalin, HCN is found in the seeds of bitter almonds, in the seeds of peaches, apricots, plums, cherries, etc.

Physico-chemical and toxic properties

Hydrocyanic acid is a colorless transparent liquid with a smell of bitter almonds. boiling point + 25.7 ° C, freezing point 13.4 ° C. The relative density of its vapor in air is 0.93. Hydrocyanic acid vapors are poorly absorbed by activated carbon, but are well absorbed by other porous materials.

When interacting with alkalis, HCN forms salts (potassium cyanide, sodium cyanide, etc.), which are not much inferior in toxicity to hydrocyanic acid itself. When a hydrogen atom is replaced by halogens, halandtions (cyanogen chloride, cyanogen bromide, cyanogen chloride) are formed. Hydrocyanic acid and cyamides interact with sulfur (non-toxic rhodomides are formed), as well as with aldehydes and netons (low-toxic cyanhydrides are formed). These reactions underlie the detoxification of the poison. In aqueous solutions, the acid and its salts dissociate to form the CN- ion. Hydrocyanic acid is a weak acid and can be displaced from its salts by other, even the weakest, acids (for example, carbonic).

The main route of penetration of hydrocyanic acid vapors into the body is inhalation. The average lethal concentration is 2 mg × min / l, fatal poisoning with hydrocyanic acid salts is possible when they enter the body with contaminated water or food. In case of poisoning by mouth, lethal doses for humans are: HCN - 1 mg / kg; KCN - 2.5 mg/kg; NaCN - 1.8 mg/kg.

Mechanism of toxic action and pathogenesis of intoxication

As is known, at this stage, the chain of cytochromes (cytochromes B, C1, C, A, and A3) is the carrier of protons and electrons. The successive transfer of electrons from one cytochrome to another leads to the oxidation and reduction of the iron contained in them (Fe3 + "Fe2 +"). The final link in the cytochrome chain is cytochrome oxidase. It was found that the enzyme includes 4 units of heme "A" and 2 units - "A3". It is from cytochrome oxidase that electrons are transferred to oxygen delivered to the tissues by blood. It has been established that cyan ions (CN-) dissolved in the blood reach the tissues, where they interact with the ferric form of cytochrome A3 iron of cytochrome oxidase (cyanides do not interact with Fe2+). By combining with cyanide, cytochrome oxidase loses its ability to transfer electrons to molecular oxygen.

Due to the failure of the final link of oxidation, the entire respiratory chain is blocked and tissue hypoxia develops. Oxygen with arterial blood is delivered to the tissues in sufficient quantities, but they are not absorbed by them and passes unchanged into the venous bed. At the same time, the processes of formation of macroergs (ATP, etc.) are disrupted. Glycolysis is activated, i.e., the exchange from aerobic is rebuilt to anaerobic.

Clinic of defeat

As a result of tissue hypoxia, which develops under the influence of hydrocyanic acid, the functions of the central nervous system are primarily impaired. Acting in large doses, substances first cause excitation of the central nervous system, and then its depression.

Under the action of ultra-high doses of the toxicant develops lightning fast form of poisoning. The victim loses consciousness a few seconds after exposure. Seizures develop. Blood pressure after a short rise falls. After a few minutes, breathing and cardiac activity stop.

At slow flow In the development of intoxication, several periods can be distinguished.

Period of initial phenomena characterized by slight irritation of the mucous membranes of the upper respiratory tract and conjunctiva of the eyes, an unpleasant bitter taste and burning sensation in the mouth. There is a smell of bitter almonds. Salivation, nausea, sometimes vomiting, dizziness, headache, pain in the heart area, tachycardia (sometimes bradycardia), and increased respiration are observed. Coordination of movements is disturbed, weakness is felt, a feeling of fear arises. These signs appear almost immediately after exposure to the poison. There is practically no hidden period.

Dyspnoetic period characterized by the development of excruciating shortness of breath. There is a pronounced increase in the frequency and depth of breathing. The initial excitation of respiration, as intoxication develops, is replaced by its oppression. Breathing becomes irregular - with a short inhalation and a long exhalation. Increased pain and tightness in the chest. Consciousness is oppressed. Severe bradycardia, dilated pupils, exophthalmos, vomiting are observed. The skin and mucous membranes acquire a pink color. In mild cases, hydrocyanic acid poisoning is limited to these symptoms. After a few hours, all manifestations of intoxication disappear.

The dyspnoetic period is replaced period of seizures. Convulsions are clonic-tonic in nature with a predominance of the tonic component. Consciousness is lost. Breathing is rare, but there are no signs of cyanosis. The skin and mucous membranes are pink. The initially observed slowing of the heart rate, an increase in blood pressure and an increase in cardiac output are replaced by a drop in blood pressure, increased heart rate, and its arrhythmia. Acute cardiovascular failure develops. Possible cardiac arrest. Corneal, pupillary and other reflexes are reduced. Muscle tone is significantly increased.

Following a short convulsive period, if death does not occur, develops paralytic period. It is characterized by a complete loss of sensation, the disappearance of reflexes, muscle relaxation, involuntary defecation and urination. Breathing becomes rare, superficial. Blood pressure drops. The pulse is frequent, weak filling, arrhythmic. A coma develops, in which the victim, if death does not occur from respiratory arrest and cardiac activity, can be for several hours, and sometimes even days. The body temperature of those affected in the paralytic period is lowered.

Inhibition of tissue respiration leads to a change in the cellular, gas and biochemical composition of the blood. The content of erythrocytes in the blood increases due to the reflex contraction of the spleen and the release of cells from the depot. The color of venous blood becomes bright scarlet due to the excess content of oxyhemoglobin (HbO). The arterio-venous difference in oxygen sharply decreases. The content of CO2 in the blood decreases due to less formation and increased excretion during hyperventilation of the lungs. Such dynamics of the gas composition initially leads to gaseous alkalosis, which is then replaced by metabolic acidosis. Underoxidized metabolic products accumulate in the blood: the content of lactic acid increases, the content of ketone bodies (acetone, acetoacetic and b-hydroxybutyric acids) increases, the sugar content increases (hyperglycemia).

The duration of the course of the entire poisoning, as well as individual periods of intoxication, varies considerably (from several minutes to many hours). It depends on the amount of poison that has entered the body, the previous state of the body and other reasons.

Consequences of intoxication

The severity, nature of complications and consequences of poisoning largely depend on the duration of the hypoxic state in which the poisoned remains. Particularly frequent are violations of the functions of the nervous system. After transferring acute poisoning, headaches, increased fatigue, and impaired coordination of movements are observed for several weeks. Speech is difficult. Sometimes paralysis and paresis of individual muscle groups develop. Possible mental disorders.

There are persistent changes in the functions of the cardiovascular system due to myocardial ischemia. Respiratory system disorders are manifested by the functional lability of the respiratory center and its rapid exhaustion under increased loads.

Features of the action of halogen derivatives of hydrocyanic acid

Cyanogen chloride (CICN) as a poisonous substance was first used during the First World War in October 1916 by French troops. Cyanogen chloride is a colorless transparent liquid that boils at 12.6°C and freezes at -6.5°C. It has an irritating odor (the smell of chlorine). Vapor density in air 2.1.

Cyanogen bromide (BrCN) first used during the First World War (1916) by the Austro-Hungarian troops in the form of a mixture of 25% cyanogen bromide, 25% bromoacetone and 50% benzene. Cyanogen bromide is a colorless or yellow crystalline substance, very volatile, with a pungent odor. Boiling point 61.3ºС, melting point 52°С. The vapor density in air is 7.

Both compounds (especially C1CN) are similar in toxicity to hydrocyanic acid.

Cyanogen chloride and cyanogen bromide, acting like HCN, also have an irritating effect. They cause lacrimation, irritation of the mucous membranes of the nose, nasopharynx, larynx and trachea. In high concentrations, it can cause toxic pulmonary edema.

Medical protection measures:

Special sanitary and hygienic measures:

• use of respiratory protective equipment in the focus of chemical contamination;
• participation of the medical service in conducting chemical reconnaissance, conducting an examination of water and food for TCV contamination;
• a ban on the use of water and food from unverified sources.

Special treatment measures:

• the use of antidotes and means of pathogenetic and symptomatic therapy;
• preparation and conduct of the evacuation.

Medical protective equipment

Antidotes used for cyanide poisoning are divided into 2 groups:

1) methemoglobin formers;

2) linking the CN group.

1) Methemoglobin formers:

As you know, once in the body, cyanides do not interact with hemoglobin iron, which is in a divalent state, and, having penetrated into the tissues, they bind to the ferric iron of cytochrome oxidase, which loses its physiological activity. If a poisoned person is quickly introduced in the required amount of a methemoglobin former, then the resulting methemoglobin (ferric iron) will enter into chemical interaction with poisons, binding them and preventing them from entering the tissues. Moreover, the concentration of free toxicants in the blood plasma will decrease, and conditions will arise for the destruction of the reversible bond of the cyan ion with cytochrome oxidase.

The cyan-methemoglobin complex formed is an unstable compound. After 1-1.5 hours, this complex begins to gradually disintegrate. However, since the process of dissociation of CNMtHb is extended in time, the slowly released cyan-ion has time to be eliminated. Nevertheless, with severe intoxication, a relapse of intoxication is possible. Among the methemoglobin-forming agents - cyanide antidotes, include: sodium nitrite, amyl nitrite, 4-dimethylaminophenol, anticyan, methylene blue. It should be remembered that methemoglobin is not able to bind with oxygen, so it is necessary to use strictly defined doses of drugs that change no more than 25-30% of blood hemoglobin.

The most available methemoglobin former is sodium nitrite (NaNO2). When helping the poisoned, sodium nitrite is administered intravenously (slowly) in the form of a 1-2% solution in a volume of 10-20 ml, under the control of blood pressure.

amyl nitrite designed for first aid. An ampoule with amyl nitrite (1 ml), which is in a cotton-gauze wrapper, should be crushed and placed under a gas mask. It can be reapplied if necessary. Currently, the antidote properties of the drug tend to be explained not so much by its ability to methemoglobin formation (which is weakly expressed), but by increased cerebral blood flow, which develops as a result of the vasodilating effect of the substance.

Antician is another substance that can be used as an antidote. In case of hydrocyanic acid poisoning, the first injection of anticyan in the form of a 20% solution is made in a volume of 1.0 ml intramuscularly or 0.75 ml intravenously. When administered intravenously, the drug is diluted in 10 ml of 25-40% glucose solution or isotonic sodium chloride solution. The rate of administration is 3 ml per minute. If necessary, after 30 minutes, the antidote can be re-introduced at a dose of 1.0 ml, but only intramuscularly. After another 30 minutes, a third administration at the same dose can be carried out, if there are indications for this.

4-dimethylaminophenol hydrochloride is produced in ampoules in the form of a 15% solution, administered intravenously at the rate of 3-4 mg / kg of the patient's weight mixed with a glucose solution. Does not cause collapse.

Has a partial methemoglobin-forming effect methylene blue. The main effect of this drug is its ability to activate tissue respiration. The drug is administered intravenously as a 1% solution in a 25% glucose solution ( chromosmon) 50 ml.

2) Linking CN-group:

Sodium thiosulfate(Na2S2O3). As already mentioned, one of the ways of transformations of cyanides in the body is the formation of rhodanium compounds when interacting with endogenous sulfur-containing substances. The resulting thiocyanates excreted from the body with urine are about 300 times less toxic than cyanides.

The true mechanism for the formation of rhodanide compounds has not been fully established, but it has been shown that with the introduction of sodium thiosulfate, the rate of the process increases by 15-30 times, which justifies the expediency of using the substance as an antidote for cyanide poisoning. The drug is administered intravenously as a 30% solution of 50 ml. Sodium thiosulfate potentiates the action of other antidotes. It is advisable to start the provision of emergency care with methemoglobin formers, and then switch to the introduction of other drugs.

Glucose. The antidote effect of the drug is associated with the ability of substances containing an aldehyde group in the molecule to form stable, low-toxic compounds, cyanohydrins, with hydrocyanic acid. The substance is administered intravenously in the amount of 20-25 ml of a 25-40% solution. In addition to the ability to bind the toxicant, glucose has a beneficial effect on respiration, cardiac function and increases diuresis.

Preparations containing cobalt. Cobalt is known to form strong bonds with the cyan ion. In animal experiments, hydroxycobalamin (vitamin B12) has been shown to be effective in the treatment of potassium cyanide poisoning. The drug is very effective, slightly toxic, but expensive, which required the search for other compounds. Among the agents tested were cobalt acetate, gluconate, glutamate, histidinate, and dicobalt salt of ethylenediaminetetraacetate (EDTA). The last drug, which is used in some countries in clinical practice, turned out to be the least toxic and effective. In our country, cobalt preparations are not used as antidotes.

In the process of helping the poisoned, the use of other means of pathogenetic and symptomatic therapy is also envisaged. Hyperbaric oxygen therapy has a positive effect.

Mechanisms of toxic action of hydrocyanic acid

Cyanides inhibit redox processes in tissues, disrupting the last stage of the transfer of protons and electrons by a chain of respiratory enzymes from oxidized substrates to oxygen.

As is known, at this stage, the chain of cytochromes (cytochromes b, C1, C, a and a3) is the carrier of protons and electrons. The successive transfer of electrons from one cytochrome to another leads to the oxidation and reduction of the iron present in them (Fe3+ « Fe2+). The final link in the cytochrome chain is cytochrome oxidase. It has been established that the enzyme includes 4 units of heme "a" and 2 units - "a3". It is from cytochrome oxidase that electrons are transferred to oxygen delivered to the tissues by blood. It has been established that cyan-ions (CN-) dissolved in the blood reach the tissues, where they interact with the trivalent form of iron of cytochrome a3 cytochrome oxidase (cyanides do not interact with Fe2+). By combining with cyanide, cytochrome oxidase loses its ability to transfer electrons to molecular oxygen.

Due to the failure of the final oxidation link, the entire respiratory chain is blocked and tissue hypoxia. Oxygen with arterial blood is delivered to the tissues in sufficient quantities, but they are not absorbed by them and passes unchanged into the venous bed. At the same time, the processes of formation of macroergs (ATP, etc.) are disrupted. Glycolysis is activated, that is, the exchange from aerobic to anaerobic is rebuilt.

In addition to the direct action of cyanides on tissues, a significant role in the formation of acute symptoms of damage, has reflex mechanism.

The body has specialized structures, the sensitivity of which to the developing deficiency of macroergs is much greater than all other tissues. The most studied of these formations is the carotid glomerulus (glomus caroticum). The carotid glomerulus is located at the bifurcation of the common carotid artery into the internal and external. About 20 ml of blood per 1 g of tissue flows through it per minute (0.6 ml through the brain). It consists of two types of cells (according to Hess): type I, mitochondria-rich glomus cells, and type II, capsular cells. The endings of Hering's nerve, which connects the structure with the CNS, penetrate the bodies of type II cells and come into contact with type I cells. M.L. Belenky showed that reflexes from the glomus arise with changes in PaO2, pH, and other metabolic parameters, which are noted even with minimal violations of the conditions necessary for the implementation of the process of oxidative phosphorylation. The strongest stimulating agent of this structure is potassium cyanide. It was concluded that the main physiological role of the carotid glomerulus is to signal the CNS about an impending energy metabolism disorder. There is an assumption that the starting link of the reflex reactions formed in the glomus is a decrease in the level of ATP in type I cells. A decrease in the level of ATP provokes the release of chemicals by glomus cells, which excite the endings of Hering's nerve. The sensitivity of glomus to a number of neuroactive compounds, for example, N-cholinomimetics, catecholamines, is well known (Anichkov S.V.). However, it is also known that none of them changes the sensitivity of the structure to cyanide.

Hydrocyanic acid

The action of adequate stimuli on the glomus is accompanied by CNS excitation, increased blood pressure, bradycardia, increased and deepened respiration, release of catecholamines from the adrenal glands and, as a result, hyperglycemia, etc. That is, all those reactions that are noted in the early stages of intoxication with substances of general toxic action. No matter how the toxicants disrupt the mechanisms of energy supply, the reaction of the body is largely the same. Manifestations of intoxication are effects that form first as a result of excitation and overexcitation of specialized regulatory systems (for example, glomus), and then - a violation of bioenergetics directly in the tissues, and, first of all, quickly responding to a shortage of macroergs (the brain).

Study question 5.Clinic, prevention and general principles of medical care for hydrocyanic acid lesions in the outbreak and at the stages of medical evacuation