Why is hydrogen sulfide dangerous for humans? The effect of hydrogen sulfide on the human body

Translation of an article by Rui Wang. Rui Wang - Professor of Biology and Vice President for scientific work Lakehead University, President of the Canadian Physiological Society, a leading expert in the metabolism and physiological functions of low molecular weight gases that play the role of gaseous mediators - including nitrogen monoxide, carbon monoxide and hydrogen sulfide.

Scientists have shown that hydrogen sulfide (H2S), a gas that is poisonous in large quantities, is formed in small doses in the body and performs many functions important for normal life.

Some of them are given below. However, H2S can also have pathological effects: for example, in excessive amounts it reduces insulin production, and there is evidence of its anti-inflammatory effects.

Imagine walking through the emergency department of a hospital with its walls shining with cleanliness, thoroughly washed with a disinfectant solution - and suddenly you hear the characteristic fetid smell of rotten eggs!

This situation seems incredible, but the source of the odor - hydrogen sulfide (H2S) - may in the near future become an integral part of any emergency department.

The toxicity of hydrogen sulfide (H2S) to humans has been known for centuries. Currently, this gas ranks first on the list of toxic substances during the extraction, pumping and processing of oil and gas. We begin to smell it at a concentration in the air of 0.0047 ppm.

At a concentration of 500 ppm, hydrogen sulfide causes breathing problems, and at a concentration of 800 ppm it causes death in five minutes. At the same time, surprisingly, hydrogen sulfide is essential for life.

In order to understand how the foul-smelling gas became an important component of physiological processes, let’s move back in time 250 million years.

Then, at the end of the Permian period, life on Earth was hanging on by a thread - the so-called great extinction occurred, which became one of the major disasters in the history of our planet.

According to the most common hypothesis, it was caused by the release of carbon dioxide during massive outpourings of volcanic rocks in Siberia, which triggered a chain reaction of environmental changes and led to a critical decrease in oxygen levels in the waters of the World Ocean.

These shifts in ocean composition were detrimental to aerobic (oxygen-consuming) marine species, but allowed anaerobic organisms, particularly green sulfur bacteria, to flourish.

The rapid proliferation of such bacteria has made the ocean completely unsuitable for the last aerobic species, because sulfur bacteria produced hydrogen sulfide in large quantities. Eventually, apparently, this poisonous gas began to be released into the air, destroying land plants and animals. By the end of the “great extinction”, 95% of marine animal species and 70% of land animals had died.

Perhaps the role of hydrogen sulfide in physiological processes in humans is a legacy of those ancient times. Only species capable of surviving in an atmosphere of hydrogen sulfide, and sometimes consuming it, were able to survive the “great extinction.” Apparently, this ability has been preserved to some extent in our country.

Trusting your sense of smell

Hydrogen sulfide (H2S) is not the only toxic gas involved in physiological processes in humans. In the 1980s Evidence began to appear that the body produces nitrogen monoxide NO in small quantities. It soon became clear that it plays the role of a mediator - a signaling molecule that affects cell functions.

Work awarded the Nobel Prize in Physiology or Medicine for 1998 showed that nitrogen monoxide is involved in many physiological processes, in particular in the regulation of immune responses and in the transmission of signals between neurons, and also causes vasodilation. Subsequently, similar functions were discovered for carbon monoxide (CO), a deadly, colorless and odorless substance commonly known as carbon monoxide.

Study of the physiological role of CO and NO

Research into the physiological role of CO and NO led me to the belief that other gaseous mediators may exist in the body. As a result of constant thoughts on this topic, in the summer of 1998, the idea finally occurred to me that H2S could be such a mediator. Returning from work one day, I noticed an unpleasant smell in the house.

It turned out that it came from the glass cabinet where our family heirlooms were kept, namely a spoiled Easter egg that my eldest daughter had painted for school homework.

At that moment, a question arose to me: if hydrogen sulfide is formed in rotten eggs, then could it not be produced in human organs and tissues?

Since my research on CO and NO focused on the effects of these gases on the cardiovascular system, I decided to conduct a similar study on the effects of H2S. The choice turned out to be successful.

Hydrogen sulfide is found in blood vessels

In the first experiments carried out by our team, it turned out that hydrogen sulfide is contained in small concentrations in the blood vessels of rats. Since the physiological characteristics of rodents and humans are very similar, it could be confidently assumed that this gas is also formed in human vessels.

This discovery inspired optimism, however, to draw conclusions about the physiological role of H2S, simply stating the fact of its presence in the vascular wall was clearly not enough.

At the next stage, it was necessary to investigate the mechanisms of hydrogen sulfide formation.

Cystathionine gamma lyase enzyme

Our attention was drawn to the enzyme cystathionine gamma lyase, which is involved in the formation of H2S in bacteria. Previous work has shown that it is found in the liver, where it plays a role in the formation of some sulfur-containing amino acids (the building blocks of proteins).

At the same time, there was no evidence of the presence of cystathionine gamma lyase in the vascular wall. As expected, we received such data. It turned out that in blood vessels, under the action of cystathionine gamma-lyase, hydrogen sulfide, ammonia and pyruvic acid are formed from the amino acid L-cysteine.

What role does this gas play in the vessels?

So, the source of H2S in the vascular wall has been identified. Now it was important to find out what role this gas plays in the vessels. Knowing that NO causes relaxation of vascular muscles, we hypothesized that H2S could act in the same way. This hypothesis turned out to be correct: when immersed in a solution containing hydrogen sulfide, the rats' blood vessels dilated.

As a result of all the work carried out, it seemed that H2S, like NO, is involved in the regulation blood pressure. At the same time, the molecular mechanisms of H2S action remained undiscovered. The first data on such mechanisms were obtained by us in studies on isolated vascular cells and published in 2001.

These data turned out to be quite unexpected: while NO causes vascular relaxation by activating the smooth muscle enzyme guanylate cyclase, then H2S causes the same effect in a completely different way.

Under the influence of this substance, the permeability of the so-called ATP-dependent potassium channels (KATP) increases - protein complexes built into the membrane of cells (in particular, vascular smooth muscles) and allowing potassium ions to pass through. As a result, the release of potassium from the cell increases, its charge changes, which leads to a decrease in the permeability of other calcium channels. As a result, the entry of calcium into the cell is reduced, and this leads to relaxation of smooth muscles and dilation of blood vessels.

It's time to move from isolated cells to intact animals. In our experiments, administering a hydrogen sulfide solution to rats led to a decrease in blood pressure, apparently due to dilation of the arteries and a decrease in resistance to blood flow.

Thus, increasing evidence suggested that H2S is involved in the regulation of blood pressure by causing vascular relaxation. However, it was still necessary to prove that the effects of the gas when introduced from the outside and when produced in the vascular wall are identical.

To investigate the natural effects of H2S, we bred a line of mice with an inactivated (“knocked out”) cystathionine gamma lyase gene. In such animals, H2S is, of course, not formed in the vessels. Then, for five years, we studied mice together with teams led by Solomon Snyder from Johns Hopkins University and Lingyun Wu from the University of Saskatchewan (Canada). Our efforts were not in vain.

In 2008, we published a detailed paper in which we showed, in particular, that in our rodents, as they age, the blood vessels narrow and blood pressure (measured using miniature cuffs placed on the tail) increases significantly. When hydrogen sulfide was administered to such mice, the pressure decreased.

The data from our work left no doubt that H2S plays a key role in the regulation of blood circulation. In addition, they made it possible to resolve one of the long-standing mysteries of physiology. The fact is that for a long time after the Nobel Prize-winning work on NO research, it was known that the action of this substance alone cannot completely explain the expansion blood vessels.

Thus, in animals with inactivated genes responsible for the formation of NO in endothelial cells (the inner lining of blood vessels), peripheral vessels still retain the ability to relax. However, the nature of the vasodilator factor remained mysterious.

According to our data, this factor is H2S. In our first studies, we discovered the enzyme cystathionine gamma-lyase, which is responsible for the formation of hydrogen sulfide, in smooth muscle cells, but later it was found in the endothelial cells of mice, cows and humans - and even in larger quantities than in smooth muscles. It remains unclear what the relationship is between the vasodilatory function of NO and H2S, although some data suggest that NO causes predominantly relaxation of large vessels, and H2S - small ones.

New super drug?

The discovery of hydrogen sulfide synthesis in blood vessels and its role in the regulation of blood pressure has attracted the attention of many researchers looking for new ways to protect the heart from ischemic damage (i.e. damage caused by a decrease in blood supply, and therefore oxygen delivery).

A typical example of such damage is myocardial infarction, when the vessel supplying the heart is blocked by a thrombus, and the death of the part of the heart supplied by this vessel occurs. In 2006, Gary Baxter, now at Cardiff University in Wales, and co-authors published a paper that provided the first evidence of a beneficial role for H2S in ischemic heart injury.

The work used isolated rat hearts supplied not with blood, but with an oxygenated saline solution. The model of ischemic damage was the cessation of the flow of such a solution through one of the coronary arteries (vessels supplying the heart). It turned out that adding H2S to the solution a few minutes before blocking the artery reduced the size of the damaged area.

A year later, David Liefer of Emory University showed that genetically engineered mice with increased production of hydrogen sulfide in the heart were better able to withstand myocardial ischemia caused by coronary artery occlusion and were more resistant to the damage that often occurs after blood flow is restored (called reperfusion injury).

These and other data suggest that H2S may be used to prevent and treat hypertension, myocardial infarction and stroke. In addition, the vasodilating effect of hydrogen sulfide can be used in other conditions associated with disorders of vascular function, for example, erectile dysfunction (erectile dysfunction). It is known that the basis of erection is the dilation of the vessels of the penis and an increase in blood flow to it.

The effect of Viagra is due precisely to the fact that it increases the duration of the dilating effect of NO on blood vessels. There is evidence that H2S can have a similar effect, although the role of this substance in the human male reproductive system has yet to be studied (it is known, for example, that CO is produced in the tissues of the penis, but this gas does not promote erection, but ejaculation).

Hydrogen sulfide is produced not only in the heart and blood vessels. It is also formed in the nervous system, only under the action not of cystathionine gamma lyase, but of another enzyme - cystathionine beta synthase. The function of H2S in the nervous system is unclear. According to some data, it can play the role of a neuromodulator - a substance that increases or decreases the excitability of neural circuits. It is possible that H2S is involved in long-term potentiation, a process that facilitates communication between neurons and plays a role in learning and memory.

It has been shown that under the influence of hydrogen sulfide in nerve cells, the level of the antioxidant glutathione increases, which protects cells from the action of damaging factors. Finally, H2S may play a role in pain perception, which mediates responses to noxious stimuli.

In addition, hydrogen sulfide can affect metabolism, i.e. biochemical processes that ensure the production and use of energy, and the synthesis of substances. In surprising experiments, Mark Roth and his colleagues from the University of Washington showed that inhalation administration of small doses of H2S to mice leads to a slowdown in metabolism and, thereby, to the progression of certain diseases.

The heart rate of such mice immediately after the start of inhaling H2S dropped by half, and they went into a state of suspended animation: metabolic processes decreased so much that inhaling oxygen and H2S was enough for the animals to survive without any negative consequences.

It seemed that during such hydrogen sulfide anabiosis, metabolism was maintained at a minimum level for vital organs until normal energy supply was restored.

30 minutes after stopping H2S inhalation, the metabolic rate was restored.

If hydrogen sulfide suspended animation turned out to be effective and safe in humans, then it could become a powerful method of emergency care. Giving H2S inhalation to car accident victims or myocardial infarction patients could save time needed for transport to hospital and specialized care.

With the help of hydrogen sulfide, it would be possible to maintain those in need of transplantation in a state of suspended animation until they receive a donor organ - moreover, it would be possible to prolong the viability of the donor organs themselves.

One can imagine the use of H2S in areas of military conflicts or natural disasters: inhalation of this gas could delay the emergency of blood transfusions until sufficient quantities of the latter are delivered. Inhalation of hydrogen sulfide significantly increases the survival rate of rats with a loss of 60% of blood: rats receiving H2S survived in 75% of cases, and control ones - only in 25%.

Cautious optimism

However, one should not assume that hydrogen sulfide is an ideal cure for all diseases. There are still debates, for example, about whether it alleviates or aggravates the course of inflammation. Our laboratory and others have shown that H2S plays an important role in the development of diabetes mellitus I, a form of the disease that often begins in childhood and leads to lifelong dependence on insulin injections.

It turned out that H2S is formed in the so-called beta cells of the pancreas, which secrete insulin, and in animals with diabetes mellitus I, the production of hydrogen sulfide in such cells is sharply increased. This leads, firstly, to the death of a large number of beta cells, and secondly, to the suppression of insulin release by the remaining beta cells. As a result, insulin secretion drops to a level insufficient for the normal breakdown of glucose. Thus, H2S may be one of the culprits for decreased blood insulin levels during diabetes mellitus I.

Some of the beneficial effects of H2S in rats and mice are not replicated in larger animals. Thus, in 2007, French researchers showed that when inhaled with H2S, sheep, unlike rodents, do not fall into a state of suspended animation.

In another study, inhalation of H2S in piglets led not to a decrease, but to an increase in the rate of metabolic processes.
Even if it is possible to induce hydrogen sulfide suspended animation in humans, it is unknown whether it will lead to disturbances in brain activity. True, such disorders have not been identified in laboratory animals, but it is difficult to transfer such data to human mental functions. It is not yet clear whether higher functions such as memory and thinking can be preserved under conditions of hydrogen sulfide anabiosis, when life is barely warm.

And yet, the great therapeutic potential of hydrogen sulfide is of increasing interest to pharmacologists. Several companies are already developing drugs that release this gas in the body. Thus, the Italian company CTG Pharma has created drugs that combine the properties of non-steroidal anti-inflammatory drugs (NSAIDs) and H2S carriers.

Animal experiments have shown that such drugs can be effective in treating inflammatory diseases nervous system And gastrointestinal tract, erectile dysfunction, coronary heart disease and blood vessel diseases. And the company Ikaria (New Jersey), one of the founders of which is Mark Roth, recently began phase II clinical trials (clinical effectiveness studies) of an injectable form of H2S (more precisely, Na2S) in patients with coronary heart disease or those preparing for heart or lung surgery .

Work over the past decade has shown that hydrogen sulfide, whose smell makes us naturally disgusted, is extremely important for the normal functioning of the heart, and perhaps also the brain and other organs. It is possible that it also has other, not yet known effects. All this opens up new horizons in understanding the molecular foundations of human physiology and health. The study of the effects of H2S is just beginning, but there is already every reason to believe that someday it will offer new ways to combat today’s incurable diseases.

The chemical structure of H 2 S molecules is similar to the structure of H 2 O molecules: (angular shape)

But, unlike water, H 2 S molecules are slightly polar; hydrogen bonds are not formed between them; the strength of the molecules is much lower.

Physical properties

At normal temperatures, H 2 S is a colorless gas with an extremely unpleasant, suffocating odor of rotten eggs, very poisonous (at a concentration of > 3 g/m 3 causes fatal poisoning). Hydrogen sulfide is heavier than air and easily condenses into a colorless liquid. H 2 S is soluble in water (at ordinary temperature, 2.5 liters of gas dissolve in 1 liter of H 2 O).

Hydrogen sulfide in nature

H 2 S is present in volcanic and underground gases, and in water from sulfur springs. It is formed during the decay of proteins containing sulfur, and is also released during the life of numerous microorganisms.

Methods of obtaining

1. Synthesis from simple substances:

S + H 2 = H 2 S

2. Effect of non-oxidizing acids on metal sulfides:

FeS + 2HCI = H 2 S + FeCl 2

3. Action of conc. H 2 SO 4 (without excess) for alkaline and alkaline earth Me:

5H 2 SO 4 (conc.) + 8Na = H 2 S + 4Na 2 SO 4 + 4H 2 O

4. Formed during the irreversible hydrolysis of some sulfides:

AI 2 S 3 + 6H 2 O = 3H 2 S + 2Al(OH) 3 ↓

Chemical properties of H 2 S

H 2 S - strong reducing agent

The interaction of H 2 S with oxidizing agents leads to the formation of various substances (S, SO 2, H 2 SO 4),

Reactions with simple substances oxidizing agents

Oxidation by air oxygen

2H 2 S + 3O 2 (excess) = 2SO 2 + 2H 2 O

2H 2 S + O 2 (disadvantage) = 2S↓ + 2H 2 O

Oxidation with halogens:

H 2 S + Br 2 = S↓ + 2НВr

Reactions with oxidizing acids (HNO 3, H 2 SO 4 (conc.).

3H 2 S + 8HNO 3 (diluted) = 3H 2 SO 4 + 8NO + 4H 2 O

H 2 S + 8HNO 3 (conc.) = H 2 SO 4 + 8NO 2 + 4H 2 O

H 2 S + H 2 SO 4 (conc.) = S↓ + SO 2 + 2H 2 O

Reactions with salts - oxidizing agents

5H 2 S + 2KMnO 4 + 3H 2 SO 4 = 5S↓ + 2MnSO 4 + K 2 SO 4 + 8H 2 O

5H 2 S + 6KMnO 4 + 9H 2 SO 4 = 5SO 2 + 6MnSO 4 + 3K 2 SO 4 + 14H 2 O

H 2 S + 2FeCl 3 = S↓ + 2FeCl 2 + 2HCl

An aqueous solution of H 2 S exhibits the properties of a weak acid

Hydrogen sulfide acid H 2 S 2-basic acid dissociates stepwise

1st stage: H 2 S → H + + HS -

2nd stage: HS - → H + + S 2-

H 2 S in aqueous solution is characterized by reactions common to a class of acids in which it behaves as a weak acid. Interacts:

a) with active metals

H 2 S + Mg = H 2 + MgS

b) with low-active metals (Ag, Cu, Hg) in the presence of oxidizing agents

2H 2 S + 4Аg + O 2 = 2Ag 2 S↓ + 2Н 2 O

c) with basic oxides

H 2 S + BaO = BaS + H 2 O

d) with alkalis

H 2 S + NaOH (deficiency) = NaHS + H 2 O

d) with ammonia

H 2 S + 2NH 3 (excess) = (NH 4) 2 S

Features of reactions of H 2 S with salts of strong acids

Despite the fact that hydrosulfide acid is a very weak acid, it reacts with some salts of strong acids, for example:

CuSO 4 + H 2 S = CuS↓ + H 2 SO 4

Reactions occur in cases where the resulting Me sulfide is insoluble not only in water, but also in strong acids.

Qualitative reaction to sulfide anion

One of these reactions is used to detect S2- and hydrogen sulfide anions:

H 2 S + Pb(NO 3) 2 = 2HNO 3 + PbS↓ black precipitate.

H2S gas is detected by using wet paper soaked in a solution of Pb(NO3)2, which turns black in the presence of H2S.

Sulfides

Sulfides are binary sulfur compounds with less EO elements, including some non-metals (C, Si, P, As, etc.).

Metal sulfides are of greatest importance, since many of them are natural compounds and are used as raw materials for the production of free metals, sulfur, and sulfur dioxide.

Reversible hydrolysis of soluble sulfides

Alkaline Me and ammonium sulfides are highly soluble in water, but in an aqueous solution they undergo hydrolysis to a very significant extent:

S 2- + H 2 O → HS - + OH -

Therefore, sulfide solutions have a highly alkaline reaction

Alkaline earth sulfides Me and Mg, interacting with water, undergo complete hydrolysis and turn into soluble acid salts - hydrosulfides:

2CaS + 2HON = Ca(HS) 2 + Ca(OH) 2

When sulfide solutions are heated, hydrolysis also occurs in the 2nd stage:

HS - + H 2 O → H 2 S + OH -

Irreversible hydrolysis of sulfides

Sulfides of some metals undergo irreversible hydrolysis and completely decompose in aqueous solutions, for example:

Al 2 S 3 + 6H 2 O = 3H 2 S + 2AI(OH) 3↓

Cr 2 S 3 and Fe 2 S 3 decompose in a similar way

Insoluble sulfides

Most heavy metal sulfides are practically insoluble in water and therefore do not undergo hydrolysis. Some of them dissolve under the influence of strong acids, for example:

FeS + 2HCI = FeCl 2 + H 2 S

ZnS + 2HCI = ZnCl 2 + H 2 S

Sulfides Ag 2 S, HgS, Hg 2 S, PbS, CuS are insoluble not only in water, but also in many acids.

Oxidative roasting of sulfides

Oxidation of sulfides by atmospheric oxygen at high temperature is an important stage in the processing of sulfide raw materials. Examples:

2ZnS + 3O 2 = 2ZnO + 2SO 2

4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2

Methods for producing sulfides

1. Direct combination of simple substances:

2. Interaction of H 2 S with alkali solutions:

H 2 S + 2NaOH = 2H 2 O + Na 2 S sodium sulfide

H 2 S + NaOH = H 2 O + NaHS sodium hydrosulfide

3. Interaction of H 2 S or (NH 4) 2 S with salt solutions:

H 2 S + CuSO 4 = CuS↓ + H 2 SO 4

H 2 S + 2AgNO 3 = Ag2S↓ + 2HNO 3

4. Reduction of sulfates by calcination with coal:

Na 2 SO 4 + 4С = Na 2 S + 4СО

This process is used to produce alkali and alkaline earth metal sulfides.

Hydrogen sulfide is a colorless gas with an unpleasant rotten egg odor. It is formed as a result of contact of sulfur with hydrogen. In chemistry it is also called hydrogen sulfide or hydrogen sulfite. Chemical formula - H 2 S. It is quite rare in nature. So, today we will look at the effect of hydrogen sulfide on the human body.

Properties of hydrogen sulfide

Hydrogen sulfide is released during the dissolution of organic substances, during blasting operations in mines, as a result of oil and coal processing, as by-effect production of cellophane, paints, viscose, sugar. He is in large quantities enters the atmosphere, polluting it. In landfills, hydrogen sulfide is formed when food waste rots. Since it is heavier than air, it settles in deep holes, ditches or even wells.

The gas is highly toxic. Highly flammable and explosive in combination with oxygen. It burns in the air with a bluish flame.

It also interacts well with strong oxidizing agents. On contact with metals it causes corrosion.

Hydrogen sulfide is the most active of the sulfur-containing elements.

A la "bad egg"

The gas has an extremely unpleasant smell of rotting protein. Toxicology studies the threshold of perception of a substance by different people. It has been found that some are more sensitive to this smell than others. But this applies only to its small concentrations. If there is a lot of gas in the air, it simply paralyzes the olfactory nerve, and the “victim” ceases to feel the pungent odor.

Harm of hydrogen sulfide

The effect of hydrogen sulfide on the human body can be both positive and negative. Let's consider how dangerous it is and why.

Research on this gas began in 1998. Experiments were carried out on rats. But until now, the mechanisms of the influence of hydrogen sulfide on the human and animal bodies have not been reliably studied.

Hydrogen sulfide is known to be very poisonous. People who live near factories where it is used suffer from chronic poisoning. They experience weight loss and a metallic taste in the mouth. Deterioration of vision and even fainting indicate that a person is poisoned with hydrogen sulfide and needs urgent treatment.

Even 0.1% of the gas in the air leads to poisoning. This small concentration can kill within ten minutes, but often poisoning only causes severe symptoms. If the level is higher, just one breath can be fatal.

Symptoms appear:

headache;
dizziness;
nausea;
increase in pressure.

Attention! In the sewerage, the level of hydrogen sulfide reaches 16%!

The health hazards of hydrogen sulfide

The gas has a suffocating and irritating effect on the body. It causes irritation to the mucous membranes of the eyes and respiratory tract. It is the impact on the respiratory tract that is one of the most dangerous reactions that can lead to pulmonary edema. Penetrating into the body, it blocks the respiratory enzyme. The effect of hydrogen sulfide on the human body in the air is so harmful that it can cause instant death if its concentration is high.

Hydrogen sulfide has a detrimental effect on the protein hemoglobin. It converts iron, which is part of hemoglobin, into iron sulfide. As a result, the blood becomes black and loses, partially or completely, its ability to carry oxygen.

Irritation of the mucous membranes even with a small amount of hydrogen sulfide can lead to keratoconjunctivitis, rhinitis, bronchitis, and drooling.

The gas also has a negative effect on the nervous system. Hydrogen sulfide stimulates neuronal activity. It causes depression and anxiety. With prolonged inhalation of the gas, it is possible to develop mental disorders and lesions of the autonomic nervous system. Patients also suffer from insomnia.

Doses and symptoms of poisoning

Below we will consider the negative effect of hydrogen sulfide on the human body. Signs of poisoning vary. It depends on the amount of gas in the air.

When a small amount of the substance is inhaled, pain in the eyes, redness, coughing, pain in the chest, and wheezing in the lungs are observed. Poisoning is also accompanied by nausea, fatigue and headache.

Higher concentrations worsen the symptoms described above. It is also possible for the heart to deteriorate, pulmonary edema, bronchopneumonia, agitation or, on the contrary, fainting, and decreased blood pressure. The liver may enlarge and body temperature rises.

Severe poisoning causes loss of consciousness and even coma. Manifested by convulsions, hallucinations, respiratory and cardiac dysfunction. May end in death. With a favorable outcome, the symptoms are replaced by deep sleep. Later, asthenic syndrome develops. With proper treatment it disappears, but in some cases it is complicated by encephalopathy.

Very high concentrations of gas in the air cause instant death due to paralysis of the respiratory nerve and heart. In this case, irritation of the mucous membranes simply does not have time to develop.

However, the properties of hydrogen sulfide and its effect on the human body directly depend on the dose and method of application.

The benefits of hydrogen sulfide for blood vessels

Hydrogen sulfide is a poison, which, however, can heal. Moreover, a small amount of it is even present in our body. Scientists have long proven that the gas is formed in minimal concentrations in the stomach of people and animals. This function is genetically programmed. Mutation of the gene that regulates its production causes serious diseases - Parkinson's and Alzheimer's syndromes, atherosclerosis, hypertension.

The fact is that the gas affects the blood vessels, increasing their lumen. This helps reduce blood pressure and improve blood circulation. Injecting non-toxic doses of hydrogen sulfide into the body combats hypertension. At the same time, the gas prevents the development of atherosclerosis. This is due to the fact that cholesterol plaques are deposited only on the walls of damaged blood vessels. Hydrogen sulfide has an anti-inflammatory effect on them, protects the walls of blood vessels from loss of elasticity, and increases their resistance to damage.

Hydrogen sulfide and nerve cells

Hydrogen sulfide also has a positive effect on nerve cells. They are damaged by free radicals, which cause cancer, but the gas neutralizes them. Thus, it protects the brain from damage. It has been proven that in people suffering from brain diseases, the content of hydrogen sulfide in the body is lower than normal. In addition, it stimulates the nutrition of neurons and improves memory.

These data are confirmed by experiments on rats.

Does hydrogen sulfide improve erection?

In America, they continue to study the effect of hydrogen sulfide on the body of people and animals. In a Californian university clinic, cavernous bodies were taken for research (this biomaterial remains after sex reassignment operations). It turned out that the introduction of hydrogen sulfide relaxes smooth muscles. Subsequently, experiments on rats showed that the higher the dose of hydrogen sulfide, the longer the erection lasts. However, it is too early to say that the gas can be used as a new Viagra, since scientists have not yet figured out the mechanisms of its action.

Hydrogen sulfide and youth

Experts from a Chinese university recently reported that the effect of hydrogen sulfide on the body can be rejuvenating. The thing is that gas can activate the klotho gene. Klotho is responsible for longevity and also restores blood pressure.

In addition, the introduction of hydrogen sulfide stimulates the production of an enzyme called sirtuin. It prevents oxidative processes in the body and slows down its aging.

The benefits of hydrogen sulfide baths

The positive effect of hydrogen sulfide on the human body in water with the correct dosage is very great. The content of the substance in water may be minimal, but sometimes doctors prescribe fairly high doses. However, only a doctor can prescribe hydrogen sulfide baths.

The gas easily penetrates through the pores, mucous membranes and respiratory tract, entering the bloodstream. It spreads through the blood throughout the body, stimulating its work. Result of hydrogen sulfide baths:

increasing immunity;
improving blood circulation and reducing blood pressure;
healing of skin lesions;
elimination of inflammation;
normalization of carbohydrate metabolism;
reduction of cholesterol in the blood;
acceleration of metabolic and oxidative processes;
normalization of the functions of the central and autonomic nervous system;
improving the functions of the skeletal system.

Baths are indicated for a huge range of diseases, including urological, gynecological and endocrine. In addition, they are able to treat even severe intoxications (for example, after mercury poisoning). These baths treat skin, muscles, tendons, and bones. However, they have many contraindications.

The duration of such a session is from 8 to 12 minutes. The course of treatment usually does not exceed 12 sessions. Therapeutic baths are taken every other day.

So-called half-baths with hydrogen sulfide are also popular in sanatoriums. Usually this water procedures for arms or legs. Also, water enriched with this substance is used for rinsing the mouth and hair. They wash their faces with it and make compresses and lotions from it.

Hydrogen sulfide acid is also used in cosmetology - a solution of this substance helps eliminate acne, tighten the skin and reduce the appearance of cellulite.

Attention! A hydrogen sulfide bath can only be carried out in specialized rooms where there are powerful air purifiers. Otherwise, intoxication from hydrogen sulfide vapor can be fatal.

Conclusion

So, today we looked at the effect of hydrogen sulfide on the human body. We briefly discussed its benefits and harms. Like many poisons, it is actively used in medicine and cosmetology, but in high doses it is very dangerous. This proves that it can only be used externally under medical supervision.

Since childhood, the smell of rotten eggs reminds everyone of what hydrogen sulfide is. The colorless gas with the chemical formula H2S is highly flammable and burns with a blue flame during fires.

A poisonous toxin rarely causes acute poisoning, but without treatment it worsens human health even in small doses. People are exposed to it in industrial environments where crystalline sulfur can burn. The substance is produced in the laboratory using a gas generator.

Spread of substance

The combination and production of sulfur and hydrogen is associated with the decay of organic matter, rocks with sulfide compounds, which is why it is common in the mining, coke, gas and oil industries. Hydrogen sulfide water is found in industrial wastewater and sewage water. The maximum permissible concentration (MPC) in the air is 10 mg/m3, but in the presence of hydrocarbons - up to 3 mg/m3. There is an accumulation of hydrogen sulfide in volcanic rock, in places where sulfuric mineral waters come to the earth's surface or where organic waste is stored in deep pits.

Workers at sewage treatment plants, sewerage workers, pumping stations, tunnels, wells, miners and chemical laboratory employees.

The use of sulfides is common in metallurgy in the processing of non-ferrous metal ores, in light industry as phosphors and in electronics. The substance exhibits Chemical properties reducing agent, can be used to produce sulfur and sulfuric acid.

Toxicity and detection

The toxin has a third hazard class and is approximately 5-10 times less toxic than cyanide. Its physical properties determine the severity of intoxication. Hydrogen sulfide is heavier than air and condenses into a colorless liquid and quickly dissolves in water.

The odorless gas is not detected at concentrations below 1 ppm, the minimum tactile threshold is 0.18 mg/m3. It stinks of rotten eggs at a dose of about 40 mg/m3, and at a maximum permissible concentration of 40 to 150 mg/m3 it has a sweetish odor. A dose above 150 mg/m3 causes rapid temporary paralysis of the olfactory nerves, which leads to the inability to recognize it.

Healing waters with sulfur

Hydrogen sulfide in water is not always dangerous. In a well with drinking water the permissible concentration is below 0.03 mg/l, and upon settling, the water will become cloudy due to the displacement of sulfur by oxygen. The benefits of hydrogen sulfide solution are associated with the medicinal qualities of sulfide acids. This is where they came from mineral water, which are formed naturally when water and inorganic sulfur rocks come into contact.

Hydrogen sulfide water with a concentration of 10-40 mg/l reduces the production of gastric juice, eliminates constipation and promotes the excretion of bile. It is recommended to drink it in case of liver damage and heavy metal poisoning, but take it only on the recommendation of a doctor.

Poisonous effects of hydrogen sulfide on humans

There are two ways of hydrogen sulfide poisoning:

inhalation;
contact with skin or mucous membranes.

At the cellular level, the substance binds to iron molecules and inhibits cytochrome oxidases in mitochondria and blocks oxygen delivery.

Oxygen starvation - this is precisely what is dangerous about the gas, which forms sulfides when it enters the blood.

Signs of poisoning appear when the accumulation of sulfides exceeds the body's ability to eliminate them. The substance easily dissolves in fats, therefore it easily penetrates into any cells, especially the central nervous system and lungs.

The range of manifestations depends on the concentration and duration of exposure to hydrogen sulfide on the human body.

Acute poisoning associated with high doses of the toxin has several forms:

Mild: manifested by irritation of the mucous membranes and respiratory tract. A person feels pain in the eyes, soreness and scratching in the throat, and becomes sensitive to color. Cough, runny nose may intensify, and bronchospasm may occur. Externally it manifests itself as redness of the eyes, spontaneous blinking and closure (blepharospasm).
Moderate: appears when the substance penetrates through the lungs into the blood. A person suffers from headache, dizziness, weakness, nausea and vomiting, and diarrhea. Coordination of movements may be impaired, and there may be a tendency to agitation and fainting. Externally manifested by blueness of the lips. The doctor detects an increase in blood pressure and an acceleration of the pulse. Urinalysis reveals protein and columnar cells. Sometimes the temperature rises, symptoms of bronchitis and pneumonia appear.
Severe: severe vomiting, bluish skin, cardiac dysfunction and choking. A deep coma usually ends in death. If a person falls into deep sleep and then wakes up, this indicates a favorable outcome. Intoxication is manifested by apathy, asthenia, stupor, and damage to the central nervous system gradually develops. Pulmonary edema may develop.

Under the influence of doses above 1000 mg/m3, a fulminant or “apoplectic” form is observed, which is manifested by convulsions and fainting. Death occurs within 20 minutes due to paralysis of the respiratory center (brain stem) or due to paralysis of the heart.

Subacute intoxication acts more slowly, headaches, weakness or fatigue gradually increase. The person sweats, the mucous membranes of the mouth turn red, and pain occurs when swallowing. The eyes become dry and conjunctivitis develops. Salivation increases, nausea occurs, the stomach hurts in paroxysms, diarrhea occurs with characteristic black-green stools.

Chronic poisoning

Low levels of exposure to hydrogen sulfide are not uncommon. Some countries have developed standards for industrial air emissions. Impact in residential buildings is not considered at the state level, although nearby factories and agricultural facilities, oil and gas developments, and wastewater treatment plants pollute drinking water, especially in rural areas where treatment is not available.

If a person often suffers from eye inflammation, rhinitis, bronchitis and laryngitis, diarrhea and nausea, complains of loss of strength, weakness with sweating, headaches, sleep disturbances against the background of low blood pressure and slow heartbeat, he may be experiencing constant hydrogen sulfide poisoning. Contact with solutions results in rashes. A blood test will detect hypochromic anemia, changes in the size and deformation of red blood cells, and an increase in the number of monocytes. A person may not be able to distinguish the smell of hydrogen sulfide, which indicates addiction.

Signs of hydrogen sulfide poisoning depend on its accumulation in the atmosphere. With low-intensity exposure, irritation of the eyes and mucous membranes is observed, but in general the body does not suffer. Complications occur after inhalation of gas in concentrations above 1000 mg/m3 in atmospheric air:

acute respiratory distress syndrome;
acute myocardial infarction;
neuropsychiatric complications.

The manifestations of long-term neurological complications are not studied, since in most cases exposure to hydrogen sulfide leads to death. After acute or subacute poisoning, there is a tendency to diseases of the gastrointestinal tract, bronchi and lungs, heart pathologies and heart attacks, organic lesions of the central nervous system. Sometimes, due to the effect of hydrogen sulfide on the body, a person only experiences headaches.

First aid measures for poisoning

The chemical properties of hydrogen sulfide make it easy to find an antidote for poisoning - inhaling oxygen mixed with chlorine.

First health care consists of immediately transferring the victim to fresh air or a well-ventilated area. Respirators are used to avoid prolonged inhalation of the substance. The concentration of hydrogen sulfide in the air is measured to assess the severity of poisoning and take measures for treatment. Sometimes first aid is supplemented by intubation and oxygen therapy at the site of poisoning.

Treatment and prevention

Treatment is carried out in the department intensive care, where ventilation of the lungs is prescribed with the creation of positive pressure in the respiratory tract in case of severe damage.

Acidosis is corrected based on the amount of lactate in the blood. Symptoms of hydrogen sulfide poisoning are similar to cyanide, so induced methemoglobinemia will prevent hypoxia. The victim is injected with 10 ml of a 3% sodium nitrate solution over 2-4 minutes, and the desired level of methemoglobin is achieved in 30 minutes. The antiseptic methylene blue is also administered intravenously. For pale skin and hypotension, treatment is supplemented with subcutaneous injections of norepinephrine, cordiamine and caffeine. Anticonvulsant therapy includes nitrous oxide.

In the absence of a response to intravenous administration of nitrates or in case of persistent disturbances in the functioning of the central nervous system, hyperbaric oxygenation is used.

In case of local eye irritation, it is necessary to use lotions with 3% boric acid on the eyes, apply petroleum jelly to the eyelids, and drops of novocaine with adrenaline into the conjunctival sac.

Prevention of poisoning is developed for hazardous industries that require:

control air composition;
conduct periodic medical examinations;
formulate an action plan in case of accidents.

What is hydrogen sulfide?

HYDROGEN SULPHIDE, H 2 S, (hydrogen sulfide, hydrogen sulfide) is a colorless flammable gas with a pungent odor, boiling point 60.35 °C. Aqueous solution - hydrosulfide acid. Hydrogen sulfide is often found in oil and gas fields.

Hydrogen sulfide H 2 S is toxic: acute human poisoning occurs at concentrations of 0.2–0.3 mg/m 3 , concentrations above 1 mg/m 3 are fatal. Hydrogen sulfide H 2 S is an aggressive gas that provokes acid corrosion, which in this case is called hydrogen sulfide corrosion. When dissolved in water, it forms a weak acid which can cause pitting in the presence of oxygen or carbon dioxide.

In this regard, without modern gas treatment stations and desulfurization modules, hydrogen sulfide can cause severe damage to people. The maximum permissible concentration of hydrogen sulfide in the air of the working area is 10 mg/m3, and in a mixture with C1–C3 hydrocarbons it is equal to 3 mg/m3.

Without hydrogen sulfide treatment stations, a variety of equipment in the oil, energy, transport and gas processing industries seriously suffers and fails.

What happens to metals if hydrogen sulfide is not removed?

Hydrogen sulfide - H 2 S - total metal corrosion

Hydrogen sulfide reacts with almost all metals, forming sulfides, which act as a cathode in relation to iron and form a galvanic couple with it. The potential difference of this pair reaches 0.2–0.48 V. The ability of sulfides to form microgalvanic pairs with steel leads to rapid destruction of process equipment and pipelines.

It is extremely difficult to combat hydrogen sulfide corrosion: despite the addition of acid corrosion inhibitors, pipes made from special grades of stainless steel quickly fail. And even sulfur obtained from hydrogen sulfide can be transported in metal tanks for a limited period of time, since the tanks are prematurely destroyed due to hydrogen sulfide dissolved in sulfur. In this case, the formation of polysulfanes HS n H occurs. Polysulfanes are more corrosive elements than hydrogen sulfide.

Hydrogen sulfide, when added to unsaturated compounds, forms mercaptans, which are an aggressive and toxic part of sulfur compounds - chemical poisons. It is they that significantly worsen the properties of catalysts: their thermal stability, intensify the processes of resin formation, loss and deposition of slag, sludge, and sediment, which causes passivation of the surface of the catalysts, and also enhance the corrosive activity of the material of technological devices.

H 2 S significantly enhances the process of hydrogen penetration into steel. If during corrosion in acidic environments the maximum proportion of hydrogen diffusing into steel is 4% of the total amount of reduced hydrogen, then in hydrogen sulfide-containing solutions this value reaches 40%.

The presence of oxygen in the gas significantly accelerates corrosion processes. It was experimentally found that the most corrosive gas is the one in which the ratio of oxygen to hydrogen sulfide is 114:1. This attitude is called critical.

The presence of moisture in the gas leads to corrosion of the metal, but the simultaneous presence of H 2 S, O 2 and H 2 O is the most unfavorable from the point of view of corrosion.

The corrosive effect of these impurities on metal increases sharply with increasing pressure.

The rate of corrosion of gas pipelines is directly proportional to the pressure of the gas passing through this gas pipeline. At pressures up to 20 atm. and wet gas, even traces of hydrogen sulfide 0.002–0.0002% vol. are enough to cause significant corrosion damage to the pipe metal, limiting the service life of the gas pipeline to 5–6 years.

Due to the corrosive effects of hydrogen sulfide present in gases, the service life of power generation equipment (GPES - GTU) and equipment during gas production, transportation, processing and use is significantly reduced.

In field conditions, pipes, valves, combustion chambers and pistons are particularly susceptible to corrosion. power plants power plants, gas meters, compressors, refrigerators.

A significant portion of hydrogen sulfide reacts with metal and can be deposited in the form of corrosion products on the valves of power plants, compressors, on the internal walls of equipment, communications and main gas pipelines.

Relevance of the problem of gas purification from hydrogen sulfide

The urgency of the problem of purifying gas from hydrogen sulfide is enhanced by the requirements to ensure environmental safety when developing sulfur deposits and reducing harmful emissions into the atmosphere.

At the same time, special attention is paid to improving existing and developing new desulfurization technologies that eliminate emissions of toxic hydrogen sulfide and its combustion products into the environment.

Despite all the listed disadvantages, hydrogen sulfide is a valuable chemical raw material, since a huge amount of inorganic and organic compounds can be obtained from it.