Polychlorinated biphenyls (biphenyls) are the most common anthropogenic compounds that are classified as persistent organic pollutants. At their core, PCBs are derivatives of chlorinated biphenyls. We can say that this is an arbitrary number of chlorine molecules (from 1 to 10), which represent two benzene rings.

Particularly acute today is the problem of pollution of our environment. PCBs primarily arise from the activities of plants that process waste and other waste or industrial by-products. Not the last place here is occupied by the combustion of various types of fuel. It is also necessary to highlight the production of artificial compounds for use in industry or agriculture.

What are the dangers of polychlorinated biphenyls?

Today the use of PCBs as heat carriers, dielectrics or coolants has already been banned. But their similar use in the past left its mark on the cleanliness of our environment. As they say, we are paying for our predecessors.

Polychlorinated biphenyls are a rather difficult pollutant due to their persistence. These connections are almost indestructible. There are also different favorable environments for PCBs. For example, compounds accumulate quite well in water or at the bottom of various structures.

The problem of PCBs getting into food products remains relevant. This is possible due to the use of various types of contaminated land in agriculture.

The most vulnerable products to the accumulation of polychlorinated biphenyls are animal fats and fish products. This situation is due to the fact that these compounds have the property of multiplying in adipose tissue.

All polychlorinated biphenyls are inherently carcinogenic. Which means the ability to cause acquired immunodeficiency and various liver diseases. PCBs accumulate in most foods of animal origin. They mainly accumulate in fats.

Poisoning with polychlorinated biphenyls has various consequences. The most common are skin diseases, liver damage, decreased immunity, headaches, dry and wet cough, fatigue and exhaustion. Children who are poisoned with PCBs are at risk of being delayed in their development.

Polychlorinated biphenyls include a large group of non-polar chlorine-containing compounds, which are used as hydraulic fluids, non-flammable liquids, insulators in transformers. In total, 209 such compounds may exist.

unique physical and chemical properties: non-flammability; resistance to action. acids and alkalis, oxidation and hydrolysis; low solution in water; thermal stability; high electrical resistivity; low vapor pressure at ordinary temperatures.

PCBs are found in copy paper, lubricants, inks, paints, cement additives, pesticides, and adhesives.

PCBs are easily absorbed and enter the body through skin, inhalation and oral administration. The main source of PCBs for humans is oral intake from foods rich in fatty components. After absorption, depending on the degree of chlorination, PCBs are metabolized in the liver, as a result of which their toxicity increases. The presence of a large number of chlorine atoms in the biphenyl ring of PCBs makes their molecule difficult to reach for the action of various enzymes. PCBs can also penetrate the placenta of pregnant women, causing stillbirth.

elimination of individual PCBs occurs very slowly with half-lives between 1-10 years. Excretion occurs mainly through the gastrointestinal tract, a small part through the kidneys and breast milk.

The toxic effect of PCBs is associated with the effect on the central nervous system, gradual hair loss, disruption of liver function, development of liver tumors, suppression of the immune system

in the blood of PCBs from 2-5 μg/kg. In men this figure is higher and it invariably increases with age. The concentration of PCBs in adipose tissue is 1000 times higher than in the blood.

The class of polychlorinated dibenzodioxins (PCBD) and dibenzfurans (PCDBF) includes 210 isomeric compounds. These compounds are formed during the synthesis of organochlorine compounds (for example, biocides), during the combustion of garbage (chlorine-containing compounds), during the operation of internal combustion engines, during the combustion of fuel; present in industrial emissions and tobacco smoke. The main amount of PCBD and PCDBF enters the human body with food (fish, meat, dairy products, eggs). The excretion of PCBD and PCDBF decreases with increasing degree of halogenation of the compounds. The half-life in humans ranges from 5 to 7 years.

The mechanism of action of 2,3,7,8-PCBD (the most toxic of this group) is associated with the synthesis of altered cytochrome P-450, which modulates metabolism. In addition, PCBD is characterized by immunosuppressive, teratogenic and carcinogenic effects.

23. Nitrites and nitrates: the main sources of entry into the human body, the effect of nitrites and nitrates on the human body, medical care for acute poisoning with nitrites and nitrates.

The main sources of entry into the human body:

Food products:

Vegetables and fruits: Nitrates have long been used as an element of mineral nutrition for plants. Plants take up nitrates from the soil through the root system.

Nitrates are then reduced by nitrate reductase to nitrites and then nitrites to ammonia (catalyzed by nitrite reductase), which is used for the synthesis of amino acids and proteins. Some crops restore nitrates in the root system completely, others to a lesser extent. Nitrates accumulate mainly in the roots, stems, petioles, and veins of plants. Leaves and roots are richer in nitrates than fruits. The most intensively accumulating nitrates are black radish, beets, lettuce, sorrel, radishes, rhubarb, celery, spinach, parsley leaves, and dill.

The nitrate content in plants increases with irrational use of mineral fertilizers. Organic fertilizers promote the accumulation of nitrates, while phosphorus and potassium fertilizers can inhibit this process in some plant species.

Meat and fish products: The nitrate content in surface and groundwater varies widely depending on geochemical conditions, the use of nitrogenous fertilizers, industrial emissions of nitrogenous compounds, waste disposal methods and waste products. In the water of the city water supply system, the nitrate content is usually low (up to 10 mg/l). High concentrations of nitrates are found in groundwater and well water. Nitrates begin to be felt in water already at a level of about 8 mg/l; they give it an astringent, sourish-salty taste. When the nitrate content is 1500-2000 mg/l, the water has a bitter taste and is unfit for consumption.

Nitrates entering the human body with water are 1.25 times more toxic than nitrates entering with food. Air:

The nitrate content in the air varies from 1 to 40 mg/m3. At high concentrations in the air they have an irritating effect on the upper respiratory tract.

The effect of nitrites and nitrates on the human body:

Nitrates entering the human body are easily absorbed in the upper gastrointestinal tract. The main part of nitrates is metabolized by intestinal microflora living in the gastrointestinal tract. Depending on the type of microorganisms, the pH of the environment and the available nutrients, the following are formed: nitrogen oxides, hydroxylamine, ammonia. Nitrites pose the greatest danger to humans. Easily absorbed into the gastrointestinal tract, they enter the blood and, penetrating the membrane of red blood cells, react with hemoglobin. During the redox reaction, iron becomes trivalent, as a result of which hemoglobin is oxidized into methemoglobin, nitrites are reduced to NO, and hemoglobin function is disrupted. As a result, oxygen enters the tissues in insufficient quantities, despite increased oxygenation of the blood. The red blood cells of a healthy person contain on average 2% methemoglobin. If its content exceeds 50%, the person dies. Nitrates are also considered as one of the main precursors of carcinogenic N-nitroso compounds. Nitrosamines in high concentrations have a pronounced hepatotoxic effect. A direct correlation has been established between the amount of nitrogenous fertilizers used and mortality from stomach cancer.

Chronic poisoning of children with nitrates is caused by:

Tendencies towards an increase in height and body weight with a decrease in chest circumference, muscle strength of the hands, vital capacity

Excitability of the central nervous system

Increased activity of sorbitol dehydrogenase and cholinesterase, aldolase activity

Changes in a number of immunological parameters: tension of T-cell immunity, imbalance of the B-immune system, decreased activity of nonspecific defense factors

Medical care for acute poisoning with nitrites and nitrates:

First aid:

Gastric lavage with water and baking soda

Prescription of adsorbent (activated carbon), saline laxative

Complete rest (economical use of energy)

Decreased methemoglobin content:

Administration of methylene blue 1% and solution intravenously, 10 mg/kg, administered in portions at intervals of 10-15 minutes or chromosmon (1% solution of methylene blue in 25% glucose solution)

Prescription of sodium thiosulfate 30% solution is administered intravenously slowly 5-10 ml

Introduction of ascorbic acid 5% solution, up to 50-60 ml

Oxygen therapy

Forced diuresis

Prescribing cardiac medications

Polychlorinated biphenyls

Polychlorinated biphenyls (PCB) or polychlorinated biphenyls (PCB) - a group of organic compounds that includes all chlorine-substituted biphenyl derivatives (1-10 chlorine atoms connected to any carbon atom of biphenyl, the molecule of which is composed of two benzene rings), corresponding to the general formula C 12 H 10-n Cl n.

Chemical structure of PCBs.

They were first synthesized in 1929. The peculiarity of these substances is their heat resistance and the possibility of using them as an insulator in electrical engineering. Colorless and odorless, PCBs are also chemically stable. For these reasons, PCBs have been added to many materials.

Polychlorinated biphenyls (PCBs) belong to the group of persistent organic pollutants (POPs), the monitoring of which is mandatory in developed industrial countries due to their high danger to the environment and public health.

PCBs are resistant to hydrolysis and biotransformation in water, but when photolyzed in sunlight, PCBs can, through a series of sequential reactions, form dioxins, much more toxic pollutants than PCBs. PCBs can enter the soil not only with waste in industrial areas, but also when sedimentary sludge is used as fertilizer. It is believed that up to 80% of the total amount of PCBs produced worldwide has so far entered the environment, with most of this amount ending up in fresh and marine waters. PCBs may be formed from organochlorine pesticides (DDT) in the upper atmosphere under the influence of ultraviolet rays. The decomposition of organochlorine pesticides to the simplest biphenyls can also occur in sea water. Over the many years of intensive use of PCBs in industry in many countries of the world, huge quantities of these compounds have been introduced into the environment, and currently pollution by these xenobiotics affects the entire biosphere. Along with organochlorine pesticides, PCBs are the most common products that pollute water in natural bodies of water. It is believed that the concentration of PCBs in unpolluted fresh waters should not exceed 0.5 ng/l, and in moderately polluted ones 50 ng/l. The threshold concentration of trichlorobiphenyl, which changes the organoleptic properties of water, is 0.13 mg/l. Being stable compounds, PCBs accumulate in environmental objects and are transmitted through food chains. Aquatic organisms - hydrobionts, fish, mollusks, crustaceans accumulate PCBs. The content of chlorinated hydrocarbons, in particular PCBs, in fish meat and liver can reach several tens of mg/kg. Even a single PCB contamination of bottom sediments can lead to permanent local contamination of aquatic organisms for a long time (up to several years) after this contamination has occurred.

PCBs are quite toxic. The proven multifaceted damaging effect of these substances on a number of organs and systems, along with the ability for long-term accumulation in adipose tissue.

The danger of PCBs for human health lies, first of all, in the fact that they are powerful factors of immune suppression (“chemical” AIDS). In addition, the entry of PCBs into the body provokes the development of cancer, damage to the liver, kidneys, nervous system, and skin (neurodermatitis, eczema, rashes). Once in the body of the fetus and child, PCBs contribute to the development of congenital deformities and childhood pathologies (developmental delays, decreased immunity, damage to hematopoiesis).

However, the most dangerous effect of PCBs on humans is their mutagenic effect, which negatively affects the health of subsequent generations of people. That is why in the EEC countries, the USA and Canada, these compounds have been prohibited for production and use since 1973. They have established mandatory monitoring of PCBs in environmental objects and food products. The problem is that PCBs are practically indestructible and can accumulate in biological objects and food products. By the time the world community realized their danger, a huge amount of these compounds had already been produced (from 1929 to the mid-70s), globally polluting the Earth and constantly circulating in environmental objects. For example, PCBs are constantly found in the breast milk of women in Western Europe, which served as a mandatory limitation for the duration of breastfeeding to 1.5 - 2 months. and prompted the transition in most of these countries to artificial feeding of infants with purified formulas. Once in the body, PCBs are well absorbed in the gastrointestinal tract, in the lungs, penetrate the skin and accumulate mainly in adipose tissue. Most adipose tissue samples contained PCB levels of 1 mg/kg or less, and large amounts of up to 700 mg/kg were found in adipose tissue samples from occupationally exposed individuals (blood levels of 0.3 and 200 µg/100 ml, respectively) .

PCBs have relatively low acute toxicity, but, due to their cumulative properties, accumulate in the liver, first leading to its enlargement and then to damage. PCBs partially penetrate the placenta and can be excreted in breast milk. Analyzes of breast milk collected from two women in Arkhangelsk and Kargopol showed that the toxicity of breast milk in this region is not due to dioxins, as expected, but to polychlorinated biphenyls, which was subsequently confirmed in other cities of Russia.

organic toxicant persistent pesticide

PCBs can have embryotoxic effects, causing a decrease in the number of implantation sites, the number of newborns and an increase in the duration of pregnancy. With long-term administration of PCBs to rhesus monkeys before and during pregnancy, as well as during lactation, early miscarriages, premature births, and death of fetuses soon after birth were observed.

Symptoms of PCB exposure include chloracne, eye irritation, lethargy, headaches and sore throat.

In Japan in 1968, about 16 thousand people were poisoned and many of them died. The production of PCBs was banned in the 1970s due to the high toxicity of most related PCBs and mixtures. They are classified as persistent organic pollutants that bioaccumulate in animals.

chemical

Polychlorinated biphenyls (PCBs) belong to a group of foreign compounds of anthropogenic origin. In their structure, PCBs are two unfused benzene rings (connected by a single C-C bond), with one to ten hydrogen atoms replaced by chlorine atoms.

The problem of global environmental pollution with PCBs is primarily associated with industrial waste processing (incinerators), combustion of fuels (wood, coal or oil) and the production of a number of synthetic compounds used in industry and agriculture (for example, organochlorine pesticides).

Also, a big role in environmental pollution was played by the fact that PCBs were widely used for a long time as refrigerants, dielectrics, coolants, etc. (now such use of PCBs is prohibited).

In the environment, PCBs are practically not destroyed and accumulate in various environments (especially in water and bottom sediments). Due to their stability and lipophilicity, PCBs are concentrated along food chains.

As in the case of dioxins, PCBs enter food products when contaminated areas are used for agricultural purposes (former landfill areas and near them, near PCB synthesis plants and places where they are widely used, etc.).

Taking into account their ability to accumulate in fatty tissues and increase their concentration along the food chain, food products with the highest content of PCBs will be animal fats and products containing them (especially fish and products from it).

The toxic effect of PCBs is associated with their carcinogenicity, ability to cause secondary immunodeficiency, and cause liver damage. Polychlorinated biphenyls accumulate in virtually all food products of animal origin and are concentrated in fattier foods and their components.

The most common skin conditions observed in PCB poisoning include chloracne, rashes, and unusual ulcers. Liver damage, decreased immune response, fatigue, headaches, and cough are also observed. When children are poisoned, developmental delays are also observed.

In basic food products (fish, seafood, margarines), PCBs are regulated at a level of 2 to 5 mg/kg.

An interesting feature of PCBs is their simultaneous presence with dioxins. If a food product contains dioxins, then PCBs will certainly be present (there is no inverse relationship, i.e. if there are PCBs, dioxins are not always present). This makes it possible to study PCBs in products instead of dioxins (easier, since the permissible concentration of dioxins is 3-4 orders of magnitude lower) and to conduct testing for dioxins only if a significant amount of PCBs is present.

Polychlorinated biphenyls (PCBs) belong to a group of chlorinated hydrocarbons, the number of which currently reaches 300 types. In recent decades, PCBs have been quite widely used in the electrical industry (in capacitors, high-voltage transformers), in the production of varnishes, paints and many synthetic materials (about 1 million tons of them are produced worldwide). Since the late 60s. PCBs had highly pronounced toxic properties (carcinogenic, mutagenic), which led to the emergence of complex environmental problems. The use of certain types of biphenyls in agriculture and health care to combat vectors of infectious diseases has led to their accumulation in some types of agricultural products. Studies of soils in the Moscow region have shown that they are contaminated with persistent organochlorine compounds (DDT and its metabolites, PCBs - up to 30% of the total amount). PCBs have also been found in significant quantities in vegetables, rice, cotton, etc. Some PCBs enter the environment from waste incineration plants, and the emergence of polychlorinated dioxins poses a particular danger. Therefore, in many countries the use of PCBs is limited or used only in closed systems - transformers (Germany). The use of biphenyls leads to various diseases (Yusho disease).[...]

Polychlorinated biphenyls (PCBs) are produced as cooling and insulating media for transformers, softeners in the varnish and adhesive industry, and as hydraulic fluids. They are non-flammable, heat-resistant and serve as the basis for a variety of solvents. However, being highly toxic compounds, PCBs have a harmful effect on the organs responsible for metabolism, the nervous system. Due to their resistance, PCBs are widely distributed in the environment, and due to their high solubility in fats, they easily penetrate into the tissues of humans, animals and plants and accumulate there. Although their use is limited and partially banned in many countries, PCBs continue to enter the food chain as a result of "imports" from developing countries.[...]

Polychlorinated biphenyls, like mercury, have fungicidal and bactericidal effects. Therefore, they are included in various industrial products, such as paper. When paper is burned, these substances are released without any changes because they are highly resistant to temperature. As a result, polychlorinated biphenyls became ubiquitous, which has been attributed to DDT for more than two decades.[...]

Industrial production of PCBs was started in the 1930s by many countries, including Germany, the USA, Czechoslovakia, Japan, the USSR, etc. At the same time, many products related to PCBs and having a similar composition received different trade names. In just 70 years, their global production amounted to about 1.5 million tons. They were used as liquid dielectrics in various electrical equipment (transformers, capacitors, etc.). The toxic effect of PCBs was discovered only in the 60s.[...]

The danger of these substances is associated with their ability to accumulate in truffle (food) chains, primarily in fatty tissues. Their maximum permissible concentrations in the atmosphere and soil are set at 0.001 mg/m and 0.06 mg/kg, respectively. When burned incompletely, for example in landfills, PCBs form dioxins and dibenzofurans.[...]

Poisoning with polychlorinated biphenyls causes chlorosis-chloracne, which results in skin lesions that are difficult to cure and leave behind scars. In addition, the composition of the blood changes, poisoning affects the liver and the state of the nervous system. There are suggestions that these substances also have a carcinogenic effect.[...]

The toxicity of polychlorinated biphenyls increases markedly with increasing chlorine content. Given the high stability and lipophilicity of these compounds, it is necessary to set low maximum permissible concentrations for them, since there is a danger of accumulation of substances in the body. With a chlorine content of 42%, the MRC is 1 mg/m3; with a chlorine content of 54%, the MRC is 0.5 mg/m3 (see section 2.2.2).[...]

Contamination.PCB. Polychlorinated biphenyls (PCBs) are a whole family of related compounds. They do not ignite easily and are used in transformers, capacitors, etc. People who received doses of PCBs during work experience damage to the nerves, skin, and liver. In the United States, PCBs are found in the waters of all major rivers. The MPC established in this country for river water is 2 mg/l. The greatest danger to people is fish from the lake. Ontario and R. Hudson. In its muscles there are up to several tens of mg of PCBs per 1 kg (P. Revelle, Ch. Revelle, part 2, 1995).[...]

In water bodies, mercury and polychlorinated biphenyls accumulate in fish; cleaning water bodies requires the subsequent extraction of these organisms, which makes this method ineffective. [...]

SWAMP - an excessively moist area of ​​the Earth's surface, characterized by the accumulation of dead, undecomposed plant residues in the upper horizons, which then turn into peat. Lowland (eutrophic) lakes are formed as a result of swamping of eutrophic lakes, are located in low places and are fed by groundwater. Highland soils (oligotrophic) are formed as peat accumulates from lowland soils and are fed primarily by precipitation. There are 108.7 million hectares under agriculture in Russia, which is 6.3% of the total area of ​​the country's land fund. See also Swelling Contour.[...]

The transport of dioxins, dibenzofurans and polychlorinated biphenyls in the atmosphere is also associated with their sorption on soot particles (dust, ash, etc.) or in moisture, followed by deposition and evaporation. In table Table 3.2 shows average data on the content of PCDD, PCDF and PCB in the air of industrial regions of Europe, North America and Russia 111 -201. In most cases, they are contained in the air at a level of 10 1 -10 2 g/m3, and with increasing distance from the sources of emission of these substances, their concentration decreases quite quickly. It has been shown [21] that when moving from the city center to the outskirts and beyond, the total content of the sum of PCDD and PCDF in the air decreases from 1.4 to 1.1 and 0.4 pg/m3, respectively. The paper proposes a mathematical model that describes the transport of dioxins from stationary point sources, for example from chimneys, and from spatially distributed sources, for example, industrial and household waste dumps. The fallout of dioxins from the air onto the soil occurs according to an exponential law with a Gaussian distribution in the downwind direction 23].[...]

In both cases we are talking about compounds that disintegrate extremely slowly in the soil and can accumulate in it with the constant addition of sludge. Finally, sludge may contain borates, which are found in detergents and cosmetics. In small concentrations, boron is beneficial to plants, but its increased content leads to chlorosis (discoloration of leaves) and necrosis (death of leaf segments). The toxic limit concentration for herbs, for example, is 270-570 ppm relative to dry weight. [...]

Polycyclic aromatic hydrocarbons in many ways. Similar to polychlorinated biphenyls, they are almost insoluble in water, have a high boiling point and are difficult to destroy. Nevertheless, these substances have become widespread worldwide.[...]

The main method for determining residual quantities of pesticides and polychlorinated biphenyls (PCBs) in soils remains gas chromatography with selective detectors (ECD, TID and MSD) and HPLC/UFD, and for their isolation from soil samples - liquid extraction followed by purification of the extract by SPE (see . section 2.2. in chapter II) and its concentration.[...]

In particular, bioaccumulation coefficients for polychlorinated biphenyls, which are actively sorbed by bottom sediments and included in the cycles, have high values. The corresponding coefficient values ​​for aquatic invertebrates and fish reach 7,101, and for birds of prey 108 - 109

When the Earth's surface is polluted with superecotoxicants - chlordioxins, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, long-lived radionuclides, a sharp increase in the number of genetic disorders, allergies, and deaths is recorded. All these substances are xenobiotics and enter the environment as a result of accidents at chemical plants and nuclear power plants, incomplete combustion of fuel in automobile engines, and ineffective wastewater treatment.[...]

Microorganisms, like higher order organisms, metabolize polychlorinated biphenyls extremely slowly. Forms with a lower chlorine content (about 30%) are less stable and are more easily excreted from the body than highly halogenated (>60% C1) compounds. The high lipophilicity of the entire class of compounds determines their exceptionally long lifetime.[...]

ISO 6468 specifies a gas chromatographic method for the determination of certain organochlorine insecticides, polychlorinated biphenyls and chlorobenzenes, other than mono- and dichlorobenzenes, in water.[...]

Until recently, polychlorinated biphenyls (PCBs) were produced in large quantities at factories in Dzerzhinsk and Novomoskovsk. The main consumer of these products is the electrical industry. The production of transformers and capacitors with PCBs began in the 1960s and continued until 1989-1990. . In general, to date, more than 1.2 million tons of PCBs have been produced in the world, of which from 300 to 500 thousand tons in Russia. Our country has also produced about 100 thousand transformers filled with Sovol (a mixture of PCBs). It is estimated that 35% of PCBs entered the environment and only 4% of this amount was destroyed.[...]

In fresh and marine water bodies, as well as in aquatic organisms, in addition to organochlorine pesticides, similar polychlorinated biphenyls (PCBs) and terphenyls (PCTPs), used in industry, are found. In terms of their physicochemical properties and physiological effects on the body, as well as methods of analysis, they are very close to organochlorine pesticides. Therefore, differentiation of these groups of chlorinated hydrocarbons is necessary.[...]

The second group includes substances that, with a lesser degree of evidence, are carcinogenic to humans (DDT, nitropyrene, polychlorinated biphenyls, cobalt, nitrosodiethylamine, etc.).[...]

In addition to petroleum products, wastewater from industrial enterprises contains hydrocarbons, heavy metals, radioactive substances, polychlorinated biphenyls and many others. etc. Municipal wastewater, in addition to household chemicals, contains pesticides, dyes, detergents (detergents), and feces.[...]

In some sections of small rivers in the Cherepovets area, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) in a concentration of 0.2-0.33 μg/l were detected in quantities from 3 to 43 MPCs, which is three orders of magnitude higher than the levels recommended by WHO for surface reservoirs.[...]

Stockholm Convention on Persistent Organic Pollutants (POPs) of the Biosphere. According to the Protocol, some artificially synthesized organic substances, in particular polychlorinated biphenyls, when released into the environment, have an extremely negative impact on human health. Being chemically and biochemically very stable, they are not destroyed in environmental objects and are transmitted through trophic chains to people, suppressing their immunity, provoking the appearance of malignant formations. The mutagenic effect also affects the health of subsequent generations. The drama of the situation is aggravated by the fact that by the time the world community realized the danger of POPs, a huge amount of them had already been produced, globally polluting the Earth.[...]

Substances included in the group of persistent organochlorine compounds pose a particular danger to biota and humans. These are organochlorine pesticides (DDT, HCB, HCH) and polychlorinated biphenyls (PCBs). The latter, due to their unique properties - chemical, thermal and biological stability and high dielectric constant, have found wide application in electrical engineering and other industries. The danger of these substances is associated with their ability to accumulate in ecosystems along trophic chains (primarily in adipose tissue). Currently, almost all countries have adopted laws banning or severely limiting the use of PCBs.[...]

Of course, one of the most promising methods for extracting PCDD and PCDF from soil samples is supercritical fluid extraction. This method was initially applied to the analysis of polychlorinated biphenyls in sediments.[...]

Unlike oil and heavy metals, chlorinated hydrocarbons constitute a group of xenobiotics, i.e., non-natural components of the environment. [...]

The accumulation coefficients of heavy metals in plankton are 102-104, concentrations in commercial fish are up to 60 billion“1 in the Pacific Ocean, and an order of magnitude higher in the Baltic Sea. Significant amounts of DDT and its derivatives and polychlorinated biphenyls (PCBs) enter the ocean (atmospheric transport is the main channel).[...]

The method is applicable for the determination of the above substances in the presence of up to 0.05 g/l of suspended solids, organic matter, suspended particles and colloids. Under these conditions, it is possible to determine organochlorine insecticides and chlorobenzenes at their content from 1 to 10 ng/l, polychlorinated biphenyls - at a content from 1 to 50 ng/l. [...]

Soil is considered contaminated when it contains so many pollutants that they can become a source of secondary pollution and pose a danger to human health. Most often, contamination occurs with compounds of heavy metals, petroleum hydrocarbons, polyaromatic hydrocarbons, polychlorinated biphenyls and various organic solvents.[...]

In addition to the volatile organic compounds (JIOCs) listed in Table. 1.3, water can also be contaminated with organic compounds of medium volatility.[...]

The last stage of preparing water for drinking and other needs is its disinfection, i.e. getting rid of pathogenic microorganisms, since it is well known that such terrible diseases as cholera, typhoid fever, infectious hepatitis, etc. can spread through water. For many years, disinfection water treatment was carried out by treating it with chlorine. However, it became known that polychlorinated biphenyls are poisons and are found mainly in fats. When oxidized, they form absolute poisons - dioxins. The lethal dose of dioxins in the body for pigs, which are test objects, is 10 mcg/kg of their weight. But this dose can be increased gradually. This has led scientists to conclude that chlorination may be harmful. In many countries in the 80s they switched to fluoridation of water treatment, but it turned out that it was also harmful. Therefore, all over the world and in Russia they also give preference to water treatment by ozonation.[...]

At present, the effect of traces of organic compounds in drinking water on the human body is still poorly understood, but nevertheless, sanitary studies have been carried out indicating the danger of consuming water contaminated with organic chemicals. Thus, carcinogenic activity was discovered in a number of chlorinated compounds, including organochlorine pesticides, such as aldrin, DDT, daldrin, hexachlorane, etc., as well as polychlorinated biphenyls (PCBs). As a result, the use of a number of pesticides in the United States is banned, and the production of biphenyls is being phased out. In the USSR, the production and use of aldrin is also prohibited, and strict restrictions have been adopted on the use of DDT (they are prohibited from being used in the agricultural production of food and feed crops). Much attention has recently been paid to trihalomethanes (THMs) due to their carcinogenic hazard. The content of these compounds in water increases sharply after its treatment with chlorination, and one of the sources of THMs is humic acids, which are widely present in natural groundwater, and under the action of chlorine on which THMs are formed.[...]

According to a preliminary study, approximately 110,000 tons of pollutants and pollutants are generated annually in Finland. Some of them are processed by industry, so 65,000 tons per year were taken as the initial data when designing a new facility for processing complex waste. This waste stream entering the plant consists of oily waste, incinerated organic waste, solvent waste, small batches of complex waste, inorganic waste, polychlorinated biphenyl (PCB) waste and herbicide waste.[...]

While still rarely used in environmental laboratories, size exclusion chromatography (SEC) is a very elegant method for fractionating pollutants based on the shape of their molecules. The main reason why this method has not become more popular is the need to equip HPLC equipment with refractometric detectors and relatively expensive columns for exclusive chromatography. [...]

In places where water is used by the population, 29% of samples do not meet established standards for sanitary and chemical indicators and 26.6% for microbiological indicators. In general, in Russia, more than 20% of samples from municipal and departmental water supply systems do not meet hygienic standards for sanitary and chemical indicators, and, respectively, 8.9 and 13.6% for microbiological ones. The accumulation of solid waste negatively affects the condition of the soil cover. About 17% of soil samples do not meet sanitary and hygienic standards. Heavy metals, pesticides and polychlorinated biphenyls are not a complete list of harmful substances that pollute the soil.[...]

If we talk about chemical pollution, then first of all you should pay attention to various organic compounds. Overall, the input of allochthonous organic matter (about 1 Gt C/yr, or less than 5% of the primary production of ocean biota) appears to be insignificant compared to the total amount of Corg produced by marine ecosystems. An even smaller share (0.01 Gt/year, or 0.05% of primary production) is the flow of anthropogenic polluting components, which primarily include petroleum hydrocarbons (PH), synthetic surfactants, and organochlorine pesticides ( OCPs), polychlorinated biphenyls (PCBs) and phenols.[...]

Particularly toxic, carcinogenic and other hazardous wastes, for which strict MPC standards have been established in air, water and soil, can be neutralized in plasma. At temperatures above 4000 °C, due to the energy of the electric arc in the plasmatron, oxygen and waste molecules are split into atoms, radicals, electrons and positive ions. When cooling in the plasma, reactions occur with the formation of simple compounds CO2, H20, HC1, HP, P4O10, etc. Tests, including the destruction of mixtures of CC14 with methyl ethyl ketone and water and the destruction of transformer oil containing 13-18% polychlorinated biphenyls and the same amount of trichlorobenzene, showed that the efficiency of destruction of chlorine-containing components exceeded 99.99995%. The gases leaving the plasma-chemical reactor must be purified from acids and anhydrides by known methods before being released into the atmosphere.