G hygienic and epidemiological significance of the soil. Hygienic value of the soil. Chemical composition of soils and sanitary and epidemiological requirements. Nitrites and nitrates

14.11.2019

The soil is of great epidemiological importance. It can contain and be transmitted to humans by direct contact and indirectly pathogens of many infectious and parasitic diseases. The factors of transmission of pathogens are: dust, soil-contaminated hands, food products(vegetables, fruits, berries, leafy greens, mushrooms, etc.), water, equipment, inventory, dishes, containers, etc. Pathogens can be carried by animals, rodents and insects.

The main source of soil contamination with pathogenic microorganisms and helminth eggs are the physiological functions of humans and animals, wastewater, etc. Over time, as a result of soil self-purification processes, they die off, but retain their viability in it for a significant period.

Practically permanent and long-term inhabitants of the soil are spore-forming pathogenic microorganisms, the spores of which remain viable in the soil for decades. Basically, these are the causative agents of wound infections (tetanus, gas gangrene), botulism, anthrax.

Soil, especially contaminated with organic substances, can be a factor in the transmission of pathogens of bacterial and viral intestinal infections - dysentery, typhoid fever, paratyphoid fever A and B, salmonellosis, viral hepatitis, pseudotuberculosis, etc. The survival time of these pathogens in the soil can vary from several days to several months. So, in the soil, bacteria of the typhoid-paratyphoid group can be up to 400 days, dysentery - up to 100 days.

The soil can be contaminated with opportunistic pathogens coming with human excretions (BGKP, E.coli, B.cereus, Proteus, Cl.perfringens, etc.).

The soil plays a specific role in the transmission of geohelminths (roundworm, whipworm). The specific role is determined by the need to get the eggs of geohelminths with human secretions into the soil, where they go through a certain development cycle and acquire invasive properties. Only after "ripening" in the soil, roundworm eggs can cause human invasion (disease). Ascaris eggs can remain viable in the soil for up to 1 year, with soil particles infecting food products that are used as food without heat treatment.

Soil contaminated with organic substances serves as a habitat for rodents, which are sources of such dangerous infections as rabies, plague, tularemia, etc., as well as a favorable place for the development of flies that can carry pathogens of intestinal infections (Fig. 1).

Rice. 1. Major infectious diseases,

In the mechanism of transmission of which the soil is involved

Sanitary and epidemiological significance of the soil

Now sanitary and epidemiological requirements are higher than ever. The very first measures to protect human health were aimed at sanitary protection of the soil, as people walked barefoot, slept on the ground or in dugouts, drank underground water, ate food grown on the ground. The problem of the influence of soil on human health has historically been of great interest. The norms established in our time are based on SanPiN 2.1.7.1287-03 "Sanitary and epidemiological requirements for soil quality." Rules have been established on maintaining the quality of soils, on observing hygiene standards for living, on the construction and operation of facilities.

The federal law "On the sanitary and epidemiological well-being of the population" (1999) regulates the state of the territories settlements and soil microflora. In the soil approved by sanitary analyzes, the total number of bacteria in 1 g does not exceed 2.5-3 million.

Hygienic assessment of soil quality is given by the content of nitrogen, carbon, chloride and the Khlebnikov number. The cleaner the soil, the closer the number is to one. It shows the ratio of humus nitrogen and organic nitrogen as a whole.

Soil structure and components

The hygienic value of the soil is to promote healthy life. Since it is part of the biosphere and the upper globe of the earth's crust, it consists of compacted solid particles, between which there are pores. They serve for the transport of air, steam, water or smaller particles, as well as for the development of microflora.

Chemical is very diverse and is represented by mineral and organic substances. In other words, humus. It is an essential component for the normal development of plants and obtaining high yields. In different natural areas, the soil can be radically different. Its formation is influenced by climate, geochemical conditions, relief. That's why it's so varied. vegetable world planet, which entails the diversity of animal species, because the existence of fauna is inextricably linked with flora. For convenience, there is a classification of soils by composition, which is based on the study of the ratios of sand, dust and clay in soils.

single-grain structure. The soil easily sags under the influence of gravity. For construction, the ratio of soil voids should be minimal. This type very unstable and does not withstand vibrations and shocks.
Honeycomb structure. The soil consists of sand and silt particles ranging in size from 0.02 to 0.002 mm. When settling, the particles are attracted to each other and form compounds. A large void forms between them, which gives the soil friability.
Lumpy structure. This type of soil is due to the attraction of charged clay particles. In marine conditions, they are affected by salt - an electrolyte. It promotes compaction. Although in other cases this type has a low density.
The dusty structure is formed during the reconstruction of the clay surface and the repulsion of particles from each other. Over time, it loses its strength.
The coarse-grained structure is found in combined soils. The space between coarse-grained particles is filled with fine-grained ones. Due to this, the soil can withstand heavy loads.
The matrix clay structure resembles a coarse-grained one, but fine-grained particles predominate in it. This type is very stable in nature.

Organic part of the soil

This includes all types of influence on the soil of living beings:

The animals, mesofauna, and the microorganisms that form it form the burrows and pores needed to move water and air. In the same way, plant roots open underground channels.
Plants with long taproots that penetrate deep layers and absorb nutrients. Fibrous roots, which are closer to the surface, easily decompose and increase organic matter.
Microorganisms, fungi and bacteria. They affect the chemical exchange between roots and soil, accumulate nutrients.
People who control vegetation cover, which leads to the destruction of territories.

Soil hygienic assessment takes into account the presence of all the necessary components in it and the minimum number of polluting factors.

Sources of pollution

The soil "suffers" from living beings, carrying out their activities in it and on it. The main "supplier" of pollution is man, but not only him.

Sources of pollution:

Inorganic: industry, transport (heavy metals).
Organic: natural waste (animal carcasses, dead plants), human waste (oil, detergents, pesticides).
Radioactive.
Microbial agents: fungi, helminths, bacteria, spores, protozoa.

Some of them have a particularly strong effect on the hygienic value of the soil.

Nitrites and nitrates

These compounds do not linger in the soil and are quickly absorbed into the water or absorbed by the crop, that is, they get into food. Vegetables grown in autumn with fertilization at low temperatures and low light intensity tend to be very high in nitrates, unlike fruits and other crops. They are dangerous to consume, as studies have established a link between nitrates and cancer. Particularly high risk negative consequences for pregnant women and fetuses. If nitrates have been found in a mother's breast milk, her baby is most likely susceptible to methemoglobinemia. It's called the "blue baby" syndrome.

Heavy metals

Mercury, cadmium, lead and arsenic are considered very dangerous. Organic arsenic is a natural element in the earth, absorbed by plants and concentrated mainly in the leaves. But inorganic can be harmful. It causes a number of pathologies in living forms.

Pesticides

This includes any mixtures and liquids designed to expel, kill and get rid of any insects, rodents, fungi or weeds. First, they are spread by air currents, precipitation, vapor droplets and particles. Then they are carried by water: currents, drains, spills, rains. In parallel, pesticides are deposited on animal hair, human clothing and other objects. Applying them, you need to think about the possible consequences:

Damage to third-party organisms (bees).
Long stay of pesticides in the air.
Their distribution.

Persistent organic pollutants (POPs)

Toxic chemicals adversely affect the environment. First, they are intensively carried by wind and water. Being used in one country, they can easily be transferred to a neighboring one. Secondly, they do not disappear anywhere, they accumulate and can be transmitted by animals along the food chain. These items include paint and lubricant additives, mosquito repellant sprays, waste from incineration and medical preparations. A person consumes them with food, with untreated water, as a result of direct contact. Often this leads to reproductive, behavioral, neurological, endocrine dysfunction and immune system weakness.

polluting masses
Aldrin, dieldrin	Sources and uses
Chlordane	Insecticides commonly used on corn and cotton fields against termites.
endrin	Insecticide for vegetables and cereals, potatoes, sugarcane, beets, fruits, nuts, citrus and cotton.
Mirex	Cotton and cereal insecticide, also useful in rodent control. An agent for the fight against ants, termites and mealybugs.
Heptachlor	An insecticide used primarily against soil insects and termites is suitable for malaria control.
PCB	Product for various industrial processes and applications, used as a heat transfer medium, additive for paint, paper or plastics. Unintentionally produced when burning.
Toxaphene	Product for pest control of crops and livestock, and for the destruction of unwanted fish in lakes.
Dioxins and furans	Produced by combustion, including the incineration of municipal and medical waste.

Soil contamination and environment due to direct absorption harmful substances into the soil and objects close to it. Chemicals settle in the respiratory tract and are absorbed into the skin of organisms.

Helminth infections

Radiation

Sources can be nuclear explosions, disposal of radioactive waste, mining of radioactive ores, accidents at nuclear power plants.

household waste

Waste is a by-product of human activity that no longer performs useful functions.

Infectious: pathogenic substances, swabs, materials or equipment that have come into contact with infected patients, excrement).
Pathological: human tissues or fluids (body parts, blood, other body fluids, fetuses.
Sharp: needles, syringes, scalpels, blades, broken glass.
Pharmaceutical preparations, bottles or boxes contaminated or containing medicines.
Genotoxic: Substances with genotoxic properties (cytotoxic drugs).
Chemical: laboratory reagents, expired disinfectants, solvents.
Heavy metals: batteries, broken thermometers, pressure gauges.
Pressurized containers (gas cartridges, aerosols).
Radioactive: radioactive substances (unused fluids from radiation therapy or laboratory research, soiled glassware, packaging or absorbent paper).

There are several ways to solve the problem with garbage: processing, burning and falling asleep with earth. Due to these factors, a significant part of the waste does not disappear anywhere and affects the chemical composition of the soil. Therefore, it is worth giving Special attention recycling, the search for alternative sources of food in order to exploit and deplete the earth less. It is also worth considering the search for its artificial analogues. The ecological significance of the soil must be taken care of now so as not to face global cataclysms in the future.

How to save soil

There are many simple activities available to each of us:

To save natural soil, you can use other substrates for growing crops. They should perform only two functions: serve as a support for the root system and contain water, nutrients that ensure growth.

Hygienic and epidemiological significance of the soil. Pollution and self-purification of the soil. Indicators of the sanitary condition of the soil, their significance

Importance of soil Climate-forming factor Endemic significance Epidemiological significance Source of chemical and biological contamination of food, atmospheric air, surface and groundwater external environment people» of exogenous chemicals Environment for the neutralization of liquid and solid waste Environment that affects the planning and construction of populated areas, individual buildings, their improvement and operation.

Endemic significance Under the influence of the geological formation of the earth's crust and natural disasters, natural biogeochemical provinces are formed, which contain either an excess or a lack of trace elements. The population living in such provinces for a long time develops various endemic diseases. CARIES FLUOROSIS ENDEMIC GOITER

As a result of human activity, namely around industrial enterprises, airports, thermal power plants, agricultural lands and other objects, artificial biogeochemical provinces are formed. Staying in such regions can lead to the development of acute and chronic poisoning among the population, an increase in morbidity rates, congenital malformations and fetal anomalies. Acute gastritis Liver disease

Epidemiological significance 1. The soil is a favorable environment for many pathogenic microorganisms. It transmits: intestinal infections (typhoid fever, salmonellosis) viral infections (hepatitis A, poliomyelitis) zoonoses (brucellosis, tularemia) anaerobic infections (gas gangrene) dust infections (tuberculosis) helminthiases (ascariasis, trichuriasis) habitat and breeding of rodents, flies, fleas and mosquitoes, which are carriers of diseases.

Soil self-purification is a complex and lengthy biological process, as a result of which organic substances are converted into water, oxygen, mineral salts and humus, and pathogenic substances die off.

Proteins Ammonification (O 2+) amino acids + ammonia and its salts + fatty and aromatic acids Ammonification (O 2 -) + indole, mercaptans, hydrogen sulfide Nitrification (O 2+) nitrates, sulfates, phosphates, carbonates

(O 2+) CO 2 + H 2 O Fats (O 2 -) CO 2 + H O + foul-smelling fatty acids

(O 2+) Carbohydrates CO 2 + H 2 O (O 2 -) CO 2 + H 2 O + methane + other foul-smelling gases Microorganisms (non-spore-bearing) Humus (humus) Consists of hemicellulose, fats, organic acids, minerals, protein complexes.

Soil sanitary indicators The sanitary number is the ratio of "soil protein nitrogen" (humus nitrogen) to the total amount of organic nitrogen in the soil. Normally, it is 0.98 -1.0 The total number of bacteria in 1 g of soil. Normally 1-3 million E. coli titer (indicator of fresh contamination). Normally not less than 1 gram. Titer Cl. Perfringens (indicator of old pollution). Normally not less than about 1 gram. The number of helminth eggs (Ascaris) in 1 kg of soil. Normally, they shouldn't be.

With an increase in the chemical load, the epidemic danger of the soil may increase. In contaminated soil, against the background of a decrease in antagonists of pathogenic intestinal microflora and a decrease in its biological activity, there is an increase in the number of pathogenic enterobacteria and geohelminth eggs, which are more resistant to chemical soil pollution than representatives of natural soil microbiocenoses. This is one of the reasons for the need to take into account the epidemic safety of the soil of settlements.

Biological contamination of soils is an integral part of organic pollution caused by the presence of pathogens of infectious diseases, as well as harmful insects and mites, carriers of pathogens of humans, animals and plants.

Few pathogens live in clean soil. These are mainly pathogens of wound infections (tetanus, gas gangrene), botulism and anthrax. These spore microorganisms can survive in the soil in a viable state for 25 years.

Pathogens enter the soil with excretions of humans and animals, with wastewater from medical institutions, etc. In clean soil, they, as a rule, die quickly. However, in soil heavily polluted with organic substances and containing chemicals, self-purification processes are disrupted. The soil, constantly polluted with organic substances, always contains pathogens of intestinal infections (dysentery, typhoid fever), the survival time of which can vary from several months to one and a half years.

Contaminated soil is a favorable place for the development of flies. Sanitary and entomological indicators determined in the soil are larvae and pupae of synanthropic flies. Synanthropic flies (house, house, meat, etc.) are of great epidemic importance as mechanical carriers of pathogens of a number of infectious and invasive human diseases (cysts of intestinal pathogenic protozoa, helminth eggs, etc.). The period of development of a fly from a larva to a sexually mature individual is 4-7 days.

The presence of larvae and pupae in the soil of populated areas is an indicator of the unsatisfactory sanitary condition of the soil and indicates poor cleaning of the territory, improper collection and storage of household waste in sanitary and hygienic terms, and their untimely disposal.

Soil contaminated with organic matter promotes the reproduction of rodents, which are sources and carriers of especially dangerous zoonotic infections (plague, tularemia).

So soil can be a transmission factor for:

v diseases caused by spore-forming microorganisms (tetanus, botulism, gas gangrene);

v zoonotic infections (anthrax, brucellosis, glanders);

v geohelminthiases (ascariasis, trichuriasis) and biohelminthiases (enterobiosis, teniasis, teniarinhoz);

v intestinal infections (dysentery, typhoid and salmonellosis);

v especially dangerous infections (plague, cholera);

v dust infections (tuberculosis);

v viral infections (poliomyelitis, hepatitis A).

Soil as an element of the biosphere. Soil is the surface part of the lithosphere, formed after the appearance of life on Earth under the influence of climate, plant and soil organisms. Soil is an integral part of the circulation of substances in nature, in agriculture it is called earth, in construction - soil, in medicine - soil. The soil forms the chemical composition of human food, drinking water and, to some extent, atmospheric air. AT environmental plan Soil is the most important ecological link, which, through climate, food, air and water, ensures the survival of a person in a given area, forms his health, disease status and life span. In addition, the soil is the absorber of everything living on Earth. Constantly polluted and self-purifying, the soil is an indispensable participant in the biological cycle of living beings on Earth.

The chemical composition of the soil. The soil consists of mineral, organic and organo-mineral complexes, compounds, soil solutions, air, soil microorganisms, insects, animals and pollutants. For the hygienic assessment of the soil, it is important to know its natural chemical composition. Minerals make up 60-80% - it is silica, quartz, aluminosilicates. Of particular interest is microelements - F, J, Mn, Se - their increased or decreased content affects the formation of natural geochemical provinces with their endemic diseases (fluorosis, caries, endemic goiter). Hygienic assessment of the degree of soil contamination with inorganic compounds is based on a comparison of their content with MPC, for example: Cr - 0.05; Hg - 2.1; Pb - 20.0; Mg - 1500.0; As - 45.0 mg/kg of soil. organic matter are represented in the soil by (1) proper organic acids (humic and others), (2) substances synthesized by soil microorganisms called humus, and (3) substances alien to the soil coming from outside. In humic substances, huge reserves of Earth's carbon are concentrated.

All the remains of plants and animals entering the soil are processed by soil flora and fauna. The ability of the soil to process organic substances that have fallen into it and the level of processing that has occurred is indicated by degree of processingorganic matter into humic substances, as judged by the humification coefficient, which is determined by the formula:

humus carbon ____________ norm: 1-2

vegetable carbon O pollution soils are judged by the total soil nitrogen and the Khlebnikov number.

Khlebnikov number = humus nitrogen norm = 0.98-1.0

total organic nitrogen The cleaner the soil, the closer this number is to 1.0.

Soil moisture plays an important role. Only in it do all chemicals move, chemical and biological processes take place that carry out self-purification of the soil and supply food to everything living in it and on it. Endemic value of the soil.Natural soil composition is a characteristic feature of the area. The hygienic significance of soil composition is such that it determines the set of elements in people's food. this region. Often the soil lacks any elements. So in most of Russia - fluorine and iodine. In the Murmansk region there is an excess of fluorine in the soil, in the Omsk region there is a lack of fluorine and iodine. And it leads to endemic diseases - fluorosis(excess fluorine), caries(lack of fluorine), to premature aging and endemic goiter(lack of iodine). There are soils with a naturally high content of selenium, plants grown on it contain an increased amount Selena, which causes alkaline disease in livestock and poisoning in humans. Increased content arsenic leads to stomach cancer; molybdenum- molybdenum padagra and cancer of the esophagus. These are naturally endemic soils, living on them leads to massive "local" - endemic diseases. Prevention of geoendemic diseases is either the addition of missing substances to food (iodine, fluorine, selenium), or the inclusion in the diet of additional food obtained from other regions that are safe for this substance.

Hygienic value of the soil. The main soil factors that have a huge impact on human health and are of great hygienic importance. Soil - affects the thermal regime of the area, the composition of air and vegetation. Healthy areas are elevated, dry, sunny. Unhealthy - low located, cold, flooded, damp, with frequent fogs. The soil is an important link in the food chain- "external environment - a person": 1) how manufacturer food (B, F, U, vitamins, minerals, microelements) - affects a person through nutrition and 2) how provider all chemical, physical and biological anthropogenic contaminants that have entered the soil and remained untreated into the body through food. Soil - natural neutralization environment waste through self-purification. The soil is a huge laboratory in which the processes of synthesis and destruction of organic substances, photochemical processes, the formation of new organic substances, the death of many bacteria, viruses, helminth eggs, and insects are constantly going on. The soil is used to clean and neutralize sewage, sewage, garbage. Soil is the determining factor geoendemic diseases inherent in the area (fluorosis, goiter). So are diseases as a result of its anthropogenic pollution (for example, with heavy metals); polluted soil is a source of chemical, physical and biological pollution of the environment (air, water, plants). Soil is a factor in the spread of a series infectious diseases (wound, botulism), epidemic diseases (groups of intestinal, anthrax) and helminthiases(ascariasis). For hygienists, the surface layer of the soil is important - 25 cm (arable). It is in it that plants grow, it is more often polluted and from it pollution enters the air, water bodies and plants. It is to this layer that hygienic requirements are imposed. Based on the fact that the soil consists of solid particles - grains and free spaces between them - pores filled with air, the hygienic properties of the soil are determined by porosity, air permeability, moisture capacity, hygroscopicity and capillarity.

Porosity- this is the percentage of pores in the soil (in sandy - 40%, peat - 82%). Breathability- the ability to pass air. Water permeability- the ability to pass water (its filtration capacity). moisture capacity- how much water the soil can hold (its adsorption capacity). Capillarity- the ability of the soil to raise water from the lower layers upwards. These properties depend on the mechanical and chemical composition of the soil. Therefore, before choosing a site for construction, a hygienic assessment of the state of the territory is carried out: sanitary and topographic examination, physical and mechanical analysis, radiological, sanitary and toxicological, sanitary and bacteriological, entomological and helminthological studies. The hygienic purity of the soil is judged by the results of sanitary-bacteriological, sanitary-helminthological, sanitary-entomological and sanitary-chemical studies. Sanitary and bacteriological examination determines: 1) the total number of microorganisms per 1 g of soil; 2) the number of thermophiles per 1 g of soil (microorganisms that create temperatures in composts up to 60-70 ° C; 3) coli-titer (indicator of organic pollution); 4) titer-perfringens (an indicator of the degree of human presence in the total pollution) and 5) the presence of pathogenic microorganisms, usually very difficult to detect. Sanitary-helminthological examination determines the presence of helminth eggs in the soil, which is an indicator of fresh fecal contamination. The number of viable eggs per 1 kg of soil is determined - they should be absent, the number of larvae, pupae and eggs of flies per 0.25 m 2, which should normally be absent. In the sanitary-chemical study, soil nitrogen and carbon are studied. The research results are evaluated as a whole. Thus, an increased content of organic nitrogen and carbon in the soil without an increase in ammonia at a low coli-titer and in large numbers helminth eggs indicates fresh fecal pollution, as well as the absence of organic matter mineralization processes (the soil does not “digest” pollution well). The simultaneous presence of organic nitrogen and chlorides indicates long-term soil pollution and the presence of intensive utilization of organic substances (the soil “digests” pollution well). A good process of humus formation is also indicated by the Khlebnikov number approaching 1. The detection of nitrates + chlorides + low titer-perfringens indicates that there was a long-standing soil contamination without fresh inputs. The epidemiological significance of the soil. In uncontaminated soil, there are constantly spore microorganisms - causative agents of wound infections(tetanus, gas gangrene), botulism, which enter it in the form of live bacteria from the intestines of large warm-blooded animals (cows, elks) and fish. In favorable conditions for them in the intestines of animals, these microorganisms "work" as decomposers, decomposing plant food. Once in the soil, they are covered with a dense shell - a spore, under which they retain their viability for decades. If wound infectious diseases are not transmitted to other people, then parasitic forms - pathogens - may also be found in contaminated soil. epidemic(contagious) diseases: anthrax and intestinal group (dysentery, typhoid fever, viral hepatitis A, leptospirosis, giardiasis). The term of their survival in the soil is up to several months, except for anthrax, the spores of which remain in the soil for centuries. Soil is a transmission factor of a series helminthiases- ascariasis, whipworm and hookworm, eggs that remain viable in the soil up to 7-10 years. soil - place offspring 27 species of flies, one of which - "house fly" is important for the spread of epidemic intestinal diseases - dysentery and typhoid fever.