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Water as a factor in the environment, its hygienic and epidemiological significance. Rationing the quality of drinking water



The drinking water supply development program is an integral part of the plan for the socio-economic development of territories within the Russian Federation.

Water is essential for sustaining life and it is therefore important to provide consumers with good quality water.

As you know, the human body consists of 65% of water and even a slight loss of it leads to serious health conditions. With a water loss of up to 10%, there is a sharp anxiety, weakness, tremor of the limbs. In an experiment on animals, it was found that the loss of 20-25% of water leads to their death. All this is explained by the fact that digestion processes, cell synthesis and all metabolic reactions occur only in the aquatic environment.

Despite the exceptionally large role of water for humans, its consumption for drinking purposes is small. In a temperate climate during moderate work, the adult body spends 2.5-3 liters of water per day. But with hard work (especially in hot climates or in hot shops), the need for water can increase up to 10 and even up to 15 l / day.

The hygienic significance of water is not limited to its physiological role. A large amount of water is necessary for sanitary and household purposes.

When calculating water consumption, it is necessary to take into account the irregularity of water consumption both in individual hours and in the seasons of the year. Based on the degree of improvement of the settlement, “Water Consumption Standards” have been developed, which are agreed with the Ministry of Health and introduced into building codes and rules (Table 1).

Water can fulfill its hygienic role only if it has the necessary qualities, which are characterized by its organoleptic properties, chemical composition and the nature of the microflora.

The best way to ensure the safety of drinking water is to protect water sources from pollution. First of all, sources of drinking water supply should be protected from pollution by waste products of humans and animals, which may contain various bacterial and viral pathogens, as well as protozoa and helminths. Human pathogens that can be transmitted orally with drinking water are shown in Table 2 (WHO data).

Persistence in water characterizes the ability of pathogenic microorganisms and parasites to maintain viability and the ability to reproduce. The persistence is influenced by temperature, ultraviolet radiation of sunlight, the presence of biodegradable organic carbon, etc.

The presence of salmonella, shigella, pathogenic E. coli, cholera vibrio, viruses and many other pathogenic microorganisms in water can lead to intestinal diseases.

Infants and young children, people who are weakened or living in unsanitary conditions, people who are sick and elderly are at greatest risk of infection through water. For these people, infectious doses are significantly lower than for most adults. Diseases transmitted through water can also be transmitted through personal contact, ingestion, and aerosols, and this maintains a reservoir of patients and carriers of diseases. Outbreaks of diseases transmitted through water are usually accompanied by the simultaneous infection of a significant part of the population.

A second health risk is the presence of toxic chemicals in the water. It differs from the risk caused by microbiological contamination in that only very few chemical components in the water can lead to acute health problems. Experience has shown that in accidents, water usually becomes unfit for drinking due to unpleasant odor, taste and appearance.

Norms of domestic water consumption for settlements

The fact that chemical pollutants are not usually associated with acute effects makes it possible to classify them as lower priority than microbial pollutants. Problems associated with the chemical components of drinking water arise mainly due to the ability to have an adverse effect on health with prolonged exposure.

Table 1

The degree of improvement of residential areas Average daily water consumption per inhabitant, l / day
For agricultural areas: drinking and drinking needs (excluding water consumption for irrigation) with water use from water columns 30-50
Construction by buildings equipped with internal water supply and sewage without bathtubs 125-160
The same with bathtubs and local heaters 160-230
The same with centralized hot water. 250-350
Particular attention should be paid to those polluting agents that have cumulative toxic effects (for example, carcinogens, heavy metals and some trace elements - fluorine, strontium, uranium, molybdenum, etc.). The famous Russian scientist V.I. Vernadsky and him

student A.P. Vinogradov developed the doctrine of biogeochemical provinces, i.e. areas characterized by an excess or deficiency of individual trace elements in soil, water, plants, which made it possible to explain the causes of the so-called endemic diseases of humans and animals.

Fluorine. With a content of more than 1.5 mg / l - stage 5 fluorosis; less than 0.7 - tooth decay (range from 0.7 to 1.5 mg / l). Damage to teeth proceeds in several stages:

1. Symmetrical chalky spots on tooth enamel.

2. Pigmentation (spotting enamel).

3. Tigroid incisors (transverse striation of tooth enamel).

4. Painless tooth decay.

5. Systemic fluorosis of the teeth and skeleton. Malformations of skeletal development in children, cretinism.

Molybdenum - an excessive content in water leads to an increase in the activity of xanthine oxidase, sulfhydryl groups and alkaline phosphatase, an increase in uric acid in the blood and urine, and pathomorphological changes in internal organs (provinces in Armenia, Moscow and Tomsk Oblast, etc.).

Strontium and (Uranus) are prone to material and functional cumulation. A ubiquitous element, the concentration in groundwater can be tens of mg / l. It can enter water bodies with sewage from enterprises engaged in their extraction or using in the technological process. The exchange of strontium in the body is well studied, it has been found that a significant part of it is deposited in bone tissue. Excretion is carried out mainly through the intestines. Admission to the body leads to inhibition of the synthesis of prothrombin in the liver, a decrease in cholinesterase activity, activation of osteogenesis (inclusion of 8g in the bone tissue), which reduces the incorporation of Ca into the bone tissue and leads to the development of "strontium rickets". Aquatic pathogens transmitted by oral route, their relevance to water supply
Pathogenic organism Water supply health hazard Persistence in systems Chlorob Dose Resistance Relatively infectious Is there a carrier animal
1 2 3 4 5 6
Bacteria
Campylobacter
Jeijuni, C. coli high average low average Yes
Pathogenic
Escherichia coli high average low high Yes
Salmonella typhi high average low high not
Other Salmonella high long low high Yes
Shigella spp. high short-term low average not
Vibro cholerae high short-term low high Yes
Yersinia enterolitica high long low high (?) Yes
Pseudomas aeruginosa average can breed average high (?) not
1 2 3 4 5 6
Aeromonas spp. average can breed low high (?) not
Viruses
Adenoviruses high (?) average low not
Enteroviruses high long average low not
Hepatitis a high (?) average low not
Hepatitis E Enteroviruses high (?) (?) low not
Norwolk virus high (?) (?) low not
Rotavirus high (?) (?) average not (?)
Small round viruses average (?) (?) low not
Protozoa
Entamoeba histolytica high average high low not
Giardia intestinalis high average high low Yes
Cryptosporidium
parvum high long high low Yes


1 2 3 4 5 6
Protozoa
Dracunculus medinensis high average average low Yes
? - unknown or unclear

and The detection period at the stage of infection in water at 20 ° C: short - up to 1 week; average - from 1 week. up to 1 month; long - over 1 month.

b When the infectious agent is in a free suspended state in the treated water at normal doses and contact time. Medium resistance - the pathogenic agent may not be completely destroyed; low resistance - the pathogen is completely destroyed.

a Dose at which infection is caused in 50% of healthy adult volunteers; for some viruses, it is an infectious unit.

g Results of experiments on volunteers.

The main route of infection is through skin contact, but infection of cancer patients or people with immunodeficiency can also occur through the oral route.

Endemic goiter - a disease associated with low intake of iodine, i.e. with a decrease in its content in food (daily requirement of 120 mg). Water has a signal value.

Nitrates - their increased content causes toxic cyanosis (methemoglobinemia), especially in breast-fed infants, more often in rural areas when using well water for breeding infant formula.

Methemoglobinemia is observed not only in children, but also in adults. Nitrates + amines = carcinogens. The content of nitrates (MD) from year to year is growing due to organic pollution of surface and underground water sources. In the Belgorod Region, untreated wastewater is used to increase the yield, as a result of which the water content in the water reaches 500-700 mg / l, including in children's recreation camps.

The harmful effect of nitrates is manifested when nitrates are reduced to nitrites, and their absorption leads to the formation of blood hemoglobin. Dysbacteriosis and weakness of methemoglobin reductase observed at this age contribute to the defeat of infants.

It should be noted that the use of chemical disinfectants for cleaning and disinfecting water often leads to the formation of chemical by-products, and some of them (dioxins, nitrates, residual aluminum) are potentially dangerous.

The hazard characteristics of the most common substances in drinking water are given in table 3 (SanPin 2.1.4.559.96).

As follows from table 3, the chemicals formed during water treatment can have a toxic effect on the human body and it is very important to monitor their formation.

It is also necessary to take into account the radiation health risk associated with the presence in the water of radionuclides that naturally enter it, although under normal conditions the proportion of radionuclides in the environment as a whole is much higher than in drinking water.

In accordance with the Federal Law “On Drinking Water”, the satisfaction of the population’s needs for drinking water in their places of residence is carried out by measures aimed at developing centralized priority or decentralized (local) drinking water supply systems.

In the Russian Federation, 1,052 cities (99% of the total number of cities) and 1,785 urban-type settlements (81%) have centralized water supply systems. However, in most cities there is a lack of water supply capacities.

In 6 cities and 380 urban-type settlements there is no centralized water supply.

Sources of centralized water supply are surface water (their share is 68%) and groundwater (32%).

Atmospheric waters (snow, rainwater) for drinking water supply are used only in low-water areas, the Arctic and in the South. This water is weakly mineralized, very soft, contains few organic substances and is free from pathogenic microorganisms.

Groundwater, located underground, form several aquifers, depending on the occurrence.

Atmospheric precipitation, filtered through the pores of permeable rocks and accumulating above the first waterproof layer from the surface (clay, granite, waterproof limestone), form the first aquifer, which is called groundwater. The depth of groundwater, depending on local conditions, ranges from 1.5-2 to several tens of meters. During filtration, water is freed from suspended particles and microorganisms and enriched with mineral salts.

Groundwater is transparent, have a low color. The amount of dissolved salts is small, but increases with increasing depth. With fine-grained rocks (starting from a depth of 5-6 m), water contains almost no microorganisms. Hazard characteristics of the most common substances in drinking water
No. Substances The most probable Hygienic Muta Geno Hit Note
route to standard gene toxic organs and systems
drinking water mg / l act female action
1 2 3 4 5 6 7 8
1. Acrylamide Water treatment with polyacrylamide flocculants 0.01 + CNS reproductive function Excess cancer risk
2. Aluminum Water coagulation 0.5 + CNS Violations in water purification technology
3. Ammonia Contaminated source, disinfection of water with chloramine. 0.1 Nitrites form
4. Barium Natural factor, polluted source 0.1 CC system, reproduction. function
5. 3,4- benzapyrene Polluted source 0.000005 By criterion for excess cancer risk
1 2 3 4 5 6 7 8
6. Benzene Polluted source 0.01 CNS, blood (leukemia), etc. Long stored in groundwater
7. Beryllium Polluted source 0,0002 + - - -
8. Boron Polluted spring, natural 0.5 Railway tract, repro. function
9. Hexachlor-benzene Polluted source 0.05 Liver, skin By criterion for excess cancer risk
10. DDT (di-Chlorodiphenyl trichlorosyl) Polluted source 0, (For industrial waste water) ± + CNS, kidneys, liver, teratogen, etc. Extremely stable, accumulates in food chains, in the human body.
eleven. Dibromo-chloromethane Water chlorination 0,03 Liver, kidney
12. Dichloro-benzene Polluted source 0.002 Kidney Long stored in groundwater
1 2 3 4 5 6 7 8
thirteen. Dichloro methane Water chlorination 0.5 Kidney Also
14. Dichloro-ethylene Water chlorination 0,0006 + Liver, immune system Also
fifteen. Iron Contaminated source, natural factor, corrosion of waterworks 0.3 Irritating effect, hemochromatosis, allergy Precipitation in the distribution system, the growth of iron bacteria
16. Cadmium Contaminated source, migration from materials 0.001 + Kidneys, adrenal glands, duct, bone system With a deficiency of calcium and protein, absorption is increased.
17. Cobalt Polluted source 0.1 Hematopoietic system
18. Manganese Contaminated source, Migration from materials 0.1 CNS, hematopoiesis When washing, dyeing
19. Copper Also 1,0 - - Liver, kidneys, gastrointestinal tract
20. Molybdenum Also 0.25
1 2 3 4 5 6 7 8
21. Arsenic Also 0.05 CNS, skin, vascular system Inorganic arsenic is more dangerous
22. Nickel Also 0.1 + Canal tract, red blood Women are more sensitive
23. Nitrates Contaminated source, ozonation of ammonia-containing water 4,5 (according to Ш3) Blood, cardiovascular system Hazardous metabolic products, nitrosamines
24. Nitrite 3.0 NO2
25. Polychlor.
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Water as a factor in the environment, its hygienic and epidemiological significance. Rationing the quality of drinking water

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