METHOD OF HYGIENIC ESTIMATION OF DRINKING-WATER. ENDEMIC FLUOROSIS AND CARIES AS A HYGIENIC PROBLEM, ITS PROPHYLAXIS. HYGIENIC ESTIMATION OF THE SOIL SANITARY STATE. MODERN HYGIENIC AND BIOETHICAL PROBLEMS OF THE INHABITED PLACES CLEANING. A METHOD OF CALCULATION OF HUMAN’S ENERGY LOSSES AND REQUIREMENTS IN THE NUTRIENTS (OR FOOD SUBSTANCE). NORMS OF HUMAN’S PHYSIOLOGY REQUIREMENTS IN THE MAIN FOOD COMPONENTS AND ENERGY

Hygienic significance of water

Water physiological functions:

–       flexibility – about 65 % of body mass of adult person consists of water. 70 % of water is the intracellular water, 30 % – extracellular water (in blood), (7%) – lymph and 23 % – intertissue fluid. Water makes up 20 % of the bone mass, 75 %, of the muscle mass, 80% of the connective tissue mass, 20% of blood plasma mass, 99% of vitreous body of an eye. Major part of water is a component of macromolecular complexes of proteins, carbohydrates and fats, forming the jelly-like colloid cells and extracellular structures together with them. The smaller part of it is in a free state;

–       participation in metabolism and interchange of energy – all assimilation and dissimilation processes in organism occur in water solutions;

–       role in support of osmotic pressure and acid-base balance;

–       participation in heat exchange and thermoregulation – at evaporation of 1 g of moisture from lungs’ surface, mucous membranes and skin (latent heat of evaporation) organism loses 2.43 kJ (0.6 kcal) of heat;

–       transportation function – delivery of nutrients to cells with blood and lymph, removal of waste products from the organism with urine and sweat;

–       as a component of dietary intake and a source of macro- and microelements supply to organism;

–       there are neuropsychic disorders that are resulted from impossibility to satisfy thirst if water is not available or if it is of bad organoleptic characteristics. According to I.P. Pavlov’s doctrine on higher nervous activity, odour, taste, after-taste, water appearance, clarity (transparency) and colour are irritators that influence the whole organism through central nervous system. Worsening of organoleptic characteristics of water causes the reflex effect on water intake schedule and some physiological functions, for example it oppresses the secretory function of stomach. Drinking of such water causes the defence reaction in human organism – the feeling of aversion, which makes a person to refuse such water irrespective of thirst.

Epidemiological and toxicological role of water

Water can participate in spread of infections in the following ways:

–       as transfer factor of pathogens with the fecal-oral transfer mechanism: enteric infections of bacterial and viral origin (typhoid, paratyphoid А, В, cholera, dysentery, salmonellosis, coli-entheritis, tularaemia /deep-fly or rabbit fever/, viral and epidemic hepatitis А, or Botkin disease, viral hepatitis E, poliomyelitis and other enterovirus diseases, such as Coxsakie, EСНО etc.); geohelminthosis (ascaridiasis, trichocephaliasis, ankylostomiasis); biohelminthosis (echinococcosis, hymenolepiasis); of protozoal etiology (amebic dysentery (amebiasis), lambliasis); zooanthroponosis (tularemia, leptospirosis and brucellosis);

–       as a transfer factor of pathogens of the skin and mucous membrane diseases (when swimming or having another contact with water): trachoma, leprosy, anthrax, contagious molluscum, fungous diseases (i.e., epidermophytosis);

–       as the habitat of disease carriers – anopheles mosquitoes, which transfer malarial haemamoeba and others (open water reservoirs).

Symptoms of water epidemics:

–       simultaneous appearance of big number of enteric infected people, i.e. jump of population morbidity – so-called epidemic outburst;

–       people who used the same water source, the same pipeline of water supply network, the same water-pump, shaft well etc. will suffer from diseases;

–       morbidity level will stay high for the long period of time to the extent of water contamination and consumption;

–       morbidity curve will have one, two, three, or more peaks. First of all those diseases that have short incubation period will be registered (coli-entheritis, salmonellosis – 1-3 days, cholera – 1-5 days, typhoid – 14-21 days and at last – those with the longest period: virus and epidemic hepatitis А and Е – 30 days and more);

–       after the taking of antiepidemic measures (liquidation of the contamination source, disinfection of water supply network, sanitation of wells) the outburst fades away and morbidity goes down drastically;

–       still, for some time morbidity remains above the sporadic level – so-called epidemic tail. This is caused by the appearance of big amount of new potential sources of infection (sick people and infection carriers) during the epidemic outburst and activation of other ways of the pathogenic microorganisms spreading from these sources – domestic contact (through dirty hands, dishes, children toys, personal hygiene articles), through food or by living carriers (flies) etc.

Toxicological role of water consists in it containing chemical agents that may negatively influence people health causing different diseases. They are divided into chemical agents of natural origin, those, which are added to water as reagents and chemical agents, which come into the water as the result of industrial, agricultural and domestic pollution of water supply sources. Insufficient or non-effective treatment of such waters at waterworks procures the continuous toxic effect of small concentrations of chemical agents, or, rarely, in cases of accidents and other emergency situations – acute poisonings.

 

Balneal role of water

Water is used in medicinal purpose for rehabilitation of convalescents (drinking of mineral waters, medicinal baths), and also as tempering factor (bathing, swimming, rub-down).

Domestic and economic role of water

Sanitary-hygienic and domestic functions of water include:

–       water usage for cooking and as a part of dietary intake;

–       usage of water as means of keeping body, clothes, utensil, residential and public premises and industrial areas, settlements clean;

–       watering of the green areas within settlements;

–       sanitary-transport and disinfection functions of water – disposal of residential and industrial waste through sewer system, waste processing on plants, self-purification of water reservoirs;

–       fire fighting, atmospheric pollution clearing (rain, snow).

Economical functions of water:

–       usage in agriculture (irrigation in crop and gardening, greenhouses, poultry and cattle breeding farms);

–       industry (food, chemical, metallurgy etc.);

–       as the route of passenger and cargo transportation.

 

Dental fluorosis is a health condition caused by a child receiving too much fluoride during tooth development. The critical period of exposure is between 1 and 4 years old; children over age 8 are not at risk. In its mild form, which is the most common, fluorosis appears as tiny white streaks or specks that are often unnoticeable. In its severest form, which is also called mottling of dental enamel, it is characterized by black and brown stains, as well as cracking and pitting of the teeth.

The severity of dental fluorosis depends on the amount of fluoride exposure, the age of the child, individual response, as well as other factors including nutrition. Although water fluoridation can cause fluorosis, most of this is mild and not usually of aesthetic concern. Severe cases can be caused by exposure to water that is naturally fluoridated to levels well above the recommended levels, or by exposure to other fluoride sources such as brick tea or pollution from high fluoride coal.

A mild case of dental fluorosis (the white streaks on the subject’s upper right central incisor) observed in dental practice

Dean’s fluorosis index was developed in 1942 and is currently the most universally accepted classification system. An individual’s fluorosis score is based on the most severe form of fluorosis found on two or more teeth.

Dean’s Index
Classification	Criteria – description of enamel
Normal	Smooth, glossy, pale creamy-white translucent surface
Questionable	A few white flecks or white spots
Very Mild	Small opaque, paper white areas covering less than 25% of the tooth surface
Mild	Opaque white areas covering less than 50% of the tooth surface
Moderate	All tooth surfaces affected; marked wear on biting surfaces; brown stain may be present
Severe	All tooth surfaces affected; discrete or confluent pitting; brown stain present

Fluorosis

Fluorosis is a crippling and painful disease caused by intake of fluoride. Fluoride can enter the body through drinking water, food, toothpaste, mouth rinses and other dental products; drugs, and fluoride dust and fumes from industries using fluoride containing salt and or hydrofluoric acid.

Fluorosis can occur as

• Water-borne Fluorosis (Hydro Fluorosis)

• Food-borne Fluorosis

• Drug and Cosmetic induced Fluorosis

• Industrial Fluorosis

Fluorosis can affect young and old; men and women alike.

Fluorosis occur as

• Dental Fluorosis

• Skeletal Fluorosis and·

• Non-skeletal Fluorosis

Fluorosis is a public health problem required to be managed by both Medical and Public Health Engineering Professionals (i.e Water Supply Implementing Agencies).

Fluorine, a gaseous element is a halogen which being most electronegative  and reactive of all elements does not occur in free form iature. This element was isolated in 1886 by Nobel laureate Henri Moissan and it combines directly with most elements and indirectly with few to form fluorides. Fluorides are ubiquitous iature and are present in rocks, soil, water, plants, foods and even air.

The relationship between fluoride and dental caries was first noted in the early part of the 20th century when it was observed that residents of certain areas of U.S.A. developed brown stains on their teeth. These stained teeth, though unsightly were highly resistant to dental decay and caries (Black and May 1916). In the 1930’s it was discovered that the prevalence and severity of this type of mottled enamel was directly related to the amount of fluoride in the water (Smith et al. 1931). Subsequently it was recognized that fluoride consumption in optimal amounts in the water supply imparted protection against the development of dental caries without staining the teeth (Dean 1938).  Another benefit of fluorides is that the incidence of osteoporosis seems to occur less frequently in regions with high fluoride content in water than in those in which the inhabitants consumed little fluoride. Although, the importance of this element to normal mineralization of hard tissues and formation of caries resistant enamel has been recognized, there has been as yet no conclusive evidence proving that it is an essential element for human health (McClure 1970). Indeed, fluoride deficiency syndrome is yet to be described.  This may be due to the fact that human body requirement of this micronutrient must be small, which is met with naturally through food and water. Excessive ingestion of fluoride through water, food or dust causes acute toxicity or a debilitating disease called ‘fluorosis’ a term coined and first used by Cristiani and Gautier in 1925. Acute fluoride intoxication is rarely seen and results most frequently from accidental ingestion of large amounts of fluoride compounds. The acute lethal dose of fluoride for the 70 kg man is 2.5-5.0 grams. Chronic fluoride poisoning is more common and can affect animals as well as humans.  Excessive intake during pre-eruptive stage of teeth leads to dental fluorosis and further continued ingestion over years and decades causes bony or skeletal fluorosis. Lastly crippling disease produces neurological manifestations. A disease in animals called ‘gaddur’ believed to have arisen from fluoride intoxication caused by periodic volcanic eruptions that have been taking place since 1000 AD is mentioned in Icelandic literature (Roholm 1937). A disease of the teeth and bones of horses and cattle called ‘darmous’ was known to have been prevalent in North African coast for centuries and later came to be identified as one caused by fluorides (Velu 1933).

Feil first mentioned fluorosis in humans as an occupational disease in 1930. This was substantiated when the occurrence of skeletal fluorosis in cryolite miners in Denmark was reported. Skeletal fluorosis was next reported as a disease endemic to an area in. Their study led to the publication of first reports of neurological manifestations of fluorosis in late stages. Subsequently cases of endemic and industrial fluorosis have been reported from various parts of India, Asia, Africa, Europe, North and South America. Endemic fluorosis is usually restricted to tropical and subtropical areas, and is frequently complicated by factors such as calcium deficiency or malnutrition. Endemic fluorosis is widely prevalent in China, India, Middle east, North Africa, Ethiopian rift valley and other parts of Africa. Sixty odd industries use fluorides and hence pollution can occur in them if proper precautions are not taken.

High incidence of endemic fluorosis in India is due to the fact that large areas of the country contain water supplies having high levels of fluoride.

All states of India except northeast reported cases of fluorosis and 25 to 30 million people are exposed to high fluoride intake and half a million suffer from skeletal fluorosis. In China 300 million people are living in endemic areas of fluorosis of whom 40 million have dental fluorosis and 3 million suffer from skeletal changes (Li and Cao 1994).

Metabolism of fluoride:

Biological effects of fluoride intoxication are related to the total amount of fluoride ingested whatever the source be it food, water or air.

Sources of fluoride:

1. Foods: Nearly all foods contain small quantities of fluoride and the total daily intake through any average human diet is small except in endemic regions. In certain endemic regions of India the fluoride content of vegetables and food may be very high (Chari et al 1974). The contribution of food to the total daily intake of fluoride varies from region to region. Staple diets rich in Sorghum, Ragi or Bajra containing high silicon besides fluoride seem to aggravate fluoride toxicity in some endemic areas of India (Pandit et al 1940;Anasuya Das 1996).

2.     Water and Beverages:

In case of natural waters, the variation in the fluoride content from region to region is dependent upon such factors as the source of water, type of geological formation and the amount of rainfall. Surface waters generally have low fluoride while ground waters may have high concentrations of fluoride as has been found in many parts of the world. The highest fluoride concentration of 28.9 PPM was reported from India (Chari et al 1974). The fluoride content of seawater varies from 0.8 to 1.4 PPM, which explains why the fluoride content of diet rises when seafoods are consumed. Among beverages tea has an exceptionally high fluoride content which varies in different brands from 122-260 PPM or more. Each cup of tea may supply 0.3-0.5 mg of fluoride. Bottled beverages, which are increasingly being consumed around the world, have a variable and some have high content of fluoride and should be considered as additional sources of fluoride.

The fluoride intake dependent upon consumption of drinking water and beverages is determined by such factors as body size, physical activity, food habits and variations in atmospheric temperature and humidity (Galagon and Vermillon 1957). That is why in tropical countries like India, the daily fluoride intake is very high. Farm laborers drink lot of water from wells and naturally have high fluoride intake and are at risk of developing fluorosis.

3. Air: The atmosphere has very low fluoride content and in 97% of non-urban areas fluoride is hardly detectable. The fluoride content of atmosphere is seen to have risen wherever there is volcanic action or industrial activity.  Volcanic fumarole vapors have high concentration of fluoride and industrial emissions from those engaged in mining or manufacture of fluoride containing minerals may be hazardous.  Low-grade coal has high levels of fluoride and smoke may be a souce of fluoride pollution.

Total daily fluoride intake:  The fluoride contents from all the sources determine the human intake of fluoride. In majority of endemic areas around the world, the main contribution is from water and only in few areas of India and China significant amounts come from foods and rarely the polluted air is the culprit.  The estimated range of safe and adequate intake of fluorides for adults is 1.5 to 4.0 mg per day and it is less for children and those with renal disease. The daily intake of fluoride in endemic regions varies from 10 to 35 mg and can be even higher in summer months.

Absorption of fluorides: Soluble inorganic fluorides ingested through water and foods are almost completely absorbed and also those inhaled from the respiratory tract.  But absorption of less soluble inorganic and organic fluorides varies from 60-80% (Cremer and Buttner 1970). Fluorides are absorbed from the gastro-intestinal tract by a process of simple diffusion without any mechanism of active transport being involved. Various dietary components apparently influence the absorption of fluoride from the gut. It has beeoticed that salts of calcium, magnesium and aluminum when added to diet reduce the quantum of fluoride absorption on account of the formation of their less soluble compounds.  This is the reason why waters with high calcium and magnesium content check the incidence of fluorosis, as indicated by epidemiological studies (Jolly et al 1969).  Therefore, it is to be expected that all other factors being equal, the incidence of skeletal fluorosis would be less where the calcium and magnesium content of drinking water is high (Raja Reddy1985).  It is noteworthy that administration of magnesium salts (serpentine and magnesium hydroxide) to patients suffering from fluorosis and experimental animals has increased the fecal and urinary excretion of fluorides. Similarly, increased absorption of fluoride from gastrointestinal tract ensues from the addition of substances like phosphates, sulphates and molybdenum to the diet and these can increase fluoride toxicity (Ericsson 1968).

Distribution of fluorides:

About 96-99% of the fluoride retained in the body combines with mineralized bones, since fluoride is the most exclusive bone seeking element on account of its affinity for calcium phosphate (Armstrong and Singer 1970). But it has been noticed that there is no significant retention of it in the body if very small quantities of fluorides are ingested (McClure et al 1945). In fact, there was no discernible retention of fluoride when upto 4-5 mg was ingested daily. But when more than 5 mg were ingested about half of it appeared to have been retained by the skeleton and rest excreted through urine. Observations show that after absorption from the gut fluoride enters the circulation, the plasma fluoride accounting for the three-fourths of the total amount of fluoride found in the whole blood and cells for the rest.  Fluoride in plasma exists in free ionic and bound forms, the latter bound to the serum albumin forming about 85% of the total amount fluoride in plasma (Taves 1968). Plasma fluoride in normal individuals ion-fluoridated areas ranges from 0.14-0.19 PPM and is higher in fluorotic patients (Singer and Armstrong 1969).  Newer methods, which only measure ionic component of plasma fluoride levels are lower and range between 0.004-0.008 PPM when drinking water contained traces of fluoride and varied from 0.1-0.02 when water was fluoridated. Plasma fluoride concentrations tend to increase slowly over the years.  It is seen that plasma levels of fluoride do not fluctuate widely despite a wide variation of fluoride levels in drinking water presumably because of the action of some regulatory mechanisms, which have not yet been clearly identified (Singer and Armstrong 1961). The sequestration of fluoride into the skeleton, urinary excretion and loss sustained through sweat help in regulation of plasma fluoride. The levels of fluoride in most soft tissues of the body are lower than 1 PPM but are higher than those of plasma. The fluoride content of brain is 0.4-0.68 PPM and the concentration in C.S.F. is 0.1 PPM, which is lower than that of plasma (Hodge and Smith 1965).

The uptake of fluoride by the skeleton is very rapid and depends upon the vascularity and the rate of its growth.  The fluoride uptake of young bones is faster than that of mature bones.  The fluoride is incorporated more readily in the active, growing and cancellous areas than in the compact regions.  It has been observed that skeletal fluoride concentration increases almost proportionately to the amount of fluoride ingested and the duration of its ingestion (Spencer et al 1975). The amount of fluoride present in various bones of same skeleton differs from bone to bone with pelvis, vertebrae registering higher fluoride content than limb bones.  Even in the limb bones amount of fluoride deposited in them depends upon the activity of muscles attached to them. In caged monkeys fluoride content of upper limb bones is more than the lower limb bones. It is this increase in the fluoride content of skeleton that provides the most reliable clue to excessive fluoride intake.  The other indicators such as urine and soft tissue levels, which manifest wide fluctuations, cannot be relied upon. Once incorporated into the hard tissues, the fluoride is retrievable, though with difficulty and entails an extremely slow process of osteoclastic resorption spread over many years.

Clinical features:  Fluoride intoxication presents an extraordinary degree of uniformity in its clinical manifestations.  It occurs in humans as dental and skeletal fluorosis. They are separated by a prolonged, relatively symptom free interval, during which the skeleton does not stop accumulating fluoride.  In its advanced stages, skeletal fluorosis causes crippling deformities and neurological complications.

Dental fluorosis:  Dental fluorosis mainly involves enamel but severe intoxications may affect dentine as well as pulp. Enamel fluorosis occurs when fluoride concentrations in or in the vicinity of the forming enamel are excessive during its pre-eruptive development.  Mottling of teeth is one of the earliest and most easily recognizable features noticed in the first decade of life. 

Both sexes are equally affected. It is the permanent teeth that are affected and they lose their normal creamy white translucent color and become rough, opaque and chalky white.  Pitting and chipping are other marks of fluorosis. Brown or black pigment gets deposited on the defective enamel and once established tends to remain there permanently.  Incidence of dental fluorosis in endemic areas exhibits a linear relationship to the fluoride content of water but it may also vary with other factors (Jolly et al 1968). Dental fluorosis does not obviously occur, when there has beeo exposure to fluoride in the first decade of life.

Pre skeletal stage:  The duration of this stage may vary with the amount of fluoride daily ingested.  Reportedly, it ranges from 10 to 30 years or even longer in endemic areas and from 10 to 15 years or longer in cases of industrial fluorosis (Singh and Jolly 1970; Franke et al 1970). It is usually free of any signs or symptoms in its early stages in endemic regions. The persons concerned may occasionally complain of pains in the small joints of the limbs and back, which are often mistaken for rheumatoid arthritis or ankylosing spondylitis. However, various reports from Europe and America suggest that there would be symptoms corresponding to gastrointestinal, musculoskeletal, respiratory and visceral systems during this stage (Roholm 1937, Waldbott 1956; Petraborg 1974). The majority of these visceral symptoms may be due to allergy to fluoride in susceptible individuals or the effect of fluoride on the various target organs and these are nonspecific.

Skeletal fluorosis:  Early in the development of fluorotic changes in the skeleton, the patients often complain of a vague discomfort and paresthesiae in the limbs and the trunk. Pain and stiffness in the back appear next, especially in the lumbar region, followed by dorsal and cervical spines.  Restriction of the spine movements is the earliest clinical sign of fluorosis.

The stiffness increases steadily until the entire spine becomes one continuous column of bone manifesting a condition referred to as ‘poker back’. In man the spine is most likely to be affected first and severely because of its being required to sustain the erect posture (Murray 1950).  When the condition becomes severe and chronic, various ligaments of the spine become calcified and ossified. The stiffness that first appears in the spine soon spreads to various joints in the limbs owing to the involvement of the joint capsules, the related ligaments, tendinous attachments to the bones and interosseous membranes.

The involvement of the ribs gradually reduces the movement of the chest during breathing, which finally becomes mainly abdominal. When that happens the chest assumes a barrel shape. With the increasing immobilization of the joints due to contractures, flexion deformities may develop at hips, knees and other joints, which make the patient bedridden. Bony exostoses may also appear over the limb bones, especially around the knee, the elbow and on the surface of tibia and ulna. Despite the fact that the entire bone structure has become affected, the mental faculties remain unimpaired till the last stage is reached.

The stage at which skeletal fluorosis becomes crippling usually occurs between 30 and 50 years of age in the endemic regions.

The factors which govern the development of skeletal fluorosis are (a) the prevalence of high levels of fluoride intake,

(b) continual exposure to fluoride,

(c) strenuous manual labour

,(d) poor nutrition and

(e) impaired renal function due to disease (Pandit et al 1941;Daver 1945; Raja Reddy 1985).

In regions with very high fluoride content the disease may affect younger age groups including children. The longer the exposure to fluoride higher will be its incidence. In tropical countries skeletal fluorosis occurs even while drinking low levels of fluoride. It is the farm laborers who are prone to develop fluorosis rather than those engaged in sedantary occupations. Epidemiological observations revealed that nutritional status might influence chronic fluoride toxicity.

DENTAL CARIES

Dental caries is a bacterial disease that begins with demineralization of the outermost dental enamel and progresses, if not halted, to loss of tooth substance and infection of the dental pulp. Demineralization begins with acid formation in dental plaque, the acid being a by-product of the metabolism of simple carbohydrates (sugars, cooked starches) by certain plaque-resident bacteria, principally the mutans streptococci. If demineralization is not checked, it leads to tissue loss and further bacterial penetration. The carious process is reversible in the early demineralization stage: Fluoride and other minerals in plaque can buffer the acid and lead to remineralization of the early lesion. Prevention of dental caries, therefore, is based on promoting an intra-oral environment in which demineralized enamel can quickly be remineralized, and where plaque pH does not remain below neutral for prolonged periods.

According to the United States Department of Agriculture, average sugar consumption in the United States rose from 122 pounds per person in 1981 to 154 pounds per person in 1997, one of the highest levels of sugar consumption in the world. Reasonable restriction of simple-carbohydrate foods (candies, sugared soft drinks, cookies) is prudent for caries-susceptible persons, despite the paucity of population-based data to demonstrate the effectiveness of such action. Dental sealants, applied directly to teeth by a dentist or hygienist, are highly effective at preventing caries on the chewing surfaces of the teeth.

Fluoride acts in several ways to prevent caries. The principle action is thought to be that fluoride in dental plaque inhibits the initial demineralization of enamel, and then promotes remineralization of early lesions. The constant availability of fluoride in plaque to respond to acid challenges leads to the gradual establishment of a more acid-resistant enamel crystal as a result of the repeated cycles of demineralization and remineralization. Fluoride also inhibits glycolysis, the process by which cariogenic bacteria metabolize simple carbohydrates, and there is evidence that fluoride also has antibacterial action in plaque. There may be some incorporation of fluoride into the enamel crystal prior to tooth eruption, which may increase resistance to solubility in acids.

Fluoride in toothpaste is considered by many researchers to be the most effective use of fluoride in controlling caries, although today fluoride is available from a variety of sources. Brushing with a fluoride toothpaste twice each day, a social norm in American society, ensures that fluoride will be present in dental plaque when an acid challenge arises. Addition of fluoride to public water supplies at around 1.0 parts per million has particular benefits for lower socioeconomic groups who may not brush their teeth that often. Fluoride is also used effectively in school-based programs as a mouthrinse or as fluoride supplements, and dentists can apply fluoride gels or varnishes directly to the teeth of their more caries-susceptible patients. Use of fluoride in all these ways is considered to be the chief reason for the remarkable improvement in the oral health of Americans between 1980 and 1995.

Classification of water supply sources

Water supply sources are divided into ground and surface:

–      middle waters with pressure (artesian) and without pressure that lie in aquifers (water-bearing horizons,) (sandy, gravelled, cracked) between impermeable to water layers of soil (clay, granites), therefore safely protected from penetration of pollutants from the surface. Middle water replenishes in feeding zones – places, where the auriferous stratum pinches out onto the surface, located considerably far away from the water take point. Middle waters are characterized by not very high, stable temperature (5-12°С), constant physical and chemical composition, steady level and considerable flow; they contain almost no microorganisms, especially pathogenic. Such waters are epidemically safe and don’t require disinfection;

–      underground waters that are located in aquifers above the first impermeable layer of soil and therefore, in case of them lying not very deep, they are insufficiently protected from penetration of pollutants from the surface. They are characterized by seasonal fluctuations of chemical and bacteriological composition and level, flow that depends on frequency and number of precipitations, availability of open-air water reservoirs, depth and soil type. Getting filtrated through the 5-6 m or bigger layer of clean fine-grained soil ground waters become clear, colourless, contain almost no pathogenic microorganisms. Supplies of ground water are small, therefore, in order to use them as a source of centralized water supply, the artificial recharge (replenishment) of them using special technical facilities is required;

–      spring water, flowing out from aquifers that pinch out onto the surface due to descending relief, e. g. on the hill slope, in deep ravine.

– perched groundwater, lying next to the ground surface, is formed as a result of atmospheric precipitates filtration within a small area. Very small supplies and bad water quality do not allow recommending perched groundwater as the source of domestic and drinking water supply.

Surface waters are divided into flowing (running) waters (rivers, waterfalls, glaciers), stagnant (dead-water, still water) (lakes, ponds, artificial open water reservoirs). Their water composition depends much on the soil at the territory of water intake, hydrometeorological conditions, and varies sufficiently during the year depending on the season or even on the weather. Compared to ground waters, surface water sources are characterized by big amount of suspended substances, low clarity, higher colour due to humic substances that are washed away from the soil, higher content of organic compounds, presence of autochthonic microflora and dissolved oxygen. Open-air reservoirs can easily be polluted from outside, therefore, from epidemiological point of view they are potentially unsafe.

In some water-poor or arid areas, the imported and precipitation (atmospheric) water (rain, snow), which is stored in indoor water reservoirs or artificially filled wells, is used.

The best is the situation when quality of water in the source of water supply completely meets the contemporary criteria of the good water quality. Such water doesn’t require any treatment and the only concern is not to spoil its quality at the stages of its take from the source and delivery to consumers. But disinfection of such water is the part of sanitary requirements anyway. Only some underground middle waters are like this, mostly – artesian (pressure) waters. In all other cases water in the source, especially the surface water, requires quality improvement: lowering of suspended materials concentration (clearing) and colour (decolouration), getting rid of pathogenic and conditionally pathogenic microorganisms (disinfection), sometimes chemical composition improvement using special treatment techniques (desalination, softening, defluorination, fluorination, deferrization etc.).

 

Sources of the surface water reservoirs pollution

The main source of pollution of surface water reservoirs are sewage waters (especially untreated or insufficiently treated water) that are created as the result of the water use in private life, industry, poultry and cattle factories etc. Partial pollution of water reservoirs occurs in the result of surface drainage of rain, storm waters and waters that appear during snow melting. Sewage waters and surface drainage add a big amount of suspended solids and organic compounds to water of reservoirs that results in more colour and water turbidity increase, clarity (transparency) lowering, oxidation and biochemical oxygen demand (BOD) increase, amount of dissolve oxygen lowers, concentration of nitrogen-containing substances and chlorides increases, bacterial insemination grows. Together with industrial wastewaters and sewage from farmlands, as it was mentioned before, various hazardous toxic chemical substances get into water reservoirs.

Water in open reservoirs may be polluted in the result of its use for transport purposes (passenger, freight shipping, timber floating), when working near river-beds (e.g., extraction of river sand), during watering animals, at sports competitions, recreation of population.

 

Self-purification (natural purification) of open-air water reservoirs

Self-purification (natural purification) of open air water reservoirs takes place in the result of various factors’ effect: а) hydraulic (mixing and dilution of pollutants by water of water reservoir); b) mechanical (precipitation/sedimentation of suspended solids); c) physical (solar radiation and temperature effect); d) biological (interaction of water plant organisms and microorganisms with sewage organisms that got into reservoir); e) chemical (elimination of contaminants as the result of hydrolysis); f) biochemical (conversion of some substances into other due to biological elimination, mineralization of organic substances as the result of biochemical oxidation caused by water autochthonic microflora). Natural purification with pathogenic microorganisms occurs due to their death as the result of antagonistic action of water saprophytic organisms, antibiotic substances, bacteriophages etc. In case of pollution of water reservoirs by domestic and industrial wastewaters, processes of natural purification may be stopped. Water in reservoirs becomes overgrown (vegetation burst of aquatic plants, plankton), putretaction of water.

 

Selection of the source of centralized domestic and drinking water-supply

It is based on two theses:

–       consumer supply with adequate amount of good quality drinking water (water quality in reservoir must be suitable for conversion using up-to-date water treatment methods into potable water of good quality that would meet all requirements of State Standard (2874-82, SSRandN 136/1940) currently in force);

–       control of the highest sanitary reliability of the source (selection of the source is based on assessment and prognosis of its possible pollution).

The source of centralized domestic and drinking water-supply is to be selected as follows: 1) middle water (artesian) aquifers; 2) middle water (not-artesian) aquifer; 3) underground waters, which are refilled artificially; 4) surface waters (rivers, water reservoirs, lakes, canals).

When selecting the source, water amount sufficiency for covering all needs of the built-up area is considered, water supply points (water intakes) are defined and organizational opportunities for sanitary protection zones are assessed.

Hygienic principles are assumed as the basis of selection of water- supply source; water quality requirements of ground and surface sources, selection procedure are represented in SS 2761-84 “Centralized domestic and drinking water supply sources. Hygienic, technical requirements and selection guidelines”.

 

Technique of water sampling for laboratory analyses

During water sampling from open reservoir or a well the temperature of water is measured by a special thermometer (Fig. 16.1.) or by an ordinary chemical thermometer, the vessel of which is wrapped up with some layers of gauze bandage. Temperature is taken directly in the water source. Thermometer is put down into the water for 5-8 min., then it is quickly drawn up and temperature is read.

Fig. 16.1 Thermometer for taking temperature of water in reservoirs and wells (а), bathometers for water sampling for analysis (b).

 

Water sampling from open reservoirs and wells is carried out using bathometers of different design and supplied by double cord for putting the instrument down to specified depth and for opening the cork of the vessel at that depth (Fig. 16.1-b).

For water sampling from flowing water reservoirs (river, brook) there is a design of bathometer with stabilizer that directs a neck of the vessel against the stream.

Water sampling from water tap or equipped catchment is carried out:

–      for bacteriological analysis. Sample is put into a sterile bottle of 0.5 l volume, with bulky cork, wrapped with paper cap from above after preliminary singeing of outlet port of the tap or catchment by spirit flame and letting water out from the tap during at least 10 min. In order to avoid bulky cork wetting, only three quarters of the bottle is filled with water to leave at least 5-6 cm of air space under the cork. The bottle with bulky cork is preliminary sterilized in drying box at 160⁰ С during one hour;

–      for short sanitary-chemical analysis (organoleptic criteria, main indices of chemical compound and water pollution). About 1 liter of water is taken into a chemically clean glassware, which was preliminary rinsed with water to be sampled (for complete sanitary-chemical analysis 3-5 l of water are taken off).

During sampling a covering letter is written down. This letter indicates: type, name, location, address of the water source (surface water reservoir, artesian well, mineshaft, catchment, water tap, water-pump); its short specification, weather state during sampling and during last 10 days; reason and goal of sampling (regular inspection, adverse epidemic situation, population complaints about deterioration of water organoleptical properties); laboratory, to which the sample is sent; required extent of examinations (short, full sanitary-chemical analysis, bacteriological analysis, determination of pathogenic microorganisms); date and hour of sampling; research result received during sampling (temperature); who tested (surname, position, institution); signature of an official person, who took the sample.

Samples must be delivered to the laboratory as quickly as possible. Bacteriological analyses must be started during 2 hours since taking samples or in case of keeping samples in refrigerator at 1-8°С at the latest 6 hours. Physical and chemical analysis is made during 4 hours after taking a sample or in case of keeping a sample in refrigerator at 1-8°С at the latest 48 hours. In case of inability to perform the analysis during specified terms, sample must be preserved (except samples for physical-and-organoleptical and bacteriological analyses, and for BOD determination that must be necessarily made during terms specified above). Samples are preserved by 25% of H₂SO₄ – solution on the basis of 2 ml for 1 l of water or by another method depending on factors to be determined.

Taken sample comes with accompanying form, in which one indicates address details, kind of water source, where samples are directed, aim of the analysis, date and time of taking a sample, signature of an official person, which took this sample.

 

Hygienic characteristics of water supply systems of settlements

There are centralized and decentralized water supply systems.

Centralized system (water pipeline) includes: source of water (middle water with or without pressure, opeatural water reservoir or artificial storage reservoir), water intake facility (artesian well, artificial flooding with waterside intake well equipped with filter system), water-lifting facility (water-engines or pumps of the first lifting), main facilities of water supply station, where water clearing, discolour, disinfection are executed, and sometimes there also takes place special water treatment (fluorination, defluorination, deferrization etc.) to improve water quality, reservoirs for water storage (reservoirs of pure water), water-pumping station of the second lifting and water supply network – system of water pipes, which provide consumers with water.

Artesian water (middle water with pressure) often does not need purification, sometimes – only disinfection, rarely – application of special methods of the water quality improvement. In case of use of water from open reservoirs in water pipeline, it should obligatory undergo purification, which is performed at treatment facilities of water supply station and provides for water clearing, discolour and disinfection.

Coagulation is used to purify the water – chemical treatment of water with aluminium sulphate according to the following reaction:

Al₂(SO₄)₃ + 3Ca(HCO₃)₂ = 2Al(OH)₃ + 3CaSO ₄ + 6CO₂

Aluminium hydroxide in form of rather big plates absorbs suspended in water contaminants and humic colloidal particles, as the result of this process water becomes clear and colourless. Dose of coagulant depends upon water alkalinity rate, presence of bicarbonate in it, amount of suspended substance and water temperature. When carbonate hardness is small (less than 4°), we add 0.5-1.0 % solution of soda or slaked lime. To accelerate coagulation the flocculating agents (polyacrylamide) are added into water.

After coagulation water comes to sedimentation tanks, then through filters to reservoirs for pure water and by means of pumps of the second lifting it is pumped into water supply network.

After the filtration water is obligatory disinfected using ozone treatment, UV radiation or chlorination methods.

Chlorination is the simple, effective and cheapest method of water disinfection, but chlorine imparts unpleasant odour to water, and if there is any chemical pollution (due to discharge of industrial sewage water to reservoirs) chlorination facilitates formation of chlorine-organic compounds, for which carcinogenic action, and formation of chlorophenol compounds having unpleasant odour are inherent. As a result of this method of chlorination with pre-ammoniation has been worked out: preliminary introduction of ammonia solution into water binds chlorine in the form of chloramines, which disinfect water, at the same time chlororganic and chlorophenol compounds do not form.

Most often decentralized (local) water supply is realised using shaft or tube wells, and more rarely using groundwater intake structures (catchments). Underground (subterranean) water, which accumulates in waterbearing aquifer over the first water-holding horizon, is used in wells. Such water laying depth amounts to some dozens of meters. A well in the conditions of local water supply serves as water intake, water-lifting and water-dispensing facilities simultaneously.

The distance from the well to a water consumer should not exceed 150 m. It is necessary to place wells considering relief, because wells should be placed higher on slope than all sources of pollution (cesspool, underground filtration area, compost pit etc.) at a distance more than 30 – 50 m. In cases when a potential source of pollution is situated higher on slope than a well due to relief, the distance between them should not be less than 80 – 100 m, and in some cases – eveot less than 120 – 150 m.

A well is a vertical shaft of square or circular cross-section that reaches the water- bearing aquifer. Sidewalls of the shaft are fortified with impervious material (concrete, iron concrete, bricks, wood and others). Layer of gravel about 30 cm in height is thrown up onto the bottom. Overground part of the well, which is called the log cabin, should not be less than 1.0 m in height above ground level. When making the well we should build “loamy key trench” of 2 metres deep and 1 metre wide around the well and a riprap within a radius of 2 m with slope directed away from the well. Drainage ditch should be provided for rainwater drain. There should be a fence within a radius of 3-5 metres around the common wells. Water from the well is pumped up or lifted using winch with public dip-bucket. A log cabin should be tightly covered and a shed should be built over the cover and the winch.

“Sanation” of shaft well is complex of measures, which includes repair, washing and disinfection of the well as a construction to prevent water pollution in it. For the purpose of prevention, sanation of the well is carried out before putting it into operation, and then depending upon epidemic situation, periodically after washing and remedial maintenance or general overhaul 1 time per year. Prophylactic sanation includes two stages: 1) washing and repair and 2) terminal disinfection. When making terminal disinfection, one treats the log cabin and inner part of the well by means of irrigation method (irrigation with 5% chlorinated lime solution or 3% calcium hypochlorite solution on the basis of 0.5 dm³ per 1 m² of log cabin surface using hydraulic sprayer) first. Then one waits till the well fills up with water to usual level whereupon disinfection of underwater part of the well by means of volumetric method is carried out (necessary amount of chlorinated lime or calcium hypochlorite is dissolved in small volume of water on the basis of 100 ― 150 mg of active chlorine per 1 dm³ of water in the well, cleared by precipitation obtained solution is poured out into the well; water in the well is vigorously stirred during 15-20 minutes, then the well is covered and left for 6-8 hours with prohibition of taking water from it during this period of time).

In case of unfavourable epidemic situation (the well is a factor of spreading enteric infection), if the fact of pollution of water in the well is proved in laboratory or there are scientific evidences of water pollution with faeces, cadavers of animals, other foreign substances, sanitation is performed according to epidemiologic indications. At that, the procedure of well cleansing includes three stages: 1) preliminary disinfection of underwater part of the well using volumetric method, 2) washing and repair and 3) terminal disinfection first using irrigation method and then – volumetric method.

In case of insufficient improvement of water quality after performed disinfection (sanation) of the well, sometimes prolonged disinfection of water in the well is performed using dosaging cartridges. Dosaging cartridges are cylindrical pots made of porous ceramics with inner volume equal to 250, 500 or 1000 cm³, where chlorinated lime or calcium hypochlorite is put inside. The amount of calcium hypochlorite, which activity is minimum 52 %, is calculated according to the following formula:

X₁ = 0.07·X₂ + 0.08 X₃ + 0.02 X₄ + 0.14 X₅  ,

where: X₁ – the amount of agent that is necessary to be loaded inside the cartridge (kg),

  X₂ – volume of water in the well (m³),

  X₃ – discharge (output) of the well (m³/year),

  X₄ – water pumping (m³/day),

  X₅ – chlorine absorption of water (mg/dm³).

Prior to starting the filling up, one should hold the cartridge in water for 3 – 5 hours, and then fill up with chlorinated agent in calculated amount, pour in additional 100 – 300 cm³ of water, mix thoroughly, close up the cartridge with ceramic or rubber plug, hang it in the well and submerge into the water column at a depth of approximately 0.5 m below upper level of water and 0.2 – 0.5 m above bottom level.

Catchment is a concrete reservoir built near the spring outlet at the bottom of a hill or a mountain; it is equipped with discharge pipe through which water is constantly flowing out. The reservoir is partitioned with wall of proper height into two chambers. The first chamber serves as a sand collector for precipitated sand that is being washed out by spring water, and the other chamber accumulates pure water, which is constantly flowing through the discharge pipe. The place under the pure water outlet is equipped with drainage concrete chute inclined towards a stream, river.

 

Hygienic characteristics of water quality criteria

Organoleptic properties of water are divided into 2 subgroups: 1) physical and organoleptic – combination of organoleptic characteristics that are perceived by sense organs and are evaluated according to the strength of perception and 2) chemical and organoleptic – content of particular chemical substances, which can irritate receptors of corresponding analyzers and cause one sense or another.

Odour – is the ability of chemical substances to evaporate and, producing sensible steam pressure over water surface, to irritate receptors of mucous membranes of nose and paranasal sinuses, and in such a way to cause corresponding sense. There is the following differentiation of odours: natural (aromatic, marshy, putrefactive, fishy, grassy and etc.), specific (pharmaceutical) and indeterminate odours.

Taste and aftertaste — is the ability of chemical substances, existing in water, to irritate taste buds, which are placed on the surface of tongue/tongue surface, and to cause corresponding sense. One can differentiate salty, bitter, sour and sweet tastes. The rest are aftertastes: alkaline, marshy, metallic, aftertaste of mineral oil and etc.

To characterize the strength of odours, tastes and aftertastes of water there is a standard five-point scale:

0 — odour (taste, aftertaste) is absent, it caot be detected even by experienced flavourist (taster),

1 — very slight one, consumer caot detect it, but it can be detected by experienced flavourist (taster),

2 — slight one, consumer can detect it only in case of drawing consumer’s attention to it,

3 — perceptible one, consumer easily detects it and shows negative reaction,

4 — distinct one, water is unusable,

5 — very intensive one, can be detected at a distance, so water is unusable.

State sanitary norms and rules (SSRandN) 136/1940 represents the assessment of the strength of odour and aftertaste according to dilution indices (DI).

Unpleasant odours, tastes and aftertastes of water restrict consumption of such water and force to search for other sources, as they indicate that water can pose epidemic and chemical hazard. Specific odour, taste and aftertaste are evidence of water pollution in consequence of industrial sewage water ingress or superficial run-off from agricultural land into water body. Natural odour, taste and aftertaste are evidence of presence in water of organic and nonorganic substances that have been generated in consequence of vital functions of water organisms (algae, actinomycete, fungi and etc.) and biochemical transformation processes of organic compounds (humic substances) that get to water from the soil. Odour of ground water sources can depend upon availability of hydrogen sulphide in it, and odour of water from wells can depend upon the log cabin wood. These substances can be biologically active, not indifferent (neutral) for health, and have allergenic properties. They are efficiency criteria of water purification at water supply stations.

Colour — is natural property of water, depends on humic substances, which are washed out from the soil during formation of surface and ground water reservoirs and give water yellow-brown tint. Colour is measured in degrees using spectrophotometers and photocolorimeters by comparison with the colour of scale of chrome and cobalt or platinum and cobalt solutions, which simulate the natural water colour.

Polluted water can have an unnatural colour caused by colouring substances, which can come into water reservoirs together with sewage water of light industry enterprises, certaionorganic compounds both of natural and man-caused origin. Thus, iron and manganese may cause colour of water from red to black, copper – from faintly azure to blue-green colour. This index is called colour of water. To measure it, water is poured into cylindrical vessel with flat bottom, a sheet of white paper is placed 4 cm away from the bottom, then water from cylindrical vessel is poured off until one can see the white colour of the paper through the column of water in the cylindrical vessel i.e. until colour disappears. Height of this water column evaluated in cm characterises water colour.

Suspended materials concentration (turbidity) — is natural property of water that depends on the content of suspended substances of organic and nonorganic origin (clay, sludge, organic colloids, plankton and etc.). Suspended materials concentration (turbidity) is measured using nephelometers, spectrophotometers and photocolorimeters by simulation kaolin scale, which is set of suspensions of white clay (kaolin) in distilled water. Suspended materials concentration of water is evaluated in mg/l by comparison of optical water density with the density of standard suspensions of kaolin, according to State standards (SSRandN) 383 – in nephelometric turbidity units (NTU).

Opposite characteristic of water is transparency – ability to transmit light rays. Transparency is measured by Snellen method: one pours water into cylindrical vessel with flat bottom, place standard font with the letters of 4 mm height and 0.5 mm thick at a distance 4 cm from the bottom, and then we pour water from the cylindrical vessel off until we can read letters through the column of water in the cylindrical vessel. Height of this water column, evaluated in cm, characterises water transparency.

Colour, tinted, turbid water evokes sense of aversion that restricts consumption of such water and forces searching of new sources of water supply. Increase of colour, suspended materials concentration (turbidity) and decrease of transparency may be the evidence of water pollution with industrial sewage water, which contains organic and nonorganic substances, which can be hazardous to people health or generate harmful substances during water treatment with reagents (for instance, chlorination). Water with high colour index can be biologically active due to humic organic substances. There are efficiency criteria of water purification and decolour at water supply stations. Suspended and humic substances impair water disinfection (prevent mechanical penetration of active chlorine into bacterial cell).

Temperature influences greatly on: 1) organoleptic properties of water (odour, taste and aftertastes); water with temperature more than 25°C provokes vomiting reflex; according to the international standard the temperature should not exceed 25°C, cool water with temperature (12–15°С) is considered to be the best water; 2) rate and intensity of water purification and disinfection processes at water supply stations: with temperature increase up to 20–25°C and thanks to better coagulation the processes of water purification and decolour improve, efficiency of water penetration through activated carbon becomes worse in the result of decrease of activated carbon adsorption capacity, diffusion of molecules of decontaminating chlorinated substances inside bacterial cell intensifies, thus disinfection becomes better.

Solid residue (total salinity) — is the quantity of solutes, mainly mineral salts (90 %), in 1 litre of water. Water with solid residue up to 1000 mg/l is called fresh water, one with solid residue from 1000 to 3000 mg/l – saltish water, one with solid residue more than 3000 mg/l ­– salt water. Salinity of 300—500 mg/l is considered to be optimal. Water with solid residue below 50—100 mg/l is considered as low saline water and it has unpleasant taste; water with solid residue 100—300 mg/l is considered as satisfactorily saline water, and water with solid residue equal to 500—1000 mg/l — is considered as a super saline water but still acceptable.

Saltish and salt water has unpleasant taste. Use of such water is accompanied by increase of hydrophilia of tissues, water retention in body, decrease of diuresis by 30—60 %, in consequence of which, load on cardiovascular system increases, clinical course of ischemic cardiac disease, myocardiodystrophy, morbus hypertonicus becomes more serious and risk of acute attack of these diseases becomes higher; it can cause dyspepsia as a result of alteration in secretory and motor functions of stomach, irritation of mucous membranes of small and large intestines and increase of intestinal peristalsis for persons, who had changed residence; it also causes aggressive clinical behaviour and serious clinical course of nephrolithiasis and cholelithiasis.

Systematic use of low saline water results in water-electrolytic dyscrasia, which is based on the reaction of osmoreceptive field of liver that causes increased release of sodium into blood and is accompanied by water redistribution among extra- and intracellular fluid.

Hydrogen index (pH value) — is natural property of water that depends on the presence of free hydrogen ions. Water in most of surface water reservoirs has pH value within the range of 6.5 to 8.5. pH value of ground water varies in the range from 6 to 9. Stagnant water, rich in humic substances (with pH value up to 7), is considered as acidic water. Ground water that contains much hydrocarbonates (with pH value more than 7) is considered as alkaline water.

Change of water active reaction is the evidence of water supply source pollution with acidic or alkaline industrial sewage waters. Active reaction influences the processes of water purification and disinfection: in alkaline water the process of water purification and decolour improves due to better coagulation; in acidic medium the process of water disinfection accelerates.

Total hardness — is the natural property of water that depends upon the presence of so-called salts of hardness, namely: calcium and magnesium (of sulphates, chlorides, carbonates, hydrocarbonates and others). We differentiate general, reduced, constant and carbonate hardness. Reduced or hydrocarbonate hardness is hardness that depends upon Ca²⁺ and Mg²⁺ bicarbonates, which during water boiling turn into insoluble carbonates and precipitate according to the following equations:

Ca(HCO₃)₂ = CaCO₃ + H₂O + CO₂.

Mg(HCO₃)₂ = MgCO₃ + H₂O + CO₂.

Hardness that remains after water boiling during 1 hour and depends upon the presence of Ca²⁺ and Mg²⁺ chlorides and sulphates, which do not precipitate, is called constant hardness.

Total hardness of water is evaluated in mg-equiv/l. Formerly, for hardness evaluation they used degree of hardness: 10° = 0.35 mg-equiv/l, 1 mg-equiv/l = 28 mg CaO/l = 2.8°.

Water with total hardness value below 3.5 mg-equiv/l (10°) is considered as soft water, from 3.5 to 7 mg-equiv/l (10—20°) — as moderately hard water, from 7 to 10 mg-equiv/l (20—28°) — as hard water and water with total hardness value more than 10 mg-equiv/l (28°) is considered as extremely hard water.

Content of hardness salts of more than 7 mg-equiv/l imparts bitter taste to water. Sudden change from soft water to hard water can cause dyspepsia. In regions with hot climate use of water with high hardness causes deterioration of urolithiasis clinical course. Salts of hardness impair absorption of fats because of their saponification and creation of insoluble calcium-magnesia soaps in bowels. Thus, penetration of polyunsaturated fatty acids (PUFA), liposoluble vitamins, and certain microelements into organism is restricted (water with hardness value more than 10 mg-equiv/l increases endemic goiter risk). High hardness causes dermatitis initiation because of irritant action of calcium-magnesia soaps, which are created at skin oil saponification. The higher is hardness of water, the more complicated is culinary foodstuff processing (meat and legumes are boiled soft much worse, tea is brewed poorly, deposit appears on the walls of pots), consumption of soap increases, hair and skin become coarse after wash; fabrics turn yellow, lose their softness, elasticity and ventilation property because of impregnation of calcium-magnesia soaps.

Long-drawn use of soft water, which has low content of calcium, can cause calcium deficiency in human organism (violet spots appear on enamel of the children, who live in regions with soft water, which are caused by decalcification of dentin; endemic osteoarthritis (Kashin-Bek disease), which is endemic polyhypermicroelementosis of strontium, iron, manganese, zinc, fluorine appears in localities where content of calcium in drinking water is low). Water with low content of electrolytes that cause hardness, promotes development of cardiovascular diseases.

Chlorides and sulphates are widely spread iature and constitute the greater part of solid residue of fresh water. They get into water of water reservoirs both as the result of natural processes of washing out from the soil and pollution of water reservoirs with different sewage water. Natural chloride content in surface water reservoirs is small and varies within the limits of several dozens of mg/l. Water that penetrates through the brackish soil can contain hundreds and even thousands mg of chlorides in 1 litre of water.

They influence organoleptic properties of water – impart it salty (chlorides) or bitter (sulphates) taste. Taking into consideration the great number of chlorides in urine and sweat of people and animals, in domestic sewage water, liquid domestic wastes, sewage water of stock-raising and poultry farms, surface run-off from pastures, chlorides are also used as indirect sanitary and chemical criteria of epidemic safety of water. But chlorides, which get into water reservoirs with industrial sewage waters, for example, of metallurgical works, have nothing common with the probable simultaneous biocontamination and bacterial pollution.

Iron. In surface water reservoirs iron is present in the form of persistent humic acid iron (IIІ), in the ground water — as divalent Fe hydrocarbonate (II). After ground water has been lifted on the surface, Fe (II) is oxidized by atmospheric oxygen and forms Fe (IIІ) with Fe hydroxide (III) according to the following reaction:

4Fe(OH)₂ + 2H₂O + O₂ = 4Fe(OH)₃.

Fe hydroxide (III) dissolves poorly and forms brown flocks in water that causes colour and concentration of suspended materials in water. When there is a noticeable content of iron in water, in consequence of above mentioned transformations water will obtain yellow-brown tint, become turbid and get viscous metallic aftertaste.

Manganese. In concentrations that exceed 0.15 mg/l, manganese causes pink colour of water, imparts unpleasant taste to water, paints linens when washing, makes deposit on pots. If manganese compounds (ІІ) in water can be oxidized, negative effect on the organoleptic properties of water is increased (at water aeration, if concentration of manganese in water is more than 0.1 mg/l, there will be originated brownish black sediment of MnО₂, at ozonization for the purpose of water disinfection pink colour of water can occur as a result of formation of Mn⁷⁺ salts (permanganates)).

Copper. In concentrations that exceed 5.0 mg/l, copper imparts distinct unpleasant astringent taste to tap water. In concentrations, which are more than 1.0 mg/l, linens are painted when washing; corrosion of aluminium and zinc pots takes place.

Zinc. High concentration of zinc in water makes worse organoleptic properties of water. In concentrations that exceed 5.0 mg/l, zinc compounds impart distinct unpleasant astringent taste to water. At that opalescence can appear in water and pellicle can occur on the water during boiling.

Criteria of safety according to chemical composition – are indices of maximum allowable concentrations of chemical substances (MAC), which may have negative impact on people health causing progress of different diseases.

Chemical substances of natural origin (beryllium, molybdenum, arsenic, lead, nitrates, fluorine, selenium, strontium) cause initiation of endemic diseases. Some of them (molybdenum, selenium, fluorine) are among micro bioelements, which amount in human organism does not exceed 0.01 %, and which are essential for human. They should necessarily be received by human organism in optimal daily doses, which must be strict otherwise hypomicroelementoses or hypermicroelementoses can progress. The rest of them (beryllium, arsenic, lead, nitrates, strontium) being received in excessive amount can have toxic action.

Chemical substances that come in water as a result of industrial, agricultural and domestic pollution of water supply sources. They include heavy metals (cadmium, mercury, nickel, bismuth, antimony, tin, chromium etc.), detergents (synthetic cleaning agents or surface-active substances), pesticides (DDT, HCCH (hexachlorocyclohexane), trichlorfon, metaphosphate, 2.4-D, atrazine etc.), synthetic-base polymers and their monomers (phenol, formaldehyde, caprolactam etc.). Their concentration in water must be nonhazardous for the health of people and their descendants when they use such water permanently for the whole life. The concentration of such substances in water must guarantee not only against acute and chronic poisonings, but also against the nonspecific harmful effect connected with the depression of general resistance of human organism. It must provide preservation of reproductive health, guarantee against mutagenic, carcinogenic, embryotoxic, teratogenic, gonadotoxic effect and against other long-term effects. Such concentrations we call maximum allowable concentrations (MAC).

Criteria that characterize epidemic safety of water are subdivided into 2 subgroups: the sanitary and microbiological criteria and the sanitary and chemical criteria.

Sanitary and microbiological criteria of epidemic safety of water. Absence of pathogenic microorganisms – agents of infectious diseases – is a criterion of epidemic safety of water. However, the analysis of water to determine the presence of pathogenic microorganisms is rather long, difficult and labour-intensive process. Thus, the assessment of epidemic safety of water is made using method of indirect indication of possible presence of pathogenic agent, and the following two indirect sanitary and microbiological criteria – total microbial number (TMN) and amount of sanitary-representative microorganisms – are used for this purpose.

TMN – is a number of colonies, which have grown when sowing 1 ml of water on 1.5 % beef-extract agar after incubation during 24 hours at temperature equal to 37 °С.

It is very important to discover colibacillus group bacteria (CBGB), which are in excrements of people and animals, in water. CBGB include the following bacteria species: Echerihia, Enterobacter, Klebsiella, Citrobacter and other representatives of Enterobacteriaceae, which are gram-negative rod bacteria, do not form spores and capsules, ferment glucose and lactose with formation of acid and gas at temperature equal to 37 °С during 24-48 hours and have no oxidase activity. Endo medium is selective nutrient medium for CBGB, where CBGB grow in the form of dark-red colonies with metallic lustre (Е. coli), red lacklustre colonies, pink or transparent colonies with red centre or borders.

Presence of CBGB in water is evidence of previous excrementitious pollution and consequently — of possible contamination of water with pathogenic microorganisms of colibacillus group. Quantitatively, the presence of CBGB is characterized by the two following indices: CBGB index and CBGB titre. Colibacillus index (coli index) — is amount of bacteria of colibacillus group in 1 litre of water, CBGB titre (coli titre) — is the minimal volume of analyzed water in ml, in which one bacterium of colibacillus group is detected.

Sanitary and chemical criteria of epidemic safety of water are evidences, first of all, of presence of organic substances and products of their decomposition in water that indirectly indicates the probability of water epidemic danger. This occurs when water of water reservoirs is polluted with domestic sewage water, waste water of stock and poultry farms etc. The most significant of the criteria are given below.

Permanganate oxidizability — is quantity of oxygen (in mg) that is necessary for chemical oxidization of easily oxidable organic and nonorganic (Fe (II) salt, H₂S salt, ammonium salts, nitrites) substances, which are available in 1 litre of water. Here KMnO₄ is oxidizing agent. Artesian water has the least permanganate oxidizability – up to 2 mg О₂ per 1 litre of water. For water from shaft wells this index makes up 2-4 mg О₂ per 1 litre, for surface water reservoirs it can be equal to 5-8 mg О₂ per 1 litre and more.

Bichromate oxidizability or chemical oxygen demand (ChOD) — is quantity of oxygen (in mg) that is necessary for chemical oxidization of all organic and nonorganic reducing agents in 1 litre of water. Here K₂Cr₂O₇ is oxidizing agent. Pure ground waters have ChOD index within 3-5 mg/l, surface waters – 10-15 mg/l.

Biochemical oxygen demand (BOD) — is quantity of oxygen (in milligrammes) that is necessary for biochemical oxidization (due to activity of microorganisms) of organic substances, which are available in 1 litre of water, at temperature equal to 20 °С during either 5 days (BOD₅) or 20 days (BOD₂₀). BOD₂₀ is also called complete BOD (BOD _compl.).

The more polluted with organic substances water is, the higher is BOD criterion of the water. BOD₅ criterion for water from pure reservoirs is less than 2 mg О₂/l (BOD₂₀ is less than 3 mg О₂/l), for water from comparatively pure reservoirs — 2-4 mg О₂/l (BOD₂₀ 3—6 мг О₂/l), for water from polluted reservoirs — more than 4 mg О₂/l (BOD₂₀ is more than 6 mg О₂/l).

Dissolved oxygen — is quantity of oxygen that is available in 1 litre of water. It is significant for sanitary regime of open water reservoirs. Oxygen of the air diffuses through water and dissolves in it. Some amount of oxygen is created due to vital functions of chlorophyll water-plants. Parallel with the process of water oxygen enrichment, oxygen is spent for biological oxidation of organic substances (processes of natural purification of water reservoir) and for respiration of aerobic aquatic life, fish in particular. To prevent impairment of processes of natural purification and loss of aquatic life, oxygen content in water reservoirs should not be less than 4 mg/l. When sewage waters, which have great amount of organic substances in their content, get into water reservoirs, BOD increases and amount of dissolved oxygen, which is spent for oxidation of organic substances, decreases.

Nitrogen of ammonium salts, nitrites and nitrates. Decomposed protein remains, cadavers of animals, urine, and excrements are sources of nitrogen for natural waters. As the result of processes of natural purification of water reservoirs, mineralization of complex nitrogen-containing protein compounds and urea alongside with creation of ammonium salts, which later on are oxidized forming firstly nitrites and finally nitrates, occurs. Exactly the same way the natural purification of water reservoirs from organic nitrogen-containing polluting substances that get into water reservoirs as a constituent of different sewage water and surface run-off occurs.

In pure natural surface and ground water reservoirs content of nitrogen of ammonium salts is within the limits of 0.01-0.1 mg/l. Nitrites, as an intermediate product of further chemical oxidation of ammonium salts, are present iatural water in very small quantities – 0.001-0.002 mg/l. If their concentration exceeds 0.005 mg/l, this fact is the significant indication of the source pollution. Nitrates are the final product of oxidation of ammonium salts. Availability of nitrates in water in the absence of ammonia and nitrites is evidence of comparatively long-term presence in water of nitrogen-containing substances, which have time to complete mineralization. In pure natural water the content of nitrogen of nitrates does not exceed 1-2 mg/l. In ground waters we can observe higher content of nitrates as a result of their migration from the soil in case of organic pollution of the soil or in case of intensive application of nitrogen fertilizers.

General hygienic requirements to drinking water include the following:

–         good organoleptic properties (transparency, comparatively low temperature, good refreshing taste, absence of odours, unpleasant aftertastes, colour, apparent to the naked eye inclusions and so on);

–         optimal natural mineral composition, which guarantees good taste properties of water, the receiving of some necessary for organism macro- and microelements;

–         toxicological safety (absence of toxic substances in hazardous to organism concentrations);

–         epidemiologic safety (absence of agents of infectious diseases, of helminthiasis etc.);

–         water radioactivity – within the limits of set levels.

 

Sanitary inspection of centralized water supply is subdivided into preventive one and regular. Preventive inspection includes sanitary examination of the design of water pipeline and all the components of water pipeline, supervision of the process of its construction and putting into operation.

Before the constructed water pipeline is put into operation, the following sanitary protection zones are to be designated:

– strict regime zone, which includes the defined part of water area in the place of water intake and upstream, territory around the water-purifying facilities;

– restriction zone – the territory, where any construction and operation of facilities, which can pollute this territory and the water reservoir, is prohibited;

– survey zone, which includes the whole water supply network.

Sanitary regular inspection is exercised using methods of more detailed (during repairs, reconstructions) regular periodical inspection, sporadic one, and sometimes (in case of gross sanitary abnormalities or intestinal infectious diseases) even urgent sanitary inspection. Such inspection is necessarily accompanied by water sampling and by the laboratory analysis of water. Results of this analysis are assessed according to of State Standard 2874-82 “Drinking water (quality requirements)” and State sanitary rules and norms (SSRandN) No.136/1940 „Drinking water. Hygienic requirements to water quality of centralized domestic and drinking water supply” (Appendix 3).

Results of laboratory analysis of water samples taken from local water supply sources are assessed according to “Sanitary regulations on arrangement and maintenance of wells and catchments used for decentralized domestic and drinking water supply” No.1226-75 (Appendix 4).

 

Requirements to drinking water quality of centralized water supply

(Extract from State Standard 2874-82 “Drinking water. Hygienic requirements and quality control” and State sanitary rules and norms (SSRandN) № 136/1940 “Drinking water. Hygienic requirements to water quality of centralized domestic and drinking water supply”

Applies to tap drinking water at centralized domestic and drinking water supply

Organoleptic criteria of drinking water quality

 * — dilution index, DI (till odour, aftertaste disappear),

** —nephelometric turbidity units NTU.

*** — values enclosed in brackets can be allowed in consideration of specified situation.

Criteria of drinking water epidemic safety

 

^* — For 95% of water samples from water supply network that are analyzed during a year,

^** — For 98% of water samples that get into water supply network and are analyzed during a year. In case of excess of CBGB index at the stage of identification of the colonies that have grown, extra analyses are to be made to discover presence of excrementitious coli forms,

^*** — If presence of excrementitious coli forms are discovered in 2 successively taken samples, it is necessary to start making analyses of water within 12 hours to discover presence of agents of infectious diseases of bacterial or viral ethiology (according to epidemiologic situation).

Toxicological criteria of drinking water chemical composition safety

^* Value enclosed in brackets can be allowed in case of water treatment with reagents that include aluminium,

^** List of controllable pesticides is drawn up in consideration of specified situation.

 

Drinking water radiation safety criteria

Note: For special regions the Norms of drinking water radiation safety are to be submitted to chief government sanitary inspector of Ukraine approval

 

Criteria of physiologic value of mineral composition

 

Requirements to drinking water quality of decentralized water supply

(Extract from “Sanitary regulations on arrangement and maintenance of wells and catchments used for decentralized domestic and drinking water supply”,

№ 1226-75).

1.     Organoleptic criteria:

– odour, points,                                                                                maximum 2–3

– aftertastes, points                                                                                    maximum 2–3

– transparency, cm                                                                            minimum 30

– turbidity, mg/dm³                                                                                     maximum 1.5

– spectral colour, degrees                                                                           maximum 30

– temperature, °С                                                                              8-12

– surface appearance                                                    absence of visible impurities

2.     Bacteriological criteria of epidemiologic safety:

– microbial number, CFU /cm³                                                           maximum 200-400

– coli index, CFU /dm³                                                                     maximum 10

3.     Sanitary and chemical criteria of epidemic safety:

– permanganate oxidizability, О₂ mg/dm³                                            maximum 4

– ammonium nitrogen, mg/dm³                                                          maximum 0.1

– nitrite nitrogen, mg/dm³                                                                  maximum 0.005

– nitrate nitrogen, mg/dm³                                                                  maximum 10.0

– chlorides, mg/dm³                                                                          maximum 350

         4. Chemical and organoleptic criteria:

– solid residue, mg/dm³                                                                     1000 (1500)

– hardness, CaO mg-equiv/dm³                                                         maximum 10

– iron, mg/dm³                                                                                  0.3 (1.0)

– sulphates, mg/dm³                                                                          maximum 500

         5. Criteria of safety according to chemical composition:

– fluorine, mg/dm³                                                                            0.7-1.5

– nitrates, mg/dm³                                                                             maximum 45.0

– other chemical substances                          within the limits of maximum allowable concentrations (MAC) according to (SSRandN)  № 4630-88.

 

HYGIENIC ESTIMATION OF THE SOIL SANITARY STATE. MODERN HYGIENIC AND BIOETHICAL PROBLEMS OF THE INHABITED PLACES CLEANING.

Basic physical properties and texture of soil

Lithosphere (the earth’s crust) – mineral and organic covering of the Earth, which extends from its surface to magma. It consists of lithosphere itself, which is formed from magma rocks destroyed by physical, physicochemical and chemical processes before beginnings of life on Earth, and soil.

Soil is a surface layer of lithosphere (from few millimeters in mountains and up to 10 kilometers in lowlands), which was formed after beginnings of life on Earth as the result of climate, flora and life (microorganisms and roots of higher plants) influence. Soil consists of the surface or fertile layer (0-25 cm) or humus layer, which is characterized by fertility and which is cultivated at growing plants, and of soil itself.

Soils are very different depending on conditions of their formation, first of all on climate and flora. In Ukraine most common are chernozem (black earth soils) (54.0% of territory), then –– grey forest soils (18.2% of territory) and sod-podsol soils (7.8% of territory).

 

Basic physical properties of soil:

– texture – percentage of soil particles according to their sizes. It is determined by screening through Knopf sieves. There are 7 types (called “numbers”) of such sieves with apertures of different diameters from 0.25 to 10.0 mm (fig. 18.1). Soil texture consists of the following elements: stones and gravel (size > 3 mm); coarse sand (3-1 mm), medium (1-0.25 mm), fine (0.25-0.05 mm); coarse dust (0.05-0.01 mm), medium (0.01-0.005 mm), fine (0.005-0.001 mm); silt (< 0.001 mm). According to texture, soils are classified based on specific weight of physical sand (particles of size > 0.01 mm) and of physical clays (particles of size < 0.01 mm).  (Appendix 3);

– porosity – total volume of pores in the unit of soil volume, which is expressed in percents. The bigger is the size of some elements of soil tissue, i.e. its granularity, the bigger is the size of pores in homogeneous soil. The biggest pores are in rocky soil, smaller ones are in sandy soil, very small pores are in clay soil, and the smallest ones – in peat soil. At that total volume of pores, expressed in percents, increases, i.e. soil porosity is as higher as smaller is the size of some elements of soil tissue. Thus, porosity of sandy soil is 40%, and peat soil – 82%;

Knopf sieves for soil texture analysis

 

– air permeability – soil ability to let air through its thickness. It increases when size of pores is bigger and doesn’t depend on their total volume (porosity);

– water permeability – soil ability to absorb surface water and to let it pass through. Permeability consists of two stages: imbibition, when free pores gradually get filled with water till total saturation of soil and filtration, when, in the result of total water saturation of soil, water starts moving in soil pores because of gravity;

– moisture capacity – amount of moisture, which soil is capable to retain due to sorptive and capillar powers. The smaller is the size of pores and the bigger is their total volume, i. e. porosity – the bigger is the moisture capacity. The finer is soil texture, the higher is its moisture capacity;

– soil capillarity – soil ability to lift water via capillaries from the bottom layers up. The smaller is the size of soil texture particles – the bigger is soil capillarity, but in such soil water goes up higher and slower.

In soils of light texture (sandy, clay sandy, light loamy) compared to heavy soils (clays, heavy loams) physical sand prevails, pores are of the larger size, porosity isn’t high, air and water permeability, filtration capacity are considerable, capillarity and moisture capacity are low. On the one hand, processes of soil bio-decontamination run rather quickly in such soils, on the other hand, migration of chemical substances from soil into ground and surface water reservoirs, ambient air and plants is more considerable.

Soil consists of biotic (soil microorganisms) and abiotic components. Abiotic components include hard substance of soil (mineral and organic compounds and organomineral complexes), soil moisture and soil air.

60––80% of mineral (non-organic) substances of soil are represented by crystalline silica or quartz. The important place among mineral compounds is occupied by alumina-silicates, i.e. feldspar and mica. Also to alumina–silicates belong secondary clayey minerals, i.e. of montmorilonite group (montmorilonite, notronite, beidelite, saconite, hectorite, stevensite). Their hygienic importance is them being the cause of absorbing capacity and volume of cations’ absorption (i.e. heavy metals) by soil.

Beside silica and alumina–silicates, almost all elements of Mendeleyev’s table appear in mineral compound of soil.

Organic substances of soil are represented both by soil organic (humic acids, fulvic acids etc.) compounds, which are created by soil microorganisms and which are called humus, and by strange for soil organic substances, which came into the soil from outside in the result of natural processes and technogenic (anthropogenic) pollution.

Soil moisture can be both in solid and liquid forms, and in the form of vapour. From hygienic point of view of the most interesting is liquid moisture, which can be in forms of: 1) hygroscopic water, which is condensed on the surface of the soil particles; 2) membranous water, which remains on the surface of soil particles; 3) capillary water, which is kept by capillary forces in thin pores of soil; 4) gravity free water, which is influenced by gravity or hydraulic head and fills in soil big pores.

Soil air is a mixture of gases and vapour, which fills in soil pores. According to its composition it differs from atmosphere air and constantly interacts with it by diffusion and concentration gradient. Soil air and water oppose to each other in respect of space in pores. Natural compound of soil air is controlled by oxygen utilization rate and carbon dioxide generation as the result of microbiological processes of mineralization of organic substances. With growth of depth content of carbon dioxide in soil air increases and oxygen content – decreases.

 

HYGIENIC SIGNIFICANCE OF SOIL

 

Soil is:

– the medium, where processes of transformation and soil energy accumulation take place;

– leading member of turnover iature, the medium, in which different complicated processes of destruction and synthesis of organic substances take place continuously;

– main element of biosphere, where processes of migration, transformation and metabolism of all chemical substances both of natural and anthropogenic (technogenic) origin take place. Migration takes place both in short (soil –– plant –– soil, soil –– water –– soil, soil –– air –– soil) and long (soil –– plant –– animal –– soil, soil –– water –– plant –– soil, soil –– water –– plant –– animal –– soil, soil –– air –– water –– plant –– animal –– soil etc.) migration chains;

– forms the chemical structure of foodstuffs of vegetable and animal origin;

– plays an important role in formation of water quality of surface and ground sources of domestic and drinking water-supply;

– affects qualitative structure of contemporary atmosphere;

– of endemic importance – anomalous natural chemical structure of soil in endemic provinces is a reason of rise and local spreading of endemic diseases (geochemical endemic diseases): endemic fluorosis and caries, endemic goiter, foot-and-mouth disease (FMD), molybdenum gout, endemic osteoarthritis or Kashin-Beck disease, endemic cardiomyopathy (Keshan’s disease), selenosis, boric enteritis, endemic nephropathy etc.;

– of epidemic importance – it can be a transmission factor of pathogens of infection diseases and invasions to people: enteric infections of bacterial (typhoid, paratyphoids А and В, bacillary dysentery, cholera, coli-entheritis), viral (virus A hepatitis, enterovirus infections: poliomyelitis, Coxsackie virus infection, ЕСНО) and protozoa ethiology (amebiasis, lambliosis); zooanthroponosis (types of leptospirosis: infectious jaundice or Vasyl’yev – Vail disease, anicteric leptospirosis, brucellosis, tularemia, anthrax); mycobacteria of tuberculosis; spore-forming clostridia – pathogens of tetanus, gas gangrene, botulism; geohelminthosis – ascaridiasis, trichocephalosis, ankylostomiasis.

– the place for liquid and soil domestic and industrial waste disposal due to natural purification processes (soil sanitary significance). Soil natural purification is characterized by presence of saprophytic decomposers, nitrifying and nitrofying bacteria, elemental organisms, larvae, worms, fungi, viruses, coliphages and by its physical–and–chemical properties. It consists in soil capability to transform organic compounds into mineral substances good for plants’ assimilation:  carbohydrates – into water and carbon dioxide; fats– into glycerin and fatty acids and then – also into water and carbon dioxide; proteins – into amino acids with ammonia and ammonia salts evolvement and their further oxidation to nitrites and nitrates; protein sulfur – into hydrogen sulfide etc.

 

Sanitary purification of settlements

It is a set of measures that provide for the fulfillment of hygienic requirements during arrangement and exploitation of equipment and facilities that are meant for collecting, temporary keeping, transportation, destruction and utilization of solid and liquid domestic and industrial waste.

Waste – these are remains of substances and articles that have been created as the result of domestic, economic and industrial human activity, and cannot be used at the scene of their creation so that their accumulation and keeping make the sanitary condition of the environment worse. They are divided into liquid: 1) sewage from cesspool toilets; 2) slops (from cooking and dish and floor washing etc.) and 3) waste waters: domestic, industrial, runoffs, municipal waste water and solid: 1) garbage (domestic refuse); 2) rubbish (kitchen waste products); 3) waste from patient care and prophylaxis institutions (including specific ones –– used dressing, used disposable autotransfusers and syringes, remains of medicines, remains of organs and tissues after surgical operations, dead bodies of laboratory animals etc.); 4) institutional waste (schools, preschool institutions, high schools and academies, offices, etc; 5) waste of public catering establishments; 6) waste of animal origin (dead bodies of animals, pus, forfeit foodstuff); 7) waste of commercial facilities; 8) industrial waste; 9) slags from boiler houses; 10) construction waste, urban soil; 11) street sweepings.

There are three different systems of waste disposal: “flushing” removal, “pick-up” removal and combined removal.

Flushing system is used in the settlements, which are provided with sewerage (pipe) system through which liquid and partially fine solid waste float to waste disposal plants; the rest of solid waste is removed by special motor transport.

Pick-up system is used in the settlements without sewerage systems. At that both liquid and solid domestic waste (SDW) is removed to areas of disposal and utilization by special motor transport. Such method of disposal of solid waste is called purification, and of liquid wastes – sanitation.

Combined system is used in the settlements that are partially provided with sewerage system. According to combined system liquid waste from the part of settlement, provided with sewerage system, is removed through this system, and from the part of the settlement where there is no sewerage system – with the help of cesspoolage transport. All solid waste is removed by sanitary purification transport.

Sanitary purification of settlement must be systematic (to be performed according to agreed plan and schedule), regular (waste removal in warm season – daily, in cold season – once per 1-3 days), utility (to be performed by utilities and community services, or trusts) and to be independent from wishes of some officials or institutions. It consists of three stages: I –– collection and temporary keeping of solid domestic waste; II –– removal; III –– disposal and treatment.

Collection, removal (transportation) of solid domestic wastes. In case of neighbourhood-based system SDW is collected into special dustbins that are located at specially arranged plots on the territory near the houses and later on, according to the schedule, it is removed by special motor transport to the place of disposal. In case of door-to-door-based system waste is collected in apartments. At the certain time inhabitants take it out to a dust–cart. There are two different methods used in case of neighbourhood-based system – method of “fixed” container (waste from dustbins is emptied into dust–carts and dustbins are placed back) and method of “disposeable” container (dustbins together with solid waste are removed by dust-carts to waste disposal places, while empty and clean dustbins are left instead of the used ones).

For garbage and other solid waste removal special motor cars – dust–carts ‑ are used. For method of “fixed” container they use dust–carts 93/М, 53/М, КО-404, КО-413 etc., for method of “ disposeable ” container – dust–carts М-30. They are mounted on the chassis of the trucks GAZ-93а, GAZ -53, MAZ -500А.

Solid domestic waste disposal. All methods of SDW disposal have to meet the following basic hygienic requirements:

– they must provide reliable disposal, transformation of waste into harmless from epidemic and sanitary point of view substrate. From epidemic point of view solid domestic waste is very dangerous: when titer is 10^-6-10^-7, titer of anaerobes is – 10^-5-10^-6, microbial number achieves tens and hundreds of billions, contains pathogenic and conditionally pathogenic bacteria, viruses, eggs of helminthes. Especially dangerous is waste from patient care and prophylaxis institutions, which is approximately 10-100 times more contaminated by microorganisms than domestic waste;

– quickness – ideal method is the one that makes possible effective waste disposal during the same period of time in which the waste is formed;

– they must prevent laying eggs and larvae and chrysalides development of flies (Musca domestica) both in waste during its disposal and in substrate, which was obtained in the result of the disposal;

– they must prevent access of rodents during waste disposal and to convert waste into unfavourable for their life and development substrate;

– they must prevent air pollution by volatile products of demolition of organic substances (SDW contain up to 80 % of organic substances, 20-30 % of which easily rot in summer and at the same time evolve stinking gases: hydrogen sulphide, indole, skatole and mercaptans);

– in the process of waste disposal neither surface nor ground waters may be polluted;

– they must provide the best and safe for people’s health use of SDW properties, because they contain up to 6% of utilizable waste; by its burn one can receive heat energy, by biothermal treatment –– organic fertilizers, and food waste may be used for cattle feeding.

According to the final result methods of SDW disposal are divided into: utilizing (waste processing into organic fertilizers, biological fuel, separation of secondary raw materials, e. g. scrap metal, for industry, use as a power–plant fuel) and liquidation (land disposal, sea disposal, incineration without help of heat). According to technological principle methods of disposal are divided into: 1) biothermal (plough-lands, improved dumps, waste store grounds, waste composting fields, bio–chambers, plants for biothermal treatment; in rural area in farms –– compost heaps, hotbeds); 2) thermal (combustion plants without or with utilization of heat energy, which is created in the result of this process; pyrolysis leading to formation of fuel gas and similar to mineral oil – lubricating oil); 3) chemical (hydrolysis); 4) mechanical (waste separation with further utilization,  pressing into construction blocks); 5) combined.

Most widely used are biothermal methods. They are based on the complicated processes of soil natural organic purification from pollutants that may be represented in diagram:

 

Biothermal disposal makes it possible to solve two tasks: 1) to decompose complex organic matters of waste and its metabolism products (urea, uric acid etc.) into simpler compounds in order to synthesize by special microorganisms in presence of ambient air a new, stable, safe from sanitary point of view substance, called humus; 2) to destroy vegetative forms of pathogen and conditionally pathogenic bacteria, viruses, protozoa, eggs of helminthes, eggs and larvae of flies, seeds of weeds.

Efficiency of biothermal method of waste disposal depends on:

– aeration of waste (it is necessary to fan 25 air volumes for 1 volume of SDW);

– waste moisture (if moisture < 30 %, SDW must be moistened artificially; if > 70 %, it is necessary to install  devices for its lessening);

– content of organic substances in waste that are capable to rot easily (mustn’t be  < 30 %, in the ration of carbon to nitrogen 30:1), and inorganic compounds (less than 25 %);

– waste particles’ size (optimal size is 25-35 mm);

– waste active reaction (рН) (optimal рН is 6.5-7.6);

– degree of output contamination by mesophilic and thermophilic microorganisms (artificial inoculation is carried out for stimulation of purification);

– thermal conditions (more quickly temperature will rise in the thickness of waste, better and more reliable biochemical destruction of organic substances and pathogenic microflora will be).

Sanitary inspection of systems of waste collection, transportation and disposal requires objective assessment of their efficiency, which is impossible without territory sanitary survey, soil sampling and its laboratory analysis.

Methods of land parcel sanitary inspection and soil sampling

Sanitary inspection of the land parcel includes:

– definition of ground assignment (territory of a hospital, preschool institutions, schools, industrial enterprises, objects of waste disposal of domestic, industrial, construction origin, etc);

– visual inspection of the parcel, determination of character and location of sources of soil pollution (distance), relief, drain direction of precipitation waters, flow direction of ground waters;

– determination of soil texture (sand , clay sand, loamy soil, chernozem);

– determination of points for soil sampling for analysis: places near the source of pollution and near test area of known clean soil (at a distance of this source).

Samples are taken by “envelope” technique on rectangular or square areas of 10×20 meters or more. In each of five sampling points of the “envelope” 1 kg of soil is taken from the depth of 20 cm for samples. An average sample of 1 kg mass is prepared from taken samples.

Each taken sample is accompanied by a covering letter, which includes information about place, address and assignment of the parcel, soil type, relief, ditch level of subterranean waters, goal and volume of the analysis, inspection results received at the place, date and time of sampling, weather of previous 4-5 days, who took a sample, his signature. Samples are packed into closed glassware and polyethylene bags.

Criteria of soil sanitary state

 

All indices are divided into direct (allow to assess the level of soil contamination and level of danger for population health directly from the results of laboratory analysis of taken samples /Appendix 3/) and indirect (allow to draw a conclusion of the existence of soil contamination, its prescription and duration by comparison of the results of soil laboratory analysis with test clean soil of the same type, which was taken as a sample from non-contaminated areas).

Sanitary number of Khlebnikoff – is a ratio of humus nitrogen (pure soil organic substance) to total organic nitrogen (consists of humus nitrogen and nitrogen of strange for soil organic substances that contaminate it). If soil is pure, sanitary number of Khlebnikoff equals to 0.98-1.

Soil coli–titer – is a minimal amount of soil in grammas, in which one bacteria of colibacillus group is found.

Soil anaerobe titer (perfingens–titer) – is a minimal amount of wastes in grammas, in which an anaerobic clostridia is found.

Soil microbial number – is a number of microorganisms in one gram of soil that grew up on 1.5% beef-extract agar at temperature 37⁰С during 24 hours.

 

Soil classification according to texture (according to N.А. Kachinskiy)

 

 

Filtration capability of soils of different texture

 

A hole of 0.3×0.3 m in diameter and 0.15 m in depth is dug and quickly filled up with water (12.5 dm³). With the help of chronometer the period of absorption is timed.

 

Scale for assessment of sanitary state of soil*

*Under condition of soil sampling in the depth of 0-20 cm.

 

 

Assessment of soil sanitary state according to chemical analysis of soil air

 

 

Assessment guide scale of the population health state in dependence on soil contamination levels by exogenic chemical substances (ЕCS)

 

Technique of hygienic assessment of sanitary state of soil

When drawing a report on hygienic assessment of sanitary condition of soil it is reasonable to use a scheme (algorithm) that provides for the following 6 stages:

І –  goal and task are determined. Thus it is necessary to state a hygienic value of sanitary condition of natural soil at the time of the assignment of the parcel for new settlement construction. During the regular sanitary inspection it is necessary to assess the sanitary condition of artificially created soil on the ground areas for residential and public building, playgrounds for children and sport grounds. When the epidemic situation is unfavorable, it is necessary to find out if soil is a factor in spreading pathogenic microorganisms. Sometimes, when investigating cases of acute and chronic poisonings it’s necessary to determine the level of soil contamination by toxic chemical substances (pesticides, heavy metals etc.). Sanitary condition of soil may be studied in order to assess the efficiency of sanitary purification of the settlement territory, during the regular sanitary inspection of sewage disposal plant and facilities of utilization and extermination of SDW in order of assessment of their work efficiency.

II – according to set tasks a required extent of examinations is set. Thus, during the hygienic assessment of natural soil of the ground areas assigned for new settlement construction, complete sanitary analysis of every index of sanitary condition is required. During the hygienic assessment of artificially created soil of settlements, in case of favorable epidemic situation, it is reasonable to carry out examinations by sanitary analysis reduced scheme: determination of total and hygroscopic moisture, Khlebnikoff’s sanitary number, chlorides, soil oxidation, microbial number, titer of coli-group bacteria, anaerobe titer, number of eggs of helminthes, number of larvae and chrysalides of flies. In case of unfavorable epidemic situation it is important to include tests on presence of pathogenic bacteria and viruses into reduced sanitary analysis. When investigating cases of acute and chronic poisonings for the assessment of the level of soil contamination by chemical poisonous substances it is sufficient to determine texture of soil, total and hygroscopic moisture and content of hazardous substances: pesticides, heavy metals, arsenic etc. (Appendices 4, 5).

III – completeness of presented materials and availability of sanitary examination data are controlled, soil sampling schemes, methods of their preliminary analysis, time constraints of analysis, soil samples’ keeping are assessed, availability of soil laboratory analysis results in accordance to the required research program are controlled.

IV – sanitary examination results are analyzed: а) sanitary–topographical characteristic of the area; b) sanitary-technical characteristic of the objects that influence condition of the area; c) sanitary-epidemic situation. Preliminary conclusion concerning grounds for suspicion that soil can be contaminated by exogenic chemical substances or being a factor of spreading infections is drawn.

V – laboratory results of soil analysis are assessed according to all data, that are required by examination program. According to indirect indices based on comparing the examined and test (“pure”) soil one, conclusion about the fact of existence, prescription and durability of contamination is drawn. According to direct indices, based on sanitary assessment of the condition of soil (Appendices 4, 5), level of soil contamination and stage of its danger for the population health is assessed.

VI – general conclusion about sanitary condition of soil, stage of its contamination and danger for the population health is drawn, future soil pollution effect on population health depending on its levels is forecasted (Appendix 6), preventive measures of  further deterioration of sanitary state of soil and ways of its improvement are offered.

 

A METHOD OF CALCULATION OF HUMAN’S ENERGY LOSSES AND REQUIREMENTS IN THE NUTRIENTS (OR FOOD SUBSTANCE).  NORMS OF HUMAN’S PHYSIOLOGY REQUIREMENTS IN THE MAIN FOOD COMPONENTS AND ENERGY.

Calculation methods of determination of dietary intake energy value and nutrient composition

The balance and budget methods of nutrition research are based on the nutrition appropriations for organized collectives or family, individual profits and allow to assess the group nutrition only approximately.

The questionnaire, weight methods allow to determine the quantity of used nutrients more exactly, but these methods don’t also give a possibility to assess the daily intake quantitative composition.

The laboratory methods of determination of the daily intake energy value and nutrients are more accurate, but require the complicated and long–lasting research and considerable expenses. That is why these methods caot be used systematically during medical control of nutrition for different population groups.

The calculation methods are very accurate, available for the permanent systematic medical control of nutrition for different population groups, don’t need additional expenses and too much time for calculation if the technical calculation devices are available.

The following data are required for the assessment of the actual nutrition of organized collectives using the calculative methods:

– physiological norms of nutrition with scientific background and designed for different population groups;

– based on this data, the food menu schedule (the nutrition plan for collective) usually for a week is worked out;

– tables of food products chemical composition – reference source about energy value and nutrients for each food product.

The need in the variety of nutrition and its daily sufficiency have to be taken into consideration during the design of the menu schedule. The daily sufficiency is assessed by the multiplication of the one-day quantity of each food product (except daily equally used products, e.g. bread) by 7 days. After that different meals are planed for the whole week. The same meal has not to be repeated more than three times per week in this case.

E.g. the one–day norm of cereals is 40 g, macaroni – 60 g. It is 280 g and 420 g respectively per week. It allows to plan different meals for different days. The variety of nutrition and prevention of the monotonous intake may be reached by this.

The duties of the doctor responsible for medical monitoring of the nutrition in a certain collective during the formation of the menu schedule include:

– the assessment of meals in respect to the energy value and nutrient composition – proteins, fats, carbohydrates, vitamins, mineral and flavoring agents/substances;

– providing the variety of meals during the week;

– control of the adequate replacement of certain food substances because of their absence;

– correct registration of food products waste (which is adjusted in special tables);

– even distribution of meals and certain food products according to their energy and nutrient content by the different food intakes and other.

The energy value and nutrient composition of each product in accordance to the menu schedule is calculated by proportion using “Tables of food products chemical composition” (appendix 3) on which all the food substances and their caloricity per 100 g of product are presented.

The quantity of proteins and fats is calculated separately, or only the quantity of animal proteins is determined for the animal and vegetable food substances ratio calculation. The quantity of vegetable proteins is then found by substracting the quantity of animal proteins from the general protein quantity.

The daily intake distribution by separate food intakes is determined in percentage according to its energy value. The following distribution is recommended for three meals per day: 30% of the value for breakfast, 40-45% – for lunch, 20-25% – for dinner. The second breakfast with 10-12% of value, including a part of the first breakfast and a part of dinner is added in case of four meals per day.

Such main aspects have to be represented in the conclusion about the assessment of the collective nutrition:

1) Adequacy of the energy value and all food substance quantities (proteins, fats, carbohydrates, vitamins, mineral substances, microelements) to the energy expenditure, physiological need in them (calculated by the students on the previous lesson) and norms of nutrition (see appendix 2 next lesson).

2) Adequacy of the ratio between the vegetable and animal proteins and fats, polysaccharides and disaccharides to the physiological need. As mentioned above based on their energy value the animal proteins have to constitute no less than 55%, the vegetable fats – no less than 30%, mono-, disaccharides – no more than 18-20% of their general quantity according to the physiological norms.

3) The vitamin sufficiency in the intake, correct ratio between the vitamin A and carotene considering their inevitable loss during food products culinary processing.

4) The mineral substances especially Са, Р and their ratio, Fe, and microelements sufficiency. Spices and flavoring agents presence.

5) The repeating of meals during the week (the variety of nutrition).

6) Based on the discovered defects the recommendations for optimization of products menu are made considering the foreseen changes in physical activity of controlled collective.

Calculation results of the dietary intake nutrient composition and energy value according to the menu schedule are put into the table (appendix 2) for convenience of analyses.

Peculiarities of requirements for nutrients and energy of different age groups, occupations, gender and physical status people

 

1.     Peculiarities of the children and adolescents nutrition

In view of body growth and development children of different age groups require relatively bigger amount of plastic nutrients, first of all proteins, mineral salts, more fats, carbohydrates – the energy sources, and also the catalytic substances – vitamins, microelements as the metabolism of the growing organism is far more intensive.

If an adult requires 1.5 g of proteins per 1 kg of his body weight, a child before 1 year of age – more than 4 g/kg, 1-3 years of age – 3.8-4 g/kg, 4-6 years of age – 3.5 g/kg, 7-10 – 3.0 g/kg and so on. Moreover, 60-75 % of all proteins should be of animal origin with obligatory contain of milk and milk products in the diet.

The general amount of nutrients and their daily energy value for children and different age groups adolescents are given in the “Norms of the physiological requirements of the Ukrainian population for the essential nutrients and energy”, № 272-99 (see Appendix 2, № 1,2,3). It becomes clear from these Norms that the absolute amount of nutrients and their energy value increases, thus, from the calculation of body mass unit it naturally decreases, approaching to the norm of adult population.

 

2.     Peculiarities of the geriatric people nutrition

This category of population has the decreased metabolism intensity, decreased physical activity and workload, these people usually suffer from development of different geriatric diseases or their complex; therefore the requirement for nutrients and energy also gradually decreases, all this is taken into account in the same “Norms of the physiological requirements of the Ukrainian population for the essential nutrients and energy”, № 272-99 (see Appendix 2, № 13).

As it can be understood from these Norms, the content of mineral salts and the majority of vitamins remains the same in the daily ration; it is connected with the necessity of the skeleton calcination (bone fragility increases with age) and the support of catalytic substances (enzymes, hormones) at the same level as their synthesis also decreases at this age.

 

3.     Peculiarities of nutrition of people involved in mental and physical activity with different level of emotional and physical stress

People involved in mental and operating activity usually work in conditions of hypodynamia. It influences their health and body resistance to different diseases unfavorably. Therefore for the purpose of these diseases prophylaxis, it is recommended, that these people are engaged in permanent physical training. But not all people can afford it because they need subjective will stimulus and extra time.

Energy value and content of proteins, fats and carbohydrates for this adult working population group is far lower than for people involved in physical activity. But the content of mineral salts and the majority of vitamins remains the same as for the previous group. It can be explained by the fact that mental activity needs enough enzymes and hormones, the synthesis of which is connected with the supply of the body with full-value proteins, mineral salts, microelements and vitamins.

People involved in physical activity or sportsmen who expend more muscular energy related to the hardness and intensity of their work (or training) require more proteins, fats, carbohydrates and also energy in the diet according to the groups of physical work intensity (see Appendix 2, № 5,7).

 

4.     The dietary nutrition peculiarities of people with different nosological forms of diseases

The dietology course suggests 15 (with same variations) worked out and scientifically substantiated diets for different nosological groups of diseases. These diets differ in the products variety and the way of their cooking.

The main peculiarity of the nutrients composition of these diets is the same or even increased content of proteins (up to 100-120 g) except such diseases as gout, urine acid diathesis, glomerulonephritis etc. The amount of fats and carbohydrates usually is decreased, but the content of mineral substances, microelements, vitamins remains the same and in case of some diseases like infectious ones – increased, as a part of them is wasted with perspiration.

In detail the patients’ nutrition is studied in the course of diet therapy.