METHODICAL INSTRUCTION FOR STUDENTS OF THE 3 COURSE

MEDICAL FACULTY

LESSON # 4 (PRACTICAL – 6 HOURS)

Themes:  

1. Hygiene of water and water-supply. Technique of the sanitary inspection of the water supply sources and water sampling for bacteriological and sanitary and chemical analysis. Method of hygienic assessment of drinking water according to the results of the sanitary inspection of water supply systems and results of laboratory analysis of samples – 3 hours.

2. Methods and means of the water purification and disinfection on centralized and decentralized water supply. – 3 hours.

 

Aim:

1.       To learn the methods of estimation of organoleptic properties and chemical water compound.

2. To know the methods of cleaning and disinfecting of water.

3. To master the methods of the determination of active chlorine content in chlorine lime and the   chlorine’s need of water.

4. To estimate modern hygienic demands to the organisation of water supply for population.

5. To learn the rules of taking water samples from different sources.

6. To estimate quality of potable water using the results of its laboratory tests and its conformity to standards  “The potable water”.

 

PROFESSIONAL ORIENTATION OF STUDENTS

Without water there would have beeo life. Water plays an important role in life of people. It satisfies their physiological, sanitary-hygienic household needs. But water can also have negative influence on human organism if it has unfavorable organoleptic properties, chemical compound or pathogenous microorganisms and helminthes’ eggs. Water must answer to demands, which are established in state standards, norms and rules.

 Natural water, as a rule, consists of different kinds of admixtures of natural and antropogenic origin, which can worsen water quality and be dangerous for people’s health. It is important to make water quality better. The most spread methods of disinfection are different methods of chlorination. The application of different water improving quality methods enables to use maximum of district’s water resources and to provide the population with good-quality drinkable water. In modern conditions according to significant water supply of large cities there is a necessity in speeded up cleaning of water. Acceleration of hanging particles precipitation, elimination of color of water and improving of filtration takes place in presence of coagulant.

The population should be provided not only with enough of water, but also with qualitative water. Water should not cause any pathological change in the organism, should not cause of spread of infectious diseases, and also not to cause unpleasant sensations.The potable water must conform to requirements of standard “The potable water”.

      

    METHODOLOGY OF PRACTICAL CLASS (9⁰⁰-12⁰⁰ hour).

Theme № 1. Hygiene of water and water-supply. Technique of the sanitary inspection of the water supply sources and water sampling for bacteriological and sanitary and chemical analysis. Method of hygienic assessment of drinking water according to the results of the sanitary inspection of water supply systems and results of laboratory analysis of samples

 

Work 1. Organoleptic valuation of water

         Definition of transparency of water.

 Examined water pour into the glass and watch on white background. Determine the level of transparence: water transparent, a little turbid, and turbid.

         Quantitative valuation of transparency can be done using Snelen’s type №1 (to read special print through layer of water). Water is concerned transparent if it is possible to read of print clearly through 30 cm layer of water. Transparence of water depends on quantity of the turbid substances. Turbidity of drinking water must not exceed 1,5 mg/dm³.

         Determination of coloring of water.

 Color of water is determined simultaneously with determining of water transparency. Determine whether the water is colorless, hardly is appreciable yellowish, light yellow, yellowish, yellow, watching the water in the glass form the side.

         Quantitatively intensity of water colouring is determined by comparing with chrome-cobalt scale and is expressed in degrees of colouring. Natural water should have colouring not more than 20⁰. 

         Determining of smell of water.

 Flask with 100 сm³ of investigated water close by a fuse and overturn several times, then open and determine character and intensity of the smell.

         Character of water smell determine on the basis of sensation of a smell, which is perceived (ground, chloric, petroleum etc.). Intensity of smell determine according to special 5 mark scale (0 point – absence of a smell; 1 point – smell is not felt by consumer, but is found out at laboratory examination; 2 point – weak smell is felt if an attention is paid on it; 3 point – appreciable smell; 4 points – the expressive smell that makes water unsuitable for using; 5 points – rather strong smell). According to the demands of state standard water smell should not exceed 2 points. Heating of water can strengthen its smell.

         Method of determining of smell intensity in points can be used on the 1^st stage of laboratory research of quality of drinking water, water from sources of water supplying and reservoirs of recreationary water using.

         Size of dilution in water can be determines on the 2^nd stage. In this case for the dilution the same investigated water is used, but previously released from the smell. With this purpose water is poured with the speed 0.25 dm³/minute through columns with carbon activated. Directly before the investigation 200, 135, 65, 50, 33, 25, 20 sm³ of investigated water is poured into a series of flasks, which are carefully washed up by water without a smell. The volume of liquid is increased to 200 sm³ by dechlorated water. Flasks with a liquid are heated up to 20 degrees centigrade, then are shaken up and them determine in which flask starting from the smallest dilution smell reaching a threshold is felt. This concentration is accepted for threshold and is registrated. For the investigation at 60 degrees centigrade samples are diluted separately, covered with clock glass and located into water bath with water temperature 60 degrees centigrade.

Scale of dilutions for rough definition of dilution threshold

        

 At research of water with an intensive smell (smell is found out already in dilution 20:80). It is necessary to investigate the further dilutions.

Determining taste of water.

         Determination taste of water is made only in rendered (harmless) water or obviously pure water at temperature 20 degrees centigrade. In doubtful cases water is boiled in flask, then cooled till room temperature taken into mouth by small portion for 3-5 seconds, but not swallow. Determine character of taste and aftertaste (salty, bitter, ferruterous, metal, tart etc.) and its intensity in points, using 5-point scale. According to demands of state standard intensity of taste and aftertaste must not exceed 2 points.  

Determination of water temperature

         Temperature of water is measured directly in water source while taking samples by immersing in water mercury thermometer in metal frame, which has divisions on 0,10⁰С. Temperature on depth, is measured with the help of thermometer, which is situated inside of bathometer. 

Work 2.

Chemical methods of estimation of water quality

         Determination of ammonia and salts of ammonia

         The definition is based on ability of ammonia and salts of ammonia to form the painted connections (yellow colour) with Nessler’s reactive. Pour into flask 10 cm³ of investigated water, add 5 drops of 50 % solution of Seignette salt and 4 drops of Nessler’s reactive. If ammonia is present, colour will appear in 5 minutes. Determine approximately concentration of salts of ammonia according to intensity of coloring which has arisen using a table.

Approached definition of salts of ammonia in water

Concentration of salts of ammonia must not exceed 0.1 mg/dm³

The determination of nitrites

         The determination of nitrites is based on interaction of nitrites with Griss’ reactive, therefore is formed connection painted from pink up to intensively red colour. Pour 10 sm³ of examined water and add 0.5 sm³ or several crystals of Griss’ reactive. After 20 minutes determine the concentration of nitrites in water according to intensity of painting using a table.  

 

The concentration of nitrites in drinking water should not exceed 0.002 mg/dm³ .

The concentration of nitrates in drinking water should not exceed 40 mg/dm³ (at account oitrogen of nitrates – 10 mg/dm³). 

        

Determination of sulphates

Pour into tube 5 sm³ of researched water, at 5 drops (1:5) chloric acid and several drops of 10 % solution of barium chloride. The occurrence of white turbidity specifies the contents in water of salts of sulphuric acid.

 The concentration of sulphates in drinking water should not exceed 250 (500) mg/dm³ .

 

Determination of chlorides

Qualitative determination of Cl^–. In the colorimetric tube pour 5 ml of water and add three drops of silver nitrate solution with a mass fraction of 10%. Approximate chloride ion content is determined by precipitation or turbidity in accordance with the requirements of table

Table

 Qualitative determination of chlorides in the water 

The concentration of chlorides in drinking water should not exceed 250 (350) mg/dm³ 

 

Determination of iron

Pour 10 sm³ of researched water into flask. Add several drops of hydrochloric acid and 10% ammonium rhodanide, mix. Occurrence of red colouring specifies presence of salts of iron in water.

 

Concentration of iron in water should not exceed 0.3 mg/dm³.

 

Theme № 2. Methods and means of the water purification and disinfection on centralized and decentralized water supply

Work 1.

 The determination of content of active chlorine in 1 % solution of chloric lime .

The method is based on the ability of active chlorine to supersede the equivalent quantity of iodine from a solution of potassium iodide. Ousted iodine is being titrated by hyposulfite.

For the analysis prepare average test of the lime chloride by careful hashing of several tests taken from different places of a vessel with lime chloride. Then 3,55 g of average test of the chloride of lime is being pounded with small quantity of distilled water, and then leads up in measuring flask by distilled water up to 1L, where it is being left up to the enlightenment.

In measuring flask to 50 ml of distilled water add 10 ml of the clarified solution of the chloric lime, 5 ml of 10% solution of potassium iodide and 5 ml of a solution of a hydrochloric acid (1 : 5). In 5 minutes ousted iodine is being titration by 0,01normal solution of hyposulphite before occurrence of pale yellow coloring, then add 1 ml of 0,5 % solution of starch and continue to titration till the disappearance of dark blue coloring. 1 ml of 0,01normal solution of hyposulphite connects 1,269 mg of iodine, which corresponds to 0,355 mg of chlorine. The quantity of 0,01normal solution of hyposulphite Na (ml), spent on titration, corresponds to the percentage contents of active chlorine in a researched sample of the chloric lime .

It is inexpedient to use lime chloride with the contents of active chlorine less than 20% for the decontamination of water.

Work 2.

 Determination of the chlorine’s need of water

In the field conditions the choice of the doze of chlorine will be carried out by a three-glass test. 2 drops, 4 drops, 6 drops of 1 % solution of the lime chloride bring by a special pipette (1 ml = 25 drops) to three glasses with 200 ml of water accordingly. After that mix and leave for 30 minutes. Then to each glass add 5 ml of 10 % solution of potassium iodide, 5 ml of a solution of hydrochloric acid (1:5) and 1ml of 0,5 % solution of starch. The occurrence of light-blue coloring testifies to presence of residual chlorine at the researched water.

For definition of quantity of residual chlorine the researched water is being titrated by 0,01normal solution of hyposulfite till the disappearance of colouring. The content of residual chlorine (mg/l) in researched water one can define by using this formula:

А = 0,355 x а x К x 5,

Where a – the quantity of 0,01normal solution of hypo sulfite spent on titration of 200 ml of water, ml; К – correction factor to a titer of hyposulfite (0,96).

The need of water in chlorine is equal to that doze of chlorine, after the addition of which the residual chlorine in the researched water makes 0,3-0,5mg/l.

The technique of work and all calculations are written in the protocols of the researches. In the end the student should prove a conclusion:

а) about the opportunity of the use of lime chloride for the decontamination of water;

b) About the amount of the need of researched water in chlorine;

c) Necessary quantity of 1 % solution and dry lime chloride for the decontamination of 1 dm³ of water.

Work 3.

 Methods of water clearing, decontaminating of water centralize and decentralize of water supply.

To decide a situational problem from estimation of potable water quality with allowance of sanitary-and-technical and sanitary-and-topographic data, findings of physical, chemical, bacteriological analysis. To compare reduced with parameters of standards ”Potable water”. Give conclusion about grade and nature of contamination of water. 

 

INDIVIDUAL STUDENTS PROGRAM

Theme № 1. Hygiene of water and water-supply. Technique of the sanitary inspection of the water supply sources and water sampling for bacteriological and sanitary and chemical analysis. Method of hygienic assessment of drinking water according to the results of the sanitary inspection of water supply systems and results of laboratory analysis of samples – 3 hours.

Control questions:

1.     Physiological, sanitary-hygienic, economic-technical and epidemiological importance of water and norms of water supplying for population.

2.     Rules of taking water samples from different sources.

3.     Organoleptic indexes of water quality, methods of their qualitative analysis, hygienic norms.

4.     Sanitary-hygienic importance of nitrogen-containing substances, methods of their qualitative analysis.

5.     Sanitary-hygienic importance of iron sulphates, methods of their qualitative analysis.

6.     Sanitary-hygienic importance of water oxidation and biochemical consumption of oxygen, methods of investigation.

7.     Influence of water microelements on health of population.

8.     Self-clearing of reservoirs.

9.     Hygienic requirements to quality of potable water.

10. Characteristic of the underground waters.

11. Characteristic of the superficial waters (open reservoirs).

12. Zones of sanitary protection, opened and underground springs of water supply.

 

Theme № 2. Methods and means of the water purification and disinfection on centralized and decentralized water supply – 3 hours.

 

1.     Hygienic characteristic of the methods of the improvement quality of water.

2.     Chemical methods of water disinfection.

3.     Characteristic of the chloric lime: reception, structure, active part. The mechanism of the bactericidal action of chloric lime.

7.     Give the definition of the notion “chlorine absorption of water”, “the need of chlorine”, “residual chlorine”.

8.     The technique of chlorination of water by normal dozes.

4.     Hygienic characteristics of basic water quality improving methods.

5.     Clearing and discoloration of water.

6.     Natural settling and sluggish filtrating of water.

7.     Coagulating, settling and fast filtrating of water.

8.     Express methods of water quality improving

9.     Requirements of a well and disinfection of well

10. Disinfection of water at centralized water supply.

 

SEMINAR DISCUSSION OF THEORETICAL ISSUES (12³⁰ – 14⁰⁰ hour).

1.     Physiological, sanitary-hygienic, economic-technical and epidemiological importance of water and norms of water supplying for population.

2.     Rules of taking water samples from different sources.

3.     Organoleptic indexes of water quality, methods of their qualitative analysis, hygienic norms.

4.     Sanitary-hygienic importance of nitrogen-containing substances, methods of their qualitative analysis.

5.     Sanitary-hygienic importance of iron sulphates, methods of their qualitative analysis.

6.     Sanitary-hygienic importance of water oxidation and biochemical consumption of oxygen, methods of investigation.

7.     Influence of water microelements on health of population.

8.     Self-clearing of reservoirs.

9.     Hygienic requirements to quality of potable water.

10. Characteristic of the underground waters.

11. Characteristic of the superficial waters (open reservoirs).

12. Zones of sanitary protection, opened and underground springs of water supply.

13. Hygienic characteristic of the methods of the improvement quality of water.

14. Chemical methods of water disinfection.

15. Characteristic of the chloric lime: reception, structure, active part. The mechanism of the bactericidal action of chloric lime.

16. Give the definition of the notion “chlorine absorption of water”, “the need of chlorine”, “residual chlorine”.

17. The technique of chlorination of water by normal dozes.

18. Hygienic characteristics of basic water quality improving methods.

19. Clearing and discoloration of water.

20. Natural settling and sluggish filtrating of water.

21. Coagulating, settling and fast filtrating of water.

22. Express methods of water quality improving

23. Requirements of a well and disinfection of well

24. Disinfection of water at centralized water supply.

 

TEST EVALUATION AND SITUATIONAL TASKS

TEST QUESTIONS:

1. Unit of measurement measure transparency of water is

A.   degree;

B.    centimetres;

C.   percent;

D.   mg equ/l;

E.    dm³.

2. Name the organoleptic indexes of water quality:

A.   ammonium;

B.    smell;  

C.   nitrates;

D.   sulphates

E.    arsenium; 

3.     How many zones of sanitary preservation   are to be set round the place of water supply for a city from a river?

A.   One.

B.    Two.

C.   Three.

D.   Four.

E.    Five.

4. The concentration of  sulphates in drinking water should not exceed

A.   100 mg/l;

B.    250 mg/l; 

C.   150 mg/l;

D.   40 mg/;.

E.    0,4 mg/l.

5. Superficial waters are characterized by…

A.   high mineralization;

B.    high oxidity and colority;

C.   constant chemical composition;

D.   constant temrerature;

E.    absent patigenic organizms

6. What disease can cause surplus of fluorine in water (more 1,5 mg/dm³ )?

    А. Caries

    В. fluorosis;

    С. Stomatyt.

    D. Gingivitis.

    E. Osteoporoz.

SITUATIONAL TASKS

Task№1

          Water from mining wells contains 20 mg/dm³ of nitrates. Is it possible to use such water for cooking milk mixture for children artificial feeding (indexes of epidemiological safety satisfies hygienic norms)?

        

Task №2.

         Water from trumpet-well contains:

– Transparency more than 30 cm;

– Colouring 4⁰;

– Smell – 1 point;

– Taste – 2 points;

– Index coli form bacteria – 2 CFU/dm³

– General microbe index – 35 CFU/ cm³.

Is it possible to use such water for drinking?

                  

Task 3. On the titration of 5 sm³ of 1% solution of the lime chloride it was spent 35,2 sm³ of 0,01 normal solution of natrium hyposulfite with the correction factor 0,96. To determine the content of active chlorine in the lime chloride, to give the recommendations concerning its use with the purpose of the decontamination of water.

Task 4. As a result of the performance of the three-glass test it was determined, that the absorption of chlorine of water makes 1,4 sm³. What is the need of water for chlorine?

Task 5.  For the decontamination of 1 ton of water it is necessary 1,5 dm³ of 1 % solution of lime chloride. How much dry lime chloride is necessary to take for this purpose?

Task 6 To provide water disinfection by overchlorination using method of weight doses and 1 % solution of chloride lime. How much  (in cm³) do we need to add to 1 dm³ of water?

Task 7.  It was used 18 drops of 0,7 % solution of sodium hyposulphite on titration of 500 cm³ of rechlorinated water. How much free chlorine left in each liter of water?

Task 8.  In chlorinated water there were found 3,44 mg/dm³ of chlorine residue. Give recommendations for making water quality better.

Task № 9.

Decide by self-testing a problem:

1.Sanitary-and –topographic data: The water source is placed near mounting into 3 km from settlement and 100m from field condition.

2.Sanitary-and-technical data

    The source has no captage . The water is picked from natural channel.

3.The physical analysis of water:

    Transparency – 35 cm;    Smell – 2 balls;    Colouring – 5⁰ ;   Taste – 2 balls

4.Chemical analysis:

Nitrogen of ammonia –0,3 mg/dm³

Nitrogen of nitrites – remains

Nitrogen of nitrates – 60 mg/dm³

The sulphates – 200 mg/dm³

The iron – 0,2 mg/dm³

Chlorides – 240 mg/dm³

Oxidation – 4 mg/dm³

General hardness – 6 mg ekv/dm³

5.The bacteriological analysis:

    General microbial number into 1cm³ –250,  index coli form bacteria -1.

To give exploration to reduced facts, to formulate   proposition.

 

CORRECT ANSWERS OF TEST EVALUATIONS AND SITUATIONAL TASKS:

1.     B;

2.     B;

3.     C;

4.     B;

5.     B;

6.     B.

 

Answer on situation task # 1:    

          Nitrates are index of old contamination of water by remains of animal origin or by salts of nitric acid. If their concentration in water exceeds 45 mg/dm³, they can lead to development of water nitrate methemoglobinemia in children. In our case contents of nitrates does not exceed allowed quantity, that’s why it is possible to use such water for cooking mixtures for children. 

 

Answer on situation task # 2:

All counted indexes satisfy demands of state standard for drinking water. Low colouring, general microbe index, high index of coli form bacteria, presence of smell 2 points allows to concern such water valuable for drinking.  

 

Answer on situation task # 3: 

Taking into account the correction factor, it was spent 33,44 sm³ (35,2 x 0,96) of 0,01normal solution of hyposulphite Na. 1 sm³ of 0,01normal solution of hyposulphite Na corresponds to 0,355 sm³ of chlorine. So, in taken 5 sm³ of 1% solution of lime chloride for research there is 11,45 sm³ of free chlorine (33,44 x 0,355 = 11,87), and in 1 sm³ – (11,87 : 5) = 2,4 mg.

1 sm³ of 1% solution of lime chloride contains 0,01 g of dry lime chloride. So, in researched chloride of lime there is:

0,01 g – 0,0024 g (2,4 mg) of active chlorine

In 100 g – Х, so,

 Х = (0,0024 x 100)/0,01 = 24 %

From here, researched lime chloride with the content of 24% of active chlorine can be used for the decontamination of water. For the given purposes the activity of lime chloride should be not less than 20 %.

 

Answer on situation task # 4:  

The need of water for chlorine equals to the amount of the absorption of chlorine plus the optimum (the amount of residual chlorine (0,3-0,5 mg/dm³) according to hygienic requirements). So, in our task the need of water for chlorine is equal to 1,7-1,9 mg/dm³.

         Answer on situation task # 5: 

As in 1 sm³ of 1 % solution there is 0,01 grammas of dry lime chloride, in the given task on 1,5 dm³ of water 15 grammas of lime chloride are necessary.

 

Answer on situation task # 6:  Overchlorination by method of weight doses foresees usage for 1 dm³ of clear water 25 mg, and for 1 dm³ of not clear water 50 mg of chloride lime. 100 cm³ of 1% solution have 1000 mg of dry chloride lime. According to this 25 and 50 mg will contain in 2,5 and 5 cm³ of 1 % solution.

In 100 cm³ of 1 % solution of chloride lime is 1000 mg of dry chloride lime, and x – 25 cm³ of chloride lime, x = (25 x 100) /1000 = 2,5 cm³ (1 % solution of chloride lime)

 

Answer on situation task # 7: 

Standard answer. 1 drop of 0,7 % solution of sodium hyposulphite is equal to 0,04 mg of chlorine. So, 500 cm³ of water consist of: 18 x 0,04 = 1,72 mg of chlorine residue. In recalculation on 1 dm³ the quantity of chlorine residue consist of 3,44 mg. Maximum quantity of chlorine residue = 0,5 mg/dm³. So, we can’t use this water for drinking without previous rechlorination.

 

Answer on situation task # 8: 

Standard answer. If we want to drink this water, we need previously to dechlorinate it. For this reason we use sodium hyposulphite: 3,5 mg of sodium hyposulphite neutralize 1 mg of free chlorine. In that case we need to neutralize 2,94 mg of chlorine (3,44 – 0,5 = 2,94). In 1 dm³ of water should be left 0,5 mg of free chlorine. So, for dechlorination of this water we should add: 2,94 x 3,5 = 7,87 mg of sodium hyposulphite.

Answer on situation task # 9: 

     Comparing the given results with standards it is possible to indicate that water do not meet to requirements. Under the chemical data the excess of nitrogen of ammonia and nitrogen of nitrates but the kept of nitrogen of nitrites is not increased. Allowing to sanitary-and–topographic data (the water source is placed near mounting and field condition), sanitary-and-technical data (the source has no capping the water is picked from natural channel) so it is possible the contamination of water with atmospheric water. It is offered to make accomplishment of a source capping, after some time to repeat the laboratory analysis of water.

 

 Individual student work (14¹⁵-15⁰⁰ hour)  are checked by solving situational tasks for each topic, answers in test evaluations and constructive questions (the instructor has tests & situational tasks).

 

 

INITIAL LEVEL OF KNOWLEDGE AND SKILLS

are checked by solving situational tasks for each topic, answers in test evaluations and constructive questions.

(the instructor has tests & situational tasks)

 

The student must know:

1.     Physiological, sanitary-hygienic, economic and epidemiological value of water.

2.     Hygienic importance of separate groups of indexes of water quality (organoloeptic properties, indexes of epidemiological safety, harmlessness of chemical structure).

3.     Methods of water samples from different sources.

4.     Scheme of short and full sanitary-hygienic water analysis.

5.     Diseases connected with water factor.

6.     Mechanism of the bactericidal action of chlorine;

7.     Methods of chlorination of water by normal dozes;

8.     Methods of water overchlorination.

9.     Mechanism of coagulation of water

10. Technique of coagulating of water at water stations

11. Kinds of coagulants.

12. Hygienic requirements to quality of potable water for standards “The potable water”. 

13. Hygienic characteristic of different water supply sources.

 

The student should be able:

1.     To select water for chemical and bacteriological analysis.

2.     To determine organoleptic properties of water (smell, taste, colouring, transparency).

3.     To carry out the qualitative chemical analysis of water (to determine nitrogen containing substances, sulphates).

4.     To prepare 1 % lime chloride;

5.     To determine the content of active chlorine in lime chloride;

6.     To determine the absorption of chlorine and the need of water for chlorine by a three-glass test;

7.     To determine the content of residual chlorine;

8.     Make water overchlorination by method of weight and standard doses.

9.     Make calculation of quantity of sodium hyposulphite for neutralization of excessive chlorine residue.

10. To determine total base level of water (carbonaceous hardness)

11. To determine maximum dose of a coagulant by the calculated formula

12. To interpreters results of chemical analysis of water.

13. Evaluate suitability of potable water for parameters of its quality and to justify the guidelines concerning improvement of its quality.

 

REFERENCES:

Principal:

1.          Practical classes materials http://intranet.tdmu.edu.ua/data/kafedra/internal/hihiena/classes_stud/en/med/lik/ptn/hygiene%20and%20ecology/3/04.%20Hygiene%20of%20water%20and%20water-supply.htm

2.          Hygiene and human ecology. Manual for the students of higher medical institutions/ Under the general editorship of V.G. Bardov. – K., 2009. – pp. 178-209. http://www.nmu.edu.ua/kaf55-8.php

3.          Datsenko I.I., Gabovich R.D. Preventive medicine. – K.: Health, 2004, pp. 141 – 179.

4.          Lecture on hygiene.

additional:

1.          Kozak D.V., Sopel O.N., Lototska O.V. General Hygiene and Ecology. – Ternopil: TSMU, 2008. – 248 p.

2.          Dacenko I.I., Denisuk O.B., Doloshickiy S.L. General hygiene: Manual for practical studies. -Lviv: Svit, 2001. – pp. 104-124.

3.          A hand book of Preventive and Social Medicine. – Yash Pal Bedi / Sixteenth Edition, 2003 –  pp. 100-113.

 

 

Methodical instruction has been worked out by: ass-prof. Lototska O.V.

Methodical instruction was discussed and adopted at the Department sitting

30 august 2011, Minute № 1

Methodical instruction was adopted and reviewed at the Department sitting

28 august 2013, Minute № 1