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BIOSTATISTICS & HEALTH INFORMATION - SAQ Answers (8 Marks Each)

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Q1. Define Health Information and Biostatistics

• Data = discrete observations that carry little meaning alone.
• Information = data transformed by reducing, summarizing, and adjusting it (for age, sex variations) so comparisons across time and place are possible.
• Intelligence = information further transformed through integration with experience, social and political values, to guide decision-makers.

"Data that are not transformed into information, and information that is not transformed into intelligence to guide decision-makers...are of little value." - Park

1. To measure health status and quantify health problems
2. For local, national and international comparisons
3. For planning, administration and management of health services
4. For assessing effectiveness and efficiency of health services
5. For assessing attitudes and satisfaction of beneficiaries
6. For research into health and disease problems

1. Should be population-based
2. Should avoid unnecessary agglomeration of data
3. Should be problem-oriented
4. Should employ functional and operational terms
5. Should express information briefly and imaginatively (tables, charts, %)
6. Should provide for feedback of data

1. Demography and vital events
2. Environmental health statistics
3. Health status - mortality, morbidity, disability, quality of life
4. Health resources - facilities, beds, manpower
5. Utilization of health services
6. Indices of outcome of medical care
7. Financial statistics

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Q2. Sources of Health Information ****

1. Census - decennial counting of population
2. Registration of Vital Events - continuous record of births and deaths
3. Sample Registration System (SRS) - dual-record system for birth/death rates
4. National Sample Survey - periodic surveys on health, income, expenditure
5. Health Surveys - e.g., National Family Health Survey (NFHS)
6. Hospital Records - clinical data, morbidity, procedures
7. Disease Notification - compulsory notification of communicable diseases
8. Epidemiological Surveillance - monitoring of disease patterns
9. Records of Health Services - PHC records, immunization coverage
10. Research Studies - cohort, case-control, randomized trials
11. Medical Certification of Cause of Death
12. National Health Profile - compiled by CBHI
13. Other Routine Statistics - demographic, economic, social security
14. Non-quantifiable Information - policies, legislation, public attitudes

"The lifeblood of a health information system is the routine health statistics." - Park

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Q3. Census in India ********

• First regular census: 1881
• Conducted every 10 years
• Last census held: March 2011
• Usually conducted at end of first quarter (most people are at their homes)
• Legal basis: Census Act of 1948
• Supreme officer: Census Commissioner for India

• Total count of population
• Age and sex distribution
• Social and economic characteristics
• Conditions of living, income, literacy

• Provides base data for computing vital statistical rates
• Provides frame of reference for planning, action and research
• Without census data, quantified health, demographic and socio-economic indicators cannot be obtained

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Q4. Sample Registration System (SRS) ***

1. Continuous enumeration of births and deaths by an enumerator
2. Independent survey every 6 months by an investigator-supervisor

• Acts as independent check on events recorded by enumerator
• Produces denominator required for computing rates

• Major source of health information in India
• Provides Crude Birth Rate (CBR), Crude Death Rate (CDR), Infant Mortality Rate (IMR)
• Since introduction, shows steady decline in birth rate, death rate, and IMR

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Q5. Civil Registration System (CRS) ***

• India has a long tradition of registration of births and deaths
• Individual States like Tamil Nadu, Karnataka, Assam passed their own Acts
• Registration was voluntary until 1969

• Illiteracy, ignorance
• Lack of concern and motivation
• Lack of uniformity in collection, compilation and transmission
• Different systems for rural and urban areas
• Multiple registration agencies (health, panchayat, police, revenue)

• Came into force: 1 April 1970
• Provides for compulsory registration of births and deaths throughout India
• Ensures uniformity and comparability of data
• Time limit for registration: 21 days uniformly across India
• Late fee imposed for default
• From October 2018: Aadhaar number mandatory for death registration
• Responsibility: Parents/relatives for home events; Heads of hospitals/nursing homes for institutional events

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Q6. Types of Data Presentation

"Statistical data, once collected, must be arranged purposively, in order to bring out the important points clearly and strikingly." - Park

1. TABULATION

• Devices for presenting data from masses of statistical material
• First step before analysis or interpretation
• Types: Simple tables and Frequency distribution tables

2. BAR CHARTS

3. HISTOGRAM

4. FREQUENCY POLYGON

5. LINE DIAGRAM

6. PIE CHART (Sector Diagram)

7. PICTOGRAM

8. SCATTER DIAGRAM

9. STATISTICAL MAPS

• Shaded maps - areas shaded with different colours/intensities
• Dot maps

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Q7. Sampling Methods ***

(1) Simple Random Sample

• Each unit is assigned a number
• A table of random numbers is used to select units
• Each unit has equal chance of being selected
• Provides greatest number of possible samples
• Eliminates personal selection and unconscious bias

(2) Systematic Random Sample

• Pick every 5th or 10th unit at regular intervals
• Example: For a 10% filaria survey, houses are numbered, then every 10th house is selected
• Simple and easy to execute

(3) Stratified Random Sample

• Population is divided into strata (e.g., age groups, socioeconomic status)
• Random sample drawn from each stratum
• Ensures representation from all subgroups
• More precise than simple random sampling

• Cluster sampling - geographic clusters selected; all in cluster studied
• Multistage sampling - sampling done in stages (district → village → household)
• Purposive (judgement) sampling - investigator selects "typical" units
• Quota sampling - fixed number from each category

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Q8. Normal Distribution Curve ***

• Mean = Median = Mode (all coincide at the centre)
• The curve is symmetric about the mean
• Tails extend to infinity in both directions

• ±1 SD covers 68.27% of all observations (2 × 0.3413 = 68.27%)
• ±2 SD covers 95.44% of all observations (2 × 0.4772 = 95.44%)
• ±3 SD covers 99.73% of all observations (2 × 0.4987 = 99.73%)

• Basis for many statistical tests
• Calculation of probability
• Setting reference ranges in clinical medicine

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Q9. Measures of Central Tendency **** (Mean, Median, Mode)

"The word 'average' implies a value in the distribution around which the other values are distributed." - Park

(1) THE MEAN (Arithmetic Mean)

• Denoted by x̄ ("X bar")
• Formula: x̄ = Σx / n (sum of all observations ÷ number of observations)
• 'Σ' denotes summation; 'n' denotes number of observations

• Total = 810; Mean = 810 ÷ 10 = 81.0

(2) THE MEDIAN

• Middle value when data arranged in ascending or descending order
• If odd number of values: middle value is median
• If even number of values: average of two middle values

(3) THE MODE

• The value that occurs most frequently in a distribution
• Example: In a series 3, 5, 7, 7, 7, 9, 10 - Mode = 7
• A distribution may be unimodal, bimodal, or multimodal

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Q10. Measures of Deviation **** (Range, Mean Deviation, Standard Deviation)

Measures of deviation (dispersion) indicate how far the individual observations are scattered around their average.

(a) RANGE

• Simplest measure of dispersion
• Difference between highest and lowest values
• Example: BP values - 83, 75, 81, 79, 71, 90, 75, 95, 77, 94
  • Highest = 95, Lowest = 71
  • Range = 71 to 95 (or difference = 24)
• Limitation: Shows only extreme values; tells nothing about dispersion between extremes

(b) MEAN DEVIATION (MD)

• Average of deviations from the arithmetic mean
• Formula: M.D. = Σ(x - x̄) / n (ignoring ± sign)

(c) STANDARD DEVIATION (SD)

• Most frequently used measure of deviation
• Defined as "Root - Mean - Square - Deviation"
• Denoted by Greek letter σ or S.D.

• SD is always positive
• The smaller the SD, the more uniform/homogeneous the observations
• Used in calculating Standard Error, Normal Distribution, and confidence intervals
• About 68% of observations fall within ±1 SD of the mean
• About 95% of observations fall within ±2 SD of the mean

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Q11. Standard Error and Standard Deviation

• Measures the variability/spread within a single sample
• Describes how individual observations vary around the sample mean
• Formula: SD = √[Σ(x - x̄)² / n]
• Used to describe the distribution of data in a sample
• A property of the sample

• Measures the variability of the sample mean if the study were repeated many times
• Describes how precisely the sample mean estimates the true population mean
• Formula: SE = SD / √n
• The smaller the SE, the more precise the estimate of the population mean
• Used to construct confidence intervals
• A property of the sampling distribution

• As sample size (n) increases, SE decreases (becomes more precise)
• SE = SD / √n - so if n increases 4 times, SE decreases by half

• 95% CI = x̄ ± 1.96 × SE
• 99% CI = x̄ ± 2.58 × SE

"Standard deviation is a measure of variability within a sample; standard error of the mean is a measure of how accurately the sample mean estimates the population mean." - Park

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ADD A NOTE ON SOCIAL PROBLEMS AND SOCIAL PATHOLOGY

(8 Marks) — From Park's Textbook of Preventive and Social Medicine

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SOCIAL PROBLEMS

"In a community, there are both individual and social problems. Individual problems become social problems when they affect a large number of people amounting to a threat to the welfare or safety of the whole group."

• Poverty, crime and disease are the most common social problems.
• Many public health problems are social problems and vice versa.
• Alcoholism, sexually transmitted diseases, mental illness and narcotic addiction are both public health and social problems.
• Social problems like housing, divorce, population growth, and the increased number of old people have public health implications calling for a combined sociological and public health action.

"Social problems are solved by social and political action — that is by social welfare programmes, social assistance, social legislation in the community to curb social evils."

• The Prevention of Food Adulteration Act
• The Prevention of Immoral Traffic Act
• The Medical Termination of Pregnancy Act

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SOCIAL PATHOLOGY

"The term 'social pathology' is given a restricted interpretation linking it to poverty, crime, delinquency and vagrancy. In the modern context, the term is also used to describe the relation between disease and social conditions."

• The social pathology of accidents, diabetes, cardiovascular disease, cancer, and chronic bronchitis have all been subjects of recent investigations in medical literature.
• Social pathology is uncovered by "social surveys".

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MAJOR SOCIAL PROBLEMS IN INDIA (Park)

1. POVERTY

"Poverty wields its destructive influence at every stage of human life from the moment of conception to the grave." - Park

• Main reason why babies are not vaccinated
• Clean water and sanitation are not provided
• Curative drugs and treatments are unavailable
• Main cause of:
  • Low life expectancy
  • Low birth weight babies
  • Higher maternal mortality
  • Handicap and disability
  • Mental illness, stress and suicide
  • Family disintegration and substance abuse

"The poor die younger and suffer more from disability. They are exposed to greater risk from unhealthy conditions at home and at work." - Park

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2. HOUSING (A Key Social Problem with Health Implications)

1. Respiratory infections - TB, Common cold, Influenza, Diphtheria, Bronchitis, Measles, Whooping cough
2. Skin infections - Scabies, Ringworm, Impetigo, Leprosy
3. Rat infestation - Plague
4. Arthropods - Houseflies, mosquitoes, fleas, bugs
5. Accidents - Substantial proportion caused by defects in home
6. High morbidity and mortality - where housing is substandard
7. Psychosocial effects - isolation in high-rise buildings, neurosis, behaviour disorders

• "More people living within a single dwelling than there is space for" - restricts movement, prevents privacy, makes hygiene impossible
• Promotes spread of respiratory infections (TB, influenza, diphtheria)
• Psychosocial effects: irritability, frustration, lack of sleep, anxiety, violence, mental disorders

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3. PROSTITUTION

• An age-old social evil, a social problem mostly in urban areas.

1. Changes in environment
2. Breakdown of family relations
3. Parental quarrels
4. Want of affection
5. Illegitimate love
6. Easy money
7. Low I.Q.
8. Low moral standards
9. Poverty

• "Suppression of Immoral Traffic Act in women and girls" (1956) - banned commercialized prostitution
• Amended and retitled: "Immoral Traffic (Prevention) Act" 1986 - covers all persons (male or female) exploited sexually for commercial purposes

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4. DELINQUENCY

"A delinquent is one who shows deviation from normal behaviour — committed an offence, e.g., theft, sexual offence, murder, burglary."

• Social maladjustment
• Poverty
• Disturbed home conditions
• Alcoholism and drug addiction
• Modern ways of living

• Juvenile/Children's Courts
• Child welfare boards
• Remand homes
• Certified schools
• Children homes and after-care facilities

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5. DRUG ADDICTION

"A state of periodic or chronic intoxication detrimental to the individual and society, produced by the repeated intake of habit-forming drugs."

• Curiosity and tendency to experiment
• Disturbed home environment (broken homes, indifferent parents)
• Escape from tensions and frustrations (unemployment, exam failure)
• Impact of disco culture, mobile, TV, internet
• Ignorance about habit-forming nature of drugs

1. Psychological dependence - overpowering compulsion to obtain the drug by any means
2. Physical dependence - withdrawal symptoms (irrational behaviour, nausea, diarrhoea, watering of eyes and nose)
3. Development of tolerance - tendency to increase the dose

• (a) Identification and motivation for detoxification
• (b) Detoxification (requires hospitalization)
• (c) Post-detoxification counselling and follow-up
• (d) Rehabilitation
• Psychotherapy has a valuable place
• Chances of relapse are 100% if the patient does not break completely with the group

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6. ALCOHOL ABUSE

"Alcoholism is a worldwide social and medical problem." - Park

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7. DOWRY SYSTEM

• Started as innocent custom; grew into a social evil with bride-burning and suicides.

• Dowry Prohibition (Amendment) Act, 1986 - minimum punishment = 5 years imprisonment + fine of Rs. 15,000

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8. HANDICAPPED (Park's Table - 2011 Census)

1. Medical care facilities
2. Education (blind, deaf, orthopaedically handicapped)
3. Vocational training
4. Job placement and sheltered workshops
5. Pensions, scholarships and allowances

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SOCIAL SURVEYS (Method to Uncover Social Pathology)

"Social surveys disclose social pathology." - Park

• Social surveys have played an important part in the development of public health.
• Chadwick's survey led to the foundation of the General Board of Health in 1848 in Great Britain.
• Strong kinship between epidemiological survey and social survey.
• When social factors are studied in the aetiology of disease, the two merge into "social epidemiology".
• Large-scale social epidemiological studies have investigated the relationship of social factors to heart disease, cancer and arthritis.

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SUMMARY DIAGRAM (Park's Conceptual Framework)

SOCIAL CONDITIONS
(Poverty, Housing, Unemployment, Illiteracy)
          ↓
    SOCIAL PROBLEMS
(Alcoholism, Drug Addiction, Crime,
 Delinquency, Prostitution, Dowry)
          ↓
    SOCIAL PATHOLOGY
(Disease linked to social conditions:
 CVD, Cancer, TB, Diabetes, Accidents,
 Chronic Bronchitis)
          ↓
    SOCIAL SURVEYS
(Uncover social pathology)
          ↓
    SOCIAL EPIDEMIOLOGY
(Study of social factors in aetiology of disease)
          ↓
  SOCIAL/LEGAL ACTION
(Welfare programmes, Social legislation,
 Combined public health + sociological action)

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ADD A NOTE ON SOCIAL PROBLEMS AND SOCIAL PATHOLOGY

(8 Marks) — Park's Textbook of Preventive and Social Medicine

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SOCIAL PROBLEMS

"Individual problems become social problems when they affect a large number of people amounting to a threat to the welfare or safety of the whole group."

• Poverty, crime and disease are the most common social problems.
• Alcoholism, STDs, mental illness and narcotic addiction are both public health and social problems.
• Housing, divorce, population growth have public health implications calling for combined sociological and public health action.

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SOCIAL PATHOLOGY

"The term 'social pathology' links to poverty, crime, delinquency and vagrancy. In the modern context, it describes the relation between disease and social conditions."

• Social pathology of accidents, diabetes, CVD, cancer, chronic bronchitis have been subjects of recent investigation.
• Social pathology is uncovered by social surveys.

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MAJOR SOCIAL PROBLEMS (Park)

1. POVERTY

"Poverty wields its destructive influence at every stage of human life from conception to the grave." - Park

• Babies not vaccinated; no clean water/sanitation
• Low life expectancy, low birth weight, high maternal mortality
• Mental illness, stress, suicide, family disintegration, substance abuse

2. HOUSING (Poor Housing → Disease)

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3. PROSTITUTION

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4. DELINQUENCY

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5. DRUG ADDICTION

1. Psychological dependence - compulsion to obtain drug by any means
2. Physical dependence - withdrawal symptoms (nausea, diarrhoea, violent behaviour)
3. Tolerance - tendency to increase dose

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6. ALCOHOL ABUSE

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7. DOWRY SYSTEM

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SOCIAL SURVEYS (Method to Uncover Social Pathology)

"Social surveys disclose social pathology." - Park

• Chadwick's survey → General Board of Health, 1848 (Great Britain)
• Social survey + Epidemiological survey = Social Epidemiology
• Investigates social factors in heart disease, cancer, arthritis

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CONCEPTUAL FRAMEWORK (Park)

SOCIAL CONDITIONS (Poverty, Poor Housing, Illiteracy)
            ↓
     SOCIAL PROBLEMS
(Alcoholism, Crime, Drug Addiction, Delinquency)
            ↓
     SOCIAL PATHOLOGY
(CVD, Cancer, TB, Diabetes, Accidents)
            ↓
     SOCIAL SURVEYS → SOCIAL EPIDEMIOLOGY
            ↓
  SOCIAL LEGISLATION + PUBLIC HEALTH ACTION

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DISPOSAL OF URINARY CATHETER (Biomedical Waste Management)

(8 Marks) — Park's Textbook of Preventive and Social Medicine

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INTRODUCTION

"Any waste which is generated during the diagnosis, treatment or immunization of human-beings or animals, or in research activities pertaining thereto, or in the production or testing of biologicals."

• 75-90% of healthcare waste is non-risk/general waste
• 10-25% is hazardous waste (includes catheters, sharps, body fluids)

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CLASSIFICATION OF URINARY CATHETER AS BIOMEDICAL WASTE

A used urinary catheter - contaminated with urine/blood - is categorized under Category 6 (Soiled Waste) → disposed in YELLOW bag → Treatment by Incineration.

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COLOUR-CODED BAG SYSTEM (Park's BMW Rules 2016)

Note: Urinary catheter (plastic tubing) without sharp - goes in RED bag for autoclave/microwaving; catheter with urine/blood contamination - YELLOW bag for incineration.

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STEPS IN DISPOSAL OF URINARY CATHETER (Park's Protocol)

STEP 1: SEGREGATION AT SOURCE
Used catheter removed → Placed immediately into
YELLOW bag (if soiled/blood-stained) or
RED bag (if plastic, minimally contaminated)
↓
STEP 2: COLLECTION & STORAGE
Colour-coded containers at point of generation
Not stored > 48 hours at healthcare facility
↓
STEP 3: TRANSPORT
On-site: trolleys/carts within hospital
Off-site: vehicles authorized by State Pollution Control Board
↓
STEP 4: TREATMENT
Incineration (Yellow bag) OR
Autoclave/Microwave (Red bag)
↓
STEP 5: FINAL DISPOSAL
Ash from incinerator → Secured sanitary landfill
Treated plastic → Shredding → Landfill

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TREATMENT TECHNOLOGIES (Park)

I. INCINERATION (Primary method for Yellow bag waste - catheters)

"Incineration is a high temperature dry oxidation process that reduces organic and combustible waste to inorganic incombustible matter and results in a very significant reduction of waste volume and weight." - Park

1. Double-chamber pyrolytic incinerators - especially designed for infectious healthcare waste (most preferred)
2. Single-chamber furnaces with static grate - used only if pyrolytic not affordable
3. Rotary kilns - high temperature, decomposes genotoxic and heat-resistant chemicals

• Pressurized gas containers
• Halogenated plastics (e.g., PVC - important: many catheters are PVC → autoclave preferred)
• Thermometers, batteries (heavy metals)
• Sealed ampules

Important: PVC catheters should NOT be incinerated due to halogenated plastics → should be autoclaved/microwaved instead.

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II. AUTOCLAVING / STEAM STERILIZATION (For Red bag - plastic catheters)

• Uses moist heat under pressure to sterilize
• Effective for most infectious waste
• After autoclaving - waste is safe for landfill disposal
• Cannot be used for anatomical/cytotoxic waste

III. MICROWAVING

• Waste shredded and moistened, then exposed to microwave irradiation
• Reduces volume, destroys pathogens
• Suitable for plastic tubes, IV lines, catheters

IV. CHEMICAL TREATMENT

• Disinfection using chemicals (hypochlorite, glutaraldehyde)
• Used for liquid waste (urine from catheter bag)
• Urine from catheter drainage bag - treated with 1% hypochlorite before drain disposal

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HEALTH HAZARDS IF CATHETER NOT PROPERLY DISPOSED (Park)

• HIV, Hepatitis B, Hepatitis C transmission through needle-stick/contact with contaminated catheters
• Nosocomial (hospital-acquired) infections

• Injury to health workers, waste handlers, scavengers

"The general public is very sensitive to visual impact of health-care waste particularly anatomical waste." - Park

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LEGAL FRAMEWORK (Park)

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SUMMARY DIAGRAM

USED URINARY CATHETER
        ↓
Is it PVC / plastic (non-sharp)?
    ↙               ↘
  YES               Soiled / blood/urine stained
   ↓                        ↓
RED BAG              YELLOW BAG
   ↓                        ↓
Autoclave/           Incineration
Microwaving          (Double-chamber
+ Shredding          pyrolytic preferred)
   ↓                        ↓
 Landfill            Ash → Secured Landfill

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ENVIRONMENTAL HEALTH & WATER SANITATION — SAQ Answers (8 Marks Each)

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Q2. RAPID SAND FILTRATION ****

• Gravity type (Paterson's filter)
• Pressure type (Candy's filter)

• Raw water with alum (coagulant) added → passes through sand bed
• "Alum-floc" adsorbs bacteria from water - purification occurs
• Oxidation of ammonia also takes place
• Requires chemical coagulation as pre-treatment (sedimentation before filtration)

"Washing is accomplished by reversing the flow of water through the sand bed - called backwashing."

• Done daily or weekly when "loss of head" reaches 7-8 feet
• Whole process takes about 15 minutes
• In some filters, compressed air is used in backwashing

1. Can deal with raw water directly - no preliminary storage needed
2. Filter beds occupy less space
3. Filtration is rapid - 40-50 times faster
4. Washing of filter is easy (backwashing)
5. More flexibility in operation

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Q3. RAPID SAND vs SLOW SAND FILTRATION

"Slow sand filtration is still the chosen method of water purification in a number of highly industrialized cities." - Park

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Q4. NOISE POLLUTION **** — Effects and Prevention & Control

"Wrong sound, in the wrong place, at the wrong time." Noise pollution - "vast cacophony of sounds produced in modern life, leading to health hazards."

• Normal conversation: 60-65 dB
• Whispering: 20-30 dB
• Heavy traffic: 60-80 dB
• Boiler factories: 120 dB
• Safe limit: 85 dB (daily exposure limit)

EFFECTS OF NOISE EXPOSURE (Park)

1. Auditory fatigue - at 90 dB region; greatest at 4000 Hz; whistling/buzzing in ears
2. Temporary hearing loss - disappears within 24 hours; 4000-6000 Hz range affected
3. Permanent hearing loss - continuous exposure to ~100 dB; destruction of organ of Corti
4. Occupational hearing loss - from industrial noise
5. Tympanic membrane rupture - above 160 dB → permanent hearing loss

1. Interference with speech - 300-500 Hz range most disturbing
2. Annoyance - psychological response; irritability, impatience
3. Reduced efficiency - mental concentration impaired
4. Physiological changes: rise in BP, intracranial pressure, increased heart rate, breathing, sweating; giddiness, nausea, fatigue
5. Sleep interference
6. Visual disturbance - narrowing of pupil, affect colour perception, reduce night vision
7. Economic losses - noise-induced hearing loss costs industry significantly

PREVENTION AND CONTROL OF NOISE (Park)

1. Careful city planning:
   • Division into zones (industrial separated from residential)
   • Wide green belts between residential and main streets
   • House fronts ≥ 15 metres from road; thickly planted trees/bushes
   • Widening of main streets
2. Control of vehicles:
   • Heavy vehicles not routed into narrow streets
   • Prohibit indiscriminate blowing of horns and use of pressure horns
3. Acoustic insulation of buildings:
   • Detached buildings preferred over continuous buildings
   • Sound-proof buildings where necessary
4. Industries and railways:
   • Special areas outside residential zones
   • Protective green belts between installations and residential areas
5. Protection of exposed persons:
   • Hearing protection for workers (earmuffs, earplugs)
   • Limit working hours in noisy environments

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Q5. SANITARY TOILET — RCA Type Latrine **** and Role in Disease Prevention

"A low cost pour-flush, water-seal type of latrine - basically an improved version of the standard hand-flush latrine (RCA type). Consists of a specially designed pan and a water-seal trap. Connected to a pit 3 ft square and as deep. Excreta undergoes bacterial decomposition and is converted to manure (compost). Requires very little water."

• Typhoid, Cholera, Dysentery
• Hepatitis A, Polio
• Hookworm, Ascariasis, other helminthic diseases
• Diarrhoeal diseases

• Prevents contamination of soil
• Prevents contamination of water supplies
• Prevents food contamination
• Reduces fly breeding
• Reduces mosquito breeding

1. Should not pollute soil or water
2. Should not be accessible to flies, insects or animals
3. Should not create nuisance due to odour or unsightliness
4. Should be simple and cheap to construct
5. Safe and easy to use, especially for children

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Q6. SANITATION BARRIER ***

• Safe excreta disposal (latrine)
• Handwashing
• Safe water
• Food hygiene

1. Conservancy system - collection and removal of excreta
2. Water carriage system (sewerage) - best method for cities
3. Trench latrines - field/temporary use
4. Pit latrines - rural areas
5. Septic tanks - individual dwellings without sewerage
6. Aqua privy - low-cost alternative
7. Composting latrines

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Q7. CHLORINATION OF WATER ****

Action of Chlorine (Park):

"Chlorination is one of the greatest advances in water purification. It is a supplement, not a substitute to sand filtration."

H₂O + Cl₂ → HCl + HOCl
HOCl → H⁺ + OCl⁻

• HOCl (hypochlorous acid) = main disinfecting agent
• 70-80 times more effective than hypochlorite ion
• Best at pH 7; unreliable above pH 8.5

1. Water must be clear and free from turbidity first
2. "Chlorine demand" of water must be satisfied
3. Adequate contact time must be allowed
4. Residual chlorine must remain after demand satisfied

a) SUPERCHLORINATION ****

"Addition of large doses of chlorine to water, followed by removal of excess chlorine (dechlorination) after disinfection."

• Applied to heavily polluted waters whose quality fluctuates greatly
• Dechlorination done by: sodium thiosulphate, activated carbon, aeration
• Kills all pathogens including those resistant to normal chlorination

b) BREAK POINT CHLORINATION ***

"The point at which residual chlorine appears and all combined chlorines (chloramines) have been completely destroyed is the breakpoint."

• Chlorine added to water containing ammonia → forms chloramines
• As more chlorine added → chloramines destroyed → residual chlorine FALLS
• After a critical point (breakpoint) → residual chlorine begins to rise proportionally
• At breakpoint: all chloramines destroyed; free chlorine appears

"Breakpoint chlorination achieves the same results as superchlorination in a rational manner and can therefore be construed as controlled superchlorination." - Park

c) RESIDUAL CHLORINE ***

• Minimum residual chlorine required at consumer's tap = 0.2 mg/L (0.2 ppm)
• Ensures protection against recontamination during distribution
• Tested by: OT test (Orthotolidine test) or OTA test

• 0.1 ml of OT reagent added to 11 ml of water
• Yellow colour produced - intensity proportional to chlorine concentration
• Read within 10 seconds for free chlorine

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Q8. WORKING OF SEPTIC TANK ***

"A water-tight masonry tank into which household sewage is admitted for treatment."

• Capacity: 20-30 gallons (2.5-5 cu.ft.) per person; minimum 500 gallons
• Length: twice the breadth
• Depth: 1.5 to 2 m (5-7 ft.)
• Liquid depth: 1.2 m (4 ft.)
• Air space: minimum 30 cm (12 in.)
• Retention period: 24 hours

• Heavy solids settle → form SLUDGE
• Light solids/grease rise → form SCUM
• Anaerobic bacteria break down sludge into simpler compounds
• Gases (principally methane) bubble to surface
• Sludge greatly reduced in volume

• Effluent (liquid passing out of outlet) contains bacteria, cysts, helminthic ova
• Allowed to percolate into sub-soil via perforated pipes in trenches
• Aerobic oxidation completes purification in soil

"Two stages complete purification - anaerobic digestion in the tank, aerobic oxidation outside in sub-soil." - Park

• No soap/phenol (kills bacterial flora)
• Desludging at least once a year
• New tanks seeded with ripe sludge from another tank

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Q9. MODERN SEWAGE TREATMENT PLANT ***

RAW SEWAGE
    ↓
PRELIMINARY TREATMENT
(Screening - removes large solids)
    ↓
GRIT CHAMBER
(Removes grit, sand)
    ↓
PRIMARY SEDIMENTATION TANK
(Removes ~60% suspended solids)
    ↓
SECONDARY TREATMENT
  ↙            ↘
Trickling    Activated Sludge
Filter       Process (Modern)
    ↘            ↙
SECONDARY SEDIMENTATION TANK
(Humus tanks)
    ↓
DISINFECTION (Chlorination)
    ↓
EFFLUENT → River/land disposal
    ↓
SLUDGE → Sludge digestion tanks → Dried/used as manure

(a) TRICKLING FILTER METHOD (Park):

• Crushed stone bed 1-2 m deep, 2-30 m diameter
• Effluent sprinkled by rotating hollow pipes with holes
• Zoogleal layer (algae, fungi, protozoa, bacteria) oxidizes effluent
• Dead matter = "humus" (light green flocculent material)
• "Ventilation not needed - wind supplies oxygen through beds"

(b) ACTIVATED SLUDGE PROCESS (Modern method - Park):

"The heart of the activated sludge process is the aeration tank." - Park

• Effluent from primary sedimentation + activated sludge (20-30%)
• Aerated for 6-8 hours in aeration tank
• Aeration by mechanical agitation or diffuse aeration (compressed air from bottom - preferred)
• Organic matter → CO₂, nitrates, water
• Typhoid, cholera organisms destroyed; coliforms greatly reduced
• 1 acre of activated sludge = 10 acres of trickling filter
• Best for larger cities; trickling filter for smaller towns

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Q10. INTEGRATED VECTOR CONTROL MANAGEMENT *** (Biological, Chemical, Physical, PPE)

A. BIOLOGICAL METHODS:

• Gambusia fish (mosquito fish) - eats mosquito larvae in ponds/water bodies
• Bacillus thuringiensis israelensis (BTI) - biological larvicide
• Predatory insects - dragonfly larvae eat mosquito larvae
• Sterile male technique - release of sterile males to reduce breeding

B. CHEMICAL METHODS:

• Larvicides: Temephos (Abate), Malathion - applied to breeding sites
• Adulticides: DDT (now banned), Pyrethrum, Malathion spraying
• Residual insecticide spraying (IRS) - indoor wall spraying
• Space spraying - ULV (ultra-low volume) fogging for acute outbreaks

C. PHYSICAL/ENVIRONMENTAL METHODS:

• Source reduction - eliminating breeding sites
• Filling/draining stagnant water, pits, puddles
• Changing water in coolers/containers weekly
• Screening of doors/windows
• Intermittent irrigation in canals - disrupts larval development
• Proper refuse disposal to eliminate breeding of houseflies

D. PERSONAL PROTECTIVE EQUIPMENT (PPE):

• Bed nets (insecticide-treated nets - ITNs)
• Long-sleeved clothing
• Insect repellents (DEET)
• Protective footwear

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Q11. POTABLE WATER — Microbiological Standards of Drinking Water ***

"Water which is safe to drink, pleasant to taste and usable for domestic purposes."

• Colour: ≤ 5 Hazen units
• Turbidity: ≤ 5 NTU (ideally 1 NTU)
• pH: 6.5 - 8.5
• Temperature: < 25°C

• Total dissolved solids (TDS): < 500 mg/L
• Chloride: < 250 mg/L
• Nitrate: < 45 mg/L
• Fluoride: 0.6-1.5 mg/L
• Arsenic: < 0.01 mg/L
• Lead: < 0.01 mg/L

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Q12. OXIDATION POND ***

An oxidation pond (stabilization pond) is a large, shallow body of wastewater exposed to sunlight, wind and algae - natural biological treatment of sewage.

SEWAGE enters pond
    ↓
Bacteria decompose organic matter (BOD reduction)
    ↓
CO₂ + H₂O produced by bacteria
    ↓
Algae use CO₂ + sunlight → Photosynthesis → O₂
    ↓
Oxygen supports more bacterial activity
(Algae-bacteria symbiosis)
    ↓
Effluent (clarified, stabilized) exits

• Depth: 1-1.5 m (shallow - allows sunlight penetration)
• Retention time: 5-30 days
• Removes BOD: 70-90%
• Simple, low cost, no mechanical equipment
• Used in rural areas, small towns, developing countries
• Sludge accumulates at bottom

1. Aerobic ponds - shallow, algal-photosynthetic
2. Anaerobic ponds - deeper, no algae, strong BOD load
3. Facultative ponds - combination (most common)

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Q13. SOLID WASTE DISPOSAL (REFUSE) ****

1. CONTROLLED TIPPING (Sanitary Landfill) - Best method

• Refuse deposited in low-lying areas in layers
• Each layer covered with 15-20 cm of earth daily
• Anaerobic decomposition below; no flies, odour
• Area can be used after 2 years for parks/playgrounds
• NOT suitable for building construction

2. COMPOSTING

• Biological decomposition into compost/manure
• Bangalore method (see Q14)

3. INCINERATION

• High temperature combustion
• Best for infectious/hospital waste
• Reduces volume by 90%
• Expensive; risk of air pollution

4. DUMPING (Open dump)

• Simplest but WORST method
• Fly and rodent breeding, fire hazard, groundwater pollution

5. BURNING

• Open burning - causes air pollution
• Acceptable only in remote areas

6. HOG FEEDING (Piggeries)

• Kitchen/food waste fed to pigs
• Risk of Trichinella, cysticercosis transmission

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Q14. COMPOSTING **** (BANGALORE METHOD)

"Composting is a process of biological decomposition of organic matter to form manure."

• Developed at the Indian Institute of Science, Bangalore

1. Trench dug: 3 m long × 1.5 m wide × 1 m deep
2. Refuse spread in 25 cm layer at bottom
3. Covered with 5 cm layer of earth (or cattle dung slurry)
4. More refuse added in layers; alternating refuse and earth
5. Trench filled to 30 cm above ground level
6. Left undisturbed for 4-6 months
7. Temperature rises (hot fermentation) - kills pathogens
8. Compost ready after 6 months - used as manure

• Turning (aerating) the compost pile every few weeks
• Faster decomposition (ready in 3-4 months)

• Rich organic fertilizer for agriculture
• Improves soil structure
• Reduces need for chemical fertilizers

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Q15. SOURCES OF IONIZING RADIATION, HEALTH EFFECTS, PREVENTIVE AND CONTROL MEASURES ***

• Cosmic radiation
• Terrestrial radiation (rocks, soil)
• Internal radiation (radioactive elements in body - K-40, C-14)
• Radon gas

• Medical X-rays (largest man-made source)
• Nuclear weapons testing (fallout)
• Nuclear reactors/power plants
• Industrial and research uses
• Consumer products (smoke detectors)

• Roentgen (R) - exposure unit
• Rad - absorbed dose
• Rem - biological effective dose
• Sievert (Sv) - SI unit (1 Sv = 100 rem)

• Acute radiation syndrome (high doses): nausea, vomiting, bone marrow suppression, death
• Leukemia - radiation-induced (earliest malignancy to appear; latent 5-10 years)
• Carcinoma - thyroid, breast, lung, bone
• Cataract of lens
• Shortened life span
• Aplastic anaemia
• Burns (radiation dermatitis)

• Gene mutations
• Chromosomal aberrations
• Congenital malformations
• No threshold dose - any dose may cause genetic damage

1. Time - minimize exposure time
2. Distance - increase distance from source (inverse square law)
3. Shielding - lead aprons, concrete walls, lead glass
4. Monitoring - film badges, dosimeters for radiation workers
5. Maximum Permissible Dose (MPD):
   • Radiation workers: 50 mSv/year (5 rem/year)
   • General public: 5 mSv/year (0.5 rem/year)
6. Safe handling and disposal of radioactive waste
7. Regular medical surveillance of radiation workers
8. Avoidance of unnecessary X-rays in pregnancy

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Q16. THERMAL PARAMETERS (Indices of Thermal Discomfort)

1. DRY BULB TEMPERATURE (DBT)

• Ordinary air temperature measured by dry bulb thermometer
• Alone insufficient to assess thermal comfort

2. WET BULB TEMPERATURE (WBT)

• Measures temperature + humidity combined
• Wet bulb globe temperature (WBGT) - most widely used index

3. EFFECTIVE TEMPERATURE (ET)

• Combines effect of temperature, humidity and air movement
• Defined as temperature of still, saturated air producing same thermal sensation

4. CORRECTED EFFECTIVE TEMPERATURE (CET)

• ET corrected for radiation effect
• Most useful indoor index

5. WET BULB GLOBE TEMPERATURE (WBGT) - Most practical outdoor index

• WBGT = 0.7 WBT + 0.2 Globe Temp + 0.1 DBT
• Recommended limit for physical work = 28°C WBGT

6. KATA THERMOMETER

• Measures cooling power of air
• Used to assess ventilation in mines, factories

• Heat cramps - from salt/water loss
• Heat exhaustion - circulatory failure
• Heat stroke - failure of sweating mechanism; most dangerous; body temperature > 40°C

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Q17. SWACHH BHARAT MISSION (SBM) ****

To achieve "Open Defecation Free" (ODF) India by 2nd October 2019 (Gandhi's 150th birth anniversary).

1. SBM-Gramin (Rural) - Ministry of Jal Shakti
2. SBM-Urban - Ministry of Housing and Urban Affairs

1. Eliminate open defecation
2. Eradicate manual scavenging
3. Modern and scientific municipal solid waste management
4. Bring about behavioural change regarding sanitation practices
5. Generate awareness about sanitation
6. Support urban local bodies in designing, executing and operating waste management systems

• Individual household latrines (IHHLs)
• Community and public toilets
• Solid waste management (SWM)
• Behaviour change communication (BCC) - IEC activities

• Over 100 million toilets built in rural areas
• Most states declared ODF
• Focus shifted to ODF+ (sustainability) and ODF++ (solid/liquid waste management)

• Segregation at source (wet and dry waste)
• Door-to-door collection
• Transportation
• Scientific processing (composting/biogas)
• Disposal in sanitary landfills
• Target: 100% scientific disposal of municipal solid waste

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