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Environmental health > Health Aspects of Water Supply > Flashcards

Health Aspects of Water Supply Flashcards

1
Q

Two major qualities of water

A

Chemical (generally of lower importance; more time for remedial action)
MIcrobiological (outbreaks and epidemics; may have immediate adverse health effects)

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2
Q

Water related diseases are related to

A

impurities in water

*infectious/non-infectious

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3
Q

Disease transmitted through ingestion of contaminated water leading to diarrheal disease (cholera, typhoid fever, hepatitis, amoebiasis, cryptosporidiosis)

A

Water-borne diseases

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4
Q

Transmissions of water-borne diseases

A

Classical Water-borne infection cycle (demonstrates role of water contamination in transmission of water-borne diseases)
Fecal-oral route (exhibits the actors that contribute to transmission)

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5
Q

Water-borne infection cycle

A

Infected person > pathogens in excreta > contaminated water source > consumption of untreated water > susceptible person >

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6
Q

Ways by which individuals acquire disease

A

Ingestion of contaminated water

Hand-to-mouth habit

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7
Q

Why are children most vulnerable to fecal-oral route of transmission of water-borne diseases

A
  1. Consistent hand-to-mouth habit

2. Unwariness of what they are eating/drinking

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8
Q

why undertaking studies on the health impact of improvements in water supply quality is difficult

A

Infection have several and multiple routes

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9
Q

Prevention strategies for water-borne diseases

A
  1. Improve drinking wate quality through treatment
  2. Prevent use of unprotected sources (by discouraging use of springs, traditional wells, and open ponds)
  3. Proper disposal of human waste
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10
Q

Treatment of drinking water

A 
• Coagulation
• Flocculation
• Sedimentation
• Filtration
• Disinfection
→ Must be ensured
→ Only process that directly addresses problems in microbiological quality
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11
Q

Low-risk water sources

A

→ Fully enclosed or protected (capped) and no surface water can run directly into it
→ People do not step into the water while collecting it
→ Latrines are located as far as possible, preferably not on higher ground
(Waters may leech by means of gravity)
→ Solid waste pits, animal excreta, and other pollution sources are located as far as possible
→ No stagnant water within 5 meters from the source
→ Wells: buckets are kept clean and off the ground, or a handpump is used

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12
Q

One of the principal ways of breaking the fecal-oral cycle

A

Safe disposal of feces

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13
Q

A critical barrier to disease transmission

A

Adequate sanitation

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14
Q

T or F: In water-washed diseases, transmission depends on quantity of water used rather than quality

A

True

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15
Q

Two main types of water-washed diseases

A

→ Infection of the eyes and skin (scabies, fungal infections, trachoma)
→ Infection carried by lice (louse-borne epidemic typhus)

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16
Q

What causes scabies?

A

Sarcoptes scabiei

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17
Q

common symptoms of scabies

A

intense itching and a pimple-like skin rash
• Usually spread by direct skin-skin contact with a person who has scabies
→ Scabies can spread rapidly under crowded conditions where close body contact is frequent

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18
Q

What causes trachoma?

*repeated infection = scarring

A 
Chlamydia trachomatis
(spread p to p through discharge from infected child's eyes)
*blindness does not happen until adulthood
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19
Q

louse-born epidemic typhus is caused by

A

Rickettsia prowazekii

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20
Q

How is louse-borne epidemic typhus transmitted?

A
  • Transmitted by body lice and cannot persist on people who regularly wash their clothes
  • Can be due to limited access to water for regular bathing
21
Q

Disease prevented by increasing water quantity used and improving accessibility and reliability of domestic water supply

A

Louse-born epidemic typhus

22
Q
  • Pathogen spends part of its life-cycle in water (e.g. snail or other aquatic animals)
  • Parasitic worms require intermediate hosts to complete their life cycles
A

Water-based diseases

23
Q

A water-based disease which is a major public health problem wherein miracidium enters snail in water

A

Schistosomiasis

24
Q

How is schistosomiasis acquired?

A

when people come in contact with fresh water infested with larval forms (cercariae) of parasitic blood flukes, known as schistosomes

25
Q

Advanced stages of schistosomiasis involves

A

enlargement of liver or spleen

26
Q

Where is schistosomiasis prevalent?

A

tropical and sub-tropical area

27
Q

How is schistosomiasis prevented?

A
  1. Reduce contact with infected water

2. Reduce snail population

28
Q

These are spread by insects which either breed in water or bite near water (i.e.: malaria, DF, filariasis)

A

Water-vectored diseases

29
Q

Prevention of water-vectored diseases

A
  1. Destroy breeding sites of insects
  2. Environmental modification (canal/drains)
    → Water will flow faster in canals made up of cement rather than soils. Thus, this prevents insect breeding since they prefer stagnant waters
    → Piped drains instead of open drains
  3. Reduce the need to visit breeding sites
  4. Use mosquito netting
30
Q

How can the chemistry of water lead to disease?

A

→ Absence or deficiency of a necessary constituent (not generally a problem because of alternative sources)
→ Excess of a harmful chemical

31
Q

This causes poor growth of bones and teeth in the young

A

Fluoride deficiency

→ Higher incidence of dental caries

32
Q

Organic harmful chemicals

A

micropollutants (less than 1 ug/L)

*Some are toxic or carcinogenic or produce odor/taste after reacting with chlorine

33
Q

Organic chemicals which are toxic or carcinogenic or produce odor/taste after reacting with chlorine are by-products of what

A

disinfection

34
Q

Organic chemicals which may be present in concentration between 1-100 ug/L (except chloroform which can exceed this)

A

Trihalomethanes

  • by-product of chlorine disinfection wherein chlorine reacts with precursor organics from decaying matter
  • carcinogenic animals
35
Q

Examples of inorganic harmful chemicals include

A

metallic ions – mercury, lead, cadmium, vanadium

36
Q

More significant problem wrt inorganics in developing countries

A

the effect of salts in ground water – mainly chlorides and sulfates which makes the water unpalatable

37
Q

harmful chemical from sedimentary deposits deriving from volcanic rocks

A

Arsenic

38
Q

Effects of arsenic

A

Dermal lesions will appear after having at least 5 years of exposure
Affects CVS of children

39
Q

harmful chemical which is primarily from corrosive water effects on househould plumbing system

A

Lead

40
Q

Why is pH included as a mandatory (also operational) parameter?

A

it detects the presence of other contaminants.

  • extremely alkaline = contaminated with pollutants
  • acidic = heavy metals
41
Q

Effects of lead

A
  • neurodevelopment effects in children (decrease of at least 3 IQ points)
  • Increase in systolic bp of approximately 3 mmHg in adults
42
Q

What causes methemoglobinemia among infants?

A

nitrates reduced to nitrites

43
Q

most affected population wrt to nitrate excess

A

Bottle-fed infants

44
Q

Sources of nitrate

*PNSDW: 50 mg/L

A

→ Industrial pollution
→ Can be from agricultural activity (excessive fertilizers/manures)
→ Wastewater disposal
→ Waste from septic tank
→ Surface or ground waters receiving organic pollution have high nitrate levels

45
Q

A discharge from mining industry which causes severe kidney damage due to increased urinary excretion of total protein, glucose and amino acids

A

Cadmium

*causes disturbance of Ca/P reabbsorption = bone softening

46
Q

Disease due to excessive exposure to cadmium

A

Itai-Itai disease

47
Q

A branch of DTI that prescribes certain levels in all products, including pipes that can be used that contains minimum metals

A

Bureau of Products Standards

48
Q

categories of sources of chemical constituents

see trans for examples

A

Natural
Industrial sources and human dwellings
Agricultural activities
Water treatment or materials in contact with drinking water
Pesticides used in water for public health

Environmental health (17 decks)

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