Drinking water and health Luiza Gharibyan

1
Drinking water and
healthLuiza Gharibyan

• Associate professor of Yerevan State Medical
  University
• Department Hygiene and Ecology

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WHO Water/Health Facts

• Every 8 seconds a child dies of water-related
  disease
• 5 million per year die of illnesses linked to
• unsafe drinking water,
• unclean domestic environments, and
• improper excreta disposal.
• Nearly ¼ of humanity remains without proper
  access to water and sanitation
• http//www.who.int/inf-fs/en/fact112.html

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Classification of water

• Ground water. Underground waters are protected
  for just one use, as an actual or potential
  source of drinking water. All ground water is
  designated as Class 1.
• Surface water. All surface waters, lakes, rivers,
  streams and wetlands in Minnesota are either
  Class 2, protected for aquatic life and
  recreation, or Class 7, designated as Limited
  Resource Value Waters. In addition, all surface
  waters (i.e., both Class 2s and 7s) are protected
  for industrial use (Class 3), agricultural uses
  (Class 4A and 4B), aesthetics and navigation
  (Class 5), and other uses (Class 6). Thus, all
  surface waters are protected for multiple uses.

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• The detection of these constituents in both raw
  water and water delivered to consumers is often
  slow, complex and costly, which limits early
  warning capability and affordability.

5

• Reliance on water quality determination alone is
  insufficient to protect public health.
  As it is neither physically nor
  economically feasible to test for all
  drinking-water quality parameters equally,
  monitoring effort and resources should be
  carefully planned and directed at significant or
  key characteristics.

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• Some characteristics not related to health, such
  as those with significant aesthetic impacts, may
  also be of importance. Where water has
  unacceptable aesthetic characteristics (e.g.
  taste and odour), further investigation may be
  required to determine whether there are problems
  with significance for health.

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• Verification
• Verification is the use of methods, procedures or
  tests to determine if the WSP is in compliance
  with the stated objectives outlined by the water
  quality targets and/or whether the WSP needs
  modification and revalidation.

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• Verification of Microbial Quality
• For microbial quality, verification is likely to
  include some microbiological testing. In most
  cases will involve the analysis of faecal
  indicator micro-organisms, but in some countries
  this may include assessment of pathogen densities
  also.

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• Approaches to verification could include testing
  of source water, influents and effluents of unit
  processes, treatment end-point product and
  distribution systems. Conventional faecal
  indicator bacteria such as E. coli serves as the
  primary indicator for verification purposes, but
  at times and under certain circumstances it may
  be desirable to include more resistant
  microorganisms such as bacteriophages, bacterial
  spores.

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• Such circumstances could include the use of
  source water known to be contaminated with
  enteric viruses and parasites or high levels of
  viral and parasitic diseases in the community.

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• Since incremental improvement and prioritizing
  action in systems presenting greatest overall
  risk to public health are important, there are
  advantages in adopting a grading scheme for the
  relative safety of supplies. More sophisticated
  grading schemes may be of particular use in
  community supplies where the frequency of testing
  is low and reliance on analytical results is
  particularly inappropriate.

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Verification of chemical water quality

• Assessment of the adequacy of the chemical
  quality of drinking-water relies on comparison of
  the results of water quality analysis with
  Guideline Values.

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• For most chemicals leading to adverse effects
  after long periods of exposures and arising from
  water sources, the quality of water in supply is
  determined by chemical analysis and compared
  directly with tables of drinking-water guidelines
  or national drinking-water standards.

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• For additives, i.e., chemicals deriving primarily
  from materials and chemicals used in the
  production and distribution of drinking-water,
  emphasis is placed on the direct control of
  additives, rather than control of water in
  distribution.

15

• Some hazardous chemicals that occur in
  drinking-water are of concern because of effects
  arising from single exposures or sequences of
  exposures over a short period.

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• Where the concentration of the chemical of
  interest varies widely, even a series of
  analytical results may fail to fully identify and
  describe the public health risk, for example
  nitrate which is associated with
  methaemoglobinaemia in bottle fed infants.

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• In controlling such hazards, attention must be
  given to both knowledge of causal factors such as
  fertiliser use in agriculture and trends in
  detected concentrations since these will indicate
  whether a significant problem may arise in the
  future.
• Other hazards may arise intermittently, often
  associated with seasonal activity or seasonal
  conditions. Once example is the occurrence of
  blooms of toxic cyanobacteria in surface water.

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Identifying priority water quality parameters

• These Guidelines cover a large number of
  constituents in drinking-water in order to meet
  the varied needs of countries world-wide.

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• There are a large number of constituents that may
  potentially occur in water. Generally, only very
  few will be of concern under any given
  circumstance. It is essential that the national
  regulatory agency and local water authorities
  determine the relevance of constituents in local
  drinking-water systems. This will ensure efforts
  and costs can be directed to those constituents
  that are of public health relevance.

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• Guidelines are established for potentially
  hazardous water constituents and provide a basis
  for assessing drinking-water quality. It is
  recognised that different parameters may require
  different priorities for management to ensure
  public health.

21
In general the progression of priority is such
that

• Ensure an adequate supply of microbiologically
  safe water
• Manage key inorganic contaminants known to cause
  adverse health effects in humans
• Maintain acceptability of drinking-water quality
  to prevent consumers seeking other potentially
  less microbiologically safe supplies
• Address other chemical contaminants

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Assessing microbial priorities

• The most common and widespread health risk
  associated with drinking-water is microbial
  contamination, the consequences of which are such
  that its control must always be of paramount
  importance. It may be impossible to attain the
  targets population-wide in the short or medium
  term and it is therefore necessary to ensure that
  priority is given to improving and developing
  water supplies to populations at greatest public
  health risk.

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• Microbial contamination of large systems has the
  potential to affect a large number of people
  through potentially large outbreaks of
  water-borne disease. Improvement of quality in
  such systems is therefore a priority.

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• Nevertheless, the majority (around 80?) of the
  global population without access to improved
  water supply is rural. Similarly small and
  community supplies in most countries contribute
  disproportionately to overall water quality
  concerns. Identifying local and national priories
  should take factors such as these into account.

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Assessing chemical priorities

• The selection of chemicals for consideration in
  the Guidelines for Drinking-water Quality takes
  into account the frequency and concentration that
  the chemical is detected in drinking-water,
  and/or those for which member states have
  specifically requested guidance because of a
  range of concerns. Guideline values are developed
  for those chemicals considered to be potentially
  hazardous to human health and occur significantly
  at concentrations of concern for public health.

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• The selection of chemicals for consideration in
  the Guidelines for Drinking-water Quality takes
  into account the frequency and concentration that
  the chemical is detected in drinking-water,
  and/or those for which member states have
  specifically requested guidance because of a
  range of concerns. Guideline values are developed
  for those chemicals considered to be potentially
  hazardous to human health and occur significantly
  at concentrations of concern for public health.

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• Risk management efforts and resources should give
  priority to those chemicals in water systems that
  pose a risk to human health, or to those with
  significant aesthetic impacts.

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• Only a few chemicals have been shown to cause
  widespread actual health effects in humans as a
  consequence of exposure through drinking-water.
  These should be addressed in all circumstances in
  priority setting and include fluoride, arsenic,
  nitrate and lead.

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• In some cases, assessment will indicate that no
  risk of significant exposure exists at national,
  regional or system level. However, the scale of
  health effects associated with these chemicals
  indicates that they should be considered under
  all circumstances.

30
Water, sanitation and health the
current situation

• The prevailing worldwide situation regarding
  water supply and sanitation services is a source
  of concern in different respects.

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• Globally, some 1.1 billion people are currently
  without access to improved water supply and about
  2.4 billion don't benefit from any form of
  improved sanitation services (figures for 2000).
  The majority of these people live in Asia and
  Africa. In Africa, for example, two out of five
  people lack improved water supply.

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• Significant discrepancies between rural and urban
  services continue to contribute to the burdened
  life in rural areas. On the other hand, the
  world-wide urbanization causes a great number of
  people to live in informal, overcrowded
  peri-urban settlements where coverage remains
  especially low.

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• Other points of concern are the increasing
  pollution of both surface and groundwater sources
  from pesticides, industry and untreated household
  waste waters.

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• The over-extraction of water for agriculture and
  manufacturing, which causes the water table to
  decline in many parts of the world, is another
  bad practice which is producing severe
  consequences to the sustainability of these
  resources.

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Water supply data at global level

• The percentage of people worldwide who have
  access to an improved water supply has risen from
  78 in 1990 to 82 in 2000. Some 902 million more
  people have been served during the decade (537
  million in urban and 365 million in rural areas).

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• Data representing 94 of the Asian population
  suggest that only 48 of the population has
  sanitation coverage, by far the lowest of any
  region of the world. The situation is even worse
  in rural areas, where only 31 of the population
  has improved sanitation, compared with 78
  coverage in urban areas.

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• Total water coverage in Asia is also the second
  lowest, after Africa, at 81. But again, water
  supply coverage is lower in rural areas (75)
  compared with that in urban areas (93).
• Because of the population sizes of China and
  India, along with other large nations in the
  region, Asia accounts for the vast majority of
  people in the world without access to improved
  services.

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• Eighty percent of the global population without
  access to improved sanitation, and almost
  two-thirds without access to improved water
  supply, live in Asia.
• At present, approximately one-third of the Asian
  population is urban and two-thirds live in rural
  areas. But this balance is predicted to shift
  over the coming decades. By the year 2015, the
  urban population is projected to be 45 of the
  region's total, and grow to just over one-half of
  the total Asian population by 2025.

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• To meet the international development target of
  halving the proportion of people without access
  to improved services by 2015, an additional 1.5
  billion people in Asia will need to access to
  sanitation facilities, while an additional 980
  million will need access to water supply.

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Water-related Diseases

• Potential water borne pathogens
• BacteriaVibrio choleraeShigella
  CampylobacterFrancisella tularensisAeromonas
  Legionella pneumophilaSalmonellaToxigenic
  Escherichia coliLeptospiraYersinia
  enterocoliticaHelicobacter pylori

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Viruses Norwalk and Norwalk-likeRotavirusHepati
tis A and E

• Protozoa
• Giardia lambliaNaegleria fowleriEntamoeba
  histolyticaIsospora belliToxoplasma
  gondiiCryptosporidium parvumAcanthamoebaCyclosp
  ora cayetanensisBallantidium coliMicrosporidia

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• Typhoid and paratyphoid enteric fevers
• Typhoid and paratyphoid fevers are infections
  caused by bacteria which are transmitted from
  faeces to ingestion. Clean water, hygiene and
  good sanitation prevent the spread of typhoid and
  paratyphoid. Contaminated water is one of the
  pathways of transmission of the disease

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• The disease and how it affects people
• Typhoid fever is a bacterial infection of the
  intestinal tract and bloodstream. Symptoms can be
  mild or severe and include sustained fever as
  high as 39-40 C, malaise, anorexia, headache,
  constipation or diarrhoea, rose-coloured spots on
  the chest area and enlarged spleen and liver.
  Most people show symptoms 1-3 weeks after
  exposure. Paratyphoid fever has similar symptoms
  to typhoid fever but is generally a milder
  disease.

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The cause

• Typhoid and paratyphoid fevers are caused by the
  bacteria Salmonella typhi and Salmonella
  paratyphi respectively. Typhoid and paratyphoid
  germs are passed in the faeces and urine of
  infected people. People become infected after
  eating food or drinking beverages that have been
  handled by a person who is infected or by
  drinking water that has been contaminated by
  sewage containing the bacteria. Once the bacteria
  enter the persons body they multiply and spread
  from the intestines, into the bloodstream.

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Distribution

• Typhoid and paratyphoid fevers are common in
  less-industrialized countries, principally owing
  to the problem of unsafe drinking-water,
  inadequate sewage disposal and flooding.

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Scope of the Problem

• The annual incidence of typhoid is estimated to
  be about 17 million cases worldwide.

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Interventions

• Public health interventions to prevent typhoid
  and paratyphoid include
• health education about personal hygiene,
  especially regarding hand-washing after toilet
  use and before food preparation provision of a
  safe water supply
• proper sanitation systems
• excluding disease carriers from food handling.

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• Diarrhoea about 4 billion cases per year cause
  2.2 million deaths, mostly among children under
  five.
• Intestinal worms infect about 10 of the
  population of the developing world and, depending
  upon the severity of the infection, lead to
  malnutrition, anaemia or retarded growth

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• Trachoma about 6 million people are blind from
  trachoma. Studies found that providing improved
  water supply could reduce the infection rate by
  25.
• Schistosomiasis about 200 million people are
  infected with schistosomiasis. Studies found that
  improved water supply and sanitation could reduce
  infection rate by 77.