PHGY 210 Lecture Notes - Cyanosis, Bromine, Constipation

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31 Jan 2013
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Diarrheal deaths, most due to waterborne infectious agents,.
While the widespread use of oral rehyderation thearphy has substantially
reduced the mortality associated with waterborne disease, intensive efforts to
provide improve water and sanitary infrastructure in developing nations have
been less successful.
Growing evidence indicates that updating the means of disposal of human
wastes improves human health to a greater extent than purveying clean water
supplies.
Sources of water:
Drinking water is obtained primarily from surface water, such as streams, rivers
and lakes or from ground water through artesian or other types of wells.
Other means of obtaining water include collecting rainwater, desalinating
seawater.
Surface water is in general, more prone to contamination by both microbial
pathogens and chemicals since it directly receives industrial and municipal
wastewater and runoff from the land.
Ground water usually less contaminated than surface water because the soil
through which it proclates serves as a filter.
Uses of water:
Most water is used by toilets, and then cloth washers, showers, faucets, leaks,
other domestic and dishwasher.
Sources of contamination:
Contaminants can enter drinking water by a variety of mechanism.
Many chemicals such as pesticides and fertilizers enter drinking water sources
after being deliberately applied to the land and washing into surface or ground
waters.
Can also enter water through moving through the soil
Our methods of treating and distributing drinking water lead to some chemical
being present within our drinking water supplies.
Sources of contaminants that discharge into receiving waters from a pope or
other identifiable device are called point sources.
Point sources include industrial wastes and sewage treatment plants.
Sources of contaminations that cannot be defined by discrete pipes or other
devices are called non-point sources.
Water treatment process:
The developed world reduced the burden of waterborne disease outbreaks by
implementing a process to treat drinking water in the late nineteenth and early
20th century.
First water is pumped from its sources. The next step involves adding a
chemical coagulant.
Water with chemical contamination may need to undergo additional treatment at
this stage, such as activated charcoal or special ion exchange resins.
Boiling water is the traditional method of water purification, but since it
requires substantial energy production.
Boiling water also involves risk of scalding the lung injury when indoor
cooking fuels are used.
Both types of water treatment techniques are only effective against microbial
pathogens and do not reduce the concentration of chemical contaminants in the
water.
Biological threats to water quality:
World health organization has described five ways water may be associated
with human disease.
Waterbrone disease are transmitted by microorganism that survive within water
and are directly ingested.
Water-washed disease are those exacerbated by inadequate washring of hands
or foods, such as trachoma, other skin and eye infections and many of the fecal-
oral pathogens that cause waterborne disease.
Water based disease are caused by organisms that spend part of their life
cycle as larval forms within freshwater and come in contact with humans
through bating or ingesting of infested water.
Water related disease such as dengue fever and malaria are caused by organisms
that breed or otherwise spend part of their life cycle in the water but do not
come in contact with human host through water exposure.
Water dispersed infections are caused by microorganism, such as legionella,
that proliferate within water supplies and are transmitted to humans by dispersal
air and inhalation.
Majority of waterborne pathogens infect the gastrointenstinal tract. In which
they enter through contamination by human or animal fecal material.
Microbial pathogens are usually categorized by human or animal fecal matieral.
Few microbial pathogesn such as legionally and maycbotermic avium speices,
have the capacity to grow within the pipes of water distribution systems.
Worldwide, the main bacterial pathogens spread by water are salmnella species,
shigella species, pathogenic E.coli and vibrio cholerae.
Typhoid fever is characterized by high fevers, abdominal pain and more often
constipation than diarrhea.
Shigella and other bacteria can cause dystentery, which is charcterizedb y more
sever adbodminal cramping with blood and mucus in the stool.
Bacteria pathogens are more effectively controlled than viral or protozol
pathogens by existing water treatment processes.
Boiling water is a traditional method for water purification.
Boiling water also involves the risk of scalding and lung injury when indoor
cooking fuels are used.
Newer techniques include ethe use of dark plastic bottles that collect solar
energy to disinfect water and the combination of chemical disinfectants and
special narrow necked storage bottles that prevent recontamination of water.
Biological threats to water quality:
Viral pathogens have shown to play an important role in waterborne
gastrointestinal disease.
Outbreaks that have been characterized as acute gastroentritinal of unknown
etiology” are felt to be mostly due to virusues.
The main waterborne viral pathogens are Norwalk and Norwalk like viruses,
enterovirsues and adenovirus types 40 and 41.
Protozoa:
Growing proportion of outbreaks of infectious origin in the united states have
been due to protozal pathogens, primarily giardia lamblia and crypoteosporidum
parvum.
Parvum cuases severe and often fatal diarrheal disease in severely
immunocomparomised people, such as AIDS or cancer chemotherapy patients.
Chemical threats to water Quality:
Nitrates:
Nitrates can accumulate in ground and surface water, both from fertilizer runoff
and also from leaching of ammonia compounds from septic tanks and other
waste systems. After ingestion, nitrates are converted into more toxic nitrates by
bacteria colonizing the gastrointestinal tract.
Nitrites oxidize the hemoglobin red blood cells ability to transfer oxygen to the
rest of the body.
Methemoglobinemia results in oxygen starvation, cyanosis and if sever enough
brain damage and death.
Nitrate exposure may also cause adverse reproductive outcomes, including
spontaneous abortion and neural tube defects.
Pesticides:
Pesticides commonly found in ground and surface water.
Industrial discharge:
MTBE is a gasoline addictive designed to lower toxic air emissions from
automobile exhausts and has constituted up to 15% of gasoline in certain
regions.
For MTBE inhalation is the procedure
The commonly found chemicals are trichloroethylene and perchloroethylene,
chlorinated solvents.
Radon:
Radon dissolves in water as it moves through cracks in the earths crust.
Radon is not human made but occurs where uranium deposits are found within
the earths crust.
Radon volatilizing from drinking water is estimated to raise indoor air
concentrations by one ten thousands of the concentration of randon in the water.
High levels of radon in household water may slightly increase the risk of lung
cancer from inhaling aerosolized water and to a lesser degree increase the risk
of gastic cancer through direct ingestion.
Arsenic: