The following
are responses and summaries of various readings related to Human Health,
Disease, and the Environment.
Life Support: Urban and
Transboundary Air Pollution
Since the Industrial Revolution people have been studying the
effects of pollutants on lung disease.
During the Industrial Revolution entire communities of North America and
Europe fell seriously ill or died from air pollutants. These episodes were a result of air
stagnation, which increased the concentration of pollutants in the atmosphere,
more specifically those of sulfur dioxide and suspended particulates. Because of these episodes scientists and
governments began studying the adverse effects of pollution – identifying the
sources of pollutants, and discovering exposure-response relationships,
eventually leading to controls against pollution. Because the air cannot be contained pollution
is able to travel across borders. Poorer
nations generally have a greater problem with pollution than wealthier ones,
especially due to the heavy use of coal for power and heating. The countries which have found ways to reduce
the emissions of pollutants from industry, power plants, and automobiles have
created new problems via the formation of acids and ozone from their
outputs. The most common adverse health
effects due to pollution are caused by sulfur dioxide, particulates,
photochemical oxidants, ozone and nitrogen dioxide, and carbon monoxide. Sulfur dioxide is a result of the combustion
of fossil fuels such as coal and crude oil, generally affiliated with power
plants and oil refineries. Great
reductions in the measurements of sulfur dioxide and related pollutants were
achieved after the Clean Air Act of 1970s America. However, the tall stacks which were
implemented merely send the pollutants higher into the atmosphere where they
are able to change into acid aerosols.
Particulates are the result of industrial activity which put off
particles into the air which do not easily dissipate. Particulate counts have been shown related
with an increase in mortality rates.
Finer particles have been shown to be much more detrimental to
respiratory systems than more coarse particles. In areas with high particulate
levels deaths in children from respiratory illnesses is equally high. In the developing world only infant diarrhea
accounts for more deaths in children under the age of five. Ozone and nitrogen dioxide are most commonly
produced by sunlight on the output of automobiles. When the amount of sunlight is greatest
during the summer the greatest amount of ozone is produced. The safest area to avoid exposure to ozone is
indoors because ozone seems to be unable to contact surfaces chemically
unchanged. Carbon monoxide is another
major automobile emission. Many major
U.S. cities have exceedingly unhealthy levels of carbon monoxide. Carbon monoxide impairs the transport of
oxygen throughout the cardiovascular system, the effects of which can be
headache, dizziness, fatigue, and even death.
Poorer nations who use wood, crop residues, animal dung, and other
carbon based fuels for cooking and heating are especially at risk for indoor
pollution. The government has failed
greatly in studying the problem of pollution indoors. Nations need to work together in finding
solutions to the ever-growing pollution problem, as it is a global issue not
only local one.
Water Quality and Water
Resources
Over two million children die every year due to diarrhea
related illnesses, often attributed to waterborne infections. The greatest threat to the quality of water
is waste disposal. Increased quality of
waste disposal will improve human health much more than trying to find cleaner
water supplies. The majority of human
water consumption comes from surface water which is also the most susceptible
to contamination by chemicals and pathogens.
Most of human water consumption is not used for drinking, as nearly
seventy percent of the worlds water use is for the irrigation of agriculture
and most home use is for the flushing of toilets, washing of clothes,
showering, and small landscape and agriculture.
Much work has been put in to the development of legislation regarding
the issue of point source contamination in drinking water, however due to poor
enforcement point source contamination is still a problem especially in the
developing world. Chemical contamination
seems to be the greatest threat to the safety of drinking water as it is not so
easily destroyed by boiling. Often water
contaminated with chemicals requires additional treatment, usually by the use
of activated charcoal or special ion exchange resins. Bacteria contaminated waters most often cause
diarrheal diseases, however since 1980 there have been no outbreaks of
bacterial waterborne diseases in disinfected water supplies. Though viruses and protozoa related illnesses
are much more common as they are more difficult to eliminate. Nitrates are a major issue in the
contamination of water. When ingested
they are converted to a more toxic nitrite in the gastrointestinal tract. These occur most often in rural areas where
agriculture prevails and the majority of drinking water is obtained via ground
wells because fertilizers are able to seep into the drinking table easily. Though many of the worst pesticides have been
banned for use for the last thirty years many of them can still be found in the
water supplies, though it has yet to be proven that exposure to these
contaminated waters increases the risk of cancer. Radon, occurring natural in the environment,
is able to seep into the water supply and cause increased risk of lung cancer
through evaporation and inhalation, and increased risk of gastric cancer when
ingested. Arsenic also occurs naturally
in the environment and can cause skin and lung cancer, skin hyperpigmentation
and keratosis, vascular disease, and neurotoxicity. Lead, though not used for municipal water
systems for the last century, still persists and exposure can lead to decreased
intelligence and behavioral problems in children. Water usage is continuing to grow throughout
the world all the while water sources continue to decline. The relations between nations in areas of
inadequate water supplies will likely suffer in the decades to come as
populations’ water supply become more strained.
The world needs to become more efficient in its water usage to decrease
the detrimental effect on the supply, perhaps using untreated or recyclable
water in the circumstances where clean water is not a necessity. A decrease in the consumption of meat
products will also greatly reduce the amount of water used for agriculture, as
the grain required for a pound of beef needs at least ten times as much water
as an equal pound of grain for human consumption.
Ozone Depletion and
Ultraviolet Radiation
Ultraviolet radiation is the cause of photochemical smog,
bleaching of paints, and decay of plastics.
UVA is generally much less harmful than UVB radiation. Chlorofluorocarbons put off by household
substances are able to reach the stratosphere they release chlorine and
bromine. Due to this the amount of ozone
in the stratosphere has been measure to have greatly decreased in temperate and
polar zones during the last twenty years.
The effects the decrease in ozone has can be measure all the way down to
the bottom of the marine food chain. The
increase in UVB radiation is not likely to increase the rate of sunburn in
people because human skin can easily adapt to gradual change in UVB radiation,
though it is believed that increased exposure can cause skin cancer, cataracts,
and decreased cellular immunity. UVB
radiation causes damage to DNA and therefore increases the likelihood of
cancer. It has been shown that increased
exposure to UVB radiation increases the risk of skin cancer. Humans do need daily exposure to UVB
radiation in order to maintain the levels of vitamin D in their systems,
however overexposure can cause problems.
The occurrences of skin cancer is expected to reach its greatest level
by the year 2060, when the ozone is predicted to be at its thinnest. The cases of cataracts is expected to rise
one half percent for every one percent decrease in the ozone layer. UV exposure can be both beneficial and
detrimental to skin diseases, however its causing of immunosuppression could
cause a greater prevalence of cancers.
The increase in UVB exposure could affect humans indirectly by changes
to the environment, though it would be difficult to quantify this. Though efforts have been made to reduce the
ozone depleting emissions of the world, it is difficult for more cash strapped
developing nations to change without the help of the wealthier nations.
U.S. Food Imports
Rarely Inspected
The FDA is only able to inspect about 1.3 percent of imported
foods which make it into the U.S. annually.
Experts believe that the FDA, and United States government in general,
do not have the resources or manpower to effectively ensure the safety of the
food which makes its way to our grocery store shelves. The rules and
regulations regarding food safety practices in other nations outside of the
United States and Western Europe are often poorly enforced if existing at
all. The food supply has become global
and therefore the FDA is finding itself stretched too thin. It must focus on the foods and producers
which are most likely to be contaminated with potentially harmful bacteria and
chemicals. The problem arises when food
that is not expected to be contaminated makes its way in without any inspection
occurring at all, happening more often than believed. China and other developing nations are the
main cause for the contaminated foods which enter the U.S. as the laws
regarding their inspection are often very lax in comparison to our own. Just over the last ten years the U.S.
consumption of Chinese exports has tripled.
China is only bested by Mexico in its suspicion by the U.S. food
inspection services. The FDA continues
to have its budget reduced thereby decreasing the amount of food that gets
inspected upon import. The best way the
consumer can insure the safety of their food, and reduce the load on the
government agencies, is to buy food labeled as having been grown or acquired
locally within our own borders. The laws
regulating the sell of local foods are much more stringent than those of
imports and will thereby generally be a safer product.
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