Have you ever taken a second thought as to what is in the water you drink? Have you ever been worried it has been tainted with a toxic element? For some people in Southern Asia and other rural areas in the world, the only access to water they have is that of well water contaminated with high levels of arsenic. This widespread pollution of a vital resource has harmed millions of humans across the world, but what can be done?
First, we
must understand what we are dealing with. Arsenic is a metalloid (semi-metal)
that is naturally found in the Earth’s crust. It is found in two forms in
nature, organic and inorganic, where inorganic arsenic is highly toxic. Arsenic
can also exist in a temporary gaseous form called arsine. Arsine is extremely
toxic and is responsible for cases of arsenic poisoning in industrial processes.
Trace quantities of arsenic are found in rock, water, soil, and air however
concentrations may be higher in certain areas due to human activities. Smelting
and mining, fossil fuel combustion, and pesticide use are the biggest
anthropogenic contributors of arsenic into the environment. Arsenic
concentrations are also higher in urban areas, where industrial processes
release amounts of arsenic into the environment. Although domestic production
of arsenic was stopped in 1985, arsenic is still used in preserving wood,
chemotherapy, coal-fired power plants, purifying industrial gases, and as an
alloying agent. Arsenic is naturally released into the environment through
weathering of arsenic-containing minerals and through volcanic eruptions. In
areas with soil rich with arsenic deposits, the groundwater supplies often
becomes contaminated from runoff and leaching.
Humans can be exposed to arsenic through food,
water, and air. The most common source is through groundwater contaminated with
high levels of inorganic arsenic that are naturally present in the environment.
Therefore, drinking water, crop irrigation, and food prepared with contaminated
water are all fairly accessible sources of arsenic. Levels of arsenic in other
foods are relatively low, however fish tend to contain high levels of arsenic
due to its presence in the water they live in. These levels are usually
harmless levels of organic arsenic, however some fish can contain dangerous
amounts of toxic inorganic arsenic. As for air exposure, smelting and the
combustion of fossil fuels release large amounts of arsenic into the
atmosphere, usually in urban areas. Humans can also be exposed to arsenic due
to their job and living situation. People working in environments where arsenic
is used in industrial processes as an alloying agent as well as farmers who
live where arsenical pesticides were once applied are exposed daily. Other
occupational hazards include people who work in industries that deal with wood
preservation, the production of lasers and semiconductors, and the glass
industry.
Inorganic arsenic is acutely toxic; once one is exposed to a large
amount of inorganic arsenic, the harmful effects appear within hours or days of
exposure. These symptoms include vomiting, diarrhea, stomach pain, and could
lead to coma and death. This acute poisoning is rare and only occurs with
intentional poisoning or through occupational hazard. However, chronic exposure
to inorganic arsenic in small concentrations can also lead to a variety of
different health effects. The most common effects are skin changes and cancer
of the bladder, skin, or kidneys. Hyper-pigmentation of the skin, skin lesions,
and rough patches on the palms and soles of the hands and feet are the initial
effects. These often occur after five years of chronic exposure, whereas cancer
symptoms often begin to appear after ten or more years. Arsenic is classified
as a Group A carcinogenic by the Environmental Protection Agency and is
recognized by the International Agency for Research on Cancer as a known human
carcinogen. Other effects of chronic exposure include cardiovascular disease,
diabetes, and infertility.
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| A- myelinated axons B- axonopathy C- demyelination |
The neurological effects of
inorganic arsenic poisoning are not as commonly known as its carcinogenic and
cardiovascular effects. Acute consumption can first cause peripheral
neuropathy, which is simply nerve pain and damage to nerves in the peripheral nervous
system. This causes muscle cramps, numbness, spontaneous pain, and an
unpleasant distortion of the sensation of touch. Damage to the peripheral
nervous system is caused by processes called axonopathy and demyelination.
Following exposure, axons, the long fibers that extend out from the main nerve
cell body, are disrupted. Degeneration occurs in the most distal parts of the
axon, causing the axon to ‘die-back.’ There is also a breakdown of myelin,
spiral sheets of cell membranes that are wrapped around the axons larger than
one micron in the peripheral nervous system. Myelin also acts as an electrical
insulator and promotes conduction between axons. There are always large sensory
fibers in myelin that register vibration, touch, and position sense. Disruption
to these fibers decreases the ability to feel touch and vibration, causing
general numbness. Both the degeneration of axons and loss of myelin create a
‘stocking-glove’ effect seen in arsenic poisoning cases where numbness and
weakness are often experienced in the distant parts of the body, the hands and
feet.
Peripheral neuropathy is more commonly found in cases of acute
arsenic poisoning, whereas damage to the central nervous system is present in
both acute and chronic poisoning cases. Short-term exposure often results in
acute brain dysfunction such as drowsiness, dizziness, headache, confusion,
agitation, and in serious cases, coma. These symptoms are often only found in
cases of suicidal attempts or accidental exposure to a large amount of arsenic
and are accompanied with respiratory and cardiovascular problems. Patients can
also be left with serious memory impairment. Chronic arsenic exposure can lead
to neurobehavioral disorders such as impairment of cognition, judgment, and
memory. Although not proven, several cases have shown that arsenic can affect
to development of the brain in children. In one case in western Japan,
several infants were reported to have diarrhea, vomiting, and skin darkening
symptoms. It was later found that all infants had consumed the same Morinaga
milk formula that was later detected with high levels of arsenic. Fourteen
years after the initial exposure, many of the children were reported to have
very serious after-effects including central nervous system damage, mental
disorders, difficulties in studying and concentration, and eyesight problems. A
similar study was conducted on a population of children who were exposed to
arsenic through a smelter complex in San Luis Potosi, Mexico. Scientists
assessed the brain function and intellectual ability of these children through
the WISC-RM. It specifically measured concepts, knowledge, sequential, and
spatial functions rather than only assessing IQ. It was found that arsenic
exposure was connected with memory and long-term comprehension with their
memories being the most affected variable.
What many people do not realize is that arsenic poisoning is a
worldwide public health problem, especially in underdeveloped areas. Many third
world countries in Southern Asia have the highest rate of arsenic poisoning.
Millions of people in poor areas in these countries are exposed daily to
arsenic through contaminated well water that they use to irrigate their crops,
as drinking water, and in food preparation. After chronic daily exposure, these
populations tend to experience more severe poisoning symptoms due to their poor
nutrition and relatively low health status. Governments of these countries
often have weak economies and are unable to provide sufficient financial
support to attempt to resolve such a vast public health problem. Therefore,
they must rely largely on external aid from outside governments and
organizations in order to address this direct health risk to its populations.
One organization has been attempting to address the socioeconomic
issues surrounding arsenic exposure in Bangladesh, where arsenic exposure is
referred to as, “the worst mass poisoning in history.” The Arsenic Mitigation
and Research Foundation is an organization comprised of researches, doctors and
developmental practitioners that are attempting to establish safe water and
health support in arsenic affected, marginalized communities. After testing the
shallow tube wells in place, they discovered more than 66% of these water
sources were contaminated with high levels of arsenic and an estimated 77
million people in Bangladesh were exposed. Despite these discouraging
statistics, the foundation has been implementing short and long-term processes
in order to halt arsenic exposure They have installed deep-tube wells that will
hopefully produce uncontaminated water as well as providing affected
populations with long term medical support. Beyond providing tangible
solutions, they are dedicated to providing education to populations on
maintaining wells and testing water quality. They hope to build collective
ownership and control over water supplies, so communities can work together to
regulate water quality.
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| Wells painted red indicate high arsenic levels |
As picturesque as this vision for Bangladesh seems, it is not that
easy to solve such a widespread pollution of a vital resource. Deep-tube wells
could trigger arsenic contamination of deep aquifers, despite their quick
installment. It is also necessary that education and community engagement is
successful in communities or else prevention attempts will be useless. The
World Health Organization has also highlighted other preventative measures such
as substituting groundwater with low arsenic sources such as rain water and
treated surface water and to install arsenic removal systems to ensure arsenic
disposal. These can be effective, however the right technology is necessary and
can be high-cost, which governments in affected countries often cannot support.
They also suggest marking high-arsenic sources and wells, which is an easy and
effective way to reduce exposure, however an effective education is necessary.
Ultimately, it is about finding the perfect mix of community engagement and
financial aide in order to prevent further arsenic exposure and to aide
affected communities.
Sources:
http://archive.unu.edu/unupress/unupbooks/uu35ie/uu35ie0a.htm
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