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FOOD AND WATER POLLUTION
By
Dr. Dhiraj Nanda, MD(Hom)
Pollutants have entered our diet by gaining entry in the
food chain. Different pollutants enter into our diet
through consumption of pollutant contaminated food and
water.
Food pollution
The
entry of undesirable substances into the food chain
through environmental agencies i.e. air, water, soil, is
called food pollution. Pollutants may gain entry into
the food chain at any stage. Many of these pollutants
have a bio-accumulation property. These get accumulated
in the body of consumer of these polluted food-items.
A
classic example of a health problem due to
food-pollution is Minimata disease of
Japan. For years the cause of minimata disease was not
understood. The cause was traced, some years later to
mercury present in the fish, which was being released
into the sea as mercurius chloride from a nearby
industry. The action of microbes produced poisonous
compounds methyl mercury and diethyl mercury from
mercurius chloride in the sea bottom of shallow areas of
east cost of Japan which entered food-chain through fish
which was causing the disease.
In the
year 1968, pregnant women of Japan who had consumed oil
contaminated by pollutant polychlorinated biphenyl gave
birth to infants who suffered from growth retardation.
This problem, called as Yusho disease, is
another example of health problem arising from adverse
effect of food pollution.
Water pollution
River
Ganga, which is said to have divine powers to clean and
remove the sins of devotees who take plunge into its
water, had become so polluted by unplanned developmental
activities that it became essential to clean it. For
this very purpose Central Ganga Authority was set up and
Ganga Action plan was implemented. Rivers like Ganges
which have been life-lines of development of human
civilizations, have been and are even today being
treated as dust-bins to dump all types of wastes ranging
from house-hold, municipal wastes to industrial
effluents. Most of water bodies, be it rivers, ponds,
lakes or sea; are being used as dumping areas for wastes
including pollutants. In fact, tons and tons of
pollutants are being dumped into water bodies many of
which are source of supply of drinking water.
Adverse effects of food and water pollution on health
About
two-thirds of human body is made up of water. This is
why water pollutants have wide spread adverse effects.
Pollutants which gain entry into human system through
food and water can be broadly divided into following
types:
A)
Animate pollutants
Animate pollutants mainly include different bacteria,
specific pathogens and viruses. These types of
pollutants enter food and water mainly through sewage
contamination of water resources. Common diseases which
spread as adverse effects of animate pollutants include
cholera, diarrhoea, dysentery, gastroenteritis (acute
and chronic), hepatitis, poliomyelitis etc.
B)
Inanimate pollutants
Inanimate pollutants can be further divided into
following two types
1.
Inorganic chemicals; and
2.
Organic chemicals.
Polluted water is responsible for a variety of health
problems ranging from minor gastric upset to cancer.
Gastro-intestinal problems, including affections of
liver are very common manifestations from consumption of
polluted water. Bacteriological pollutants are mainly
responsible gastro-intestinal and liver infections.
Children are most prone to be affected by
bacteriological pollutants. In poor countries like India
most of children affected die because of diarrhoea which
is a manifestation in many of these problems.
The
inanimate pollutants ,both inorganic chemicals and
organic compounds, have the capacity to alter the
physical and chemical nature of the water of water body
in which these are dumped making it unfit for human
consumption. Many of these pollutants have poisonous
effects and that is why dead fishes are found in these
water bodies whenever there is increase in the levels of
pollutants. Two important sources of inanimate
pollutants are:
1.
Industries; and
2.
Agriculture.
Insecticides and pesticides which are widely used in
agricultural practices are main source of organic
pollutants such as DDT, BHC, and Organophosphates etc.
The effects of these pollutants on human health
are devastating as they cause immuno-supression.
Many of these can cross the placental barrier and affect
the development of immune system of the fetus. It is
important to note that these pollutants, even if present
in very minute quantities in water or food, tend to
accumulate in the body of consumer. This phenomenon is
called as Bio-magnification. In fact, blood samples of
residents of cities like Delhi which are far off from
agricultural fields where pesticides are used, have
shown high levels of pesticides like DDT. High levels of
pesticides have also been found in the milk of nursing
mothers of many cities which are far away from
agricultural farms. Patients, especially children, loose
the immunity to fight with infectious diseases due to
immunosuppressive action of pesticides and are unable to
recover from diseases from which they can recover
easily. The cause of death in such cases is
immunosuppressive adverse effect of pollutants not the
disease.
Another important adverse effect of pesticides is their
carcinogenic effect.
According to studies and surveys done in Australia,
Canada, China, Europe, Philippines and United States of
America; farmers (who are directly exposed to
herbicides, insecticides and pesticides) have
significantly higher risks of various types of cancers.
Pesticides also appear to be associated with auto-immune
disorders.
Inorganic chemicals such as arsenic, lead and mercury
are known for their toxic effects on human health. When
consumed for long time these produce different symptoms
of chronic poisoning along with variety of other
problems.
Consumption of cadmium causes a disease called
itai-itai which affects calcium metabolism makes
bones brittle.
Fluoride in excess as well in less concentration than
the prescribed limits has harmful effects. Low fluoride
is associated with dental carries and excess fluoride
can cause damage to skeletal tissues.
Nitrogen and phosphorus are known as bio-stimulants.
Nitrate nitrogen as NO3 in high concentrations than 45
ppm in drinking water may have fatal effects in infants.
It produces a disease called methemoglobinemia in
infants. Nitrate nitrogen also reacts with secondary
amines to produce nitrosamines which have a carcinogenic
effect.
Different pollutants released from different types of
industries have different effects on human health.
Long term effects of many of these like compounds of
arsenic, lead, mercury, nitrogens, phenols, phosphates,
sulphates, etc.,etc. include chronic poisoning.
Next
month I will conclude this series of impact of
artificial disease causing and maintaining factors with
an article impact of this artificial environment on
sexual life.
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