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Monday, March 22, 2010

Human diseases related to pollutions

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Any risk or injury caused to a person due to exposure to a particular pollutant present in any component of environment – air, water, or soil or even in the food items is called as an environmental disease.
Environmental diseases spread through the agencies of environment like air, water, and soil because the polluted air, water, or soil may contain varieties of germs of diseases, poisonous chemicals, allergens, and toxic substances. Some toxic substances and other pollutants are produced in work settings. The labourers exposed to them become easy preys to serious diseases specific to the particular work setting or occupation. Since a particular part of environment is solely responsible for specific diseases, we should study about environmental diseases with reference to different types of pollutions. But, let us discuss the occupational diseases first that form the major part of environmental Diseases.

The knowledge about environmental diseases started gaining momentum, with the recognition of the occupational diseases during Industrial Revolution. Diseases that are caused to a person due to a person’s particular type of occupation are called as occupational diseases. Pneumoconiosis like Asbestosis, silicosis, Byssinosis etc is some examples of occupational diseases. All of these diseases are caused through air pollution in the area where workers work for long hours.

The coal miners are frequently caught by the black lung disease, which is also called as Pneumoconiosis (plural- Pneumoconioses).It is the general term, applied to diseases basically caused due to the deposit of dust and particles of organic and inorganic origin into human lungs. These particles include particles of coal, sand, asbestos, and different types of minerals. Pneumoconiosis if caused due to the deposit of coal dust in the lungs of coal miners, leads to a serious lung disease called as Black Lung disease. The deposit of cotton fibres, Jute fibres, hemp fibres etc. into the lungs of human beings (and even cattle also) cause pneumoconiosis and other diseases including cancer of respiratory tract.

 Workers working in the asbestos industry are caught by the serious lung disease called as asbestosis. In this case asbestos particles entering into lungs are engulfed by macrophages found in the lung tissues. These are a group of phagocytic cells acting as the ultimate defence against the inhaled particles or fibres in the work settings. Presence of high number of these cells in the deep sputum indicates the exposure of the individual to high particulate pollution. A Large number of macrophages are killed in their attempt of engulfing particles of silica, coal, cement, and fibres of cotton industries. The contents of macrophages get spread within the bronchiolar cavities. The condition gradually becomes serious and leads to the death of the worker.

Silicosis is caused due to the deposit of silica in the lungs of workers working in silica industries or at the sand blasting sites. Byssinosis is the lung disease caused due to the deposit of cotton dust in the lungs of workers working in textile industries. The total blame for these diseases goes to the air pollution.

EMPHYSEMA: The breaking down of sensitive tissue of lungs due to air pollution and smoke of cigarette is called as Emphysema. Once this disease happens, the lungs can not expand and contract properly. About two million people in America are having this disease caused basically due to cigarette smoking.

 In fact, it is a progressive respiratory disease characterised by coughing, shortness of breath, and wheezing, developing into extreme difficulty in breathing and sometimes resulting to lung cancer and death. Due to this disease, the passages leading to the air sacs of lungs become narrowed. Tissues of lungs loose their natural elasticity and undergo destructive changes. Lungs often increase in size and become unable to supply enough oxygen to body tissues. This condition strains the heart also. It damages the bronchioles of lungs very badly due to which a man becomes unable to breathe and dies. The risk due to tobacco smoke is the voluntary risk

Diseases due to Air Pollution
Air pollution causes various types of risks to human health, either directly or indirectly. The air pollution by gases like sulphur dioxide and nitrogen oxides (NOx) cause acid rains which affects the components of environment including human beings. Emission of gases like sulphur dioxide, nitrogen oxides etc. combine with rain water to cause acid rains. Drinking of water contaminated with water of acid rain may cause serious neurological disorders in man. Similarly, pollutants emitted from industries and automobile can cause irreparable damages to human health.

Different Types of Air Pollutants, their Sources and Diseases caused due to them
Automobiles such as cars and other motorised vehicles consume fossil fuels like diesel and petrol. These fuels produce several types of pollutants on combustion inside engines of these vehicles. Diesel is the most required fossil fuel in the transport industry today. It is widely used in heavy duty engines of trucks, trains, marine transport, DG Sets etc. The popularity of diesel engines has increased up to greater extent both due to its efficiency and long service life as compared to petrol (gasoline) engines. Emissions due to burning of diesel contain less carbon monoxide, hydrocarbon and carbon dioxide but more oxides of nitrogen and particulate matter. The exhaust due to burning of diesel is a complex mixture of both the particulate and gaseous components. The size of particulate matter contained in the diesel exhaust ranges from 0.05 to 1.00 micrometer. Particulates of such small size easily enter into the respiratory system and get deposited in the air ways and alveoli. These particulates are able to absorb different hydrocarbons including carcinogenic (cancer causing) polycyclic aromatic hydrocarbons (PAHs) and nitro- PAHs that are of serious concern for human health. 

The components of diesel exhaust undergo atmospheric transformation and become more potent mutagens and carcinogens. It is evident from latest researches that the cancer potency of diesel vehicles is more than double the same of gasoline vehicles in India. The carcinogenic effects of diesel particulates is 24 times greater than that of Gasoline and 84 times greater than that of the Compressed Natural Gas (CNG).The Hon’ble Supreme Court of India has restricted the use of commercial diesel driven vehicles in Delhi due to its harmful effects. Starting from 1 April 2001 it has been made mandatory to use only compressed natural GAS in all transport buses in Delhi.

Diseases due to Water Pollution
Sewage, infectious micro organisms, plant nutrients, organic and inorganic substances and sediments are principal pollutants that cause water pollution. Out of these, the pollutants harmful to human health may be categorized as micro organisms and chemical agents.

Infectious micro organisms from sewage, municipal drains, slaughter houses, leather industries, sanatoria and hospital drains may contaminate our water sources. Various types of pathogens like viruses, bacteria, protozoa, and parasitic worms that are found in faecal matter get mixed in water through drainage systems passing through areas having poor sanitary conditions. Travelling through water sources these pathogens interfuse directly through persons handling food and water. If potable water is contaminated with these organisms, the contamination may cause several types of diseases like cholera, typhoid, gastroenteritis, diarrhoea, dysentery and skin diseases. These diseases frequently endanger the community health.

Various organic and inorganic chemicals contained in polluted water cause serious health hazards. Inorganic substances like mercury, sulphur compounds, cyanides, arsenic, lead, fluorides, nitrates, cadmium, petrochemicals, etc. join our water bodies from industrial and mine sources. Phenols, detergents, pesticides etc. join our water bodies from domestic and agricultural sources. These pollutants cause serious health problems by entering into human bodies through food and water. Stagnant water and other dirty water act as good habitats for mosquitoes and a host of other parasites and insects that cause a large number of diseases mainly in tropical areas.

Dumps of wastes on open grounds and landfill sites cause pollution of underground water through leaching. Different types of infectious diseases like cholera, hepatitis, dysentery, diarrhoea, gastroenteritis etc. are caused in human beings due to contamination of underground water. Ambala, Ludhiana, and Sonepat industrial areas of Punjab (India) were reported to contain nickel, iron, copper, chromium and cyanides in their ground waters. Effluents of metal industries that contaminate water contain cyanogens, phenol, coke, limestone, alkali, oils, mill scale, fine suspended solids, chromium, zinc, copper, silver, acids, alkaline cleansers, grease etc.  The exposure to different heavy metals causes toxic effects on human health which is detailed in the table below.

Diseases spreading through water are called as water-borne diseases. In west Bengal seven districts are badly hit by arsenic poisoning. The water from tube wells supposed to be clean and pure contains high percentage of arsenic.

The introduction of nutrients to coastal and marine waters has been a primary concern at the Stockholm Conference. The supply of fixed nitrogen to the oceans has greatly increased since last few decades. Sewage discharge is the dominant local source of marine water contamination near urban areas. However, agricultural run- offs and atmospheric deposition of carbon dioxide and acids are more responsible for marine pollution. The toxic pollutants present in sea water due to human activities join marine food chains and get deposited and magnified inside the bodies of sea animals and marine algae that are consumed as sea- food by human beings. Besides these, vast varieties of bacteria, viruses, toxic substances, fungi and worms remain present in polluted marine waters that infect humans whenever they come in contact of their bodies, or enter into their digestive tracts through food items.

Some of the diseases related to the marine contamination are listed below-
Not alone the human beings are affected by the pollution of marine waters but vast varieties of sea organisms are subjected to tragic deaths and diseases due to deposit of wastes into marine waters through human activities. Big amounts of sand and silt brought to sea by rivers get spread in the marine water and obstruct sun light against reaching deep down to the sea organisms. Thousands and thousands of fishes die due to deposit of silt on their gills. The deposit of carbon dioxide in the marine water is increasing due to human activities. It forms acid after combining with water which reacts with the shells of molluscs. This is the reason why molluscs are vanishing out of our seas and oceans.

Diseases due to Soil Pollution
            Soil is polluted by dumping of wastes from domestic, municipal, industrial, commercial, agricultural, hospital, mineral and construction sources. Toxic and non- biodegradable pollutants from these sources join food- chains and accumulate in food sources like plants and animals. Pesticides from agricultural fields enter into plants and get accumulated inside leaves, flowers, stems, roots, fruits, vegetables and grains. From there they reach to the consumers of the first order i.e. herbivores. Since, man is the top consumer, most of the non- biodegradable substances like some pesticides get accumulated in fatty tissues of humans and animals, and cause different types of neurological and reproductive diseases. In an ecosystem in which a secondary consumer or other is on the top, all the poison gets accumulated and magnified in his body. It often kills the animal. Allergies of respiratory tract, nausea, headache, fatigue, dizziness, kidney troubles, cancers, abortions, infant mortality etc. are some of the symptoms of pesticide poisoning and diseases due to soil pollution. Many cows die every year due to ingestion of plastics thrown here and there along with food items.

Diseases due to Radiation Pollution
The radioactive wastes are non- biodegradable substances that are mostly produced from laboratories, hospitals and atomic reactors etc. These substances produce highly energized particles which are very harmful to life. Radioactive emissions often cause seriously dangerous effects in human body when it is exposed to them. Atomic explosions emit such types of radiations that cause genetic disorders in men, animals and plants.     

Radiations cause both somatic and genetic diseases in human and animal bodies. The somatic effects include immediate effects like sickness and radiation syndrome as well as delayed effects like carcinogenesis, abortion, abnormal development of foetus and leukaemia. The genetic effects of exposure to radiations on human bodies include chromosomal and genetic mutations that produce permanent abnormalities in their off springs. In view of nuclear hazards due to nuclear radiations frequently occurring here and there around the globe some of the Nuclear Reactors in the world have been closed down or dislocated away from human population due to the impacts of their radiations in the local environment. An accident at the Three Miles Island Reactors in the U.S. that occurred in 1979 marked the end of nuclear power in the United States.

Diseases due to Noise Pollution:
Besides causing discomfort, noise can also produce some serious effects on human body like high blood pressure, irregular heartbeat, deafness and mental disorders. It interferes with general communications and disturbs in sleep and studies of students. It is very harmful for patients. These are the reasons why blowing of horns by vehicles has been banned in certain areas like military cantonments, schools and hospitals etc.

Excessive noise can result into cardiovascular problems also. The elevated sound level cause cardiovascular consequences due to elevated adrenalin level. This triggers narrowing of blood vessels (Vasoconstriction). Other proven effects of noise pollution are – increased frequency of headaches, fatigue, stomach ulcers, and head rush, birth defects, spine defects and abortions. Psychological effects of noise pollution are- annoyance, sleep disturbances, reading development in children, stressed mental health, aggressive behaviour etc. Noise Pollution also causes the Reading –Learning Impairment known as Dysgraphia, which is associated with noise pollution.

Environmental Noise Regulations usually specify a minimum outdoor level of 60 to 65 dB, while occupational safety organizations recommend that the maximum exposure to noise should be 40 hours per week at 85 to 90 dB.

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