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Introduction :
Adequate supply of fresh and clean drinking water is a basic need for all human beings on the earth, yet it has been observed that millions of people worldwide are deprived of this.
Industrial growth, urbanization and the increasing use of synthetic organic
substances have serious and adverse impacts on freshwater bodies.
Many areas of groundwater and surface water are now contaminated with heavy metals, POPs (persistent organic pollutants), and nutrients that have an adverse affect on health.
Water-borne diseases and water-caused health problems are mostly due to
inadequate and incompetent management of water resources. In the urban areas water gets contaminated in many different ways, some of
the most common reasons being leaky water pipe joints in areas where the water pipe and sewage line pass close together. Sometimes the water gets polluted at source due to various reasons and mainly due to inflow of sewage into the source.
Ground water can be contaminated through various sources and some of these are mentioned below.
Pesticides: Run-off from farms, backyards, and golf courses contain pesticides such as DDT that in turn contaminate the water.
Leech ate from landfill sites is another major contaminating source. Its effects on the ecosystems and health are endocrine and reproductive damage in wildlife. Groundwater is susceptible to contamination, as pesticides are mobile in the soil. It is a matter of concern as these chemicals are persistent in the soil and water.
Sewage: Untreated or inadequately treated municipal sewage is a major source of groundwater and surface water pollution in the developing countries. The organic material that is discharged with municipal waste into the watercourses uses substantial oxygen for biological degradation thereby upsetting the ecological balance of rivers and lakes. Sewage also carries microbial pathogens that are the cause of the spread of disease.
Nutrients: Domestic waste water, agricultural run-off, and industrial effluents contain phosphorus and nitrogen, fertilizer run-off, manure from livestock operations, which increase the level of nutrients in water bodies and can cause eutrophication in the lakes and rivers and continue on to the coastal areas. The nitrates come mainly from the fertilizer that is added to the fields. Excessive use of fertilizers cause nitrate
contamination of groundwater, with the result that nitrate levels in drinking water is far above the safety levels recommended. Good agricultural practices can help in reducing the amount of nitrates in the soil and thereby lower its content in the water.
Synthetic organics: Many of the 100 000 synthetic compounds in use today are found in the aquatic environment and accumulate in the food chain.
POPs or Persistent organic pollutants, represent the most harmful element for the ecosystem and for human health, for example, industrial chemicals and agricultural pesticides. These chemicals can accumulate in fish and cause serious damage to human health. Where pesticides are used on a large-scale, groundwater gets contaminated and this leads to the chemical contamination of drinking water.
Acidification: Acidification of surface water, mainly lakes and reservoirs, is one of the major environmental impacts of transport over long distance of air pollutants such as sulphur dioxide from power plants, other heavy industry such as steel plants, and motor vehicles.
Chemicals in drinking water: Chemicals in water can be both naturally occurring or introduced by human interference and can have serious health effects.
Fluoride: Fluoride in the water is essential for protection against dental caries and weakening of the bones, but higher levels can have an adverse effect on health. In India, high fluoride content is found naturally in the waters in
Rajasthan.
Arsenic: Arsenic occurs naturally or is possibly aggravated
by over powering aquifers and by phosphorus from fertilizers. High concentrations of arsenic in water can have an adverse effect on
health. A few years back, high concentrations of this element was found in drinking water in six districts in West Bengal. A majority of people in the area was found suffering from arsenic skin lesions. It was felt that arsenic
contamination in the groundwater was due to natural causes. The government is trying to provide an alternative drinking water source and a method through which the arsenic content from water can be removed.
Lead: Lead pipes, fittings, solder, and the service connections of some household plumbing systems contain lead that contaminates the drinking
water source.
Recreational use of water: Untreated sewage, industrial effluents, and agricultural waste are often discharged into the water bodies such as the lakes, coastal areas and rivers endangering their use for recreational purposes such as swimming and
canoeing.
Petrochemicals: Petrochemicals contaminate the groundwater from underground petroleum storage tanks.
Other heavy metals: These contaminants come from mining waste and tailings, landfills, or hazardous waste dumps.
Chlorinated solvents: Metal and plastic effluents, fabric cleaning, electronic and aircraft manufacturing are often discharged and contaminate groundwater.
Water-born Disease
Pollution in water cause the following Water-borne diseases:
Bacterial infections Typhoid
Cholera
Paratyphoid fever
Bacillary dysentery
Viral infections Infectious Hepatitis (jaundice)
Poliomyelitis
Protozoal infections Amoebic dysentery
Water-borne diseases are infectious diseases spread primarily through contaminated water. Though these diseases are spread either directly or through flies or filth, water is the chief medium for spread of these diseases and hence they are termed as water-borne diseases.
Most intestinal (enteric) diseases are infectious and are transmitted through
faeces waste. Pathogens – which include virus, bacteria, protozoa, and parasitic worms – are disease-producing agents found in the faeces of infected persons. These diseases are more prevalent in areas with poor sanitary conditions. These pathogens travel through water sources and interfuses directly through persons handling food and water. Since these diseases are highly infectious, extreme care and hygiene should be maintained by people looking after an infected patient. Hepatitis, cholera, dysentery, and typhoid are the more common water-borne diseases that affect large populations in the tropical regions.
A large number of chemicals that either exist naturally in the land or are added due to human activity dissolve in the water, thereby contaminating it and leading to various diseases.
Pesticides. The organophosphates and the carbonates present in pesticides affect and damage the nervous system and can cause cancer. Some of the pesticides contain carcinogens that exceed recommended levels. They contain chlorides that cause reproductive and endocrinal damage.
Lead. Lead is hazardous to health as it accumulates in the body and affects the central nervous system. Children and pregnant women are most at risk.
Fluoride. Excess fluorides can cause yellowing of the teeth and damage to the spinal cord and other crippling diseases.
In India, the most common cause of fluorosis is fluoride-laden water derived from
bore wells dug deep into the earth. Of India's 32 states, 17 have been identified as "endemic" areas for
fluorosis, with an estimated 25 million people impacted, and another 66 million "at risk."
In a news " Increased threat of fluorosis in city - Times of India, June 29, 2004 NEW
DELHI" - With one-third of Delhi's groundwater laced with excessive fluorides, the number of people falling prey to fluoride poisoning is increasing...
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According to doctors, there are three forms of fluoride poisoning or
fluorosis, the most common being dental fluorosis. The other two forms are skeletal and non-skeletal
fluorosis. Dental fluorosis causes yellow, brown or black streaks or spots on the teeth. There is no cure for dental
fluorosis. "It is this physical symptom which makes people aware, whereas skeletal fluorosis can go undetected for a long time," said Lady Hardinge Medical College's Pravesh
Mehra. Executive director of Fluorosis Research and Rural Development Foundation, A K Susheela said a large number of patients are directed to the foundation since tests for fluoride were not part
of the routine blood and urine tests conducted at government hospitals. Meanwhile, the non-skeletal fluorosis affects the soft tissues in the body and one may develop health problems in a very short interval.
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Dental fluorosis
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India's largest state, suffers from fluorosis, a debilitating disease that damages bones and teeth, research by a voluntary body shows. "The incidence of fluorosis, caused by an excess of fluoride compounds in drinking water, has been rising at an alarming rate in the state," says Mahitosh Bagoria of Health Environment and Development
Consortium. "It is estimated that around 25 percent of the rural population in the state is affected," he said...
Villagers who consume non-potable water suffer from yellow, cracked teeth, joint pains and crippled limbs and also age rapidly.
Nitrates. Drinking water that gets contaminated with nitrates can prove fatal
especially to infants that drink formula milk as it restricts the amount of oxygen that reaches the brain causing the ‘blue baby’ syndrome. It is also linked to digestive tract cancers. It causes algae to bloom resulting in eutrophication in surface water.
Petrochemicals. Benzene and other petrochemicals can cause cancer even at low exposure levels.
Chlorinated solvents. These are linked to reproduction disorders and to some cancers.
Arsenic. Arsenic poisoning through water can cause liver and nervous system damage, vascular diseases and also skin cancer.
Other heavy metals. –Heavy metals cause damage to the nervous system and the kidney, and other metabolic disruptions.
Salts. It makes the fresh water unusable for drinking and irrigation purposes.
Exposure to polluted water can cause diarrhoea, skin irritation, respiratory problems, and other diseases, depending on the pollutant that is in the water body. Stagnant water and other untreated water provide a habitat for the mosquito and a host of other parasites and insects that cause a large number of diseases especially in the tropical regions. Among these, malaria is undoubtedly the most widely distributed and causes most damage to human health.
Preventive measures
Water-borne epidemics and health hazards in the aquatic environment are mainly due to improper management of water resources. Proper management of water resources has become the need of the hour as this would ultimately lead to a cleaner and
healthier environment. In order to prevent the spread of water-borne infectious
diseases, people should take adequate precautions. The city water supply should be
properly checked and necessary steps taken to disinfect it. Water pipes should be
regularly checked for leaks and cracks. At home, the water should be boiled, filtered, or other methods and necessary steps taken to ensure that it is free from infection. |
Water-borne diseases
