Pollutants in the Drinking Water
Drinking water is water which is safe enough for drinking and cooking food. It is a vital necessity of living beings. Both the animal and plant kingdom are dependent heavily on drinking water which is also known as potable water. In 2012 it was said on the basis of a research that 89% people on our planet had access to suitable drinking water while some 1.6 billion people were deprived of safe drinking water. 66% (approx.) of weight in human beings is made up of water.
Exposure to contaminated drinking water causes an estimated half a million deaths every year. Globally water covers 70% of Earths’ surface out of which only 2.8% is fresh. These statistics substantiate the importance of safe drinking water. The World Health Organization/UNICEF Joint Monitoring Program (JMP) for Water Supply and Sanitation are the organization which are tasked to monitor the progress of Millennium Development Goal pertaining to water which is – To halve, by 2015 the population which does not have access to clean and safe drinking water and basic sanitation. This goal was reached in 2010 where 2 billion more people used clean drinking water than in 1990. However, still about 1.8 billion people use a water source which contains fecal contaminations.
The challenges in making drinking water available to increased number of population are increasing due to climate change. In India the retreating Himalayan glaciers can reduce summer drinking water by 2/3rd. This will directly affect 500 million people in the Ganges area. China also reported that 1/4th length of its 7 main rivers is so contaminated and poisonous that skin exposure to that water is also harmful.
Contaminants of Drinking Water:
All water sources contain natural contaminants – Inorganic and also Anthropogenic which are microbial or chemical. There are two types of pollution sources –
- Point Sources – Discharges of pollutants from Industrial premises and sewage treatment works are point sources. These are easier to identify and control
- Diffuse Sources – Run off from agricultural land and hard surfaces such as roads etc. These are tough to identify and control
Microbial Contamination – The contamination of drinking water by pathogens is called microbial contamination. It is the major cause of water borne diseases such as Typhoid and Cholera. These pathogens enter water due fecal matter (human fecal matter) which contains pathogenic organisms. In developing countries like India it remains the major cause of disease. The reason for microbial contamination is badly sited of septic tanks and latrines.
Chemical Contaminants – Below we will discuss the chemical pollutants that have a negative effect on health.
- Arsenic – Waterborne arsenic is a major cause of disease in the developing world especially in the Indian sub-continent in Bangladesh and Bengal. Arsenic is the only contaminant that can cause human cancer. It can cause skin, lung, bladder and liver cancer. Other than these life threatening diseases, arsenic can also result in hyperkeratosis and peripheral vascular disease.
- Fluoride – Fluoride contamination is another major cause of disease in human beings. High exposure to fluoride through water can give rise to dental fluorosis, an unsightly brown mottling of teeth and still higher exposure results in skeletal fluorosis, a condition arising from increasing bone density and which can eventually lead to fractures and crippling skeletal deformity. A person who suffers from such skeletal problems may become physically as well as economically disadvantaged for life. There are many factors which appear to influence the risk of such adverse effects, including volume of drinking water, nutritional status and, particularly, fluoride intake from other sources.
- Selenium and Uranium – Selenium and uranium also have adverse effects in humans through drinking water. High selenium intakes can give rise to loss of hair, weakened nails and skin lesions, and more seriously, changes in peripheral nerves. Uranium is a kidney toxin and has been known to mettle with proper functioning of the kidneys.
- Iron and Manganese – Water having some concentration of iron and manganese causes discoloration and turbidity. This little concentration is of no concern to human health. However, this phenomenon can cause may cause consumers to look towards other unsafe sources of water which might aesthetically appear to be safe but actually are not.
- Agricultural Chemicals – Agricultural pesticides and fertilizers are another source of chemical contamination. In this case the most important contaminant is nitrate, which can cause blue-baby syndrome, in bottle-fed infants under 3 months of age. There remains uncertainty about the precise levels at which clinically apparent effects occur and it also seems that the simultaneous presence of microbial contamination, causing infection, is an important risk factor. However, when nitrite is also present this must also be taken into account, since it is about 10 times as potent as a nitrate.
- By-products of water treatment – Water treatment is done to improve the quality of water by removing chemical as well as microbial contaminants. Unfortunately, the by-products formed during this process can also contaminate water. So, under such circumstances a trade-off is done by weighing the advantages and disadvantages against each other. There are different methods used for water treatment and each method results in different by-products. Trihalomethanes and Haloacetic acids are the contaminants which generally result from water treatment. Trihalomethanes can potentially cause cancer of the bladder, colon and rectum and adverse birth outcomes such as spontaneous abortion, (low) birth weight, stillbirth and congenital malformations. Overall, however, the evidence is inconsistent and inconclusive.
- Endocrine Disrupters – These are chemical pollutants which interfere with endocrine system for example by mimicking the natural hormones. These may result in reduction of sperm count and also cancer of breast and testes, although human evidence of this is low.
These are the major pollutants of water. Contamination of drinking water is both natural and man- made. Natural contamination such as fecal contamination is a major cause of worry in developing countries and although the diseases which result from fecal contamination are almost extinct in the developed world, constant vigilance is required.