Wastes introduced by humans into rivers, lakes, ground water aquifers and the oceans modify the environmental water quality and make huge quantities of water unsuitable for various uses.
Major Factors Responsible for Water Quality Degradation
(i) Insufficient and incomplete treatment of domestic and industrial waste water.
(ii) Eutrophication.
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(iii) Pathogens, pesticide contamination.
(iv) Stagnation of domestic sewage and contamination of ground water.
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Water borne diseases:
“Water-borne diseases are illnesses caused by consuming water contaminated by pathogenic micro-organisms.”
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Water-borne diseases are caused by protozoa, viruses, bacteria, and intestinal parasites. According to the World Health Organization, diarrheal disease is responsible for the deaths of 1.8 million people every year, majority of them are children in developing countries.
The best ways to prevent water-borne diseases are
a) avoid drinking untreated water
b) avoid consuming undercooked food
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c) maintain good personal hygiene (e.g. wash hands before eating), and
d) educate for clean sanitation
At low concentrations in drinking water, fluoride has beneficial effects on teeth. But excessive exposure to fluoride in drinking water can give rise to number of adverse effects. Although the concentration (mg/liter) of fluoride added to water can be controlled, but we cannot control the dose (mg/day). This is because one cannot control how much water people drink or how much fluoride they get from other sources.
Sources of fluoride:
(a) Fluoridated water supplies
(b) Food processed with fluoridated water
(c) Mouthwash enhanced with fluoride
(d) Toothpaste enhanced with fluoride
(e) Food supplements.
Fluoridation is not necessary
(i) The level of fluoride in mother’s milk is 0.004 ppm. It means a bottle fed baby, where fluoridated tap water (with 1 ppm fluoride) is used to make up the formula milk, will get 250 times more fluoride than nature intended.
(ii) Fluoride works from the outside of the tooth, not from inside the body, so it is not required to swallow fluoride or drink fluoridated water.
Fluoride’s dangers:
Fluoride damages the teeth, the bone, the brain, the endocrine system. It may cause osteosarcoma.
(i) Fluoride damages the teeth: A permanent discoloration and mottling of the tooth enamel (Dental Fluorosis) is caused by a child’s ingestion of fluoride (0.5-1.5 ppm) before its permanent teeth have erupted.
(ii) Fluoride damages the bone: In an area of high natural levels of fluoride (1.5-5.5 ppm), fluoride can weaken bone and increase the risk of fractures.
(iii) Fluoride damages the brain: Fluoride lowers the IQ of children, even when present at 1.8 ppm in water. It is apparent that fluorides have the ability to interfere with the functions of the brain.
Defluoridation of water
Defluoridation of water can be carried out by
a) Reverse osmosis filtration.
b) Activated Alumina Defluoridation filter
c) Nalgonda Technique.