WATER FLOURIDATION-THE SAFETY ISSUE

Dental decay is a common phenomenon to day amongst the population in some of the industrialized countries, probably due to the dietary changes which have taken place during the last 5 decades with sugar based products increasingly dominating the portfolio of processed food industry. It is estimated that practically the entire population in a country like the US suffer from some degree of tooth decay while this phenomenon is not that predominant in Europe. Dental decay is caused by bacterial plaques that develop between the teeth because of infection of the gum by microorganisms like Streptococcus mutans and some strains of Lactobacillus which thrive when the diet is rich carbohydrates mainly sugar, causing a drop in pH to about 5. At such an acidic environment the enamel material that coat the teeth are dissolved and lost damaging the tooth progressively. The legendary saying that "brush the teeth after each meal" is based on the effectiveness of removing the "food" for the bacteria left over by the meal promptly giving no cause for plaque formation. Besides almost all brands of tooth paste products contain fluorides that can help remineralization of the affected teeth.

Fluorides are known to inhibit dental decay and water used every day generally contains sufficient fluorides to afford protection to the teeth. But modern day water purification process removes practically all fluorides along with other undesirable inorganic salts to ensure its potability. After all fluoride is not proven to be an essential nutrient and there are no water standards which stipulate minimum or maximum levels permitted or mandatory. Mounting evidence about the role of fluorides in reducing tooth decay has persuaded many countries to take up "fluoridation" of water as a public health measure. Such a practice combined with use of fluoride containing tooth pastes is presumed to have halted the onslaught of dental decay in many parts of the world, benefiting over 400 million population. When water is not a convenient medium for fluoridation, others like salt, sugar, milk etc also can be candidates for mass fluoridation. Fluoride compounds Sodium Fluoride, Fluorosilicic acid and Sodium Fluorosilicate are commonly used as sources of fluoride.

As halogens are increasingly being shunned because of their carcinogenicity, fluoridation also is a suspect process in the eyes of many critics. However there is little evidence implicating this mineral in any serious health disorders. Defluoridation is still recommended when the fluoride content in water is abnormally high, especially in industrial areas, coal belts and deep under ground water. It is more or less agreed now that fluoridation of water @1 mg per liter is absolutely safe and adult human beings can tolerate a level of 0.1 mg per kg body weight. There are some organized groups still agitating for stopping compulsory water fluoridation, raising ethical and societal issues. However, if iodization of salt is accepted as a public health program to prevent mental retardation and development of goiter, there should not be any reservation about the fluoridation program too.

Fluoride absorbed by the body is circulated in the blood and when adequate fluoride intake is ensured, the saliva contains about 0.04 mg per ml of this chemical that can prevent dental decay. Under such a situation the fluoride in saliva reacts with the bacterial plaques dissolving the enamel substances and subsequently the affected teeth gets recoated with a thin layer of this solution as a part of the process of demineralization. Decay becomes a serious problem when demineralization rate exceeds remineralization pace over a period of few years. There are suggestions that Calcium present in water and Xylitol chewing gum can also retard dental decay but they can at best be complimentary to fluoridated water.

Traditional Indian practices of using neem sticks, mango leaves, charcoal powder mixed with camphor etc are known to maintain dental and gum health but very scant scientific supporting evidence is available regarding their mode of action. Most probably neem and mango may be acting as antibacterial while charcoal powder has the capacity to adsorb gases and very small particulate materials including bacteria, thus preventing the very process of plaque formation. Regular gargling with warm water after each meal has the salutary effect of flushing out residual food particles struck between the teeth and also forced removal of adhering bacteria without giving them any chance for colonization. Use of dental floss by many people serves the limited purpose of removing food particles which provide the source of food for the infectious bacteria.

V.H.POTTY

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SAFETY OF BOTTLED WATER-IS THERE A GUARANTEE?

A recent finding that mineral water packed in plastic bottles can extract dangerous chemicals from the container which will exert estrogenic functions, when consumed regularly, cannot be easily dismissed. The conclusion was drawn based on the observation that the chemicals isolated from such water samples caused an increase in the development of embryos in some species of mud snails. How far this evidence translates into any potential threat to human beings who consume water packed in plastic bottles cannot be ascertained with any certainty because of insufficient data to support such a possibility.Use of plastic bottles especially PET for disposable type of containers and Poly carbonates for reusable purpose is widely prevalent in India and therefore it must get the attention of scientists as well as the authorities concerned with this product. While small containers of capacity 500 ml to 2 liter are in use in the retail market, bulk supply with reusable containers with capacities 5 liters to 20 liters is common at the house hold level and in mass catering places.

There is a strong group of activists who feel that water packed in plastic bottles entails heavy health risks because during their manufacture a cocktail of chemicals are used for imparting various properties to the plastics. Environmentalists oppose use of plastics because for making every bottle of 1 liter capacity, 3-5 liters of water is used which is considered as wasteful. Also cited is the reported presence of Antimony, a heavy metal, in water packed in plastics, leached out from the container. Alarming picture is painted to show that water stored in plastic containers leaches more and more Antimony with time and temperature but maximum reported was less than 700 parts per trillion (ppt) while up to 20000 ppt is considered safe in potable water by international safety organizations. In another study some commercial samples of bottled water reportedly contained 38 different pollutants like Bacteria, fertilizers and industrial chemicals though many of these pollutants could have come from the source from where the water originated. The Bisphenol A (BPA) episode of recent origin is still fresh in the minds of the consumers but water is generally not bottled in polycarbonates from where BPA can be leached out. Polycarbonate bottles are popular amongst consumers as reusable water bottles but realizing the risks of BPA, polycarbonate is being shunned by all major retailers across the world.

Use of Polyvinyl chloride pipes for transport of water also is under scrutiny as it is likely to release trace chemicals like BPA, phthalates, organotin etc all with estrogenic activity. Relatively safe plastics like HDPE are increasingly being preferred for piping and storage of water for the households as well as commercial purpose. While those who consume bottled water occasionally may face relatively lesser risk of health hazards, if the house hold plastics being extensively used to store and supply water were found to be leaching out such chemicals, there is bound to be some concern. Fortunately, as of now, such fears may be misplaced, though what future holds is not certain. Going back to cement or steel storage tanks and GI pipes for water supply may yet be a safer bet in the long run.

The mud snail story from Germany may provide some grist for the anti-plastic groups to denigrate bottled water industry for some time but a critical scrutiny of the data brings out the startling fact that even in snails bred in glass bottles there were abnormal embryo development. Probably this indicates that the original water used itself had some xenoestrogen chemicals and extractive from the plastic bottles only increased the incidence. Also to be noted is that the German study was on bottled mineral water, not on normal potable water and whether the cocktail of minerals present had any role needs to be checked. Further study is warranted to come to a definitive conclusion that plastic bottles are risky to be used for packing water and damning an industry based on such scanty studies is not justified. Globally drinking water industry made 115. 4 billion liters of water in 2006 worth about $ 60.9 billion. By 2011 world will witness a production of 174.3 billion liters valued at $ 86.4 billion.

In a country like India where millions of people travel 365 days an year, bottled water is only the dependable source of bacteria-free water. Similarly millions of people gather in thousands of venues across the country for religious, social and professional meetings and bottled water is the major source of safe drinking water. Suggesting alternate containers like cans and bottles is not practical considering the cost and availability. If there is a risk proven beyond doubt through scientific evaluation, ways and means will have to be found to make the containers safer through better manufacturing technologies.

V.H.POTTY
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