publicado em 01/05/2013 às 12h20:00
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Tap water can contain bacteria that less mineral water

Research assessed the quality of three mineral water brands and found worrying levels of contamination before maturity

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Study examined pint bottles and 1.5 liters in 11 times for one year
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Study examined pint bottles and 1.5 liters in 11 times for one year

Study reveals that tap water can contain bacteria that unless the index found in packs of mineral water. The survey assessed the quality of three mineral water brands and found worrying levels of bacteria in gallons 20 liters before the expiration of the validity period. In some cases, this occurred in the first days after filling.

The numbers are the result of the work of researcher Maria Fernanda Dias Falcone, Faculty of Pharmaceutical Sciences, UNESP at Araraquara. It has analyzed the contents of bottles of half liter and 1.5 liter 11 times over a year period recommended for consumption. Already the bottles of 20 liters passed five tests, conducted over 60 days of shelf life. In total, 324 samples of six brands (not disclosed by the authors). In addition to the count of micro-organisms in Heteretróficos Plate (CHP), we analyzed the levels of fecal coliforms and bacteria such as Escherichia coli and Pseudomonas aeruginosa, which can cause diarrhea and infections, especially in children, pregnant women and the elderly.

The results show that the three types of bottle of water, a 20 liter showed the most contamination problems. In two-thirds of the 60 count bottles analyzed was found more than 500 CFU / ml - sometimes reaching 560 000 colony forming units per milliliter of water (CFU / ml), more than a thousand times the acceptable standard for water supply .

In two gallons bacteria were detected even P. aeruginosa and other so-called group of enterococci. The first is one that can be opportunistic aggravate the health status of those who have compromised immune systems. The latter are often used as indicators of contamination by sewage.

The ordinance of 2011 DNPM determined validity period of three years for returnable gallons of 10 and 20 liters. According to members of the research, contamination usually arises from failure to sanitize the industry. No use reuse (the bottle) for a limited period if it is not washed every time it is used.

This type of contamination can still occur at the source, but is more common during or after filling. The environment itself, containers and lids are potential abodes of these bacteria. The equipment used in the process, as well as storage reservoirs may also harbor populations of contaminating microorganisms.

<b> Contamination by the sun </ b>

Another possible source of contamination (albeit indirect) is sun exposure. The radiation accelerates the breakdown of organic molecules present in the water (at very low concentrations), which now have the ideal size for turning food bacteria. With food available, they reproduce and the population grows. And then, when they die, serve as food for other bacteria.

This cycle of life and death is a working hypothesis. In several samples, the researchers found low concentration of micro-organisms in the early days after filling, which in turn increased after a few days, then back to being low. For now it is only a possibility, but other studies abroad reached similar results, says Maria Fernanda.

She also warns another very common type of contamination of bottles of mineral water (which was outside the scope of the study). Occurs at the site of consumption, but can be easily avoided. You need to make the correct hygiene not only the gal as support says. Either one or the other must be washed with bleach or, at least, chlorinated water and soap at each change of container.

<b> Legal Standards </ b>

From natural sources, mineral water does not undergo any treatment. Should be free of contamination at source and preserve its original features, including the presence of various salts and a microbial fauna considered beneficial to human health. Usually in possession of the private sector, the mineral water sources must be quality certified by the National Department of Mineral Research (DNPM).

Already the public water supply, and undergo chemical and physical treatment, their quality has necessarily verified by microbiological analysis before being distributed in the cities. The principal is the CHP. Although this test is also done in the water before bottling, the legislation only sets a maximum acceptable value of 500 CFU / ml

for the liquid which goes to the taps. This is the international standard, which is followed by ANVISA (National Health Surveillance Agency). But now there is a worldwide trend to adopt the same limit also for the water bottle, full Maria Fernanda.

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