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image European Research News Centre > Medecine and Health > Swimming in clear water
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image image image Date published : 11/04/2001
  image Swimming in clear water
 
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  Thanks to meticulous monitoring, bathing water quality is improving considerably in Europe. But the lack of standardised microbiological measurement methods leaves the result open to dispute. A number of European research projects have tried to put an end to the discord, and, in the process, have provided good examples of what could become the 'support for Community policies' strand of the European Research Area launched by Philippe Busquin.
   
     
   

A poor ranking is bad for the image. Feared by tourist resorts, the European Commission's annual bathing water report, issued at the beginning of the summer, is awaited with bated breath. The latest edition (for 1999) notes a constant improvement in water quality for both coastal and river bathing water. In 1992, 84.9% of European beaches met the quality criteria laid down by the 1976 directive, in particular from a microbiological point of view. In 1999, the figure had climbed to 95.6%. For fresh water sites, the progress has been even more spectacular: up from 47.5% in 1992 to 90.5% in 1999.

This optimistic picture is the result of constant efforts by the Member States and research carried out by laboratories with the aid of the Commission. But it remains open to debate. There is no standardised method for carrying out microbiological measurements in bathing zones - measurements designed to reveal possible faecal contamination. 'The 1976 directive remains vague on the methods of analysis, the result being that laboratories use very different methods. The measurements are not fully comparable,' explains Bert Van Maele of the Environment Directorate-General.

Disparities and limits

Since the early 1990s, the Union has therefore supported a number of research projects designed, first of all, to assess the disparities between the various methods used and, subsequently, to identify a standard method which all laboratories can adopt for their analyses.

Another drawback of the present system of monitoring bathing waters is that it is basically a retrospective method. Traditional microbiological tests take about 36 hours to give a quantified result. It is not therefore possible to envisage a day-to-day management of beaches on such a basis. The Commission's annual pre-summer report on bathing water quality is based on the average measurement taken every two weeks during the previous season.

It is therefore only general trends which are picked up, the effects of particular incidents often remaining undetected. A big storm, for example, can cause the drains in a coastal town to overflow for several hours with large quantities of dirty water flowing into the sea. The two or three days which follow could see a very sharp increase in the faecal microbe content of the bathing waters. If no measurement is taken during this relatively short period this increase could well pass totally unnoticed. Besides, at the present time we do not have the technical means at our disposal to deal instantly with the problems of microbiological contamination," explains Tristan Simonart, a researcher at the Pasteur Institute in Lille (FR). "The tests do not yet exist. We will have to wait for a number of years."

Forecasts and variables

A number of studies are being carried out at present to develop computer models that can forecast water quality on the basis of a wide range of possible influences, such as hydrography, weather, capacity of purification stations, population, drain design, etc. 'The purpose of these computer models is to predict a deterioration in bathing water quality so that, if necessary, certain beaches can be closed as a preventive measure,' explains Eddie Maier, a scientific officer with the Research DG.

The European Commission held a scientific workshop on this subject at Sitges (Spain) in June 1997. The experts concluded that a more proactive approach was 'technically possible' and would provide 'a valuable and inexpensive instrument in many cases' in support of a directive on bathing water quality.

In its recent communication entitled Developing a new bathing water policy, the Commission notes that this research has given quite good results in the case of models for hydrographic basins which are small in size or only exposed to a small number of potential sources of pollution. But more extensive bathing areas with multiple potential sources of contamination require sophisticated forecasting models. Realistically, such models will probably be used only for the main bathing resorts.


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Choosing your microbes

The Microbath project (1996-1999), coordinated by the Institut Pasteur (Lille), set its sights on developing a standard method for analysing bathing water quality which could be used by all European laboratories charged with this task of protecting public health. 'It was first necessary to redefine the microbes selected as the best indicators of faecal contamination of the water,' explains coordinator Jean-Marie Delattre.

According to the 1976 directive, two families of bacteria are 'good indicators': heat-tolerant coliforms and total coliforms. 'The problem,' continues Jean-Marie Delattre, 'is that these families are much too big. They include many bacteria which have never seen an intestine in their lives. Today, everybody agrees that the best indicators are E. coli bacteria, and a group of four intestinal enterococci for recreational waters.' This selection is in line with the WHO proposal in its draft guidelines on recreational waters.

Sixteen European laboratories cooperated on the Microbath project which validated two microbiological reference analysis procedures for these two microbial indicators. The methods chosen allow a maximum margin of error of 5% and were tested on a samples of natural fresh water and sea water. During one season, the laboratories then compared their own methods with the new standardised methods. Today, the procedures adopted by the Microbath project are candidates for the status of CEN (European Standardisation Centre) standards.

The next Commission bathing water directive could make an explicit reference to a CEN or ISO standard. 'This means that the Member States should preferably use an ISO or CEN method,' points out Bert Van Maele (Environment DG), 'but they can also use other methods provided they show comparable results.'

Contact

Jean-Marie Delattre
jean-marie.delattre@pasteur-lille.fr
 
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Choosing your microbes

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