Recreation in coastal waters: health risks associated with bathing in sea water 2001: 55: 442-7
Even in resorts where seawater quality meets the European Union standard, bathers run a risk of infection, suggests research in the Journal of Epidemiology and Community Health.
The bacterial levels in seawater were measured three times a week at four beaches in Santander, northern Spain. The study lasted from the beginning of July to mid September 1998. A sample of over 2000 bathers were interviewed during this period, and included all people on the beach living in the same household. Over 1800 people were contacted again seven days later to see if they had developed any symptoms.
Predominantly gastrointestinal, skin, respiratory symptoms were reported by 7.5 per cent of the respondents. Visitors reported more symptoms than residents. Symptoms correlated with total numbers of intestinal bacteria (coliforms) and bacteria found in faecal matter, with gut and skin symptoms associated with coliform numbers.
Levels of coliforms between 2500 and 10 000 for every 100 ml of seawater increased the risk of symptoms, with swimmers 10 times as vulnerable as non-swimmers. This level is above the European Union guide standard for microbial contamination. Almost 40 per cent of water samples exceeded the guide standard for total coliforms, while 57 per cent and 38 per cent of samples exceeded the guide standard for faecal coliforms and other faecal bacteria, respectively.
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