A new study has found that despite efforts to improve water quality, those who enjoy swimming, bathing, or water sports in the sea are more likely to catch stomach bugs, earaches and other types of illness than those who don’t.

Carried out by researchers at the University of Exeter Medical School in the United Kingdom, in collaboration with the Centre for Ecology and Hydrology, the new meta-analysis looked at 19 studies which included a total of more than 120,000 participants.

The studies looked at the association between sea bathing and the rate of illness in high-income countries including the United States, U.K., Australia, New Zealand, Denmark and Norway.

The researchers found that spending time in the sea doubled the chances that swimmers reported general ear ailments and increased the chance of specifically reporting earache by 77 percent.

The chance of contacting a gastrointestinal illness also rose by 29 percent.

“In high-income countries like the U.K., there is a perception that there is little risk to health of spending time in the sea,” commented one of the study’s authors, Dr. Anne Leonard. “However, our paper shows that spending time in the sea does increase the probability of developing illnesses, such as ear ailments and problems involving the digestive system, such as stomach ache and diarrhea. We think that this indicates that pollution is still an issue affecting swimmers in some of the world’s richest countries.”

This research is the first systematic review to look at the evidence on the increased risk of illness from bathing in seawater compared with non-bathers.

Although many high-income countries have made large investments in clearing pollution from seas and improving water quality, seawater is still polluted from sources including industrial waste, sewage and run-off from farmland.

“We don’t want to deter people from going into the sea, which has many health benefits such as improving physical fitness, wellbeing and connecting with nature,” said Dr. Will Gaze, who supervised the research. “However, it is important that people are aware of the risks so they can make informed decisions.”

“Although most people will recover from infections with no medical treatment, they can prove more serious for vulnerable people, such as the very old or very young, or those with pre-existing health conditions,” he added. “We have come a long way in terms of cleaning up our waters, but our evidence shows there is still work to be done.”

The results can be found published online in the International Journal of Epidemiology. JB

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