Gutter bugs

By Nell Boyce SURFERS and swimmers are used to worrying about sewage outflows. Now they have a new concern—it seems that water flowing into the sea from the drains of city streets can also make you ill. In older American cities, and in countries such as Britain, drains on streets empty into the sewer system. But in Los Angeles and many other cities, rainfall is channelled through separate storm drains. Even during summer, says Robert Haile of the University of Southern California in Los Angeles, the city’s storm drains pour up to 100 million litres of water a day into Santa Monica Bay. Haile and his colleagues interviewed 13 278 visitors to beaches in summer 1995. They analysed water samples for potentially pathogenic bacteria and viruses, and asked swimmers whether they suffered any adverse symptoms. Bacteria and viruses were abundant near the drain outfalls, their numbers reducing gradually with distance. People who swam near the outfalls were 50 per cent more likely to suffer symptoms including fever, chills, ear discharge and coughing with phlegm (Epidemiology, vol 10, p 355). But farther than about 50 metres away from the outfalls,
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