First used by the Egyptians to keep their water fresh, copper appears to produce free radicals that attack bacterial cells. Bill Keevil and colleagues, from the Environmental Health Care Unit, University of Southampton, compared the length of time that Escherichia coli 0157 survived on stainless steel, brass and copper.

At the temperature normally used for food storage (around 4°C) the bacteria survived for more than 35 days on stainless steel, sometimes for as long as three months. But, the organisms survived for only 12 days on brass and just 14 hours on copper. At room temperature (around 20°C), the bacteria survived on stainless steel for 34 days, compared with four days on brass and just four hours on copper.

Keevil said, "Stainless steel is used throughout the world because of its perceived hygienic properties. It always looks like a nice, clean and bright surface. But a closer look reveals...

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