Copper has germ-killing effects (oligodynaic effect). In laboratory tests, EPA, Environmental Protecting Agency, Washington, has discovered that pure copper, and alloys containing more than 65 % coppper, have microbiocidal properties, eg. against MRSA, methicilline-resistant Staphylococcus aureus, Enterobacter aerogenes and Pseudomonas aeroginosa. There is hope that by exchanging superficial contact points (for example plastic door knobs against brass knobs), the 2.000.000 annual infections acquired in the hospital, of which many end deadly, can be reduced enourmously. Legionnaire's disease can be prevented by applying copper into air-conditioning systems. Copper is also used for klling germs in anesthetic devices. The microbiocidal effect of copper also applies to chlamydia, viruses, and fungi (fungicidal). In contrast to the obsolete plastic-only IUDs, worldwide out of use since around 1980, copper IUDs do not cause increased rates of infection of the upper female genital tract. Literature can be obtained from the author and from Deutsches Kupferinstitut, Düsseldorf.