Copper is a 1- and 2-valent heavy metal with a very high electrical conductivity. Copper is contained in numerous alloys.
When exposed to humid air, copper coats itself with a green patina (copper(II) carbonate). Copper is a strong poison for low organisms, humans and animals tolerate larger quantities without harm. As a trace element, it is important for the formation of blood and for plants for the formation of chlorophyll.
General use: Copper and copper alloys are used in metalworking companies, including the electrical industry, plumbing, jewellery and costume jewellery. Of the more than 20 different monovalent and divalent copper compounds, copper(II) sulphate, for example, is used to preserve hides (leather), in paints or in fertilisers.
Medical use: In the medical and dental fields, copper is used in numerous medical devices (e.g. intrauterine pessaries, alloys for dental prostheses). Copper is abundant in euro coins. A daily intake of 100 mg of copper is obtained with food. Other metals such as iron, nickel, tin and aluminium are often added to copper. These metal additions can be relevant for allergological side effects (e.g. nickel additives)
Copper as a cosmetic ingredient: Various copper compounds are used in cosmetic preparations. They generally act as skin care and moisturising agents. Some compounds have an antimicrobial effect (e.g. Copper usnate) and are used in different indications.
Allergological relevance of copper:
Irritation potential: Reports of local skin irritation by copper and its compounds are rare. They should only occur after repeated contact. Reliable data on the acute irritation potential of copper-containing dusts on skin and mucous membranes are not available.
Sensitisation potential: Copper has a low sensitisation potential. Although there is widespread use with contact of the skin and mucous membranes with copper-containing products, allergic reactions to copper (contact allergic eczema) occur only rarely. Contact allergic mucositis can (in rare cases) occur on the oral mucosa due to prolonged local contact with copper-rich amalgam fillings.
Allergological diagnostics: Epicutaneous testing: as copper sulphate 1 % in water.