Carpal Tunnel Syndrome And Tarsal Tunnel Syndrome Carpal tunnel syndrome is a condition in which irritation of the wrist's median nerve causes tingling and numbness of the thumb,...learn more Â». In This Article.
1 Argyria-characterised by a metallic, slate-grey or blue-grey pigmentation. 2  The hyperpigmentation is most apparent in the UV-exposed areas of skin, especially the forehead, nose, and hands, as well as mucous membranes. 3  Argyria results from prolonged contact with or ingestion of silver salts.
Another pigment they use is melanin, the same pigment that colors human skin. Melanin is used to make the blacks, browns, and tans in the feathers of birds and the hair of mammals. Structures that are totally black absorb all of the frequencies of light. In the case of white structures, there ARE no pigments.