In humans and other animals, chronic intake of silver products commonly leads to gradual accumulation of silver compounds in various parts of the body. As in photography (where silver is useful because of its sensitivity to light), exposure of pale or colourless silver compounds to sunlight decomposes them to silver metal or silver sulfides. Commonly these products deposit as microscopic particles in the skin, in effect a dark pigment. This condition is known as<unk>  or argyrosis. Chronic intake also may lead to silver pigments depositing in other organs exposed to light, particularly the eyes. In the conjunctiva this is not generally harmful, but it also may affect the lens, leading to serious effects. Localised<unk>  often results from topical use of substances containing silver, such as some kinds of eye drops. Generalized<unk>  results from chronically swallowing or inhaling silver compounds, either for home medicinal purposes, or as a result of working with silver or silver compounds. While silver is potentially toxic to humans at high doses, the risk of serious harm from low doses, given over a short term, is small. Silver is used in some medical appliances because of its anti-microbial nature, which stems from the oligodynamic effect. Chronic ingestion or inhalation of silver preparations (especially colloidal silver) can lead to<unk>  in the skin and other organs. This is not life-threatening, but is considered by most to be cosmetically undesirable. The reference dose, published by the United States Environmental Protection Agency in 1991, which represents the estimated daily exposure that is unlikely to incur an appreciable risk of deleterious effects during a lifetime, is 5 µg/(kg·d).<unk>  worsens and builds up as exposure to silver continues, and does not resolve once exposure stops.
Argyria
Methemoglobinemia
Pleurothotonus
Paroniria
Amblyaudia
Polymicrogyria
Achiria
Incontinentia pigmenti achromians