A disease usually caused by the ingestion of mercury or mercury compounds, which are toxic in relation to their ability to produce mercuric ions; usually acute mercury poisoning is associated with ulcerations of the stomach and intestine and toxic changes in the renal tubules; anuria and anaemia may occur; usually chronic mercury poisoning is a result of industrial poisoning and causes gastrointestinal or central nervous system manifestations including stomatitis, diarrhoea, ataxia, tremor, hyperreflexia, sensorineural impairment, and emotional instability (Mad Hatter syndrome). Synonym: hydrargyria, hydrargyrism, mercurialism. Mercury Poisoning (also known as hydrargyria or mercurialism) is a disease caused by exposure to mercury or its compounds. Mercury (chemical symbol Hg) is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses. Its zero oxidation state Hg0 exists as vapor or as liquid metal, its mercurous state Hg22+ exists as inorganic salts, and its mercuric state Hg2+ may form either inorganic salts or organomercury compounds; the three groups vary in effects. Toxic effects include damage to the brain, kidney, and lungs. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease. Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure. An OSH glossary used in safety and health at work which is, adopted by ILO