metabolically by fish to the leuco moiety, leucocrystal violet (LCV). Several studies by the National Toxicology Program reported the carcinogenic and mutagenic effects of crystal violet in rodents. The leuco form induces renal, hepatic and lung tumor in mice." Health Canada recently found medical devices that use gentian violet to be safe for use but recommended to stop using all drug products that contain gentian violet, including on animals, causing Canadian engineering schools to revisit the usage of this dye during orientation. In popular culture In Catch-22, the medics are portrayed as using gentian violet on feet and gums as a panacea. In the novel Picnic at Hanging Rock, the orphan Sara recounts how she was once punished by an orphanage's matron, who 'painted my head with gentian violet'. Engineering students in Canada use gentian violet to dye their skin and jackets, a tradition started in honour of naval engineers whose purple armbands would leave their skin dyed after countless days spent in the boiler rooms. Another story being that purple was the colour of the Titanics engineers who stayed behind to delay the sinking of the ship. See also Methyl green Methyl violet Fluorescein Prussian blue Egyptian blue Methyl blue Methylene blue New methylene blue Han purple Potassium ferrocyanide Potassium ferricyanide References Further reading . External links . Triarylmethane dyes Antifungals Anilines Disinfectants Staining dyes PH indicators Chlorides Dimethylamino compounds