International biohazard symbol warning of a potential biological hazard. This symbol is used worldwide in laboratories and on containers where biologically active agents are present. Examples of biologically active agents are bacteria and fungi, which could be infectious and potentially dangerous. The symbol was invented by engineer Charles Baldwin in 1966. The design was chosen as it was easily memorable and could be used regardless of orientation. The original background colour, blaze orange, was chosen as being easily visible under most conditions, although the symbol is also used with a bright yellow background.