Saltire detected the symbol, which often appears with balls in the quadrants formed by the arms of the chi-cross, in standards that appear on the coins of Persepolis. She suggested that early Christians endorsed its solar symbolism as appropriate to Christ. She also wrote: "although it cannot be proved, ... in the white saltire of St. Andrew we still have a reminiscence of the old standard of the Persepolitan kingdom". In the old European Union standard, a black saltire set in an orange square is the hazard symbol for irritants (Xi) or harmful chemicals (Xn). It indicates a hazard less severe
Hazard symbol to warn that the contents are poisonous. In the United States, due to concerns that the skull-and-crossbones symbol's association with pirates might encourage children to play with toxic materials, the Mr. Yuk symbol is also used to denote poison. The international radiation symbol (also known as the trefoil) first appeared in 1946, at the University of California, Berkeley Radiation Laboratory. At the time, it was rendered as magenta, and was set on a blue background. The original version used in America is magenta against a yellow background, and it is drawn with a central circle of radius "R", an internal