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
Biological hazard first specified in 39 FR 23680 but was dropped in the succeeding amendment. However, various US states adopted the specification for their state code. There are four circles within the symbol, signifying the chain of infection. Biological hazard Biological hazards, also known as biohazards, refer to biological substances that pose a threat to the health of living organisms, primarily that of humans. This can include samples of a microorganism, virus or toxin (from a biological source) that can affect human health. It can also include substances harmful to other animals. The term and its associated symbol are generally used as