Cobalt blue causes Cobalt poisoning when inhaled or ingested.[18] Prussian blue is know to liberate hydrogen cyanide under certain acidic conditions.[19] Ultramarine and azurite are not stable particularly in high-temperature and acidic conditions; additionally, ultramarine production involves the emission of a large amount of the toxic sulfur dioxide.[1] The newer Phthalocyanine Blue BN is non-biodegradable and has been found to cause neuroanatomical defects in developing chicken embryos when injected directly into incubating eggs.[20][21]