RadSafers, On 7 Sept 1995, R. S. Kay asked for information on the three-bladed symbol that warns of radiation. Ron Kathren replied on 8 Sept with a reference to an article in HP by Lloyd Stephens and Rosemary Barrett. The specific reference is: Health Physics May 1979;36(5):565-571 Stephens LD Barrett R A Brief History of the "20th Century Danger Sign." QUEST comes through again!! Bill Schadt