Exhibit / December 8, 2016

Object Name: The International Radiation Symbol
Maker and Year: Berkeley Radiation Laboratory, 1946
Object Type: Warning symbol
Description: (Richard McKenna)

The International Radiation Symbol or Ionizing Radiation Trefoil Warning Symbol was created at the University of California Berkeley Radiation Laboratory in 1946. Designed informally and originally intended  for lab use only, the  symbol was—according to Nels Garden, head of the laboratory’s Health Chemistry Group—“supposed to represent activity radiating from an atom,” and originally consisted of a magenta trefoil set against a blue background.

Among the reasons magenta was selected was its high cost, which it was presumed would prevent the sign from being displayed promiscuously, thus reducing its impact. The blue—chosen with the aim of ensuring visibility, there being little blue used in areas where the sign would be displayed—was replaced with yellow because of worries that it would fade or allow the sign to go unnoticed. Although magenta and yellow remain the color scheme codified by the American National Standards Institute for use in the United States, the trefoil in the international version is black.

The symbol proved to be extraordinarily effective and soon became an immediately recognizable avatar for the many ills—physical, psychological, political—and fears of the nuclear age.