Editing Weapon of mass destruction (section)

===Radioactive weaponry or hazard symbol===
[[File:Radiation warning symbol.svg|left|65px|Radioactivity]]
[[File:Logo iso radiation.svg|thumb|right|2007 ISO [[radioactivity]] danger symbol]]
The international radioactivity symbol (also known as [[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.<ref name="Origin of the Radiation Warning Symbol (Trefoil)">{{cite web|url=https://www.orau.org/health-physics-museum/articles/radiation-warning-symbol.html|title=Origin of the Radiation Warning Symbol (Trefoil)|access-date=13 October 2021}}</ref>

It is drawn with a central circle of radius ''R'', the blades having an internal radius of 1.5''R'' and an external radius of 5''R'', and separated from each other by 60°.<ref name="Biohazard and radioactive Symbol, design and proportions">{{cite web|url=http://www.michigan.gov/documents/CIS_WSH_part476_54539_7.pdf |title=Biohazard and radioactive Symbol, design and proportions |url-status=dead |archive-url=https://web.archive.org/web/20131231181252/http://www.michigan.gov/documents/CIS_WSH_part476_54539_7.pdf |archive-date=31 December 2013 }}
</ref> It is meant to represent a radiating atom.<ref>{{Cite web|url=https://www.orau.org/health-physics-museum/articles/radiation-warning-symbol.html|title=Origin of the Radiation Warning Sign (Trefoil)|website=orau.org|access-date=2021-10-13}}</ref>

The [[International Atomic Energy Agency]] found that the trefoil radiation symbol is unintuitive and can be variously interpreted by those uneducated in its meaning; therefore, its role as a hazard warning was compromised as it did not clearly indicate "danger" to many non-Westerners and children who encountered it. As a result of research, a new radiation hazard symbol (ISO 21482) was developed in 2007 to be placed near the most dangerous parts of radiation sources featuring a skull, someone running away, and using a red rather than yellow background.<ref>Linda Lodding, "[http://www.iaea.org/Publications/Magazines/Bulletin/Bull482/pdfs/18RadSymbol.pdf Drop it and Run! New Symbol Warns of Radiation Dangers and Aims to Save Lives] {{webarchive|url=https://web.archive.org/web/20120120125920/http://www.iaea.org/Publications/Magazines/Bulletin/Bull482/pdfs/18RadSymbol.pdf |date=20 January 2012 }}," ''IAEA Bulletin'' 482 (March 2007): 70–72.</ref>

The red background is intended to convey urgent danger, and the sign is intended to be used on equipment where very strong ionizing radiation can be encountered if the device is dismantled or otherwise tampered with. The intended use of the sign is not in a place where the normal user will see it, but in a place where it will be seen by someone who has started to dismantle a radiation-emitting device or equipment. The aim of the sign is to warn people such as scrap metal workers to stop work and leave the area.<ref>{{Cite web |url=http://www.iaea.org/newscenter/news/2007/radiationsymbol.html |title=IAEA news release Feb 2007 |date=15 February 2007 |access-date=11 January 2016 |archive-url=https://web.archive.org/web/20070217075115/http://www.iaea.org/NewsCenter/News/2007/radiationsymbol.html |archive-date=17 February 2007 |url-status=live}}</ref>