Correct radiation warning symbol.  Based on specification from [1].  The magenta-on-yellow symbol can be found at Image:radiation warning symbol-US.svg. Created by user:Fibonacci in gedit.

This image is highly optimized SVG, and uses less than 1K.  For the same symbol with a yellow background, see Image:Radiation warning symbol.svg.
No machine-readable source provided. Own work assumed (based on copyright claims).
No machine-readable author provided. Rfc1394 assumed (based on copyright claims).