Normal vector file contains no transparency effects. Best for Illustrator CS+.
You can find similar in my portfolio:
http://shutterstock.com/g/realfonts?ref=177637
Just another Warning sigh with exclamation mark. I made it symmetric with some gradient. The file in wiki (http://commons.wikimedia.org/wiki/File:Warning.svg) is not so symmetric.
The symbol for radioactive hazard, following the official proportion specifications (radius R for center circle, 1.5R to 5R for blades of trefoil). Done in Inkscape.