Lead

Lead is the metal that protected Superman from the devastating effects of kryptonite. Lead alloys are often used as solders in microwave electronics.

Lead in electronics has been banned in Europe, because it reduces IQ points when it gets into your brain. Any ban on hazardous materials is a good thing, but is a major problem, because the replacement plan is often to use pure tin plating, which can cause tin whiskers (see tin). There is no similar lead-in-electronics ban in the United States, but many component vendors are phasing out parts with lead anyway. 

Aviation gas is still stuck in the 1900s, using leaded gas and carburetors.  As of June 2016 only Algeria, Yemen, and Iraq continue widespread use of leaded gasoline, with the TEL (tetra-ethyl-lead) produced in China by Innospec. What about banning lead in car batteries? Ammunition? Fishing weights? Step it up and go!

All values except melting point are assumed to be at 25 degrees C, and may vary dramatically over temperature.