Gold is a noble element, one so chemically stable that it’s found untarnished in the ground. But under some conditions, it can be converted to gold salts, which were the standard of care for rheumatoid arthritis. However, gold salts – which are quite toxic –have been replaced with a number of superior immunosuppressive drugs over the past two decades. The Golden Age of gold salts is over.
Cancer from radioactive gold? Like there isn't enough to worry about. But during the 1930s and 40s, it happened. A small number of rings were illegally manufactured from radioactive gold and there were consequences to ring fingers decades later.
Gold is known as a noble metal because of its lack of chemical reactivity. But if you treat it right, you can get it to do some cool things. You can chew on it, make some lousy drugs, screw up the environment mining it, and (maybe) even make a super-pricey burger. Really.
What these two processes share is baked into the math of each. In fact, in that respect, they're nearly identical. They both involve some stuff (atoms or money) that is either growing or shrinking. And best yet, they both have a magic number.
Besides making wigs, or perhaps some rather bizarre clothing and artwork, there aren't a lot of practical uses for discarded human hair. But that could change thanks to a team of Japanese and South Korean chemists.