(The body sometimes confuses Lead and Strontium-90 for calcium, so this Osteoblast [the cell type that makes bones] takes them and puts them inside the bones.)

Lead doesn't just stick around poisoning your brain, some will get put in your bones and eventually will fall out of your bones years or decades later, then poison your brain.

Strontium-90 is a radioisotope found in nuclear bomb fallout, a ton of it got put into the atmosphere back when testing nuclear bombs was still a thing, so everyone who so much as breathed back then still has some little Strontiumballs in them, continuously irradiating their bones. Fun!

The post transition metals are pretty much what they say on the tin. No, these aren’t post-op transgender metals, they’re the metals that come after the transition metals on the periodic table!

Gallumball has a very low melting point (you can melt it with bodyheat), and molten gallumblob has similar properties to mercuryblob but isn't poisonous!

Tinball getting thanos snapped (tin metal likes to turn to dust when it gets too cold, a phenomenon known as tinpest)

I’ve thought long and hard about how to describe bismuth in a better way than the somewhat mad scientist Tom from Explosions&Fire. But I can’t, so I’m just gonna plagiarize quote him. 

“[Bismuth] has seen a bit of a revival lately as a bit of a ‘relatable icon element’ because it forms rainbows all the time, doesn’t like to be straight, and is incredibly dense. Personally, I’ve always thought of bismuth as lead for people who fear death.” -Tom