Source: Vaccine Excipient Summary PDF

Aluminum is an electrical conductor. If it gets into your brain, you could expect to have a short circuit.

So is iron, and we have iron in our blood!

Unlike iron, aluminum is a nonessential metal for human health. The blood-brain barrier regulates the amount of iron. However, studies have shown that some amounts of aluminum, a neurotoxin, can cross that barrier, especially if the aluminum is in nanoparticle form.