During Iron Man 2, Tony Stark faced internal struggles- both mentally and physically. As he grappled with the legacy he wants to leave, he was slowly killed by the very thing that was keeping him alive and powers the Iron Man suit- the arc reactor preventing shrapnel from entering his heart. Tony’s arc reactor was powered using a palladium core. Over time, the palladium was broken down by neutron damage, releasing deadly toxins into Tony’s bloodstream.
So how is the palladium killing Tony?
Palladium is a rare, silver-white medal that is solid at room temperatures. The metal itself has low toxicity, as it is poorly absorbed by the body. (Palladium is used in jewelry, surgical instruments, and dental fillings, so it’s a good thing that it’s poorly absorbed.) Exposure to palladium could irritate skin, eyes, or respiratory tracts, but that’s about it- most people are not exposed to large amounts of palladium. However, compounds with palladium are considered toxic and possibly carcinogenic. For example, palladium chloride has caused bone marrow, liver, and kidney damage in laboratory animals. It is possible that there would be a similar effect on humans if the dosage was high enough.
If palladium is so poorly absorbed by the human body, how is it ending up in Tony’s bloodstreams at such high levels? Ryan Carlyle over at Gizmodo broke down how he thinks the arc reactor works. In his theorized design (giving a little leeway to “comic-book physics”), reactions involving palladium are manipulated in order to run the arc reactor. Specifically, the reactor relies on two isotopes of palladium, palladium-103 and palladium-107. Palladium-103 can capture an electron, converting a proton to a neutron and releases an electron neutrino, causing palladium-103 to turn into rhodium-103. Palladium-107 beta decays, a nuclear reaction in which a neutron in converted into a proton and an electron is emitted. The beta decay of palladium-107 produces silver-107.
Armed with this theory, Carlyle details how the reactor could be killing Tony. One option is that Tony is affected by palladium directly, as the high energy collisions could cause the palladium to be thrown from the reactor into Tony’s body. However, Carlyle proposes that what Tony is actually dying of is rhodium and silver exposure.
Silver is moderately toxic, and chronic overexposure could cause damage to the kidneys, eyes, lungs, liver, or brain. Cardiac abnormalities and weakness from anemia are also potential side effects to exposure. Silver can even cause skin to turn blue or black, which would explain the color of the pattern that forms on Tony’s chest around the arc reactor.
The effects of rhodium, on the other hand, are not well understood. There just aren’t enough cases or data to make any conclusions. Which means that if someone was dying from exposure to rhodium, doctors wouldn’t be able to help them- kind of like how Tony can’t find a cure for his condition.
Thankfully, Tony fixed the problem by replacing the palladium core with a brand-new element, so he did not die in Iron Man 2 and was able to make appearances in future Marvel films and finally bring Spider-Man to the Marvel Cinematic Universe.
It was about time.
Keep calm and science on.