I read about toxicity of uranium plutonium and polonium but I don’t understand how do we know it’s a chemical toxicity. In case of Litvinenko poisoning, Wikipedia says «victim of lethal polonium-210-induced acute radiation syndrome» so it was not toxicity of polonium that killed him, it was radioactivity. Can radioactive heavy metals kill cause harm in the same way lead, cadmium and other heavy metals poison you. Or most damage will be from radiation.
In: Physics
Every element can be radioactive. This includes traditionally toxic elements like lead or arsenic, but also elements we’d consider safe like oxygen or iodine. If it’s radioactive then its radioactivity makes it poisonous for that reason alone.
Similarly, the heavier metals which are radioactive can be more or less toxic. Certainly something like uranium is still a heavy metal like lead (though probably less hazardous than lead itself), but that’s not usually what’s going to be the first to kill you.
Yes, radioactive heavy metals produce both radiation toxicity and heavy metal chemical toxicity.
For example, Uranium is known to interfere with the normal function of the kidneys, liver, and brain.
Radiation toxicity is more known because these elements are rare, and you only need to be near by a large amount to get radiation poisoning.
On the other hand, chemical toxicity requires that the chemical actually get inside you somehow. Which up until recently would never really happen.
That being said, environmental exposure to these heavy metals from waste produced by the nuclear industry or by improper PPE by workers using them is an increasing problem, even if radiation levels are safe. So we are starting to see issues arising from heavy metal poisoning by radioactive elements.
For more information on Uranium, see: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819790/
Some things are toxic. Some are radioactive. Some are both. And it’s always the dose that makes things dangerous.
Uranium (235 and 238 usually) is more toxic than radioactive, it is quite safe to touch and hold some; I would still advise against licking it for multiple reasons. Uranium ores and nuclear by-products however contain many stronger radioactive sources, so that stuff is definitely bad for you.
Other materials such as polonium-210 kill due to their high radiation.
And then there are some in-between. The very infamous radium poisonings from the early 20th century are an example. This stuff not only is quite radioactive, it also replaces calcium in your bones. This not only makes them more brittle for chemical reasons, it also eternally deposits a strong radiation source close to the bone marrow. Lots of not so fun things ensue.
On the other extreme, heavy-yet-also-technically-radioactive metals such as bismuth are of so little danger, you are probably a hundred times more likely to cut yourself on a piece and then die from sepsis. It’s toxicity is pretty low, and the radioactivity is beyond ridiculous in its lack of relevance (despite there not being a single stable isotope of bismuth).
It depends on the isotope and the length of exposure. As you mention a lot of heavy metals have common radioactive isotopes, this is not a coincidence but is due to different mechanisms both relating to the size of the atom. So things like uranium is toxic because it is a heavy metal. But for example depleted uranium or even natural uranium is not very radioactive as it contains mostly U-238 which have a half life of over 4 billion years. So it is going to give you heavy metal poisoning long before you get enough to give any radioactivity symptoms. Po-210 on the other hand is very radioactive with a half life of just 138 days, emitting alpha particles which cause even more damage then other forms of radiation. But it is not actually toxic, at least from what we can see. So it will only kill you from the radiation, either acute radiation poisoning where the radiation kills enough cells in your body that you die, or from causing cancer that kill you in the long term.
I do not know the effects of all radioactive isotopes but it is theoretically possible that there is a radioactive isotope which gives you acute radiation poisoning if you are exposed to high amounts, but then heavy metal poisoning if you get exposed to lower amounts of it. It would also pose a cancer risk at even lower exposure levels.
No one has mentioned decay chains yet. Radioactive isotopes like Uranium-232 and Plutonium-236 decay into other radioisotopes such as: radon-22, mercury-205, and iodine-231. Additionally, a majority pf isotopes create or stablize as lead isotopes.
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