Astatine

by Rosie Coates

It’s Friday: The final day of chemistry week and our final halogens and health blogpost (did you miss fluorine, chlorine, bromine and iodine?), the subject of which is astatine.  We’ll be looking at it’s uses, resources about astatine and the RSC’s global experiment.  At this point I’d love to show you a picture of some astatine but alas, I can’t do so as the stuff has never been collected in quantities large enough to pop in a bottle and look at.

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What does astatine look like in a test-tube? It doesn’t. Photo: science made simple CC-BY-SA

Rare

That’s not very surprising when you find out that it was only isolated in 1940, only identified in nature in 1943, is the least common of the elements in the Earth’s crust with less than 28g estimated to be present at any given time and all its isotopes are radioactive with half-lives of just a few hours. There can’t be much to say about its use in human health then, this is going to be a pretty short post.

Useful

Well actually, despite all of these factors against it astatine could still be useful.  Research is underway to use it as a radiotherapy agent for targeted cancer treatment.  Like its cousin iodine-131, astatine-211 undergoes radioactive decay and tends to build up in the thyroid gland.  Unlike iodine-131, however, astatine-211 doesn’t release beta-radiation.  This is good news for cancer therapies as beta-radiation travels further than alpha radiation (which astatine does emit) causing damage not just to the cancer cells but to the healthy cells surrounding them. If we can find ways to use astatine-211 instead of iodine-131 patients could get better treatment with less damage to the healthy parts of the thyroid.

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All the isotopes of astatine (At) are radioactive, but that’s not necessarily a bad thing. Photo: Nyerguds, Public Domain

Chemistry?

So much, so nuclear-physics, I hear you cry, isn’t this supposed to be chemistry week?  Well it’s chemists who are currently working on the biomolecules incorporating astatine which will take this radiation source directly to the targeted cells.  This is tricky work as the astatine doesn’t hang around for long (with a half-life of about 7 1/2 hours), can only be produced in tiny amounts and tends to fall off (remember astatine is underneath iodine in the periodic table and the reactivity of the halogens reduces as we go down the group) but some of the results do look promising.

We’ve only just begun

What I think is really brilliant about the research on astatine is that nuclear physicists, chemists and medics are working together to understand the processes, develop new approaches and use all the tools at their disposal, even the rarest element on earth, to try to improve our health. We’ve only looked at five elements this week and one of them only exists for a few hours and in tiny quantities and yet they all have important uses for our health.  Imagine what the other 113 elements in the periodic table can offer us, let alone what happens when we start to form them into compounds!

You can listen to more about astatine and the rest of periodic table in the periodic table of podcasts from the Royal Society of Chemistry and produced by The Naked Scientists

We hope you’ve had a great chemistry week and are feeling inspired by the amazing possibilities offered by chemistry.  If you’d like to get even more involved there’s still time to take part in the Royal Society of Chemistry’s Global Experiment

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Posted in Chemistry