Astatine was first produced in 1940 by Corson, MacKenzie and Segrè, a moment that completed the periodic table but introduced an element most readers have never seen.
Despite being extraordinarily rare—scientists estimate less than a gram of astatine exists in Earth’s crust at any given time—it has attracted attention for a few very practical reasons. Its atomic number is 85 and it has no stable isotopes, so everything we study is radioactive and short-lived.
The uses of astatine are small but meaningful: chief among them is targeted alpha-particle therapy for cancer, and beyond medicine it’s a useful probe for basic chemistry and nuclear physics. The element’s scarcity and brief half-lives make every application technically demanding, which is why work happens at a handful of specialized cyclotrons and radiochemistry labs.
As an aside: handling astatine is one of those lab-skill tests that separates routine radiochemistry from truly bespoke work.
Medical applications
Medicine is where astatine’s promise is most concrete, thanks mainly to one isotope: astatine-211. That nuclide emits alpha particles and has a half-life of about 7.2 hours—short enough to limit long-term radiation exposure but long enough to label a molecule and deliver it to a patient.
Because there are no stable isotopes of astatine (atomic number 85), clinical use depends on producing fresh material at nearby cyclotrons and processing it in hot cells. As a result, most clinical and preclinical work happens at specialized cancer centers and university labs with radiochemistry expertise rather than in general hospitals.
Expectations are cautious: small clinical trials and preclinical studies show strong cell-killing where alpha particles reach tumor cells, but logistics, regulatory review, and production capacity limit wider deployment.
1. Targeted alpha therapy with astatine-211
Astatine-211 is used experimentally in targeted alpha-particle therapy for certain cancers. Targeted alpha therapy delivers high-energy alpha particles directly to tumor cells, killing single cells or tiny clusters with minimal surrounding damage.
With a 7.2-hour half-life, 211At strikes a useful balance: it decays quickly enough to reduce whole-body dose yet lives long enough for labelling, quality control, and transport to a nearby clinic. The element’s discovery in 1940 reminds us how long it took from finding the element to exploring therapeutic uses.
Real-world approaches attach 211At to monoclonal antibodies or small molecules to target micrometastatic disease—ovarian cancer is a commonly cited example in preclinical and early clinical work. The limitations are practical: limited production runs, rapid decay, and the need for trials at specialized centers.
2. Radiolabeling and theranostics
Astatine can act as a radiolabel for molecules used in both therapy and diagnostics—what clinicians call theranostics. Labeling a peptide or antibody with astatine lets doctors steer alpha radiation to a tumor and, in some research protocols, track where the compound goes.
Chemically, astatine behaves in some ways like iodine, so many established labeling strategies are adapted rather than invented from scratch. Radiopharmacies perform careful radiochemical labeling, then run quality-control tests such as radiochemical purity checks and sterility assays before release.
Because of short half-lives and regulatory hurdles, most astatine radiolabeling happens at specialized facilities preparing single batches for nearby clinical or research use rather than mass production for wide distribution.
Research and fundamental science
Outside medicine, astatine’s main role is as a subject of basic research. Chemists are curious about the heaviest halogen’s behavior, while nuclear physicists map its many radioactive isotopes and decay modes. That curiosity drives small-scale experiments rather than commercial products.
Because there are no stable isotopes and the element’s atomic number is 85, every experiment must contend with radioactivity and short sample lifetimes. Still, those constraints make astatine a valuable test case for theories about relativistic effects and nuclear structure at the heavy end of the periodic table.
Researchers routinely use minute, short-lived samples as tracers or testbeds for new measurement techniques, so progress tends to be incremental but scientifically informative.
3. Probing heavy-halogen chemistry
Astatine is a unique test case for chemists studying where periodic trends start to break down. Questions include which oxidation states are accessible, how strong astatine–carbon or astatine–metal bonds are, and how relativistic effects shift expected behavior compared with iodine.
Experimental work often compares astatine to iodine and bromine, using tiny tracer amounts in solution or gas-phase setups to measure reaction preferences and bond energies. Those measurements help validate computational chemistry methods that predict properties of other heavy elements.
Practical challenges—minute sample sizes and rapid decay—mean these studies require specialized detection and lab protocols, but the payoff is improved understanding of heavy-element chemistry.
4. Nuclear physics and isotope studies
Nuclear physicists study astatine isotopes to refine models of nuclear structure and decay. Dozens of radioactive astatine isotopes have been identified, and researchers measure half-lives, alpha- and beta-decay probabilities, and the energies of emitted particles.
Those data feed into nuclear theory, improve decay-chain predictions, and support practical tasks such as radiation-safety calculations and medical isotope planning. The element’s discovery in 1940 and its position at Z=85 make it a natural subject for work on heavy nuclei near the proton drip line.
High-resolution decay spectroscopy and coincidence measurements are common techniques, and the results gradually sharpen our understanding of how very heavy nuclei behave.
Production, handling, and niche technical uses
A separate set of uses flows directly from how astatine is produced and handled: preparing 211At for clinics, using tiny amounts as tracers in radiochemistry method development, and employing it as a calibration or training source for detector systems and hot-cell procedures.
Production is almost always cyclotron-based, using alpha irradiation of bismuth targets followed by chemical separation in hot cells. That workflow produces small, time-sensitive batches measured in millicurie or megabecquerel scales per run and meant for immediate processing.
Because of rapid decay and radiological risk, handling requires shielded facilities, specialized training, and strict quality control—so these technical roles remain confined to a network of radiochemistry labs and medical centers with cyclotron access.
5. Production, tracer uses, and calibration in specialized labs
Production and handling create practical technical uses: generating 211At for adjacent clinics, using trace quantities as experimental tracers, and serving as calibration sources for alpha-detection systems. Each use exploits the isotope’s radioactivity while managing its short half-life.
The standard production route is alpha irradiation of a bismuth target in a cyclotron, followed by radiochemical separation and labeling inside hot cells. The workflow is typically: target irradiation → chemical separation → radiolabeling → quality control → rapid clinical delivery.
Yields are modest and time-sensitive, so distribution is local; radiochemistry teams also use short-lived alpha emitters for hands-on training and to validate detector calibration and separation methods under realistic conditions.
Summary
- Astatine is extremely rare (discovered in 1940, atomic number 85) and has no stable isotopes, so every sample is radioactive.
- Medical promise centers on astatine-211: its 7.2-hour half-life and alpha emissions suit targeted alpha therapy for micrometastatic disease.
- Fundamental research in heavy-halogen chemistry and nuclear decay provides valuable scientific insight rather than commercial products.
- Production is cyclotron-based and yields small, time-sensitive batches, which confines most work to specialized centers and radiopharmacies.
- Watch clinical trials and improvements in cyclotron access and radiochemistry to see whether these niche applications expand.
