HealthSeptember 8, 2026
cesium
SEE-zee-um
Definition
A highly reactive, radioactive metal element that serves as a common byproduct of nuclear fission.
How do you pronounce cesium?
Cesium is pronounced SEE-zee-um (IPA: //ˈsiːziəm//).
Where does cesium come from?
Derived from the Latin word 'caesius,' meaning 'sky-blue,' referencing the two bright blue lines in its spectrum that led to the element's discovery.
In the news
Cesium was found in a bone fragment at exceptionally high levels, serving as evidence of the long-term impact of past nuclear testing on human health.
Utah bone fragment with shocking cesium level is raising new questions about nuclear test harm
Read the full article ↗The Cool Down
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