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How many radioactive isotopes are found naturally compared with those produced artificially?

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radioactivity Figure 1: Radioactive decay of beryllium-7 to lithium-7 by electron capture (EC; see text).

There are more than 1,000 known radioactive isotopes. Of these, approximately 50 are found in nature, while the vast majority are produced artificially.1

Naturally occurring radioactive isotopes, such as those of uranium, thorium, and radium, are present in the environment within rocks, soil, and water. Some, like carbon-14, are continuously generated through interactions between cosmic rays and the atmosphere.23

In contrast, artificial isotopes are created through nuclear reactions, often by bombarding stable elements with neutrons or other particles. These man-made isotopes are essential for various applications, including nuclear medicine for diagnosing and treating diseases, as well as industrial uses like measuring material thickness. Scientists also create new isotopes to test theories regarding nuclear stability.143