Lanthanum-138 is radioactive with a half-life of 1.1 × 10 ¹¹ years and has been tested.

Metal lanthanum shell is used for the production of nickel hydrogen batteries, which is one of the main applications of lanthanum

Lanthanum metal is generally stored in mineral oil or rare gases. The content of lanthanum in the Earth's crust is 0.00183%, second only to cerium in rare earth elements. Lanthanum has two natural isotopes: lanthanum 139 and radioactive lanthanum 138.