Commercial-grade cerium metal is iron-gray in color and as soft and ductile as tin. It easily self-ignites in air and should be stored in a vacuum or in an inert atmosphere to prevent decomposition. It dissolves slowly in water and rapidly in most diluted acids except hydrofluoric acid, which produces the protective fluoride layer CeF3. Cerium is a photoelectric element and combines readily with oxygen to form its oxide CeO2 – a colorless powder that is very brittle when cold. This pyrophoric characteristic makes it ideal for use as a getter in vacuum and electron tubes to clear out traces of trapped oxygen molecules. It is also used in atomic clocks and photoelectric cells.

Cerium compounds are widely used in metallurgy, petroleum refining, glass polishing and enameling. It is used with other rare earth metals to make permanent magnets and in carbon-arc lighting (CFL). It is an essential ingredient of the mischmetal alloy used as tungsten electrodes for gas tungsten arc welding. It is also found in a range of ceramics and in xenon lamps as a replacement for mercury.

The lanthanide elements, including cerium, lanthanum and neodymium are characterized by their variable electronic structure that allows them to occupy both inner d orbitals and outer valence shells, depending on the amount of energy added or removed. This property gives rise to their useful magnetic properties. In this report, we present an in vitro cytotoxicity evaluation of the soluble chlorides and oxides of these elements using adult male Sprague-Dawley rat pulmonary alveolar macrophages.