Most of the biological, biochemical, pharmacological and toxicological studies on cerium have been carried out on small animals.

Oral administration of cerium or cerium compounds, unless the anion is toxic, has very little or no effect. This is primarily due to the fact that very little cerium is absorbed by the body. Subcutaneous injection gives a greater absorption. The excretion of cerium, however, is slow, About 50% of the cerium absorbed is deposited in the liver and 25% in the skeleton, and the elimination half-lives are about 15 days and about 14 months, respectively. Cerium was found to produce granulomas from intradermal injections. Intraperitoneal administration of cerium in concentrations of 0.01%, 0.1% and 1% in the diet for 90 days had no effect on the liver. Inhalation of the oxide and/or fluoride induces granulomas in the lung.

Cerous chloride and ceric ammonium nitrate stimulate secretationin in low doses but suppress it in high doses. Cerium, like all of the rare earths, decreases the blood pressure and serves as an anticoagulant agent.

The rare earths, including cerium, have a low acute toxicity rating.