Sodium percarbonate rapidly dissolves in water and dissociates into sodium, carbonate and hydrogen peroxide. Acute ecotoxicity tests with fish and water fleas revealed LC50 values of 71 and 4.9 mg/l. The available data show that the observed aquatic toxicity of sodium percarbonate can be explained by the formation of hydrogen peroxide. Because sodium percarbonate dissociates into sodium, carbonate and hydrogen peroxide, the environmental risk assessment is based on the risk assessment of the individual components.