Refers to the hazardous potential of a substance. Hence, to develop adverse reactions in cells and living organisms, and to compromise functionality, which can lead to the death of an organism. It can be distinguished as direct and indirect toxicity. In the first case the toxicity of the substance is based on an interaction with the organism by directly intervening in metabolic processes or molecular structures. In contrast, a substance may also cause a change of physical factors in the environment (e.g. reduction of incidence of light on plants, blockage of molting in crustaceans). Often, indirect toxicity is also understood as an effect of substances emerging from a non-toxic substance, e.g. by degradation or alteration in the body.