Phytotoxicity and phytogenotoxicity of municipal sewage sludge. The aim of our research was to evaluate the phytotoxicity and phytogenotoxicity of Warsaw municipal sewage sludge, mixed with two different types of soils, using standard plant bioassays: the Phytotoxkit and the Allium cepa Root Tip Assay. The phytotoxicity of sludge mixtures with soils was influenced by the concentration of sludge and the type of soil. In the case of sludge/sand mixtures, even a 3% sludge concentration was phytotoxic, whereas in sludge/peat substrate mixtures, the phytotoxic effect was observed only in the 25% concentration. Unfortunately, in this and also a lower (6%) concentration of sludge in a sludge/peat substrate mixture, a strong phytogenotoxic effect was noticed. Therefore, the so called biological utilisation of the considered sludge seems rather hazardous for plants, especially in the case of sandy, but also in organic soils.