Guidelines ) and used as test organisms according to the methodology compliant with the OECD 202 Guidelines and ISO 6341 standards. The multi-well Daphtoxkit F plates for the tests were purchased from MicroBioTests Inc. (Gent, Belgium). The Elendt M4 medium was aerated for 1 hour before the tests and the organisms had access to food (C. vulgaris suspension) before the start of the test. In the next step, 10 cm -3 aliquots of the solution of a given compound in Elendt M4 medium at the specified concentrations: 1000, 100, 10, 1, and 0.1 mg dm -3 (with the exception of 1-dodecylquininium bromide, which was tested at 100, 10, 1, 0.1, and 0.01 mg dm -3 concentrations) were introduced into each of the 5 cells in a given row of the Daphtoxkit F plate. In the case of the control samples, pure medium without the addition of toxicant was used. Next, no less than 20 daphnia were placed in the first column of cells.