Following the introduction of automobile catalysts in the middle of the Eighties in Germany there is an increasing emission of the platinum-group-metals (PGM) platinum (Pt), palladium (Pd) and rhodium (Rh). Still, it remains unclear if these metals are bioavailable for aquatic animals and to which extent they accumulate in the aquatic biosphere. Zebra mussels (Dreissena polymorpha) were maintained in water containing road dust at a concentration of 1 kg/10 l. Following an exposure period of 26 weeks, soft tissues of the mussels were analysed applying adsorptive cathodic stripping voltammetry (ACSV) for the determination of Pt and Rh and total-reflection X-ray fluorescence analysis after co-precipitation of Pd with mercury. This experiment revealed for the first time that all the three catalyst emitted metals were accumulated by mussels. The bioaccumulation increased in the following manner: Rh < Pt < Pd. Thus, the application of sentinel organisms in combination with modern trace analytical procedures in environmental impact studies does allow an assessment of the distribution and the degree of bioaccumulation of PGM in the environment, which is highly appreciated.