For three examples of both groups (the disinfectants biphenylol, 4-chloro-m-cresol and triclosan and the pharmaceuticals ivermectin, ibuprofen and oxytetracycline) a relative initial risk assessment (RIRA) was performed assuming a standard emission of 1 kg/d to the most relevant environmental compartment. In addition the hazard of the compounds was evaluated based upon their persistence, toxicity and bioaccumulative properties (PTB). Both estimated and measured parameters were used for this purpose. In addition to an analysis of the risks of the pharmaceuticals and disinfectants per se, the capacity to discern between the intrinsic risk of different compounds is evaluated for both criteria used. It is concluded that the RIRA has a higher discriminative value and yields more information compared to the PTB-criterion.