Many chemicals for which a ⁠PBT⁠ assessment is necessary are ionized in the environment. Therefore, the project aimed to find appropriate screening criteria for ionic organic chemicals (IOCs) to estimate their bioaccumulation potential. Twenty possible parameters were examined. The partitioning coefficient between water and fish calculated with COSMOmic showed the strongest correlation with experimental BMF data. The assumed high bioaccumulation potential was verified but not confirmed for six IOCs by conducting fish feeding studies (⁠OECD⁠ 305).