As a part of the authorization and approval process of plant protection products (PPP), the Federal Office for Agriculture (FOAG) assesses the environmental risk of PPP. For the calculation of PPP exposure of aquatic organisms, FOAG implements models that distinguish between the exposure to water-dissolved and particle-associated PPP active ingredients. Partitioning of the PPP active ingredients between the water and the particulate phase is dependent on the physical-chemical properties of the compound, in particular the soil organic carbon-water partitioning coefficient (Koc) and the octanol-water partitioning coefficient (K_ow). The goal of this study was to review the available scientific literature for information on: 1. Whether the bioavailability and toxicity of a compound to aquatic organisms are directly related to its Koc and/or K_ow. 2. Whether an increasing Koc/K_ow leads to the decrease of the compound’s toxicity due to its sorption to suspended solids (SS). The literature search was focused on aquatic organisms, in particular algae, aquatic invertebrates/ daphnia and fish. More than 50 scientific publications from the last 30 years were found to be relevant for answering these two questions. Based on the experimental scientific data provided in the published literature, the following conclusions can be drawn: 1. Bioavailability The Koc and K_ow values of a PPP active ingredient are not sufficient to predict its bioavailability in the presence of SS or natural organic matter (NOM). No quantitative relationship could be established between the amount of SS or NOM present in the water phase and a decrease in PPP bioavailability, due in part to the scarcity of published studies. 2. Toxicity A decrease in toxicity due to the presence of SS or NOM was most profound for the group of highly hydrophobic pyrethroid insecticides (log K_ow 5.7 − 6.6). For PPPs with low (log K_ow <3) and moderate (log K_ow3 − 5) hydrophobicity (triazines, carbamates, organophosphates) the available studies did not reveal a consistent effect of SS or NOM on toxicity. The presence of SS or NOM at maximum concentrations of 100 mg/L did not cause a significant reduction in toxicity in the majority of studies. As for the bioavailability, no quantitative relationship between the Koc or K_ow value of a chemical and its toxicity in the presence of SS and/or NOM could be established, due in part to the scarcity of published studies. The quality and origin of SS and NOM played an important role in their effect on PPP toxicity to aquatic organisms.