This work deals with 48 substances composed exclusively of unsubstituted six-membered fused aromatic rings. In the first step, physicochemical properties which are relevant in environmental studies such as the boiling temperature (Tb), the retention index (RI), n-octanol/water partition coefficient (K-OW) and solubility (S) are related with a series of electronic, geometric and topological descriptors. Among them are: electron affinity, the difference between electron affinity and ionization potential (GAP), Wiener, and connectivity indexes, volume, surface area, length-to-breadth ratio and enthalpy of formation. In a second step, these properties were incorporated into the descriptor matrix to build several quantitative structure-property relationships and to obtain prediction rules for the log K-OC, log K-OA, bioconcentration factor (BCF) and Henry's law constant (H). Finally, the photo-induced toxicity of freshwater organism Daphinin-Magna is modeled using the following transformed electronic descriptors: electron affinity, ionization potential and Gap. (C) 2001 Elsevier Science Ltd. All rights reserved.442125146