Although hydrophobic ultraviolet (UV) stabilizers are an emerging environmental concern because of their widespread occurrence, persistence, and bioaccumulation potential, experimental values of their partitioning properties required for risk assessment are scarce. In this study, n-octanol-water partition (Kow) and lipid-water partition constants (Klipw), which are key parameters for environmental risk assessment, were experimentally determined for five selected hydrophobic UV stabilizers (UV326, UV327, UV328, UV329, and UV531) based on third-phase partitioning among polydimethylsiloxane (PDMS), water, and n-octanol/lipid. The partition constants between PDMS and water (KPDMSw), obtained using the dynamic permeation method were used to derive Kow and Klipw. The obtained log Kow and log Klipw values were in the ranges of 7.08-7.94 and 7.50-8.34, respectively, indicating that the UV stabilizers exhibited a high bioaccumulation potential in aquatic environments. The experimental Kow and Klipw values obtained in this study provide valuable information for the evaluation of the fate, distribution, bioavailability, and toxicity of the UV stabilizers in aquatic environments.
Keywords: UV stabilizers; bioaccumulation; fate and distribution; lipid/water partition constant (Klipw); n-octanol/water partition constant (Kow); passive dosing; risk assessment.