Refinement of the P assessment of ionisable substances: Distribution and degradation of anionic, neutral and cationic organic chemicals in water-sediment systems | Umweltbundesamt

The criteria for the assessment of ⁠PBT substances were developed for neutral organic substances. Many chemicals are, however, charged under environmentally relevant pH conditions. The influence of a charge in molecule on its potential to degrade in the environment is unclear and therefore the research question of this project. The results show that especially a positive charge can strongly influence the degradation of a substance in the environment. The degradation half-live of the cationic model substance was clearly slowed down in a water simulation test (⁠OECD⁠ 309) and also in a sediment simulation test (OECD 308). First suggestions for an adaption of the method to evaluate the persistence of charged organic chemicals were made.