Improved strategy to assess chemical persistence at the water-sediment interface
The environmental fate of a compound is determined by transformation and distribution processes, which are strongly dependent on the specific environmental conditions. Biodegradability of chemicals in different environmental compartments is one of the major determinants of their environmental fate and therefore plays a crucial role in regulatory decision-making.
Simulation studies according to OECD 308 (aquatic sediment systems) and OECD 309 (surface water) are an integral part of tiered testing strategies in different legislative frameworks. However, several shortcomings of OECD 308 have been identified and discussed over the years that hamper interpretation and use of the results (e.g. a strong redox gradient in the sediment and an unrealistically high sediment to water ratio). The OECD 309 suspended sediment test is strongly related to OECD 308, but might exhibit several advantages over OECD 308. However, so far there are only limited experiences available with OECD 309.
The aim of the Cefic-funded project LRI-ECO18 is to understand the value and information content of the existing OECD 308 and 309 protocols and to develop an improved testing strategy to obtain robust degradation data for assessing persistence in sediment and water. In combination with a data analysis approach, an experimental approach is used to enable disentangling sorption from (bio)degradation and to clearly distinguish between aerobic and anaerobic conditions. Therefore, a suite of five complex to less complex water-sediment systems is used to investigate the behaviour of chemicals with varying degrees of sorption and biodegradability.
For further information please see the Cefic website.