Are substances more persistent than test systems lead to believe? Non-extractable residues: experimental examination of suitable extraction methods in view of a long-term risk for the environment

In transformation tests with organic substances in soil non-extractable residues (NER) are formed which remain there as residues. Some can be released again into the environment in the long-term and should be considered in the persistent assessment. Besides substances properties and soil characteristics the proportion of NER strongly depends on the extraction procedure. Within the European authorisation procedures, there is no precise and generally applicable definition of how NERs are to be determined and characterised.

In this project a widely applicable standardised extraction procedure for the determination of non-extractable residues was developed to improve the comparability of NER data. Further extraction methods for the characterisation of reversibly bound residues such as EDTA extraction and silylation are discussed.

The report is aimed at regulators, industry and experts from science and research.