The spread of veterinary medicinal products (VMP) and biocides onto agriculturally used areas repre-sents a very important path of entry into the environment for these product groups. For this reason, current guidance (e.g. „Guideline on determining the fate of veterinary medicinal products in ma-nure“ (EMA/CVMP/ERA/430327/2009) (EMA, 2011) stipulates experimental studies on transfor-mation of VMPs and biocides in manure. Though, the documents only contain basic regulatory re-quirements, whereas an experimental test guideline is still missing, both on EU and OECD level. To allow for a consistent assessment of studies within the registration process, a harmonized interna-tionally accepted and validated test method is needed.

A draft test guideline was developed within a previous R&D-Project “Development of test guidance for transformation of veterinary pharmaceuticals and biocides in liquid manure” (Hennecke et al., 2015). The experimental method was examined and revised by an intra-laboratory comparisons as well as an international inter-laboratory comparison (pre-validation ring test).

In the present project, an international ring test has been performed and evaluated testing a veteri-nary medicinal product (florfenicol) in pig manure and a biocide (imidacloprid) in cattle manure. Moreover, two international workshops were organized; one at the beginning in connection with pre-ceding project (Hennecke et al., 2015) and one at the end of the project to discuss and evaluate the ring test. Based on the experimental results of the ring test as well as discussions and conclusions of both workshops, a revised draft test guideline was prepared.