The spread of veterinary medicinal products (VMPs) and biocides onto agriculturally used areas represents a very important path of entry into the environment for these product groups. Within this literature study public available transformation studies with liquid manure are summarized. Transformation studies were evaluated considering the transformation fate of tested substances, the origin and characteristics of used manure, the experimental setup, the measured parameters and the main outcome of the studies. Test duration throughout the studies ranges from 2 to 374 days and study temperature ranges from 5 °C to 55 °C. As main topics within the 34 found transformation studies the high dependency of transformation on temperature, redox potential, dry matter content and many other parameters is reported. It was further critically analyzed which basic information and parameters were neglected. Unfortunately only six publications give information on the redox potential of the manure. Further, the characterization of the matrix in many cases is inadequate due to missing parameters such as dry matter content, pH, and TOC.
Additionally, public available monitoring data of VMPs in manure were collected and evaluated regarding the origin and characteristics of the manure, the minimum and maximum found concentrations, and percentage of identified compounds. Within the 27 found publications, 1568 manure samples were analyzed and 39 different active substances for VMPs and 11 metabolites and transformation products of VMPs could be found in manure. Mainly, the samples were analyzed for sulfonamides, tetracyclines and fluorquinolones. In no case a non-target approach was used. Single active substances were found in some studies with more than 100 analyzed samples in more than 50 % of the analyzed manure samples. This is the case for sulfadimidine, chlortetracycline, oxytetracycline, and tetracycline. It can be concluded that for both transformation studies and monitoring studies a standardized guidance would be beneficial for their applicability in regulatory contexts and also enhance the scientific outcome of these studies.