Spreading of manure on agricultural soils represents an important pathway by which veterinary medicinal and biocidal products enter the environment. To assess their environmental impact in the context of authorisation processes, experimental testing of transformation of these compounds in manure is considered in regulatory guidance documents. However, there is no standardised experimental test method available so far. To fill this gap, a test method was developed to examine transformation in liquid cattle and pig manure.
To address the variability of liquid manure of different type and origin, 30 manures were sampled and characterised. Three cattle and three pig manures were selected to perform anaerobic transformation studies with three radiolabelled (14C) compounds: two veterinary pharmaceuticals (salicylic acid and paracetamol) and a biocide. Spatial and seasonal variability of manure parameters was quantified, and a sampling technique was developed to obtain homogenous manure samples. Transformation studies were conducted to examine the influence of test setup, manure storage conditions, and parameter variations between manure of the same species and of different species on half-lives, formation of extractable and non-extractable residues and mineralisation rates. A test design was established that yields reproducible results for transformation studies in liquid cattle and pig manure under anaerobic conditions.
The obtained results provide a reliable basis for a test method to study anaerobic transformation in liquid cattle and pig manure. The developed method includes detailed guidance on e.g. sampling and storage of the manure, duration of the manure acclimation period, and the incubation system design. It provided reproducible results in a validation ring test performed in a follow-up project and is planned to be submitted as draft test guideline to the OECD.
For further information, see the open access publication in Environmental Sciences Europe:
Junker, T., Atorf, C., Berkner, S., Düring, R.-A., Hennecke, D., Herrchen, M., Konradi, S., Merrettig-Bruns, U., Römbke, J., Wagner, J., Weinfurtner, K. (2020). Development of a test method for transformation of veterinary pharmaceuticals and biocides in anaerobic liquid manure. Environmental Sciences Europe 32:39.
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