Aerobic or Anaerobic Transformation in Manure

The purpose of this test is to examine the time course of transformation of a test substance in manure under aerobic or anaerobic conditions and to quantify the observations in the form of kinetic rate expressions. Degradation of the test substance will be followed for the parent substance and its potential (known) transformation products. Degradation rate, mass balancing and transformation product pattern will be determined for the test substance. Degradation kinetics will also be followed for any major transformation product, if possible.

Study Design

Test setup

Typically, the test will be carried out with 14C-labelled test substance. Transformation studies in cattle and pig manure will be performed under anaerobic conditions, tranformation studies in poultry manure under aerobic conditions. Incubation will be accomplished in the dark at a temperature of 20°C. The test will be conducted using multiple flask and semi static design. Before opening the test flask a moderate stream of nitrogen or air will be used as carrier gas to collect CO2 and other volatiles in distinct traps consisting of different solutions. CH4 will be combusted and will be trapped as CO2.

Course of the test

One concentration of the test substance will be used for the test. Manure for testing purposes will be sampled from local manure storage or will be provided by the Sponsor. Characterised manure will be pre-incubated for 21 (+/- 1) days under test conditions. For examining possible abiotic degradation or other non-biological removal of the test substance, sterile samples will be prepared.

The test will run for a maximum of 120 days. Apart from samples taken directly after application, at least 6 sampling time points will be included. Time intervals will be chosen in such a way that the pattern of decline of the test substance and possible transformation products can be established.

Analysis of the test substance and transformation products

In case of the 14C-labelled test substance the analytical methods will base on LSC and HPLC coupled with UV and radio detection. LC-MS/MS can be carried out as additional analytical method. The analytical method and sample preparation will be established to allow a limit of quantification of ≤ 5% of the applied radioactivity. The residues remaining after the extraction step (non-extractable residues, NER) will be quantified by combustion.

Special test setup

  • Non-labelled test substance can also be used for the test to investigate the degradation kinetics (e.g. DT50) of the test substance.
  • Manure of other species can also be tested.
  • DTx-values can be corrected to the relevant environmental temperature.
  • To simulate more genuine environmental conditions, the test can also be performed at lower temperatures (e.g. 12°C).


  • Kinetic analysis and calculations of DT50 and DT90-values
  • Transformation product pattern including characterisation/ identification of major products

Guidelines and Literature

  • EMA (2009) Guideline on determining the fate of veterinary medicinal products in manure, EMA/CVMP/ERA/430327/2009, adopted 14 March 2011.
  • VICH (2008) Guideline on Environmental Impact Assessment for Veterinary Medicinal Products, EMEA/CVMP/ERA/418282/2005-Rev.1.
  • Working Group (September 2014) on Anaerobic Transformation in Liquid Manure, Draft for a Guideline for Testing of Chemicals