The aerobic soil degradation of 14C-phenyl-propargite was investigated in five soils (silt loam, pH 5.7; loamy sand, pH 6.0; sandy loam, pH 6.6; sandy clay loam, pH 6.9; silty clay loam, 7.6) using compounds radiolabelled in the phenyl ring. In all five soils (three from the EU and two from the US), total mineralization to CO2 and incorporation to bound residues were the major routes of degradation (22-42% and 24-38% at 90-100 days, respectively). Bound residues (max 37.6% at 120 DAT) were found to be mostly associated with the humic acid and humin fractions. Propargite was metabolised via initial hydrolysis of the propynyl sulphite side chain to form TBPC. In four soils levels of TBPC were <2%, but in one soil it reached 10.4% at 22-30 days and then degraded. Additional information from the dark control of the photolysis study was obtained: TBPC reached up to 15.6% after 15 days. TBPC-sulphate was found in one soil at levels >5% (6-8%) at three consecutive time points, while PTBP was identified in one soil at <0.5%. A number of unknown peaks were quantified in various soils, in one soil one of these reached >5%. A further study on the rate of degradation of the TBPC metabolite additionally identified TBPC-sulphate and TBPC acid as intermediates in the degradation of this compound. - RMS comments: Regarding the mineralization and the formation of bound residues, the results obtained only enable to conclude degradation pathway for the phenyl part of the molecule. As the phenyl-propargite is well mineralised, it indicates that potential degradation products including the cyclohexyl ring may be formed. Therefore, the original RMS (France required studies of route of degradation to be conducted with 14C-cyclohexyl-propargite. However, the first steps of degradation of propargite in soil is mainly via formation of TBPC. TBPC itself does not degrade to PTBP in soil under aerobic or anaerobic conditions. An evaluation of the metabolic pathway revealed that a 14C-label in the cyclic hexyl-ring of propargite would only provide additional information on the potential metabolite 1,2-cyclohexanediol, as the first steps of degradation of propargite in soil is mainly via formation of TBPC as presented overleaf.: The soil degradation of TBPC shows clearly that the cleavage of the either bond did not occur. Bound residues and CO2, TBPC sulphate and TBPC acid were observed as metabolites and no significant formation of PTBP was detected. Therefore, the small amounts of PTBP detected are formed directly only during the extraction and work up procedure probably by catalysed hydrolysis of the parent compound. Therefore, as worst case cyclohexanediol would have been formed at maximum the same amount as PTBP. The non-formation of PTBP from TBPC (by microbial degradation or photolysis) confirms that the degradation of TBPC is firstly and mainly initiated by the opening of the cyclohexanol ring. Furthermore, an extensive literature research revealed that 1,2-cyclohexanediol is completely biodegradable, with a conservative first-order DT50 of 0.71 days.