DM-PCA was the major metabolite which tended to increase steadily with time and reached nearly 10 % after one year in the US study and ranged from 3.3 to 28.0 % after 6 months in the other studies. Radiolabelled carbon dioxide steadily increased with time from both pyrazole and thienyl ring labels and accounted from 0.6 to 22.1 % of AR (P-label) and from 1.2 to 26 % of AR (T-label) at the end of the studies. The mineralisation of the T-label was consistently higher than the P-label reflecting the greater instability of this portion of penthiopyrad after cleavage. Therefore, while in most instances the data obtained regarding the two labels indicated that they behaved in a similar manner, there some differences and the evaluator notes that some metabolites (PAM, PCA and DM-PCA are only formed from the degradation of one label, so that there is only one replicate of some metabolites and not duplicate measurements. The metabolites, 753-T-DO and 753-A-OH were found between 5 and 10 % AR. Other metabolites, PAM, PCA, 753-F-DO, M12 (proposed by MS analysis as an isomer of 753-A-OH) and M11 (proposed by MS analysis as an isomer of 753-A-COOH), were present at less than 5 % of AR. Unidentified metabolites individually did not generally exceed 3.5 % AR. Non-extractable radioactivity in the six soils ranged from 7.1 to 34.2 (mean of both radiolabels), peaking at study end, while at 90 days levels of non-extractable radioactivity ranged from 9 to 24 % AR. The non-extractable fraction increased gradually with time from 6.7 to 31.1 % of AR (P-label) and from 7.5 to 39.9 % of AR (T-label). Residues remaining after harsh extractions of day 360 were submitted to the organic matter fractionation into humic acid, humin and fulvic acids. Organic matter fractionation of the non-extractable residues for the Waddesdon 2 soil indicated that more of the non-extractable radioactivity was bound to the immobile humic acids and humans (8 % of that applied) than to the more mobile fulvic acids (6 % of that applied). CO2 peaked at between 4.4 and 24.0 % AR at study end, being between 2.7 and 9.5 % AR at day 90. Volatile products other than 14CO2 did not exceed 0.1 % in any soil. No correlation between route of degradation and soil properties was observed.