Under aerobic conditions the metabolic pathway involved cleavage of the benzoyl group to form the urea CGA 238277 that was in turn hydrolysed/metabolised to CGA 224443. Metabolites identified at levels greater than 10% from 14C-dichlorophenyl labelled lufenuron contain the intact dichlorophenyl ring and are designated CGA 238277 and CGA 224443. The maximum amount of CGA 238277 ([2,5-dichloro-4-(1,1,2,3,3,3-hexafluoro-propoxy)-phenyl-urea) observed was 31.8% AR (day 30), decreasing to 6% AR (100 days). Degradation of CGA 238277 proceeds via CGA 224443 (2,5-dichloro-4-(1,1,2,3,3,3-hexafluoro-propoxy)-phenylamine) which was formed at a maximum of 32.8% AR at the end of the study. Mineralisation from dichlorophenyl ring was low, within 2-15% AR after 149 and 360 days. Under aerobic conditions the major metabolite from the difluorophenyl ring was carbon dioxide formed in 53% yield at 90 days. It is postulated that the formation of CO2 proceeds via CGA 149772 (2,6-difluorobenzamide) and CGA 149776 (2,6-difluorobenzoic acid). Bound (unextracted) residues were 34% AR from the difluorophenyl ring at 90 days decreasing to 28% at 360 days. After 90 days unextracted residues reached 59% AR from the dichlorophenyl ring and increased to 70.9% (mean) at 360 days. The difference between the two studies suggests that the bound material is not parent lufenuron but is predominantly derived from the dichlorophenyl moiety. Due to that, van der Gaauw (2004) conducted a study for bound residues characterisation. The amounts of unextractable radioactivity produced in this study (44.5-49.1% AR at 90 days) were very similar to the levels found in the previous. In this study it was possible to conclude that the unextracted radioactivity is predominately associated with humin rather than the more mobile fulvic and humic acids. Moreover, the results of the extractability tests with various solvent systems are consistent with low bioavailability of lufenuron in soil.