Results from two studies (Knowles (2001) and Hale & Trigg (1994)) suggested a possible degradation route for DE-535 under aerobic conditions. DE-535 degraded rapidly to produce DE-535 acid, which was further degraded to DE-535 phenol, DE-535 pyridinol and DE-535 pyridinone. A direct degradation of DE-535 to form DE-535 phenol is also suggested, but no suggestions as to when this route is preferred are indicated. The mineralisation at 20°C accounted for 32% AR with 14C-phenyl labelling and 6.3% AR with 14C-pyridinol labelling after 90 days (one soil). WIth 14C-pyridinol labelling four soils showed a mineralisation of 1.0 - 3.3% AR after 92 days and one soil 6.2% AR after 90 days. Non-extractable residues at 20°C accounted for 44% AR after 90 days with 14C-phenyl labelling and 38% AR with 14C-pyridinol labelling (one soil). Four other soils with 14C-pyridinol labelling had NER values in the range 28 - 35% AR, while one soil differs with only 3.4% AR. The metabolites DE-535 acid, DE-535 phenol, DE-535 pyridinol and DE-535 pyridinone were monitored in the study by Knowles (2001), whereas the study by Hale & Trigg (1994) did not monitor for DE-535 pyridinone. Nevertheless, in the study by Hale & Trigg (1994) an unknown metabolite, referred to as U2, was possible identical to DE-535 pyridinone. The main degradation products were Haloxyfop-R and DE-535 pyridinol. The soil metabolism studies covering six soils under standard conditions showed that Haloxyfop-R far exceeded the trigger value of 10% AR in all six soils with max concentrations ranging from 53 to 91% AR. DE-535 pyridinol too exceeded the trigger value in all the six soils with maximum concentrations from 29 to 52% AR. Therefore, DE-535 acid and DE-535 pyridinol are major metabolites and should be further investigated in field studies.