In the original review the route of degradation of metsulfuron-methyl was examined in 4 soils (four with the 14C-phenyl label and one with the 14C-triazine label) with pHs ranging between 5.2 and 6.7 and %oc between 0.8 and 4.02. Moderate levels of mineralisation were observed (32% with the 14C-phenyl label and 11.4% AR with the 14C-triazine label after 90 to 112 days) and unextractable radioactivity was 12 to 25% AR after 90 to 98 days. Metsulfuron-methyl was rapidly degraded in soil by chemical and biological processes and in non sterile soil, biological processes play a significant role in degradation of both parent and metabolites. Seven metabolites were identified as occurring at >10%: IN-D5803 (ester sulphonamide – 17%), IN-D5119 (acid sulphonamide – 29%), IN-B5685 (phenylurea – 17%), IN-00581 (saccharin – 47%), IN-A4098 (triazine amine – 33%), IN-NC148 (carbamoyl guanidine – 16%) and IN-B5067 (O-desmethyl metsulfuron – 11.6%). These metabolites were detected in studies with both realistic and high dose rates. In field studies the metabolites IN-D5119 (acid sulphonamide), IN-00581 (saccharin) and IN-A4098 (triazine amine) were detected.