The study [Shepler, K. (2003)] is acceptable. Imazaquin degraded in a sandy loam (soil A) and a clay loam (soil D) soil under formation of carbon dioxide (maximum 19.2/11.9% AR for soil A/soil D after 4 months), nonextractable soil residues (maximum 24.7/26.9% AR after 4 months), metabolites CL 266066 (maximum 3.1% AR) and CL 79547 (maximum 3.1% AR), a further metabolite designated Metabolite #1 (maximum 13.4/14.5% after 4 months) and a variety of minor degradates, none of which exceeding 3.4% AR. Further examination of Metabolite #1 is conducted in a separate study. After 4 months, 14CO2 accounted for 11.9-19.2% AR and nonextractable residues represented 24.7-26.9% AR. No organic volatiles were detected. Metabolite CL 266066 degraded in all tested soils under formation of considerable amounts of carbon dioxide within the 4-month study period (up to 31% AR), indicating the mineralization of the phenyl ring. CL 75947, a metabolite found in the parent metabolism study was also observed in the CL 266066 treated soils. Metabolite #1 was however not detected. The proposed route of degradation of imazaquin includes opening of the imidazolinone ring to form CL 266066 (2-(1-carbamoyl-1,2-dimethyl-propylcarbamoyl)-quinoline-3-carboxylic acid) with subsequent degradation to CL 263875 (quinoline-2,3-dicarboxylic acid) and 3-quinoline carboxylic acid (CL 75947) and multiple minor metabolites.