This regulation establishes tolerances for residues of fenamidone, [4H-Imidazol-4-one, 3,5-dihydro-5-methyl-2-(methylthio)-5- phenyl-3-(phenylamino)-, (S)-], in or on lettuce, head at 15 ppm and lettuce, leaf at 20 ppm. Aventis CropScience requested these tolerances under the Federal Food, Drug, and Cosmetic Act, as amended by the Food Quality Protection Act of 1996. Subsequent to the filing of this petition, Bayer Corporation acquired Aventis CropScience to form Bayer CropScience. Therefore, the registrant is now Bayer CropScience.