This regulation amends the exemption from the requirement of a tolerance for residues of dimethyl sulfoxide (CAS Reg. No. 67-68-5) when used as an inert ingredient (solvent, co-solvent) in pesticide formulations applied to growing crops (pre-emergent use only) to include use after the crop emerges from the soil but before harvest provided that the potential for increased residues of the formulation's active ingredient(s) in or on food commodities has been assessed. ISK BioSciences submitted a petition to EPA under the Federal Food, Drug, and Cosmetic Act (FFDCA), requesting an amendment to an existing exemption from the requirement of a tolerance. This regulation eliminates the need to establish a maximum permissible level for residues of dimethyl sulfoxide.