This regulation establishes a time-limited tolerance for residues of thiophanate methyl and its metabolite (methyl 2- benzimidazoyl carbamate (MBC)) in or on mushrooms. This action is in response to EPA's granting of an emergency exemption under section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) authorizing use of the pesticide on mushroom spawn. This regulation establishes a maximum permissible level for residues of thiophanate methyl in this food commodity. The tolerance will expire and is revoked on December 31, 2004.