This regulation establishes time-limited tolerances for residues of phosphine resulting from the use of the rodenticide zinc phosphide in or on barley and wheat grain, hay and straw and wheat aspirated grain fractions. This action is in response to EPA's granting of emergency exemptions under section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act authorizing use of the pesticide on barley and wheat. This regulation establishes maximum permissible levels for residues of phosphine in these food commodities. The tolerances will expire and are revoked on December 31, 2001.