This regulation amends an existing exemption from the requirement of a tolerance for residues of n-alkyl (C<INF>12-14</INF>) dimethyl ethylbenzyl ammonium chloride on food contact surfaces when applied/used in public eating places, dairy processing equipment, and/ or food processing equipment and utensils. The regulation will exempt from the requirement of tolerance residues in food resulting from contact with surfaces treated with antimicrobial solutions where the end-use concentration of active quaternary compound does not exceed 400 parts per million (ppm).