Several combinations of chemicals at different concentrations were evaluated subsequently for inactivation of more than 5 log CFU of E. coli O157:H7/ml within 20 min at 21°C in water containing large amounts of rumen content (10 parts water-1 part rumen content [vol/wt]). Three combinations, i.e., 0.1% lactic acid, 0.9% acidic calcium sulfate, and 0.05% caprylic acid (A); 0.1% lactic acid, 0.9% acidic calcium sulfate, and 0.1% sodium benzoate (B); and 0.1% lactic acid, 0.9% acidic calcium sulfate, and 0.5% butyric acid (C), met these criteria (Table (Table1).1). A fourth chemical combination (D) comprised of 0.1% lactic acid, 0.9% acidic calcium sulfate, and 100 ppm chlorine dioxide reduced E. coli O157:H7 populations by 2.6 log CFU/ml within 20 min and by 5.0 log CFU/ml within 120 min (Table (Table11).