ABSTRACT.  The paper analyzes changes in bacteriological meat contamination standards in the U.S. since the early 1980s when E. coli O157:H7 was for the first time identified as a new foodborn pathogen associated with the consumption of undercooked meat. Four types of risks, and the standards associated with them, are identified.  Up until 1982 meat contamination was ascertained via organoleptic standards.  Meat was considered as safe as producers’ and/or consumers’ sanitary conditions and hygiene.  In 1982, the identification of E. coli O157:H7 as a pathogen dangerous to human health resulted in a redefinition from organoleptic to biomedical standards. Meat contamination risks were measured by the extent to which sick patients could recover from foodborne diseases or die.  In 1993, as a result of the massive ‘Jack-in-the-Box outbreak’ associated with the consumption of hamburgers contaminated with E. coli O157:H7, biomedical standards were reformulated into epidemiological measures aimed at ascertaining the extent to which the country’s population was at risk of getting sick or dying from meat contamination.  Finally, in 1996, with the enactment of the Pathogen Reduction Act/HACCP, meat processing standards replaced epidemiological standards.  Meat was to be as safe as packers processed it.  Economic, political, social, scientific and technological factors contributing to the origins of each of the four types of bacteriological meat standards are analyzed.  Consequences of the changes in standards in terms of re-distribution of costs, benefits, and risks to those social actors engaged in the meat subsector are discussed.