Many decontamination processes have been developed for beef carcasses and are being established in beef processing plants. These processes include carcass washing with organic acid, steam vacuuming, steam pasteurization, and the use of antimicrobial agents such as chlorinated water. One or more methods to reduce microbial contamination are used on a majority of beef carcasses. Other sources of O157 infection are not affected by these efforts. Continuing vigilance and safe food preparation must be practiced.
Undercooked hamburger is riskier because of the kind of handling and preparation hamburger receives.
Surface bacteria may be spread throughout the meat during grinding. Also, ground meat is often made with trimmings from several cuts. This does not mean it is perfectly safe to eat other cuts raw or rare. ALL meat, poultry and fish should be cooked to the correct internal temperature. You can't tell whether ground beef is safe simply by looking at it or smelling it, which is why you should always follow the safe handling recommendations listed here.