Antimicrobial resistance.

• Position: Brief Article

Danielle Nierenbers

Antimicrobial resistance: Feeding massive doses of antibiotic drugs to healthy animals--more than 11 million kg (24 million pounds) per year in the United States alone--is threatening human health by undermining our arsenal of disease-fighting drugs, according to a January 2001 report by the Union of Concerned Scientists.

Antimicrobial drugs are mixed into the feed and water of hogs, cattle and chickens bred in factory farm-type conditions or injected into individual animals both to prevent illness that result from over-confinement and poor hygiene practices, and to enhance growth. Most frequently used in the "absence of disease," according to UCS, these drugs include penicillin, tetracycline, erythromycin, and other drugs common in human medicine.

Health professionals have been concerned about the over-use and misuse of antibiotics in human medicine and in consumer products, such as "anti-bacterial" soaps, lotions, and other products (See "Tougher Germs, at Home and On the Farm," September/October 2000). Few, if any, new classes of antibiotic drugs are in clinical development, according to a February 2001 study in the Journal of the American Medical Association.

While people usually need a prescription from their doctor for antibiotics to treat a specific ailment, agricultural use of the same drugs doesn't even require an animal to be sick before medicines are prescribed. Instead, owners of confined animal feedlots can dose their entire flocks or herds--which typically number in the thousands--to promote increased growth or prevent the diseases that result when too many animals are housed in poorly ventilated, enclosed areas.

Compiling data from several government and industry sources, UCS estimated that between 1985 and 2000, the amount of antimicrobials used non-therapeutically on American livestock rose by 50 percent.

The report finds that antimicrobial use by poultry producers has risen 307 percent per bird since the 1980s. Beef cattle are given 28 percent more antibiotics than they were 15 years ago, and hogs are fed 15 percent more. Because of...