Antibiotics Fed to Animals Drift in Air. (Suspended Drugs)

Article excerpt

Drugs added to animal feed can latch onto dust particles that become airborne and float through farm buildings, according to German scientists investigating health risks. Such antibiotics could be toxic if livestock workers inhale them and also could accelerate the evolution of drug-resistant bacteria.

Past studies have found farm-derived antibiotics in waterways (SN: 3/23/02, p. 181) and food products. The air represents a third route of unintended exposure to antibiotics, says microbiologist James Zahn of Iowa State University in Ames.

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Much of the dust in farm buildings that house animals is organic matter from feed, animal skin and excrement, bacteria, and fungi, says Jorg Hartung of the Hannover School of Veterinary Medicine in Germany. Previous research had shown that inhalation of the dust can cause respiratory problems, allergies, and other health effects in farmworkers.

To see whether farm dust contains antibiotics, Hartung and his colleagues analyzed particles that had settled out of the air in a pig-confinement building on a German farm. The researchers looked for chemical evidence of six antibiotics that had been added to feed at low doses to accelerate the animals' growth.

Of samples gathered annually between 1981 and 2000, 18 of 20 contained at least one of the six compounds, says Hannover chemist Gerd Hamscher. Tylosin, the antibiotic found most often, showed up in 16 samples, the researchers report in an upcoming Environmental Health Perspectives.

Tylosin is not prescribed to people because it tends to induce allergies, but it's chemically related to the important medical antibiotic erythromycin. …