Humans are not only exposed to high levels of antibiotics via consuming meat laced with the drugs, but also through inhaling foul air. Scientists have found that dust particles in farm buildings contain traces of antibiotics that can damage human dna. The antibiotics are added in animal feed to stimulate growth. According to the scientists, inhalation of the antibiotics could also cause bacteria living in the body to develop drug-resistance.

During their 20-year-long study, the scientists from Germany's Hanover School of Veterinary Medicine collected annual samples of dust particles that had settled in pens located in the countryside near Hamburg. Of the 20 samples, 18 contained at least one of the six antibiotics that had been added to the animals' feed. One of the compounds, tylosin, was evident in 16 samples. While tylosin is not prescribed to humans, its chemical makeup resembles erythromycin, a commonly used antibiotic. Both the drugs are so similar that bacteria resistant to one can also withstand the other.