Treated Farm Waste Contains Traces Of Antibiotics, Possibly Contributing To Spread Of Resistance

Two studies suggest agriculture is contributing to the rise of antibiotic-resistant bacteria. Syda Productions/Shutterstock

Madison Dapcevich 13 Apr 2018, 23:30

After analyzing two of the “most elite” waste treatment systems on farms today, two studies from the University at Buffalo found that antibiotics aren’t fully removed from the manure. Instead, the waste still contains antibiotics that may be leaching into the surrounding environment, potentially creating antibiotic-resistant bacteria.

If you’re eating, you might want to stop now.

Both farms extract the solid matter from cow manure before sending it through waste management technologies meant to filter the poo for use as fertilizer or bedding for animals (yes, that’s a thing). The first study, published in the journal Environmental Pollution, used a system called advanced anaerobic digestion to employ microorganisms and pasteurization to break down organic matter, reduce odors, and produce biogas (biofuel). Published in Chemosphere, the second study looked at how effective reverse osmosis – used to purify and recycle water through a series of membranes – is at removing antibiotics.

In both cases, the wastewater treatment systems left behind “concerning” levels of antibiotic residues (more so in liquid manure than solid), including the actual drugs and the molecules they are broken down into. Antibiotic compounds, according to the researchers, migrate from the liquid parts of the manure into the solid during treatment, and because these techniques are implemented after the solids are separated, the bulk of solid matter goes untreated.

This dairy farm's reverse osmosis system passes manure slurry through a series of membranes to purify and recycle water. Diana Aga 

Specifically, researchers analyzed two types of antibiotics: Tetracycline, which in humans helps treat conditions ranging from acne to chlamydia, is used to treat a variety of ailments in livestock. Ionophores, which promote growth in dairy cows and treat a parasitic disease called coccidiosis, was also analyzed. Both liquid and solid poop contained genes that showed resistance to these antibiotics.

According to the US Department of Agriculture, more than 13.6 million kilograms (30 million pounds) of antibiotics approved for food-producing livestock were sold in the US in 2016. That’s just a “fraction” of the total antibiotics used globally each year. The researchers say their studies, despite having a small sample size, point to a bigger problem: neither of these commonly used treatment systems were designed to remove antibiotics.

“This problem is not limited to agriculture: Waste treatment systems today, including those designed to handle municipal wastewater, hospital wastes and even waste from antibiotic manufacturing industries, do not have treatment of antibiotics in mind,” said study author Diana Aga in a statement. “This is an extremely important global issue because the rise of antibiotic resistance in the environment is unprecedented. We need to start thinking about this if we want to prevent the continued spread of resistance in the environment.”

Maybe it’s time to reconsider that daily double grande latte.

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