How Pumping Antibiotics Into Animals Can Cause Global Warming
China is the world’s largest producer and consumer of antibiotics, and like many other nations around the world, it does almost nothing to monitor the powerful medicine’s usage or impact on the environment. A study published in the current issue of the Proceedings of the National Academy of Sciences suggests that China’s unchecked use of antibiotics in animal production is giving rise to antibiotic resistant genes (ARGs) that pose a potential worldwide human health risk.
The study, carried out by a team of researchers from Michigan State University and the Chinese Academy of the Sciences, took place on Chinese commercial pig farms. What they found is astounding: 149 unique antibiotic resistant genes, or ARGs, some at levels 192 to 28,000 times higher than the control samples. Although China’s rampant antibiotic consumption (they use four times as much as the USA) makes it an easy target, it’s not the only place where this cultivation of ARGs is taking place.
“Our research took place in China, but it reflects what’s happening in many places around the world,” said James Tiedje, a professor of microbiology and molecular genetics and of plant, soil and microbial sciences at Michigan State University. “The World Organization for Animal Health and the U.S. Food and Drug Administration have been advocating for improved regulation of veterinary antibiotic use because those genes don’t stay local.”
Since animals aren’t equipped to absorb the enormous number of antibiotics pumped into their systems, much of it ends up in manure—an estimated 700 million tons annually from China alone. The manure is then spread as fertilizer, sold as compost, or ends up downstream in rivers or groundwater, taking ARGs with them. These dangerous genes can also be spread via international trade, immigration and recreational travel.
In some cases, ARGs become highly mobile, meaning they can be transferred to other bacteria that can cause illness in humans. This is a big concern because the infections they cause can’t be treated with antibiotics. Because of this cycle, ARGs pose a potential global risk to human health and should be classified as pollutants, says Tiedje.
“It is urgent that we protect the effectiveness of our current antibiotics because discovering new ones is extremely difficult,” says researcher Yong-Guan Zhu of the Chinese Academy of Sciences.