Everybody knows by now, we hope, that most antibiotics are fed to farmed animals, that the antibiotics excreted by those animals end up in our water (not to mention the meat, eggs, and milk consumed by non-vegans), and that this is the primary reason for the emergence of antibiotic-resistant “super-bugs.” Now there’s a new reason to worry: Antibiotics have been found in vegetables grown in fields fertilized with manure — including organic vegetables.
Here’s how it works: 70% of antibiotics used in the United States are fed to farmed animals in order to promote rapid growth and mitigate the spread of disease in crowded factory farms. Animals excrete about 90% of the antibiotics fed to them. Farmers dump manure on fields as a cheap way to replace the nitrogen taken up by crops. And — now we know — the plants grown in those fields take up trace amounts of the antibiotics along with the water and nutrients they draw from the soil.
According to a recent Environmental Health News report, researchers at the University of Minnesota have detected antibiotics in a wide variety of vegetables grown in fields fertilized by manure:
The Minnesota researchers planted corn, green onion and cabbage in manure-treated soil in 2005 to evaluate the environmental impacts of feeding antibiotics to livestock. Six weeks later, the crops were analyzed and found to absorb chlortetracycline, a drug widely used to treat diseases in livestock. In another study in 2007, corn, lettuce and potato were planted in soil treated with liquid hog manure. They, too, accumulated concentrations of an antibiotic, named Sulfamethazine, also commonly used in livestock. As the amount of antibiotics in the soil increased, so too did the levels taken up by the corn, potatoes and other plants.
Organic crops are no safer. Many organic farmers use manure, and regulations do not prohibit the use of manure from animals who have eaten antibiotic-laced feed. So, now there’s one more reason to encourage your local CSA or organic farm to take the next step and go veganic. Veganic farmers and gardeners use techniques such as crop rotation, “green manure,” and amendments such as kelp or alfalfa meal in the stead of animal products like manure, bone meal, and blood meal.