The routine feeding of antibiotics to livestock has released yet another thorn into the proverbial side of your food supply. Those antibiotics are being transferred, via manure, into the U.S. food supply.

University of Minnesota researchers, in a study funded by the U.S. Department of Agriculture, evaluated whether food crops accumulate antibiotics from soil covered with antibiotic-containing manure.

In a greenhouse setting, corn, lettuce and potatoes were grown on soil that contained hog manure with a commonly used veterinary antibiotic added.

The antibiotics were uptaken by all three crops, into both their leaves and tissue. Meanwhile, the antibiotics also transferred to the potato tubers, suggesting that root crops like carrots, radishes and potatoes may be particularly at risk of antibiotic accumulation.

Though the researchers said the effects of consuming plants that contain antibiotics are “largely unknown,” it’s thought that the contamination could cause allergic reactions or the development of antimicrobial resistance (which renders antibiotics ineffective).

The findings also have implications for organic farmers, who often use manure as their main source of fertilizer.

Journal of Environmental Quality July/August 2007, 36:1224-1230

Science Blog July 11, 2007