植物的葉子中發現抗生素的濃縮物，藥物散布在馬鈴薯的根裡，也就是說，馬鈴薯、胡蘿蔔、白蘿蔔等根莖作物，因為直接與土壤接觸，因此特別容易受抗生素污染。研究主持人杜麗佛（Holly Swanson Dolliver）指出，植物所吸收的抗生素對有機農業的影響尤其值得關注。
Foods such as corn, lettuce and potatoes have been found to accumulate antibiotics from soils spread with animal manure that contains these drugs. The study results indicate that organic foods are most likely to contain these drugs because manure is often the main source of crop nutrients for organic food production.
Funded by the U.S. Department of Agriculture, USDA, scientists at the University of Minnesota evaluated the impact of antibiotic feeding in livestock production on the environment. Study results are published in the July-August 2007 issue of the "Journal of Environmental Quality."
Plant uptake was evaluated in a greenhouse study involving three food crops - corn, lettuce, and potatoes. The plants were grown on soil modified with liquid hog manure containing Sulfamethazine, a commonly used veterinary drug. Sulfamethazine has been used to treat bacterial diseases in human and veterinary medicine and to promote growth in cattle, sheep, pigs and poultry.
Concentrations of antibiotics were found in the plant leaves, and the drugs also diffused into potato tubers, which suggests that root crops, such as potatoes, carrots, and radishes, that directly come in contact with soil may be particularly vulnerable to antibiotic contamination.
Holly Swanson Dolliver, the lead scientist in this study, notes that antibiotics consumed by plants may be of particular concern to the organic farming industry.
"Manure is often the main source of crop nutrients for organic food production, since regulations prohibit the use of synthetic fertilizers," she says.
According to the USDA, producers must manage animal materials in a manner that does not contribute to contamination of crops by residues of prohibited substances, which includes antibiotics.
However, manure containing antibiotics are not formally banned or prohibited.