antibioticsScientists at the University of Minnesota have been evaluating the impact of antibiotic feeding in livestock production on the environment.

This particular study, funded by the United States Department of Agriculture (USDA), evaluated whether food crops accumulate antibiotics from soils spread with manure that contains antibiotics.

Results from the study are published in the July-August 2007 issue of the Journal of Environmental Quality. The research was also presented in Indianapolis, IN at the Annual Soil Science Society of America Meeting in November 2006.

Sulfamethazine Uptake by Plants from Manure-Amended Soil Holly Dollivera, Kuldip Kumarb and Satish Guptaa,* a Dep. of Soil, Water, and Climate, Univ. of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108 b Res. and Dev., Metropolitan Water Reclamation District of Greater Chicago, 6001 West Pershing Rd., Cicero, IL 60804-4112 J Environ Qual 36:1224-1230 (2007)

Animal manure is applied to agricultural land as a means to provide crop nutrients. However, animal manure often contains antibiotics as a result of extensive therapeutic and subtherapeutic use in livestock production.

The objective of this study was to evaluate plant uptake of a sulfonamide-class antibiotic, sulfamethazine, in corn (Zea mays L.), lettuce (Lactuca sativa L.), and potato (Solanum tuberosum L.) grown in a manure-amended soil.

The treatments were 0, 50, and 100 µg sulfamethazine mL–1 manure applied at a rate of 56 000 L ha–1.

Results from the 45-d greenhouse experiment showed that sulfamethazine was taken up by all three crops, with concentrations in plant tissue ranging from 0.1 to 1.2 mg kg–1 dry weight.

Sulfamethazine concentrations in plant tissue increased with corresponding increase of sulfamethazine in manure.

Highest plant tissue concentrations were found in corn and lettuce, followed by potato.

Total accumulation of sulfamethazine in plant tissue after 45 d of growth was less than 0.1% of the amount applied to soil in manure.

These results raise potential human health concerns of consuming low levels of antibiotics from produce grown on manure-amended soils.