Scientists discover a method to detect trace levels of swine antibiotics in the groundwater.

Scientists from the Department of Soil, Water, & Climate at University of Minnesota have developed a simple method to quantify two types of antibiotics in animal manures, and surface and ground waters. Chlortetracycline and tylosin antibiotics are commonly used for growth promotion in swine production.

In general, as much as 90% of antibiotics fed to food animals are excreted unchanged in animal feces and urine. Researcher Kudlip Kumar explains that these animal wastes when applied to fields present a potential for the spread of antibiotics in the environment via non-point source pollution.

According to Kumar, there is not much information about the concentration of various antibiotics in manure or surface and ground waters, probably due to lack of simple methods to analyze these antibiotics at very low concentrations in various environmental samples.

In this study, the researchers developed a simple method for ultra trace determination of chlortetracycline and tylosin antibiotics. Tests of a few swine manure samples showed that they contained as high as 7.9 mg/L chlortetracycline and 5.2 mg/L tylosin. The method developed by these researchers is very sensitive and can pick-up antibiotics in surface or ground waters at parts per billion levels. The study is published in January/February 2004 issue of the Journal of Environmental Quality, published by the American Society of Agronomy-Crop Science Society of America and Soil Science Society of America.

This study was part of the research project led by Satish Gupta on fate and transport of manure applied antibiotics on land. In this project, Gupta and his team quantified the extent of antibiotics losses in rainfall and snowmelt runoff as well as through drainage from manure applied lands. There is an increasing concern that sub-therapeutic feeding of antibiotics in animal agriculture is increasing microbial resistance in the environment. As it appears very small amounts of antibiotics move in solution form and thus this new measuring method is highly useful in quantifying these trace amount of antibiotics in aquatic environment. Gupta states that small amounts of antibiotics are generally not toxic to plants and aquatic life, but on repeated manure application there is some potential for increase in antibiotic resistant bacteria in the environment. This is another facet that Gupta and his team are quantifying.