Crops absorb livestock antibiotics, science shows

Posted on January 8, 2009. Filed under: Uncategorized |

Consumers have long been exposed to antibiotics in meat and milk. Now, new research shows that they also may be ingesting them from vegetables, even ones grown on organic.
 
While there are restrictions on use of raw manure in U.S. organic farming because of concern over bacteria, no such rules are in place regarding antibiotics or hormones. Not all organic growers use manure with antibiotics, but many do, said Gupta. Even if a product has the USDA organic label, it still might harbor traces of antibiotics. [Correction 1/6/09: FDA was changed to USDA]
 
For half a century, meat producers have fed antibiotics to farm animals to increase their growth and stave off infections. Now scientists have discovered that those drugs are sprouting up in unexpected places.
 
Today, close to 70 percent of the total antibiotics and related drugs produced in the United States are fed to cattle, pigs and poultry. Although this practice sustains a growing demand for meat, it also generates public health fears associated with the expanding presence of antibiotics in the food chain.
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.
 
“Around 90 percent of these drugs that are administered to animals end up being excreted either as urine or manure,” said Holly Dolliver, a member of the Minnesota research team and now a professor of crop and soil sciences at the University of Wisconsin-River Falls. “A vast majority of that manure is then used as an important input for 9.2 million hectares of (U.S.) agricultural land.”
 
Manure, widely used as a substitute for chemical fertilizer, adds nutrients that help plants grow. It is often used in organic farming.
 
The scientists found that although their crops were only propagated in greenhouses for six weeks–far less than a normal growing season–antibiotics were absorbed readily into their leaves. If grown for a full season, drugs most likely would find their way into parts of plants that humans eat, said Dolliver.
 
Less than 0.1 percent of antibiotics applied to soil were absorbed into the corn, lettuce and other plants. Though a tiny amount, health implications for people consuming such small, cumulative doses are largely unknown.
 
“The antibiotic accumulation in plants is just another negative consequence of our animal agriculture industry and not surprising given the quantity fed to livestock,” said Steve Roach, public health program director for the non-profit Food Animal Concerns Trust.
 
There are serious societal implications regarding the discoveries already made and the questions yet to be answered, Gupta concluded.
 
“We are a chemical society and humans are the main user of pharmaceutical products,” said Gupta. “We need a better understanding of what takes place when chemicals are applied to sources of food and must be more vigilant about regulating what we use to grow food and what we put in our bodies.”
    
Read full from: environmentalhealthnews.org
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