Crops absorb livestock antibiotics, science shows

.....People have long been exposed to antibiotics in meat and milk. Now, the new research shows that they also may be ingesting them from vegetables, perhaps even ones grown on organic farms.

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........

....One finding that particularly worries food scientists is the accumulation of antibiotics within potato tubers. Tubers are an enlarged, underground stem that uptake and store nutrients from the soil. In crops like potatoes, carrots and radishes, it is the part humans eat.

“Since these tubers and root crops are in direct contact with the soil they may show a greater propensity for (antibiotic) uptake,” said Gupta.

Health officials fear that eating vegetables and meat laced with drugs meant to treat infections can promote resistant strains of bacteria in food and the environment.

Roach said “the clearest public health implication” from treating livestock with antibiotics is the development of resistant bacteria that reduces the effectiveness of human medicine. Past studies have shown overuse of antibiotics reduces their ability to cure infections. Over time, certain antibiotics are rendered ineffective.

Scientists believe antibiotics also may have contributed to the explosive rise in asthma and allergies in children over the last 20 years. Researchers at Henry Ford Hospital in Detroit, following 448 children from birth for seven years, reported that children who received antibiotics within their first six months had a higher risk of developing allergies and asthma.

Such health concerns led the European Union in 2006 to ban antibiotic use as feed additives for promoting livestock growth. But in the United States, nearly 25 million pounds of antibiotics per year, up from 16 million in the mid 1980s, are given to healthy animals for agriculture purposes, according to a 2000 report by the Union of Concerned Scientists. ......

Tainted manure can impact more than just the soil. Once applied to the land, antibiotics can infiltrate water supplies as it seeps through the soil into aquifers or spills into surface water due to runoff, explained Dolliver.

“The other thing to remember is that the field is not a sterile environment. Mice, rabbit and foxes traverse farmland while other animals graze, all with the potential to become vectors for the resistant bacteria organisms and spread it throughout different animal populations,” said Pat Millner, a U.S. Department of Agriculture microbiologist based in Maryland.

“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.”