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Study Shows Antibiotics Used in Livestock May be Making Their Way Into Our Food in an Unexpected Fashion

In college I briefly toyed with majoring in chemical engineering. Before I came to my senses (sort of -- in the end, I majored in...

Dr. Eric Barchas  |  Apr 16th 2010


740px-HestemjIn college I briefly toyed with majoring in chemical engineering. Before I came to my senses (sort of — in the end, I majored in chemistry), I took a few chemical engineering classes.

The classes often involved somewhat interesting exercises. In the exercises, students considered a system consisting of a chemical reactor and various inputs. The rates and ratios of the inputs, as well as the temperature of the reactor and other factors, would then be optimized to maximize one, and only one variable: profit for the producer. It made sense: chemical plants exist to create profit for their owners.

Several years later during vet school I took a few food and dairy production classes. I was struck by the similarity to the chemical engineering exercises. Substitute a cow for the chemical reactor. Modify and tweak inputs and other factors to maximize for one thing: profit.

Among the factors that can be tweaked and modified in food animal production are non-therapeutic antibiotics. If you add a little bit of tylosin to an animal’s feed, profit can be increased.

The addition of antibiotics to animal feed for no purpose other than increasing profit never sat right with me. Over use of antibiotics is bad for society in general. And I certainly am not interested in getting a dose of antibiotics every time I eat a burger.

Congress currently is considering legislation to restrict the use of non-therapeutic antibiotics in food animal production. I hope it passes. I am at odds with many food animal veterinarians as well as the American Veterinary Medical Association in this regard. Click here to read more.

But yet again without seeming to realize the irony, the Journal of the American Veterinary Medical Association‘s March 1, 2010 issue gave ammunition to opponents of non-therapeutic antibiotic use (see yesterday’s post for more about the generally ironic nature of the March 1 JAVMA).

Page 500 contained an article entitled “Researchers study antibicrobial uptake in crops.” The subtitle says it all: “Vegetables took in some antimicrobials from antimicrobial-spiked manure”. Antimicrobials are also known as antibiotics.

Here’s the line of thought: cows are fed antibiotics in order to increase profit. Some of the antibiotics wind up in the cow’s feces, also known as manure. Manure is a leading crop fertilizer — especially for organic crops. Now some people are wondering whether the antibiotics that are fed to cows in order to increase profits are showing up in the organic salads of people who go out of their way to avoid eating those very antibiotics in the first place. The irony just goes on and on.

To be fair, the article did not conclude decisively that vegans with organic food preferences were being dosed with tylosin. But this matter definitely deserves more study and attention. It definitely is true that medicines taken by animals or humans can end up in the environment: consider the recent studies that suggest fish are being sterilized by remnants of birth control pills found in human urine.

Whether or not non-therapeutic antibiotics are making their way into other parts of the human food chain, one thing seems obvious to me. Feeding antibiotics to animals simply to increase profits does not pass the smell test.

Photo: organic fertilizer. Tylosin content unknown. By Malene Thyssen.