The full implication of people eating chicken containing these drugs isn't even known, although previous studies have shown carcinogenic arsenic fed to chickens—something approved for use in nonorganic chicken farming—does wind up in the meat.
In the study, researchers tested feather meal, a by-product of chicken farming often used as fertilizer, because feathers accumulate important clues as to which drugs and chemicals chickens are exposed to during their short—usually about eight-week—lives.
The contaminated chicken report is the latest in a string of findings suggesting the industrial food system that supplies most supermarkets routinely engages in practices that could put consumers at risk.
And this, the study's coauthor says, is just the tip of the iceberg.
"There are a wide spectrum of public health, social justice, and environmental concerns that stem from the way we raise animals for food," explains researcher Keeve Nachman, PhD, assistant scientist and director of the Farming for the Future program at Johns Hopkins Center for a Livable Future, part of the university's Bloomberg School of Public Health. "These concerns range from the generation and transport of bacteria that are resistant to antibiotics that are critical to human medicine, to the disproportionate concentration of animal-production sites and their associated air and water pollution in low-income communities of color, to the overwhelming energy and water inputs required to grow and transport feed for food animals."
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News of these dangers is going mainstream, too. In a recent New York Times column, Nicholas Kristof outlined the dangers of the industrial poultry system, saying, "I used to be skeptical of organic, but the more reporting I do on our food supply, the more I want my own family eating organic—just to be safe."
Here's what industry is feeding your chickens, according to feather testing:
Antidepressants, painkillers, and allergy meds.
Sure, the conditions in factory farms are depressing. But researchers were surprised to find active ingredients of human antidepressant drugs like Prozac in the chicken feather product tested. The mood-stabilizing drug was detected in U.S.-sold chicken imported from China, and is apparently used to reduce anxiety in chickens, since stress can slow growth and lead to tougher meat, according to Kristof's report.
Nachman's team also detected caffeine in about half of the chicken feather samples. Caffeine is used to keep the chickens awake so they eat more and grow faster.
Surprise! Feather tests suggest large-scale poultry producers are using banned antibiotics in poultry production. "We were especially surprised to find residues of a number of over-the-counter drugs, including the active ingredients of Tylenol, Benadryl, and Prozac, but what was even more disturbing was finding residues of fluoroquinolone antibiotics, since these drugs have been banned from poultry production since 2005," Nachman says.
This class of antibiotics includes Cipro, a high-powered drug often used in humans when other antibiotics don't work. It was banned in the poultry industry about seven years ago because researchers were detecting that its use in farming was leading to antibiotic-resistant superbug strains that could potentially kill humans. To date, superbugs kill about 17,000 people in the U.S. a year.
Despite all this, the FDA has made it clear that it plans to not formally ban antibiotic use in food animal products, but rather ask farmers to voluntarily limit use.
"Our research suggests that drugs that are illegal in poultry production may still be in use," Nachman says. "Given this, I have little confidence that a voluntary approach will have any impact on the food animal industry's abuse of antibiotics."
Seek out undrugged meat.
To find more humanely and naturally raised chicken, look for local grass-fed poultry farmers who don't use routine antibiotics or arsenic in feed. (LocalHarvest.org is a good resource.) If you're shopping in the supermarket, opt for organic—standards for organic include bans on the use of antibiotics, arsenic, and many other unappetizing chicken-farming practices.