New research raises questions about whether poultry producers might still be using an antibiotic that was banned in 2005 after being linked to increasing antibiotic resistance.

poultryproduction_iphone.jpgResearchers at Johns Hopkins Center for a Livable Future (CLF) and Arizona State University tested feather meal — a byproduct made of ground-up poultry feathers commonly added to chicken, swine, cattle and fish feed — and found a surprising variety of drug residues, including fluoroquinolones, a class of antibiotics critical for fighting infections in humans.

The findings surprised scientists because the U.S. Food and Drug Administration banned the class of drugs, which includes cipro, in poultry production in 2005 in response to rising fluoroquinolone resistance among Campylobacter bacteria, a leading cause of foodborne illness.

“The discovery of certain antibiotics in feather meal strongly suggests the continued use of these drugs, despite the ban put in place in 2005 by the FDA,” said David Love, PhD, project director at CLF and lead author of the report, which was published in Environmental Science & Technology. “The public health community has long been frustrated with the unwillingness of FDA to effectively address what antibiotics are fed to food animals.”

Nick Kristof broke the story in his column “Arsenic in Our Chicken?,” which was the most emailed story on on Thursday.

“These studies don’t mean that you should dump the contents of your refrigerator, but they do raise serious questions about the food we eat and how we should shop,” wrote Kristof, reiterating that the research does not suggest a health risk to poultry consumers.

Keeve Nachman, a scientist at the Johns Hopkins Center for a Livable Future and co-author of the study, said the research team was shocked at the variety of pharmaceuticals they were able to detect.

In 12 feather meal samples, which were collected from six states and China, they found 59 pharmaceuticals and personal care products. Each sample was found to contain antibiotic residues (testing positive for between 2 and 10 different drugs).

As part of the study, researchers exposed strains of E. coli bacteria to the concentrations of antibiotics detected in the feather meal and found that the residues were strong enough to select for resistant bacteria.

Drugs not typically associated with poultry production were also detected, including the antihistamine diphenhydramine (the active ingredient in Benadryl) and the antidepressant fluoxetine (the active ingredient in Prozac). Researchers detected caffeine and acetaminophen (the active ingredient in Tylenol) in 10 of the 12 samples.

“We were kind of floored,” Nachman told the Times. “It’s unbelievable what we found.”

The National Chicken Council responded by reminding consumers that the study looked at feathers, not meat and reiterated that there is no immediate health concern.  

“Today’s chicken industry produces birds that benefit from modern technology, advances in nutrition, carefully formulated feed, biosecurity measures, access to a plentiful supply of clean water, adequate room to grow cage-free and professional veterinary attention,” said NCC in a statement.

“Consumers should know that chicken is safe, wholesome and that all chicken produced in the United States is inspected by the USDA,” added the council. “Inspectors test meat samples for chemical and antimicrobial residues; and all poultry must be in compliance with USDA standards before entering the marketplace.  When antibiotics are used in chicken production, strict withdrawal periods must be followed before the birds are processed for food.  Chicken consistently has the best record of any meat product tested for residues by USDA.”

Congresswoman Louise Slaughter (D-NY) — a microbiologist who has for years been pushing for stronger controls on antibiotics used in animal agriculture — responded angrily to the study in a letter to FDA.

“I’m outraged by this,” said Slaughter. “If the results of this study are accurate, then those culpable for endangering public health must be held fully accountable. This is really just a symptom of the bigger problem, which is that the FDA has continued to drag its feet in addressing this looming public health crisis.”

Slaughter asked the FDA to respond within 30 days with how the agency plans to investigate the issue and requested specifics on the oversight currently in place, including how many personnel are involved to “ensure proper oversight of antibiotics used to feed healthy animals.”