6:38p.m. Updates with FDA comment
A U.S. Food and Drug Administration review of 30 antibiotics used in livestock found that more than half posed a significant risk of exposing humans to antibiotic-resistant bacteria.
Despite the review, which occurred from 2001 to 2010, the federal agency allowed the drugs—used as additives in animal feed and water—to remain on the market, according to a report released on Monday by the Natural Resources Defense Council, an environmental group that based its findings on internal documents obtained under the Freedom of Information Act.
“This discovery is disturbing but not surprising given FDA’s poor track record on dealing with this issue,” Carmen Cordova, an NRDC microbiologist and the lead author of the study, said in a press release. “It’s just more overwhelming evidence that FDA—in the face of a mounting antibiotic resistance health crisis—is turning a blind eye to industry’s misuse of these miracle drugs.”
According to the report, the FDA reviewed the safety of 30 penicillin and tetracycline antibiotic feed additives that were approved for “non-therapeutic” use in farm animals—meaning drugs used for preventing disease or promoting growth of the animals, rather than treating an illness.
Eighteen of the 30 feed additives were deemed “high risk” for exposing people to antibiotic-resistant bacteria in the food supply, according to the report. There wasn’t enough data for FDA researchers to determine whether the other antibiotics were safe, the report found. The NRDC said all but two of the drugs remain approved for use. (Those two drugs were withdrawn by the manufacturers.)
The report is likely to add fuel to an already intense debate over the use of medically important antibiotics in livestock, particularly for reasons other than treating sick animals. In December the FDA released guidelines that are supposed to stop the practice of feeding antibiotics to farm animals only for the purposes of promoting growth. As Bloomberg Businessweek reported, critics including the NRDC have complained that the guidelines were voluntary and too tepid because they still allowed farmers to give antibiotics to healthy animals for disease prevention.
“The FDA has repeatedly found shortcomings with the safety of these drugs,” says Avinash Kar, an NRDC attorney. “It should be moving to take binding action. The voluntary guidance doesn’t get there.”
Asked to respond to the allegations, the FDA late Monday issued a statement
saying that the review cited by the NRDC ultimately led them to choose a
broader strategy. Rather than vet hundreds of different antibiotics, the
agency decided to provide broader guidance for all medically important
antibiotics. “The FDA is confident that its current strategy to protect the effectiveness of medically important antimicrobials, including penicillins and tetracyclines, is the most efficient and effective way to change the use of these products in animal agriculture,” the statement said.
The FDA has warned about the dangers of giving low doses of antibiotics to livestock since at least 1972. But efforts to clamp down on their use on the farm were mostly blocked by the livestock and pharmaceutical industries. Experts say that routinely feeding medically important antibiotics to livestock plays some role in antibiotic infections in humans, though its significance is widely debated.
In 2011 (PDF), penicillin and tetracycline accounted for 14.3 million pounds of the 29.9 million pounds of antimicrobial drugs sold for use in livestock. Antimicrobials include antibiotics but also such things as antifungals and antivirals.
The NRDC and other environmental groups maintain that increased use of antibiotics in agriculture is due to modern agricultural practices that raise animals in unsanitary and crowded conditions that breed disease. Farm groups characterize such facilities as more efficient, environmentally sustainable, and necessary to meet the demands of a growing world.