The amount of antibiotics sold for use in livestock rose substantially in recent years, according to the Food and Drug Administration, a pattern that experts said was troubling given the efforts to battle antibiotic resistance in humans.
In an annual report posted online Thursday, the agency said the amount of medically important antibiotics sold to farmers and ranchers for use in animals raised for meat grew by 16 percent from 2009 to 2012.
Most troubling, health advocates say, was a rise in the sale of cephalosporins, a class of drug that is important in human health, despite restrictions the FDA put into place in early 2012. The report showed an 8 percent increase in the sale of those drugs in 2012, confirming advocates’ fears that the agency’s efforts may not be having the desired effect. Sales of those drugs rose by 37 percent from 2009 to 2012.
“We’re concerned that antibiotic sales for food animal production keep increasing,” said Laura Rogers, director of the Campaign on Human Health and Industrial Farming at the Pew Charitable Trusts, a research and advocacy group.
The National Chicken Council, an industry group, said that the sale of antibiotics did not necessarily correlate with antibiotic resistance trends. It said that most antibiotics used in chicken production were not used in human medicine.
Antibiotics were the wonder drugs of the 20th century, and their initial use in humans and animals was indiscriminate, experts say. Farmers learned that antibiotics helped animals grow rapidly, and they began to add the drugs to feed and water, with no prescriptions or sign of sickness in the animals.
But it is now known that broad use leads to antibiotic resistance, which means that critical antibiotics are no longer as effective in treating infections in people.
The United States also uses far more antibiotics in livestock than many other nations, according to Pew. Animals raised for food in America are given about six times as much antibiotics as are animals in Norway and Denmark, for example.
The most sweeping federal policy aimed at curbing antibiotics use in animals was introduced last year, when the FDA asked companies that make the drugs to change the labels. Those changes meant that food animal producers would no longer be able to use antibiotics to make the animals grow faster. And if food animal producers wanted to give the drugs to sick animals, they would need to get prescription from veterinarians.
But consumer health advocates said at the time that it was unclear that the changes would have much effect. The rules left open a large loophole: Producers could simply argue that they were using the drugs to keep their animals from getting sick, not to make them grow faster.
The report also gave details — some for the first time — of how the antibiotics were used. About 70 percent were sold as animal feed additives and roughly 22 percent as drinking water additives. In all, about 97 percent of the drugs were sold over the counter without a prescription, a practice that the 2013 rules were supposed to stop.