Before it recently issued a “pretty please” to drug companies, asking them to voluntarily stop making billions of dollars off of unnecessary antibiotics sales to farmers, the Food and Drug Administration spent decades appearing to avoiding the topic. But a new report claims that the FDA actually spent 10 years internally reviewing the safety of dozens of antibiotics used in animal feed, drugs that the FDA’s own scientists said pose a high risk to human beings.

According to the report [PDF] from the Natural Resources Defense Council, between 2001 and 2010, FDA scientists looked at 30 different penicillin and tetracycline antibiotic feed additives that had previously been approved for “nontherapeutic use,” meaning they were generally being used to encourage muscle growth in animals (or, less frequently, as a prophylactic against squalid living conditions).

Through a contentious Freedom of Information Act request and subsequent litigation, the NRDC says it has uncovered documents showing that FDA scientists found that none of the 30 drugs would likely be approved under current guidelines if submitted for approval today. Furthermore, 18 of the 30 antibiotics were deemed as posing a “high risk” of exposing humans to antibiotic-resistant bacteria if they made it into the food supply. There was insufficient data for FDA scientists to make such a conclusion about the remaining dozen drugs, so it’s possible that some or all may also be considered high risk.

Additionally, according to NRDC analysis of the FDA documents, 29 of the 30 drugs fail to satisfy the original FDA safety requirements from 1973.

And yet, it appears as if the FDA did nothing to stop the use of these antibiotics on animals, claims the NRDC, which found evidence suggesting that at least nine of these additives are still being marketed today, and that all of the drugs — aside from two that were voluntarily removed from the market by manufacturers — are still approved for use on farm animals.

“These findings are troubling for a number of reasons,” writes Carmen Cordova, NRDC microbiologist and the study’s lead author. “The report again draws attention to continued FDA inaction on antibiotics used in poultry and livestock production amidst mounting evidence of a threat to public health.”

Research from numerous scientists and doctors has found a link between non-medical use of antibiotics in animal feed and the increase in drug-resistant pathogens. The Centers for Disease Control and Prevention recently stated that studies “establish a clear link between antibiotic use in animals and antibiotic resistance in humans.”

The December guidance from the FDA on antibiotics in animal feed asked drug companies to voluntarily stop selling antibiotics for non-medical purposes, however it allows that those same drugs could still be sold for vague medical purposes.

Not surprisingly, the meat and drug industries love these new suggestions. Even though it’s estimated that half of antibiotic sales in the U.S. are made to farmers for non-medical uses, one of the largest big pharma firms, Eli Lilly said it didn’t expect that the FDA guidance would have any significant impact on its sales.

That’s because the drugs can still be sold under the category of “preventative” use, even though that has the same negative long-term effect of putting these antibiotics into the food chain.

“Preventive use is use on animals that are not sick, to prevent diseases often associated with crowded and dirty conditions on many industrial farms,” Avinash Kar of the NRDC told Consumerist at the time. “That’s a big category of use.”

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