Growth-promoting antibiotics: On the way out?

In 1950, Science News ran a story showing for the first time that a potent antibiotic could do more than knock out disease. New animal experiments, we reported, “cast the antibiotic in a spectacular new role” as a livestock growth promoter. Lacing the food of hogs with trace quantities of this drug increased meat yields by up to 50 percent, scientists at Lederle Laboratories had reported at a research conference. Sixty-two years later — to the day — a federal judge has now ordered the Food and Drug Administration to resume efforts toward outlawing this nonmedical use of antibiotics.

The 1950s were rife with ebullient prognostications. And our reporter back then had found the prospect of boosting meat production with harmless quantifies of a drug exciting. Our story proclaimed that the discovery “may hold enormous long-range significance for the survival of the human race in a world of dwindling resources and expanding populations.”

But it turned out that here, as in so many instances, there’s no free lunch.

Feeding animals trace quantities of an antibiotic didn’t harm them. In fact, it launched the widespread and largely indiscriminate use of these life-saving drugs for nonmedical purposes. As germs encountered subtherapeutic doses of these medicines again and again, both in animals and the environment, bacteria evolved a resistance to them.

Before long, that resistance began emerging in humans who became infected with the same germs, or close relatives to them. The result: As in the 1930s, people were again facing life threatening illness from germs that antibiotic wonder drugs had been developed to eradicate.

FDA knew about this, of course, notes U.S. Magistrate Judge Theodore Katz in his new ruling. Thirty-five years ago, he points out, “FDA issued notices announcing its intent to withdraw approval of the use of certain antibiotics in Iivestock for the purposes of growth promotion and feed efficiency.” At that time, FDA acknowledged that nonmedical use of penicillin and tetracycline-type drugs — and the drug resistance they were spawning — threatened human health.

By law, that 1977 ruling should have set in motion a procedure of hearings that would give drug manufacturers a chance to rebut the FDA assessment. If the drug makers didn’t challenge the assessment or prove that FDA had gotten it wrong, growth promoting use of the drugs would have to end.

But those hearings never took place, which has given livestock growers a 35-year extension of the drugs’ use.

Enter the Natural Resources Defense Council. Last year, its litigators filed a lawsuit against FDA on behalf of the Center for Science in the Public Interest, Food Animal Concerns Trust, Public Citizen, and the Union of Concerned Scientists. These public-interest groups charged that FDA dropped the ball and the public was suffering. They asked the court to make FDA resume its procedural case against antibiotics in livestock feed.

For its part, FDA argued that it was in the process of working with drug manufacturers to encourage a voluntary phaseout of growth-promoting applications of penicillin and tetracycline antibiotics. So the agency argued it no longer needed to formally outlaw these uses.

Not true, argues Judge Katz in his March 22 opinion. The law is the law. Once FDA made a preliminary determination that human health was imperiled by nonmedical antibiotic uses, the process must progress toward a formal withdrawal of legal approval for this application. As long as the initial science has not been proven wrong in the interim, the agency is obligated to complete the action it started — even after 35 years.

Indeed, the judge observes, over the intervening decades “scientific evidence of the risks to human health from the widespread use of antibiotics in livestock has grown.” Those health concerns — and accumulating libraries of data — also point to risks for antibiotics that extend well beyond the penicillin and tetracyclines covered in FDA’s 1977 assessment. In fact, two citizen petitions asked FDA to end growth-promoting uses for additional antibiotics.

Last year, FDA threw out the petitions, arguing they were moot now that the agency was working with drug manufacturers towards some sort of voluntary phasedown or phaseout.

Arguing that voluntary guidelines will not satisfy these claims either, “We’re challenging the denials of those petitions,” says Avinash Kar, one of the NRDC attorneys involved. “So that part of the case is still being litigated,” he says, “and will probably result at some point in a court hearing.”

For now, Judge Katz has merely instructed FDA to go ahead and hold hearings on the fate of penicillin and tetracycline. How soon the agency must act has not yet been spelled out, Kar says: “Further court proceedings will decide the timeline. And, of course, it’s possible that FDA might appeal.”