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Animal Antibiotics and Food Safety

posted on Wed, Jun 1 2011 11:54 am by Kimberly Parks and Andy Baker-White

Animal Antibiotics

For years, animals meant for human consumption have been treated with antibiotics in their feed. This widespread practice began when it was discovered that treating the entire population at sub-therapeutic levels (below the dosage levels used to treat diseases) prevented the spread of disease and contributed to animal growth.

Concern has grown that dosing animals at sub-therapeutic levels can lead to antibiotic-resistant bacteria. If these resistant bacteria are passed to humans the antibiotics that are currently available could fail. In response to this threat, many countries have prohibited sub-therapeutic uses of antibiotics.

In the U.S. the approval of new animal drugs is governed by the Federal Food, Drug, and Cosmetic Act (FDCA) (21 USC §360b). Under the FDCA, the Food and Drug Administration (FDA) can refuse to approve a drug if its sponsor fails to demonstrate its safety.  Rather than prohibiting the sub-therapeutic use of antibiotics as other countries have, the FDA has adopted guidelines to deal with the threat such use poses.

In 2003, the FDA released Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to Their Microbiological Effects on Bacteria of Human Health Concern (GFI #152).  Before GFI #152, the drug sponsor only had to show that the drug did not have a direct negative impact on human or animal health. The possible long-term effects of low-level dosing were generally not considered.

GFI #152 introduced a hazard characterization and a more in-depth risk assessment process. The hazard characterization looks at the drug and its active ingredient and determines the likelihood that it would lead to resistant bacteria. If the hazard is high, the FDA can request a qualitative risk assessment from the drug’s sponsor. The risk assessment examines the probability that resistant bacteria would develop from using the new animal drug, the likelihood that the resistant bacteria would then be ingested by a human and the odds that ingesting the resistant bacteria would lead to negative health consequences. Each of these factors is then rated cumulatively. GFI #152 also introduced possible risk management options that include denying approval, limiting the duration of drug use and post-approval monitoring through the National Antimicrobial Resistance Monitoring System (NARMS).

In 2010, the FDA issued a draft guidance, The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals, to address continuing concern about the appropriate use of antibiotics in food animals. This guidance builds on GFI #152 and introduces two new principles: that the use of medically important antibiotics in food animals be limited to what is necessary to assure animal health and that such uses should be limited by veterinary oversight or consultation.

It is hoped that these new principles together with GFI #152’s risk assessment will curtail the excessive use of antibiotics in food animals. New drugs for animals would be restricted according to their risk level and producers would no longer be able to “self-medicate” their animals. Many issues, however, still remain. Drugs approved prior to 2003 remain available for over the counter purchase and are not subject to FDA’s new principles. Also, while the FDCA allows for the review of previously approved drugs, this authority is underutilized.

The Preservation of Antibiotics for Medical Treatment Act of 2011 was recently introduced in Congress to address the need to review previously approved drugs. This bill would amend the FDCA such that any currently approved sub-therapeutic use of a critically important drug would lose approval two years after the bill’s passage unless certain safety requirements are met. Even critically important antibiotics approved for sub-therapeutic use after passage of the bill would lose approval after two years unless it met certain requirements. The bill would also introduce language into the FDCA specifically addressing the likelihood that resistant bacteria would result from the antibiotic’s use.

On May 25, 2011, the Union of Concerned Scientists, National Resource Defense Council and other groups sued the FDA and are requesting the agency to limit the use of antibiotics in the production of food animals. The lawsuit and proposed legislation address much of the concern presented by the current system of animal antibiotic use and are important steps toward protecting public health.

This information was developed by Kimberly Parks, legal intern, and Andy Baker-White, J.D., assistant director,  for the Public Health Law Network – Mid-States Region at the University of Michigan School of Public Health.

The Network for Public Health Law provides information and technical assistance on issues related to public health. The legal information and assistance provided in this document does not constitute legal advice or legal representation. For legal advice, readers should consult a lawyer in their state.

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