Medically Important Antibiotics Are Still Being Used to Fatten Up Pigs

In this week’s Field Report, USDA data reveals that some farmers give pigs antibiotics for “growth promotion,” a practice banned since 2017. Plus: PFAS in pesticides, new rules for contract farmers, and just-published research showing a healthy diet is also better for the planet.

By Lisa Held

June 12, 2024

(Photo by Scott Olson/Getty Images)

Because scientists have identified antibiotic-resistant infections as a serious public health threat that kills more than 35,000 Americans annually, regulators at the U.S. Food and Drug Administration (FDA) have been working to reign in the misuse and overuse of antibiotics in animal agriculture—which contributes to the problem—for more than a decade. Seven years ago, the agency announced the most significant step to date: ending the use of antibiotics also important in human medicine solely for “growth promotion.”

Putting drugs in feed and water to make animals grow bigger and faster, thereby increasing profits, had been a common practice in industrial animal agriculture for decades. While the FDA didn’t end the practice whole hog, the change meant that going forward, farmers would only be able to use specific medically important antibiotics to prevent and treat disease, not fatten pigs. In 2017, the change contributed to a significant, immediate drop in antibiotics sold for use in animals.

“It was really surprising farmers actually reported their primary reason was growth promotion. Obviously, something is falling through the cracks.”

However, new data released by the U.S. Department of Agriculture (USDA) suggests some pork producers may be flouting FDA’s regulations by feeding important drugs to pigs primarily to speed their growth.

The data comes from USDA’s National Animal Health Monitoring System (NAHMS), which collected information on production practices at hog farms housing 1,000 or more pigs between December 2020 and May 2021. At various facilities raising pigs at different points in their life cycle, a percentage of producers reported feeding chlortetracycline, oxytetracycline, tylosin, neomycin, and sulfamethazine primarily for “growth promotion.” All of these drugs are considered medically important by the FDA because they are used to treat infections in humans and are classified as either “highly important” or “critically important” by the World Health Organization.

Public health advocates have long maintained that some farmers would continue to use the drugs for growth promotion because many are still approved to be added to feed for disease prevention. A spike in sales of drugs classified for “therapeutic use” after the FDA ended growth promotion backs up that theory. Now, they see this data as possibly providing more evidence, although they were still confounded by the overt way the practices were reported.

“It was really surprising farmers actually reported their primary reason was growth promotion,” said Steven Roach, the Safe and Healthy Food Program Director at the nonprofit Food Animal Concerns Trust, who has been following the issue for years. “Obviously, something is falling through the cracks.”

An FDA spokesperson declined to provide an interview and instead emailed a statement that read, in part, “The successful implementation of GFI #213 in 2017 means that it is illegal to use medically important antimicrobials for growth promotion purposes in food-producing animals, and all approved uses of medically important antimicrobials in drinking water or animal feed require the authorization (via a prescription or veterinary feed directive) of a licensed veterinarian. The FDA is reviewing the findings and will evaluate them to further our understanding of this issue and assist in our mission to protect public health.”

In response to a request for an interview, a National Pork Producers Council spokesperson sent comments via email. “The pork industry continues to promote judicious antibiotic use of antimicrobials,” they said. “It’s also important to note that veterinarians were not surveyed, and they are the main decision-makers regarding pig health interventions.” The American Association of Swine Veterinarians did not respond to an interview request.

Without more specific details on what each farmer’s veterinary feed directive said and how the data was collected, it’s hard to know whether the statistics are pointing to a serious gap in compliance with FDA’s rules.

A USDA spokesperson said in an email that the agency’s field veterinarians work with producers to collect “nationally representative, anonymized, standardized data on animal health, biosecurity, vaccination, and antimicrobial use,” and noted that participation in National Animal Health Monitoring Systems (NAHMS) surveys is voluntary.

Roach, in analyzing the data, guessed at one explanation. Many of the medically important antibiotics are fed in combination with other drugs that are classified as “non-medically important” or are not antibiotics and therefore can be used for growth promotion. So, for instance, 10 percent of the sites reported feeding chlortetracycline with BMD for “growth promotion.” BMD is not medically important and therefore can be used for that purpose, so it’s possible farmers reported the duo of drugs that way even though one of them was indicated for something else.

USDA’s answers also noted the combinations but went a step further in explaining the practices. For each medically important drug identified, the spokesperson noted that while veterinarians are not permitted to prescribe the drugs “solely for growth promotion purposes,” producers were asked to provide the “primary reason for giving these medications in feed.” (Emphasis theirs.) By that reasoning, if a farmer wants to feed one of these drugs to fatten up his pigs first and foremost, it may be considered OK as long as the drug has a secondary disease prevention benefit.

For many public health advocates, it’s a clear indication that the dividing line between growth promotion and disease prevention is incredibly thin or invisible in many cases. “We’ve always suspected that for some growers the changes were nominal, not actual, that they said, ‘That’s fine, let’s just call it prevention,’” said Lance Price, the founding director of the Antibiotic Resistance Action Center at George Washington University’s Milken Institute School of Public Health. “This provides some empirical evidence for that.”

“You have these drugs that are in current practice not important anymore, but as we become more and more desperate, other drugs become important,” Price said.

In fact, one of the other drugs the data shows pork producers have been feeding for growth promotion, tiamulin, is legal for that use since it’s not considered medically important. However, the FDA is currently reviewing comments on a proposal to move the class of drugs it belongs to—pleuromutilins—to “medically important” status as they’ve are now being used more often in humans. One reason? The drugs are unaffected by resistance that’s developed to other major antibiotic classes, such as tetracyclines and macrolides (which tylosin belongs to).

“We’re still using five times as many antibiotics to raise pigs in the U.S. as they do in the U.K. We could use a lot less.”

According to the experts, then, the only way to truly move all drugs off the conveyor belt toward no longer being effective is for FDA to go a step further and stop allowing the broader practice of putting antibiotics in feed as a prevention mechanism and only allow farmers to treat sick animals.

“We’re still using five times as many antibiotics to raise pigs in the U.S. as they do in the U.K. We could use a lot less,” Roach said. “I would like to see FDA take the next step—and hopefully it won’t take 10 years—to get rid of routine use for disease prevention as well.”

Price also said that given this limited data set that relies on voluntary participation and self-reported questionnaires points to a real issue, it bolsters the idea that federal agencies and researchers need better data overall. “This is an industry that can take thousands of pigs, kill them, package them, and ship them in a matter of hours, but they say they couldn’t possibly track actual drug use,” he said. “They do amazing stuff. They just don’t want to do this.”

PFAS Data Debate. The nonprofit organization Public Employees for Environmental Responsibility (PEER) is demanding the U.S. Environmental Protection Agency (EPA) retract a memo it released last year that reported the agency found no evidence of PFAS in its tests of commonly used pesticides. EPA initiated the tests after an environmental toxicologist found alarming levels of multiple PFAS in six out of 10 agricultural pesticides he tested.

Ever since the agency announced no evidence of contamination in the exact same chemicals, scientists and watchdog groups have been working to try to understand and explain the discrepancies. To that end, PEER submitted a FOIA request to EPA. The documents released showed the agency omitted the results of other tests that did find PFAS and left out a detail that could cast doubt on the validity of its tests. EPA maintains confidence in its results, telling PEER that the PFAS found in the other tests was attributable to “background levels” and that the detail on testing did not apply because of differences in testing sensitivity.

The debate over which tests should be relied on is likely to rage on, and the stakes are high given PFAS contamination on farms has already occurred due to other sources including sewage sludge.

Tackling the Tournament System. Farm groups including the National Sustainable Agriculture Coalition and Rural Advancement Foundation International (RAFI) applauded the USDA for introducing a rule that could significantly change how contract farmers who raise chickens for big companies including Tyson, Mountaire, and Pilgrim’s are paid. “This rule from USDA is a landmark moment for poultry growers in their long struggle for basic fairness in their contracts,” Edna Rodriguez, RAFI’s executive director, said in a press release. The industry has long been known for its “tournament system” that ultimately leaves growers in the dark about how much money they’ll make on each flock and can require them to make expensive upgrades to their infrastructure without warning.

The new rule would require companies to set a fixed base price, change how they’re allowed to calculate performance bonuses, and require them to provide a detailed accounting of how and when a grower could reasonably expect to recoup investments made in infrastructure improvements, allowing them to more effectively evaluate their options. It’s the latest in a series of rules related to chicken farmers introduced by USDA as part of the Biden administration’s efforts to increase competition and fairness in the highly consolidated meat industries. The rules are intended to give the agency the tools it needs to enforce the Packers & Stockyards Act, which has been on the books, but with no teeth, for over 100 years.

Yesterday, however, House Republicans included language to overturn the rules in their fiscal year 2025 spending bill and said they were, “reining in harmful regulations that dictate how poultry and livestock producers raise and market their animals.”

Eating Well Is Also Better for the Planet. According to a Harvard study published this week in the American Journal of Clinical Nutrition, people who eat more vegetables, legumes, and whole grains and less meat, dairy, and sugar may significantly lower their risk of several diseases and live longer. Researchers used data from the Nurses’ Health Study I and II, which followed 200,000 participants for 34 years, to look at the impact of adhering more or less closely to the “Planetary Health Diet,” which came out of the EAT-Lancet commission’s 2019 report on the best way to align diets with both nutrition and climate goals.

They found that people whose diets were most closely aligned with the diet’s recommendations had a 30 percent lower risk of premature death compared to those whose diets were furthest away from the diet’s patterns, and that the Planetary Health Diet produced 29 percent lower greenhouse gas emissions. “Climate change has our planet on track for ecological disaster, and our food system plays a major role,” said author Walter Willett, professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, in a press release. “Shifting how we eat can help slow the process of climate change. And what’s healthiest for the planet is also healthiest for humans.” Since the EAT-Lancet commission first published its recommendations, the diet has ignited significant controversies around meat eating, micronutrients, and cost.

Lisa Held is Civil Eats’ senior staff reporter and contributing editor. Since 2015, she has reported on agriculture and the food system with an eye toward sustainability, equality, and health, and her stories have appeared in publications including The Guardian, The Washington Post, and Mother Jones. In the past, she covered health and wellness and was an editor at Well+Good. She is based in Baltimore and has a master's degree from Columbia University's School of Journalism. Read more >

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