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Meat producers have fed growth-promoting antibiotics to food animals for
years. Recently, scientists have raised concerns that, in conjunction with
the general overuse of antibiotics in humans, this use of "sub-therapeutic"
levels of antibiotics in food animals may lead to serious health risks for
people. Banning the use of such drugs, however, would greatly reduce the
efficiency of the industry, driving up the cost of meat. Some in the
industry believe that the scientific evidence linking low-dose usage of
antibiotics to drug-resistant illnesses in people is too inconclusive and does not justify banning their use. Here's a look at the controversy, plus links to
more information.
Ranchers and farmers have been feeding antibiotics to the animals we eat since they discovered decades ago that small doses of antibiotics administered daily would make most animals gain as much as 3 percent more weight than they otherwise would. In an industry where profits are measured in pennies per animal, such weight gain was revolutionary.
Although it is still unclear exactly why feeding small "sub-therapeutic" doses of antibiotics, like tetracycline, to animals makes them gain weight, there is some evidence to indicate that the antibiotics kill the flora that would normally thrive in the animals' intestines, thereby allowing the animals to utilize their food more effectively.
The meat industry doesn't publicize its use of antibiotics, so accurate information on the amount of antibiotics given to food animals is hard to come by. Stuart B. Levy, M.D., who has studied the subject for years, estimates that there are 15-17 million pounds of antibiotics used sub-therapeutically in the United States each year. Antibiotics are given to animals for therapeutic reasons, but that use isn't as controversial because few argue that sick animals should not be treated.
The biggest controversy centers around taking antibiotics that are used to treat human illnesses and administering them to food animals. There is an increasing amount of evidence suggesting that the sub-therapeutic use of antibiotics in food animals can pose a health risk to humans. If a group of animals is treated with a certain antibiotic over time, the bacteria living in those animals will become resistant to that drug. According to microbiologist Dr. Glenn Morris, the problem for humans is that if a person ingests the resistant bacteria via improperly cooked meat and becomes ill, he or she may not respond to antibiotic treatment.
Concern about the growing level of drug-resistant bacteria has led to the banning of sub-therapeutic use of antibiotics in meat animals in many countries in the European Union and Canada. In the United States, however, such use is still legal. The World Health Organization is concerned enough about antibiotic resistance to suggest significantly curbing the use of antibiotics in the animals we eat. In a recent report, the WHO declared its intention to "reduce the overuse and misuse of antimicrobials in food animals for the protection of human health." Specifically, the WHO recommended that prescriptions be required for all antibiotics used to treat sick food animals, and urged efforts to "terminate or rapidly phase out antimicrobials for growth promotion if they are used for human treatment."
Although conclusive evidence directly linking the use of drugs in food animals to an increase in drug-resistant bacteria that make people sick has not been uncovered, a number of recent studies suggesting such a link concern many scientists. "There is no evidence that antibiotic resistance is not a problem, but there is insufficient evidence as to how big a problem it is," says Dr. Margaret Mellon, with the Union of Concerned Scientists.
In one study published in the New England Journal of Medicine on February 6, 2002, researchers found links that strongly suggested that the people who developed Cipro-resistant bacteria had acquired them by eating pork that were contaminated with salmonella. The report concluded that salmonella resistant to the antibiotic flouroquine can be spread from swine to humans, and, therefore, the use of flouroquinolones in food animals should be prohibited.
Another New England Journal of Medicine study from Oct. 18, 2001, found that 20 percent of ground meat obtained in supermarkets contained salmonella. Of that 20 percent that was contaminated with salmonella, 84 percent was resistant to at least one form of antibiotic.
Cipro and Baytril
Some, including the FDA, believe the overuse of Baytril, an antibiotic used to treat sick birds, led to an increase in treatment-resistant bacterial infections in humans. Baytril is used by poultry growers to protect chickens and turkeys from E. coli infection. The size of commercial chicken flocks precludes testing and treating individual birds, so when a veterinarian diagnoses one infected bird, farmers treat the whole flock by adding the drug to its drinking water. General use of Baytril, therefore, falls in the gray area between therapeutic and sub-therapeutic.
Baytril is the sister drug to Cipro, which is used to treat and prevent anthrax as well as campylobacteriosis and salmonellosis in people. The Food and Drug Administration, doctors, and consumer groups have all urged that Baytril be removed from the market on the grounds that its use in animals may eventually compromise the power of Cipro and similar antibiotics to fight disease in humans. Cipro and Baytril belong to a class of drugs known as fluoroquinolone, among the most powerful antibiotics currently available.
Baytril first came up for approval for use in chickens six years ago. Physicians have used fluoroquinolones to treat food-borne illness since 1986, but fluoroquinolone-resistant bacteria were rare until 1995, when the FDA approved the use of these drugs in drinking water for poultry. The FDA's rough estimate, using 1999 data, is that use of fluoroquinolones in chickens resulted in over 11,000 people that year contracting a strain of the campylobacter illness that was resistant to fluoroquinolones, contributing to unnecessarily severe disease.
When the FDA proposed pulling Baytril use in chickens a year ago due to sharp increases in resistance to fluoroquinolones in campylobacter bacteria, one of the two manufacturers voluntarily withdrew its product. The other, Bayer, did not.
Bayer officials continue to offer the human drug Cipro at reduced rates to the American public, saying that they are not convinced that the use of fluoroquinolones in animals can be blamed for increased resistance in people. Until more proof is found of the specific danger to humans, they will not withdraw their product from the chicken market.
The Meat Industry's Argument
For its part, the meat-production industry contends that there is not enough conclusive evidence to support measures like the FDA's proposed ban against flouroquinolones. Although none deny that the spread of antibacterial resistance is a real problem, proponents of sub-therapeutic antibiotic use in animals point out that the problem stems from overuse of all antibiotics, including therapeutic and preventative use in both animals and humans. Agricultural use may contribute to the problem, but it is impossible to determine to what extent.
In its recent report, the World Health Organization blamed the worldwide upswing in resistance to antibiotics on a combination of factors that included "overuse in many parts of the world, particularly for minor infections," and "misuse due to lack of access to appropriate treatment." The factors involved in the problem are clearly not limited to antibiotic use in animal feed.
"When someone's sick and goes to the doctor, they still expect to get a prescription," said National Chicken Council spokesman Richard Lobb. He said that people should look to themselves for the causes of antibiotic resistance, referring to the American practice of prescribing antibiotics for even the most minor of illnesses.
Increased use in hospitals may also contribute to the resistance problem. "Today, especially in intensive care wards, the amount of antibiotics in the environment can become high enough that people in the vicinity of patients receiving antibiotics are exposed continuously to low levels of antibiotics," microbiologist Abigail Salvers of University of Illinois told Scientific American. This low level of exposure, she contends, is one reason why highly resistant bacteria are developing in hospitals. She says that a similar phenomenon may be taking place in agriculture.
According to Alexander S. Matthews, president and CEO of the Animal Health Institute (AHI), removal of antibiotics from animals' feed and water "would lead to increased animal disease, a reduction in food safety and gain little, if anything, in the effort to control resistance." He suggests developing "prudent use principles."
Lowering or halting sub-therapeutic antibiotic use in animal production could have serious economic effects on the meat and poultry industry. According to a report released in May 2001 by USDA's Economic Research Service, discontinuing the use of antimicrobial drugs in hog production would initially decrease feed efficiency, raise food costs, reduce production and raise prices to consumers. According to the same report, U.S. hog producers saved about $63 million in feed costs in 1999 due to their use of low levels of sub-therapeutic drugs; they would have suffered an estimated loss of $45.5 million in 1999 if the drug use was banned.
Even within the industry, however, there is a growing movement to reduce at least the sub-therapeutic use of antibiotics in animals raised for food. Tyson Foods, Perdue Farms and Foster Farms, which collectively produce a third of the chicken Americans eat, recently declared their intention to greatly reduce the amount of antibiotics fed to healthy chicken. There is still no way for consumers to know whether one of these companies' chickens has been treated with antibiotics, although some corporate consumers, McDonald's, Wendy's and Popeye's among them, are refusing to buy chicken that has been treated with fluoroquinolones. Increased public pressure may cause the companies who grow animals for food to collectively decide that putting extra weight on feed animals isn't worth the possibility that they are putting consumers' health at risk.
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· The Use of Drugs in Food Animals: Benefits and Risks This book, commissioned by the USDA and published in 1999, addresses the many benefits and risks associated with using antibiotics in feed animals. In the chapter titled "Costs of Eliminating sub-therapeutic Use of Antibiotics," the authors conclude that if there were a ban on sub-therapeutic drug use, the annual cost to consumers would be between $4.84 and $9.72 per capita. |
· WHO: Global Strategy for Containment of Antimicrobial Resistance This September 2001 report from the World Health Organization blames a combination of factors for the worldwide upswing in resistance to antibiotics, including widespread overuse and misuse. As for the use of antibiotics in food animals, the authors say that "inefficient and inadequately enforced regulatory mechanisms regarding antimicrobial supply contribute to excessive and inappropriate drug use." The authors observe that the incidence of antibiotic-resistant campylobacter in live poultry has increased dramatically, and that resistant strains of salmonella have been detected in several countries worldwide. Earlier, in June 2000, the WHO released a major report titled "Overcoming Microbial Resistance." Here is the press release for that report, along with audio links to expert opinions about the report's findings. |
· Antimicrobial Drug Use and Veterinary Costs in U.S. Livestock Production According to this report, released in May 2001 by the USDA's Economic Research Service, discontinuing the use of antimicrobial drugs in hog production would initially decrease feed efficiency, reduce production, and raise consumer prices. The author says that U.S. hog producers saved about $63 million in feed costs in 1999 due to their use of low levels of sub-therapeutic drugs. |
· CDC: Antimicrobial Resistance This is the CDC's site dedicated to the issue of antimicrobial resistance. Elsewhere, the CDC publishes another site about antibiotics, Promoting Appropriate Antibiotic Use in the Community. Both sites have plenty of background information. |
· FDA: Antimicrobial Resistance A website under the auspices of the FDA's Center for Veterinary Medicine, the antimicrobial resistance section of this site includes FDA fact sheets and consumer information about drug resistance. Elsewhere on the FDA website is this site on antibiotic resistance, which has general background as well as links to additional resources. |
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The author of this article from the December 2000 issue of Mother Jones asks, "Is agribusiness squandering one of medicine's most potent weapons?" (Mother Jones, November/December 2000) |
· "The Challenge of Antibiotic Resistance" "Certain bacterial infections now defy all antibiotics. The resistance problem may be reversible, but only if society begins to consider how the drugs affect 'good' bacteria as well as 'bad.'" (Scientific American, March 1998) |
· "Where's the Beef on Farm Antibiotics?" In this article written by the publisher of JunkScience.com and published on FoxNews.com, the author argues that evidence to link the use of antibiotics in food animals to human health problems is scant. "Bacterial resistance to antibiotics is on the rise. ... So far, the only cause that everyone agrees about is that physicians hand out antibiotics like candy," writes the author. (FoxNews.com, Jan. 12, 2001) |
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· Beef.org: Myths and Facts About Beef Production Beef.org, the website for the National Cattlemen's Beef Association and the Beef Board, includes this backgrounder on antibiotic use in cattle. It says that "no residues from feeding antibiotics are found in beef, and there is no valid scientific evidence that antibiotic use in cattle causes illness resulting from the development of antibiotic-resistant bacteria." |
· The Coalition for Animal Health This October 2001 press release from the Coalition for Animal Health, which includes the National Cattlemen's Beef Association, the National Chicken Council, and the National Pork Producers Council, says that "the use of U.S. FDA-approved antibiotics in animals has been verified in scientific studies through the past 40 years as providing a critical, first line of defense to keep our nation's food supply safe and secure." |
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The Animal Health Institute, which represents companies that make drugs for farm animals, publishes this fact sheet about animals and antibiotics, in which it says that "there is no documented case where antibiotic use in animals has caused treatment failure in people." |
· Montana State University: Beef Briefs A beef specialist at MSU contends that there is no valid scientific evidence that feeding antibiotics to beef cattle leads to health problems in people. This is a brief overview of his position, along with his list of supporing sources. |
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· Alliance for the Prudent Use of Antibiotics The website for APUA, a 20-year-old advocacy group that promotes the proper use of antibiotics, is an excellent resource for information about drug resistance. APUA collaborates on projects with other organizations such as the U.S. Agency for International Development and the World Health Organization. Its site provides practical information for the consumer as well as in-depth information for practitioners. APUA's Project FAAIR (Facts About Antibiotics in Animals and Their Impact on Resistance) crafted this flow chart tracking the several ways that antibiotics migrate from animals to humans. |
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Keep Antibiotics Working is a coalition of health, consumer, environmental, and agricultural groups that is working to end what it deems the "overuse and misuse" of antibiotics in animal agriculture. It has compiled summaries and links to key scientific evidence supporting the coalition's position. |
· Center for Science in the Public Interest: Antibiotic-Resistance Project CSPI is a Washington, D.C.-based advocacy group that promotes food-safety awareness. Its Antibiotic-Resistance Project website includes links to several articles, including "Protecting the Crown Jewels of Medicine," its strategic plan for preserving the effectiveness of antibiotics. The site also has a legislative and regulatory update, which tracks new proposals. |
· Union of Concerned Scientists: Antibiotic Resistance The Union of Concerned Scientists is a nonprofit alliance of scientists and other concerned individuals across the country. Among other things, the website for the group's antibiotic resistance project has a glossary of terms and background information on the FDA's approach to antibiotic regulation. |
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