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Antibiotics in Agriculture

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Because organic practices recognize and respect the powerful nature of antibiotics, organic practices protect human health in the long term. Organic practices prohibit the use of hormones, antibiotics or other animal drugs in animal feed for the purpose of stimulating the growth or production of livestock. If an antibiotic is used to restore an animal to health, that animal cannot be used for organic production or be sold, labeled or represented as organic. Thus, organic practices avoid the abuse of antibiotics that could have profound consequences for treatment of disease in humans, including the serious dangers of antibiotic-resistant bacteria.

The following highlight findings concerning the abuse of antibiotics in agriculture: 

• The June 2009 issue of Environmental Health Perspectives includes a focus article entitled “The Landscape of Antibiotic Resistance.” Included are references to research showing that the practice of using antibiotics at sub-therapeutic levels in livestock feed and water has led to the persistence of these antibiotics in the environment and the possibility of antibiotic-resistant bacteria.
Source: Environmental Health Perspectives, June 2009 (http://www.ehponline.org/docs/2009/117-6/focus-abs.html).

• Researchers at the Johns Hopkins Bloomberg School of Public Health have found evidence that driving behind trucks transporting broiler chickens from non-organic farms to slaughterhouse can exposure humans to antibiotic-resistant bacteria. The study showed increased levels of pathogenic bacteria, both susceptible and drug-resistant, on surfaces and in the air of cars traveling behind trucks that carry intensively raised poultry. The findings were published in the first issue of the Journal of Infection and Public Health.

• In a report released in April 2008, the European Food Safety Authority (EFSA) expressed concerns about the growing use of antimicrobial agents in food. Citing the potentially negative impact of these agents on human resistance to bacteria and other microbes, EFSA spokesperson Alun Jones told FoodProductionDaily.com that “Antimicrobial resistance cannot be predicted—it comes from the mutation of existing bacteria…so we need to keep an eye on this issue and make sure that all the potential entry points into the food chain for such resistant bacteria are controlled.”
Source: http://www.foodproductiondaily.com/news/ng.asp?id=84762.

• Evaluating the impact of antibiotic feeding in livestock production on the environment, scientists at the University of Minnesota conducting a greenhouse study found that food crops can accumulate antibiotics from soils spread with manure containing antibiotics. Results from the study, published in the July-August 2007 issue of the Journal of Environmental Quality, showed that corn, lettuce and potatoes all take up antibiotics in the soil, with concentrations in plant tissue increasing correspondingly to the levels in the manure. Not only were antibiotics found in plant leaves, but also diffused in potato tubers, indicating that root crops that directly come into contact with soil may be particularly vulnerable to antibiotic contamination.
Source: Journal of Environmental Quality, July-August 2007.

• A study evaluating the levels of antibiotic-resistant bacteria inside, upwind and downwind from a confined animal feeding operation for swine found that bacterial concentrations with multiple antibiotic resistance were recovered both inside and at least 150 meters downwind at higher percentages than upwind. These concentrations were found within and downwind of the facility even after the use of sub-therapeutic antibiotics was discontinued. Researchers led by Shawn G. Gibbs of the University of Texas Health Science Center pointed out that these findings point to a potential health risk for those who work within or live near such facilities.
Source: Environmental Health Perspectives, Vol. 114, No. 7, July 2006, pages 1,032-1,037.

• A study conducted by a Johns Hopkins team of researchers has investigated possible antibiotic resistance in airborne bacteria in a swine concentrated animal feeding operation (CAFO). In the study, researchers collected air samples from a swine-finishing CAFO in the mid-Atlantic United States. Their conclusions: exposure to airborne bacteria from a CAFO can provide a potential pathway for transferring antibiotic-resistant bacteria from animals to humans.
Source: Environmental Health Perspectives, February 2005.

• The U.S. Food and Drug Administration has withdrawn approval for the use of Cipro-like antibiotics in poultry due to concerns it could lead to antibiotic–resistant bacteria in humans. The ban, first proposed by the Clinton Administration in October 2000, took effect in September 2005. As a result, conventional farmers will no longer be able to use the antibiotic Baytril, known generically as enrofloxacin, on poultry.

• Environmental Defense in June 2005 issued a report, “Resistant Bugs and Antibiotic Drugs,” which highlights state and county estimates of antibiotics in agricultural feed and animal waste. Among the findings: North Carolina and Iowa each are estimated to use three million pounds of antibiotics as feed additives annually, the same amount estimated to be used for human medical treatment nationwide; of the total quantity of medically important antibiotics used as feed additives, the largest fraction is used in hogs (69 percent), compared to 19 percent in broiler chickens and 12 percent in beef cattle; when all antibiotic feed additives are considered, hogs accounted for 42 percent, broiler chickens for 44 percent, and beef cattle for 14 percent.
Source: Environmental Defense, “Resistant Bugs and Antibiotic Drugs,” June 2005.

• A report by the U.S. Government Accounting Office notes that the U.S. Food and Drug Administration has determined that antibiotic resistance in humans resulting from the use of antibiotics in animals “is an unacceptable risk to the public health.” The study, entitled Antibiotic Resistance: Federal Agencies Need to Better Focus Efforts to Address Risk to Humans from Antibiotic Use in Animals, was requested by Senators Edward M. Kennedy (D-MA), Olympia Snowe (R-ME), and Tom Harkin (D-IA). Kennedy and Snowe were sponsors of a bipartisan bill (S. 1460) to phase out the routine use of medically important antibiotics in livestock and poultry that are not sick, and to provide funding to help farmers make the transition. Representatives Sherrod Brown (D-OH) and Wayne Gilchrest (R-MD) were sponsors of the companion bill (H.R. 2932) in the House of Representatives.
Source: U.S. Government Accounting Office, Antibiotic Resistance: Federal Agencies Need to Better Focus Efforts to Address Risk to Humans from Antibiotic Use in Animals, April 2004. Report posted at http://www.gao.gov/new.items/d04490.pdf.

• A report in Emerging Infectious Diseases (April 2004, www.cdc.gov/eid) has shown that the antimicrobial agent avoparcin, used extensively as a growth promoter in animal feeds, contains a cluster of intact genes that confer antibiotic resistance. Noting that many antimicrobial agents used as animal feed additives likely act as a carrier for resistance genes, authors Karen Lu, Rumi Asano and Julian Davies wrote, “Delivery systems provide the opportunity for resistant strains of bacteria to evolve and so create an enormous gene pool for antimicrobial resistance determinants in the environment.”
Source: Karen Lu, Rumi Asano and Julian Davies, in Emerging Infectious Diseases, April 2004.

• A Colorado State University study has found antibiotic drugs used to promote growth, prevent disease and increase feed efficiency in livestock are showing up in public waterways. Conducted on the Cache la Poudre River in Colorado, the study, funded by USDA and the university’s Agricultural Experiment Station showed that antibiotics used in livestock are finding their way into streams and rivers. Ken Carlson, principal investigator on the project, said future studies are needed to determine how the antibiotics made their way into public waterways, how long they stay in water and sediment, and to better understand potential dangers to aquatic life, animals and humans.
Source: Ken Carlson, Department of Civil & Environmental Engineering, Colorado State University, Fort Collins, CO.

• Research has shown waste from poultry raised in industrial chicken houses contains bacteria with antibiotic multi-resistance genes. Anne Summers and colleagues from the University of Georgia collected samples of chicken litter from Georgia chicken houses over a 13-week period. They then tested the litter for integrons (small DNA segments that assemble and express resistance genes) and associated antibiotic resistance genes.
Source: Proceedings of the National Academy of Sciences, April 19-23, 2004 online edition.

• In Letters in Applied Microbiology, Vol. 28, pages 197-205 (2004), researchers from the Institute of Food Research, Norwich, United Kingdom, reported that a probiotic diet makes chickens healthier and safer to eat, and could reduce the routine use of antibiotics.

• The World Health Organization in 2003 recommended that countries phase out the use of antibiotic growth promoters in animal feed. Basing its recommendation on a study conducted following a 1998 voluntary ban of such growth promoters in Denmark, WHO said the phase-out would help preserve the effectiveness of antibiotics for therapeutic use. According to the report, the cost of producing pigs in Denmark rose about 1 percent and antibiotic use to treat sick animals increased after the ban, but the overall amount of antibiotics used on Danish farms fell by about 50 percent. More important, the amount of resistant bacteria in pork and chicken declined substantially. For instance, before the ban, 60 to 80 percent of chickens had bacteria resistant to three widely used antibiotics. After the ban, that number had dropped to 5 to 35 percent of the birds.

• A German study of dust samples collected during two decades from a pig feeding operation revealed the presence of various antibiotics. Findings, published in the October 2003 issue (Vol. 111, No. 13) of Environmental Health Perspectives showed up to five different antibiotics in 90 percent of the samples. Warning that high dust exposure could expose farmers to inhaling dust contaminated with antibiotics, researchers from the School of Veterinary Medicine Hannover, Hannover, Germany, said their data provide evidence that dust can carry veterinary drugs in the environment.
Source: “Antibiotics in Dust Originating from a Pig-Fattening Farm: A New Source of Health Hazard for Farmers?” Gerd Hamscher, Heike Theresia Pawelzick, Silke Sczesny, Heinz Nau, and Jörg Hartung.

• Researchers at the University of Maryland School of Medicine, in collaboration with a researcher at the Veterans Administration Medical Center in Baltimore, MD, have found anitibiotic use in animals can affect the emergence of antibiotic resistant bacteria in humans. Reporting their findings in the April 23, 2002, Proceedings of the National Academy of Sciences, David L. Smith and colleagues concluded that “regulating early agricultural antibiotic use would likely extend the period that a drug can be used effectively in humans and reduce the demands for new antibiotics.”
Source: Proceedings of the National Academy of Sciences, April 23, 2002.

• Public health authorities have linked low-level antibiotic use in conventionally raised livestock directly to greater numbers of people contracting infections that resist treatment with the same drugs. Microbiologist Rustam Aminov and colleagues at the University of Illinois at Urbana-Champaign have discovered that bacteria in the soil and groundwater beneath farms seem to be acquiring tetracycline resistance genes from bacteria originating in pigs’ guts. Studying the environmental effects of antibiotics used as growth promoters on two swine farms, Aminov’s team analyzed samples from farm-waste lagoons and from groundwater reservoirs beneath the lagoons, and found that bacteria in the soil and groundwater carried tetracycline resistance genes.
Source: Applied & Environmental Microbiology, Vol. 67, page 1494 (2001). Also cited in New Scientist magazine, April 21, 2001.

• A preliminary survey of beef and poultry sold in U.S. supermarkets conducted by the U.S. Food and Drug Administration found relatively high levels of antibiotic-resistant bacteria, according to a report presented at the 101st annual meeting of the American Society for Microbiology in May 2001. FDA microbiologist Dr. David Wagner reported that investigators found “fairly substantial amounts of resistance to a number of drugs.”
Source: 101st annual meeting of the American Society for Microbiology, May 2001.

• The American Medical Association in June 2001 adopted a resolution opposing the use of antimicrobials at non-therapeutic levels in agriculture, or as pesticides or growth promoters, and urged that such uses be ended or phased out based on scientifically sound risk assessments.
Source: American Medical Association, 515 North State Street, Chicago, IL 60610, 312-464-5000. Resolution 508: Antimicrobial Use and Resistance (adopted as amended, June 2001).

• “The reason to buy meat without antibiotics is not because the antibiotics in the meat are transferred to the person, but because of how the antibiotics increase the number of antibiotic-resistant bacteria,” according to Dr. Stuart Levy, director of the Center of Adaptation Genetics and Drug Resistance at Tufts University Medical School, in a New York Times article by Marion Burros.
Source: Jan. 17, 2001, New York Times article by Marian Burros.

• Carol Goforth, the Clayton N. Little Professor of Law at the University of Arkansas, and Robyn Goforth, a biochemistry graduate student, have called for regulation of antibiotic use in livestock due to the growing problem of antibiotic-resistant infections in humans. In a paper in the Boston College Environmental Affairs Law Review, the Goforths cited the growing body of scientific literature linking sub-therapeutic doses of antibiotics in livestock to mutated, antibiotic-resistant bacteria and to outbreaks of antibiotic-resistant infections in humans.
Source: “Appropriate Regulation of Antibiotics in Livestock Feed,” by Carol Goforth and Robyn Goforth, in the Boston College Environmental Affairs Law Review, as cited in “The Cow & The Cure,” by Melissa Blouin, in University of Arkansas Research Frontiers, Spring 2001, pp. 28-29.

• In its report “WHO Global Strategy for Containment of Antimicrobial Resistance,” the United Nations’ World Health Organization (WHO) noted that farmers’ use of antibiotics to fatten livestock and poultry enables microbes to build up defenses against the drugs, jump up the food chain, and attack human immune systems. WHO urged farmers to stop the practice of using antibiotics for growth promotion if such antimicrobials are also used in humans.
Source: “WHO Global Strategy for Containment of Antimicrobial Resistance,” United Nations’ World Health Organization, September 2001 (www.who.int).

• Conventional farmers routinely feed antibiotics to livestock because flocks and herds tend to grow faster with their use. However, scientists, doctors, and government officials fear this is contributing to the rise of antibiotic-resistant “super-bugs.” Farm animals in the United States receive 24.6 million pounds of antibiotics a year, which may be fueling the rise of drug-resistant bacteria, according to the Union of Concerned Scientists (UCS). UCS noted that about 70 percent of all antibiotics made in the United States are used to fatten up livestock.
Source: “Hogging It: Estimates of Antimicrobial Abuse in Livestock,” by Margaret Mellon, Charles Benbrook, and Karen Lutz Benbrook, Union of Concerned Scientists, January 2001 (report available at www.ucsusa.org).

• Three studies published in The New England Journal of Medicine verified that antibiotic-resistant bacteria are widespread in commercial meats and poultry in the United States and also are found in consumers’ intestines. The studies show evidence that the routine use of antibiotics to enhance growth in farm animals can encourage the growth of drug-resistant bacteria, which may threaten people who undercook their meat or consume food or water contaminated by animal droppings. An accompanying editorial written by Dr. Sherwood L. Gorbach, an infectious disease specialist at Tufts University’s medical school, urged a ban on the routine use of low-dose antibiotics to aid animal growth and prevent infection because it sets up conditions for the emergence of resistant bacteria.
Source: The New England Journal of Medicine, Vol. 345: pages 1147-1154, 1155-1160, and 1161-1166, Oct. 18, 2001

• Water samples from the Ohio River and two of its tributaries contained trace amounts of commonly prescribed antibiotics, such as penicillin, tetraycline, and vancomycin. They were also present in area tap water. The results were from a science project undertaken by 17-year-old high school senior Ashley Mulroy.
Source: “Water Worries,” in Popular Science, May 2001, p. 42.

• Findings published in The New England Journal of Medicine indicate that the controversial practice of administering antibiotics to cattle may have led to the development of salmonella resistant to the antibiotic ceftriaxone. The study, led by Paul Fey of the Nebraska Public Health Laboratory, examined the case of a 12-year-old boy infected with salmonella.
Source: The New England Journal of Medicine, April 27, 2000

Organic practices offer a compelling alternative to to the overuse of antibiotics

• Researchers from the University of Florida and the Universities of Wageningen and Groningen in the Netherlands have developed a computer model called Coliwave that predicts the risk of E. coli contamination in manure. Their findings showed that the way manure is treated and stored has a huge impact on E. coli levels, with good organic practices more likely to produce foods less likely to be contaminated. However, it is still important for farmers to take measures, such as feeding a high fiber diet, to try to prevent E. coli from forming in cattle (from the March/Winter 2010 issue of The Organic Report).
• In a 2007 study for the Food Safety Consortium, researchers led by Daniel Fung, food science professor at Kansas State University, found that Jasmine tea or green tea with honey can be used to reduce pathogenic bacteria in meat. Treating turkey breast slices with combinations of Jasmine tea extract and wildflower dark honey reduced Listeria monocytogenes by 10 to 20 percent. Similar reductions were recorded when applied to hot dogs.
• In another 2007 research study funded by the Food Safety Consortium, a University of Arkansas-led team found that using bacteriocins—proteins produced naturally by other bacteria—can provide an effective way to get rid of pathogenic Campylobacter bacteria in turkeys. “If we can eliminate Campylobacter, we don’t have to worry about antibiotic resistance,” according to Dan Donoghue, a poultry science researcher at the University of Arkansas who led the project.
• A 2005 study conducted by the University of Guelph in Canada showed suppression of Fusarium in plants fertilized with Drammatic K fish hydrolysate. The findings are consistent with observations by organic growers, who have reported suppression of plant diseases when using fish hydrolysate.
• Researchers at the University of Santiago de Compostela in Lugo, Spain, have found significantly lower percentages of antimicrobial resistant E. coli isolates in organically raised poultry than in conventionally raised poultry. Conducting a comparison of antimicrobial resistance in E. coli, Staphylococcus aureus and Listeria monocytogenes strains in poultry, researchers studied 55 samples of organic poultry meat and 61 samples of conventional poultry meat.

“Accordingly with consumers’ beliefs, the statistically significant lower percentages of antimicrobial resistant E. coli isolates found in organically raised poultry support that the organic rearing of poultry may limit the presence of antibiotic-resistant intestinal bacterial in such animal foods,” the researchers concluded. Findings were published in the December 2008 issue of the Journal of Food Protection.

Other information related to antibiotic use:
• U.S. Representative Louise Slaughter (D-NY) in March 2009 introduced legislation to limit the use of antibiotics on industrial livestock farms to when the animals are sick. Proponents of the bill point out that the misuse of antibiotics in industrial farming contributes to the dramatic rise in antibiotic-resistant infections in humans. Organic farming does not allow the use of antibiotics.

• Check out this informative paper from Food and Water Watch on how antibiotic misuse on factory farms can make you sick.

This fact sheet was compiled by the Organic Trade Association, Fall 2010.

Photo courtesy of Harriet Behar.