Controversies in Science and Technology Volume 1: From Maize to Menopause: v. 1 (Science and Technology in Society) - Hardcover

University Of Wisconsin Press

Hardcover

ISBN 10: 0299203905 ISBN 13: 9780299203900

Verlag: University of Wisconsin Press, 2005

Inhaltsangabe

Written for general readers, teachers, journalists, and policymakers, this volume explores four controversial topics in science and technology, with commentaries from experts in such fields as sociology, religion, law, ethics, and politics:

* Antibiotics and Resistance: the science, the policy debates, and perspectives from a microbiologist, a veterinarian, and an M.D.

* Genetically Modified Maize and Gene Flow: the science of genetic modification, protecting genetic diversity, agricultural biotech vesus the environment, corporate patents versus farmers' rights

* Hormone Replacement Theory and Menopause: overview of the Women's Health Initiative, history of hormone replacement therapy, the medicalization of menopause, hormone replacement therapy and clinical trials

* Smallpox: historical and medical overview of smallpox, government policies for public health, the Emergency Health Powers Act, public resistance vs. cooperation.

Über diesen Titel

Über die Autorin bzw. den Autor

Daniel Lee Kleinman is associate professor of rural sociology at the University of Wisconsin–Madison and author of Impure Cultures: University Biology and the World of Commerce. Abby J. Kinchy is research assistant in rural sociology at UW–Madison. Jo Handelsman is the Howard Hughes Medical Institute Professor in the Department of Plant Pathology and codirector of the Women in Science and Engineering Leadership Institute at UW–Madison.

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Controversies in Science and Technology

From Maize to Menopause

THE UNIVERSITY OF WISCONSIN PRESS

Copyright © 2005 The Board of Regents of the University of Wisconsin System
All right reserved.
ISBN: 978-0-299-20390-0

Contents

Acknowledgements..............................................................................................................................................................................................xiIntroduction: From Maize to Menopause Abby J. Kinchy, Daniel Lee Kleinman, and Jo Handelsman.................................................................................................................3Part 1: Overuse of Antibiotics on the Farm1 Antibiotic Resistance: The Agricultural Connection Christine Mlot.........................................................................................................................................232 Agricultural Antibiotics: Features of a Controversy Brian Martin..........................................................................................................................................373 Agricultural Uses of Antibiotics: Evaluating Possible Safety Concerns Abigail A. Salyers..................................................................................................................524 Antibiotics in Animal Agriculture: An Ecosystem Dilemma Randall S. Singer.................................................................................................................................675 The Impact of Antibiotic Use in Agriculture on Human Health and the Appropriate Public Policy Response Tamar Barlam......................................................................................83Part 2: Genetically Modified Crops: Global Issues6 Genetic Modification and Gene Flow: An Overview Allison A. Snow...........................................................................................................................................1077 Introduction of Transgenic Crops in Centers of Origin and Domestication Paul Gepts........................................................................................................................1198 Agricultural Biotechnology Science Compromised: The Case of Quist and Chapela Kenneth A. Worthy, Richard C. Strohman, Paul R. Billings, and the Berkeley Biotechnology Working Group.....................1359 Hard Red Spring Wheat at a Genetic Crossroad: Rural Prosperity or Corporate Hegemony? R. Dennis Olson.....................................................................................................15010 Agricultural Biotechnology and the Environmental Challenge Peter H. Raven................................................................................................................................169Part 3: Hormone Replacement Therapy and Menopause: Science, Culture, and History11 Postmenopausal Hormones: An Overview Sylvia Wassertheil-Smoller...........................................................................................................................................18112 The Medicalization of Menopause in America, 1897-2000: Mapping the Terrain Judith A. Houck................................................................................................................19813 The History of Hormone Replacement Therapy: A Timeline Barbara Seaman.....................................................................................................................................21914 Symptom Reporting at the End of Menstruation: Biological Variation and Cultural Difference Margaret Lock..................................................................................................23615 Evidence-based Medicine and Clinical Practice David L. DeMets.............................................................................................................................................254Part 4 Smallpox and Bioterrorism16 Smallpox: The Disease, the Virus, and the Vaccine Dixie D. Whitt..........................................................................................................................................27317 The Model State Emergency Health Powers Act: A Tool for Public Health Preparedness Lesley Stone, Lawrence O. Gostin, and James G. Hodge Jr...............................................................28318 The States and the War against Bioterrorism: Reactions to the Federal Smallpox Campaign and the Model State Emergency Health Powers Act David Rosner and Gerald Markowitz.................................29719 Public Resistance or Cooperation? A Tale of Smallpox in Two Cities Judith Walzer Leavitt..................................................................................................................311Contributors..................................................................................................................................................................................................327Index.........................................................................................................................................................................................................335

Chapter One

Antibiotic Resistance

The Agricultural Connection

Christine Mlot

Dairy cows with symptoms of mastitis typically receive penicillin to stop the infection. Similarly, farmers administer tetracycline to swine and poultry to suppress respiratory diseases. Bacterial infections in catfish on fish farms and in pear trees in orchards are treated with tetracyclines or other antibiotics too. And to boost their rates of growth, healthy livestock routinely consume small doses of antibiotics in manufactured animal feeds.

As the Stanford University microbiologist Stanley Falkow has remarked, the biosphere is, in effect, bathed in a dilute solution of tetracyline, and roughly half of the one million metric tons of antibiotics (Davies 2000) in the solution have entered through the food supply (World Health Organization 2000). Most conventionally grown poultry, pork, and beef in the United States is produced with the help of antibiotics at some point. As with humans, animals are given the drugs to eliminate infections or prevent imminent ones. More controversial is the routine use of small but long-term doses of antibiotics to hasten the animals' growth to market size. Such use accounts for most of U.S. agriculture's share of antibiotics (Levy 1998; Mellon, Benbrook, and Benbrook 2001).

The use of antibiotics in agriculture, producer groups say, has given consumers an abundant and affordable supply of food, especially meat. But the intensive use of antibiotics comes with a cost. Antibiotics kill bacteria or stop them from growing by disrupting the cells' machinery. At the same time, antibiotic use selects for bacterial cells containing genes that allow the cells to disable or evade the drugs, most of which are also used to treat human infections. The resistance genes can be transferred through foodborne bacteria or other means to the human intestine and have been linked to drug-resistant infections in people and even to several deaths (World Health Organization 2000). Although the misuse of antibiotics in human medicine is also a big contributor to the development of resistance-an estimated half of antibiotics prescribed are unnecessary (Levy 1998)-agriculture's contribution cannot be dismissed.

Public health-monitoring programs are turning up increased frequencies and spread of resistant bacteria that cause foodborne illness, particularly Salmonella, Campylobacter, and toxic strains of the normally benign Escherichia coli (U.S. General Accounting Office 1999). Agricultural use of one class of antibiotic has also been linked to development of resistance to the human version of the drug among enterococci, a group of potentially deadly hospital-acquired pathogens (Kaufman 2000).

In response to these trends, researchers are looking for ways to reduce the use of antibiotics in agriculture, particularly their use as growth promoters. Remedies range from renewed attention to sanitary animal husbandry and hygiene to experimental immunological methods and truly novel forms of antimicrobials. But progress in moving alternatives to the farm has been slow and, as a recent federal plan to combat antibiotic resistance notes, requires an intensified research and regulatory push (Task Force 2001).

Ecology and Policy

Bacteriologists since Alexander Fleming, who discovered penicillin in 1928, have worried about the selective force of antibiotics and the resulting problems of resistance. Particularly on the agricultural front, however, the development of public policy to minimize the development of resistance has been lumbering. As early as 1978, the U.S. Food and Drug Administration (FDA) attempted to eliminate the agricultural use of some antibiotics that are also used in human medicine (U.S. General Accounting Office 1999). But producer and pharmaceutical groups resisted new regulations, arguing that no definitive evidence existed of harm to humans from antibiotic use in animals. The weight of evidence linking the two has since steadily increased, along with a better understanding of the nature of resistance.

In 1998 the FDA's Center for Veterinary Medicine responded with a proposal for evaluating and curtailing unnecessary drug use in animals to curb resistance (FDA 1999). Critics pointed out that the proposal did not address existing uses of antibiotics and that the agency has been slow to implement the proposal (Task Force 2001). But the proposal broke new ground for the agency in acknowledging the connection to human health. "FDA is convinced that there is more than adequate scientific evidence demonstrating that resistance develops in enteric pathogens in animals in response to drug use and that they can be transferred through the food supply to humans," said the FDA's Linda Tollefson at the May 2000 meeting of the American Society for Microbiology.

The FDA-along with the Centers for Disease Control and Prevention, the National Institutes of Health, and other agencies, including the U.S. Department of Agriculture (USDA)-also signed on to a plan, first issued in the summer of 2000, that attempted to coordinate the federal response to antimicrobial resistance (Task Force 2001). The task force grew out of 1999 Senate hearings, cochaired by Bill Frist, R-Tenn., and Edward Kennedy, D-Mass., on the wide scope of antibiotic resistance and, consequently, the multiple federal agencies and departments that need to address the issue. The report by the Task Force on Antimicrobial Resistance spelled out eleven steps for action, including a call to monitor drug use in agriculture as well as in human medicine and consumer goods. It also nudged the FDA to put into place its proposed system for approving drug use in agriculture and to reevaluate drugs currently in use.

Congress has taken further note of the issue of antibiotic resistance arising from agricultural use. Members of both the House and Senate introduced a bill, called the Preservation of Antibiotics for Human Treatment Act of 2002, which would phase out the use of certain antibiotics as growth promoters in animal feed.

Yet even the most stringent national policy is not enough, given the ease with which both people and microbes move around the globe. The interagency report aims to address international concerns, noting that the United States already lags behind other developed countries in regulating agricultural use of antibiotics. As the World Health Organization has recommended, the European Union has eliminated the controversial use of the same antibiotics as both human medicine and growth promoters for animals, with little adverse effect on the economy or public health. Denmark has voluntarily given up use of all antibiotics as growth promoters. Among developed countries, only the United States and Canada still allow chlortetracycline, oxytetracycline, and penicillin, crucial for treating humans, to also be used on animals (Angulo 2000b).

Developing countries have even fewer guidelines for proper use of antibiotics, at the same time that many are increasing livestock production. They are also battling many other bacterial diseases rarely seen in developed countries, such as food- and waterborne Shigella dysenteriae, which is now resistant to most drugs available (World Health Organization 2000). The World Health Organization (2000) points out how globalization of trade and travel all but ensures the spread of resistant microbes. A single clone of Salmonella known as DT104 emerged in England in the 1980s and is now considered to be at pandemic levels. In its hegemonic spread, the pathogen has acquired resistance to at least five kinds of antibiotics.

Paths of Resistance

Collectively, bacteria have evolved the means to dispose of each of the more than 150 antibiotics (World Health Organization 2000) developed by modern medicine. Bacterial resistance genes code for beta-lactamases, transferases, and other enzymes that have been altered through the course of bacterial evolution and now interfere with the drugs' actions. The enzymes may break down the drug or alter its target in the bacterial cell. The bacteria may also simply eject the antibiotic.

Resistance genes can be passed around inside an animal's intestine, within closely related species or strains of bacteria, and across genera through horizontal gene transfer. The genes are commonly carried on extrachromosomal plasmids that get transferred to other microbes through conjugation. When transposons, or jumping genes, bundle other resistance genes into a plasmid, the receiving microbe becomes equipped with multiple resistances. Viruses, or bacteriophages, can also infect other bacteria with resistance genes, at least in the lab (Salyers 2000).

"The spread of genes is the problem, not just the spread of bacteria," according to the microbiologist Abigail Salyers (n.d,; see also chapter in this volume). Resistance genes spawned on the farm can circulate via several avenues. In a 1976 paper in Nature, Stuart Levy, G. B. FitzGerald, and A. B. Macone documented the movement, among chickens caged together, of a gene for antibiotic resistance. They also isolated E. coli containing the gene from two farmworkers, indicating the transfer of bacteria from animals to humans whether by air or direct handling of the animals.

Antibiotic-resistant Salmonella that infected a twelve-year-old farm boy probably followed the same path (Fey et al. 2000). Writing in the New England Journal of Medicine, researchers detailed how they used DNA and enzyme analysis to show that the strain of Salmonella enterica serotype typhimurium was identical to bacteria taken from a cow on the farm that had been treated for Salmonella a month before the boy became ill. Tests showed that the bacteria were resistant to thirteen drugs, including ceftriaxone, an "expanded-spectrum" cephalosporin used for humans (Fey et al. 2000). Ceftriaxone resistance had been reported in other countries but not in the United States (Fey et al. 2000). Although ceftriaxone is not approved for use on cattle, other expanded-spectrum cephalosporins are, leading the researchers to conclude that antibiotic use on livestock is primarily responsible for generating resistance in Salmonella.

Apart from the direct path between farm animals and farmworkers, antibiotic-resistant bacteria can contaminate food during slaughter and make their way to the consumer's plate and intestines through undercooked food. Public health officials have traced this path by following the recent increase in fluoroquinolone resistance among Campylobacter in chickens and people (Angulo 2000b).

Although most people can weather a bout of Salmonella or Campylobacter food poisoning, infections can turn serious if the bacteria invade the blood. More than twenty-five thousand people in the United States are hospitalized with such serious foodborne infections, and hundreds die from them each year (U.S. General Accounting Office 1999; Angulo 2000a). Widely introduced for human use in 1988, the costly fluoroquinolones have been a key treatment for serious Salmonella and Campylobacter infections. Despite protest from public health officials (Angulo 2000a), in 1995 the drugs were approved for treating respiratory disease in chickens in the United States.

Researchers predicted that fluoroquinolone resistance would increase, and it did (Angulo 2000a). Although Campylobacter is a pathogen in humans, it is a benign microbe in chickens. It turns up in 60 to 80 percent of chickens packaged for sale in U.S. markets, according to a study by the Centers for Disease Control and Prevention. In 1998, 20 percent of the chickens on supermarket shelves carried fluoroquinolone-resistant strains, and 13 percent of human Campylobacter infections were resistant to the drugs. By contrast, a 1991 study of isolates from human Campylobacter infections turned up no fluoroquinolone resistance. In 1999, the proportion of resistant human infections rose to 20 percent (Angulo 2000b).

The increase in drug-resistant human infections, along with increasing public health concern and media attention, prompted the FDA to reverse its 1995 approval for certain agricultural use of the drugs. In 2000 the agency began the process of withdrawing approval of fluoroquinolone use for poultry (Food and Drug Administration 2000).

Fluoroquinolone resistance has also appeared in Salmonella (Pittock 2002). About 95 percent of the Salmonella DT104 strains are resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline (Angulo 2000b), and resistance to one kind of antibiotic often begets resistance to others. Resistance monitoring programs have recently detected isolates of a second Salmonella strain that resists at least eight classes of antibiotics (Gupta et al. 2003).

Some enterococci have also acquired resistance to all antibiotics, including vancomycin, considered an important antibiotic of last resort. Widespread hospital use of vancomycin has selected for vancomycin resistance in these bacteria (VRE), which can be deadly for immunocompromised patients. But epidemiological studies have also connected agricultural antibiotic use to the rise of VRE in some areas (U.S. General Accounting Office 1999).

Vancomycin is a glycopeptide, as is the veterinary drug avoparcin, and resistance to one will confer resistance to the other. Although avoparcin has not been allowed for animal use in the United States, until 1997 it was used as a growth promoter for livestock in Europe. On farms where avoparcin was used but not on other farms, researchers were able to isolate VRE from poultry and pig feces. In parts of Germany where vancomycin is rarely used in hospitals, VRE have been found in grocery meats and in people in the community at large. In contrast, because avoparcin is not used in the United States, VRE are rarely found outside hospitals. And after use of avoparcin was banned as a growth promoter, studies from Denmark and Germany indicate, the number of VRE isolates declined in both poultry and the community (World Health Organization 2000).

To combat the resistance of enterococci to vancomycin, in the fall of 1999 the FDA approved a new last-resort antibiotic. Synercid became the first human antibiotic in the class of streptogramins, but some bacteria were already primed to withstand it. An animal version of the drug, called virginiamycin, has been used in chickens and other animals to treat disease and as a growth promoter. And bacteria with a gene that confers resistance to macrolides, another class used in human medicine, have cross-resistance with streptogramins. All these uses, human and animal, seem to have contributed to a pool of genes resistant to the new drug. Looking at chickens in which virginiamycin has been used, researchers have found significant numbers of enterococci that show resistance to Synercid (Zerno 2000). Low levels of Synercid resistance have also turned up in people, including a woman who died at a Michigan hospital after the drug failed to clear her VRE infection (Kaufman 2000).

Researchers are concerned that other reservoirs of bacteria harbor resistance genes that can get passed on to human pathogens. Resistance genes have turned up in everything from bacterial cultures of cheese-the resistance genes probably originated with antibiotics given to cows-to the skin flora of people who have been treated with antibiotics for acne (Eady 2000). And the facile movement of genes in the microbial world is not just a one-way path. Resistance genes arising from the overuse of antibiotics in humans may in turn be affecting agriculture. The use of treated sewage as fertilizer on fields, for example, may be a vector for spreading to animals resistance spawned in humans.

(Continues...)

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Details zur Ausgabe

• Verlag: University of Wisconsin Press
• Erscheinungsdatum: 2005
• Sprache: Englisch
• ISBN 10: 0299203905
• ISBN 13: 9780299203900
• Einband: Tapa dura
• Anzahl der Seiten: 356
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: Nicht verfügbar