In this essay, I examine interlocking political, economic, and cultural processes involved in the continuous reproduction of the structural violence that affects migrant farmworkers in the United States. Excluded from rights and protections afforded other workers, migrant and seasonal farm labor—a social class comprising mainly undocumented Mexican and Latino persons—endures endemic poverty, poor health outcomes, and squalor living conditions. This structural violence is sustained by government neglect and illegal hiring practices and liberalized production regimes that benefit multinational corporations and large-scale agricultural producers, putting migrant workers in harm's way. Emphasizing the importance of the phenomenology of perception to the anthropology of structural violence, I argue that this system is also underpinned by a mode of perception built on specific understandings of alterity and community. The setting for this article is rural North Carolina, where I have conducted 16 months (2004–07) of ethnographic field study on tobacco farms and in farm labor camps. Among growers and other locals, I find that the faces of migrants do not compel infinite responsibility, as in the face-to-face interaction idealized by Levinas. Instead, an essentializing discourse of culture portrays migrants as "other" and "outside," equates them with trash, and makes them available for various kinds of blame. I develop the concept of "faciality" to take account of how social power overlaps with perception to legitimize patterns of social subordination, economic exploitation, and spatial segregation. I also examine everyday tactics of resistance among migrants, who take command of the stigmatizing quality of vision to morally indict manifestations of structural violence. In this study, I enhance our understanding of the dialectics of domination and subordination in U.S. agriculture, which provides fruitful ground for theorizing the dangerous constitution of structural violence in the context of transnational labor migration and international agricultural restructuring.
Cultural Anthropology has a number of other essays on on migrant labor. See for example, Shao Jing’s “Fluid Labor and Blood Money: The Economy of HIV/AIDS in Rural Central China” (2006); Yan Hairong’s “Neoliberal Governmentality and Neohumanism: Organizing Suzhi/Value Flow through Labor Recruitment Networks” (2003); and Adeline Masquelier’s “Of Headhunters and Cannibals: Migrancy, Labor, and Consumption in the Mawri Imagination” (2000).
Cultural Anthropology has also published a number of essays on Mexicano politics in the United States. See, for example, Michael J. Montoya’s “Bioethnic Conscription: Genes, Race, and Mexicana/o Ethnicity in Diabetes Research” (2007); Laura A. Lewis’s “Of Ships and Saints: History, Memory, and Place in the Making of Moreno Mexican Identity” (2001); and Arlene Dávila’s “Latinizing Culture: Art, Museums, and the Politics of U.S. Multicultural Encompassment” (1999).
About the Author
Broadly speaking, Prof. Peter Benson is keen on understanding what forms of human existence take shape amid the powerful influence of corporations and industries, moral and emotional movements in the civil society, cultural framings of citizenship and the family, public health governance and medicalization, social and historical constructions of race, and waves of transnational labor migration. Working in the United States and Latin America, his goal has been to produce ethnography that is richly informed by historical and archival research, critically attendant to political economy, and deeply appreciative of subjective experience as inspired by my fascination with existentialism and phenomenology.
His primary research project is a study of tobacco agriculture and Mexican farm labor migration against the backdrop of the antitobacco movement, the globalization and industrialization of food and farm chains, and intense struggles over immigration. His latest book, entitled Tobacco Capitalism: Growers, Migrant Workers, and the Changing Face of a Global Industry, tells the story of the people who live and work on U.S. tobacco farms at a time when the global tobacco industry is undergoing profound changes. Against the backdrop of the antitobacco movement, the globalization and industrialization of agriculture, and intense debates over immigration, he draws on years of field research to examine the moral and financial struggles of growers, the difficult conditions that affect Mexican migrant workers, and the complex politics of citizenship and economic decline in communities dependent on this most harmful commodity.
In addition, he has completed a major collaborative research project on structural adjustment, export agriculture, and political violence in highland Guatemala , which culminated in a coauthored book, Broccoli and Desire: Global Connections and Maya Struggles in Postwar Guatelmala. Tracking the commodity chain of the global broccoli trade, this book connects affluent American consumers concerned about their health and diet with Maya farmers desiring and struggling for something better. Broccoli is a starting point for a broader analysis of the social production of power and desire at multiple levels, such as shifting frameworks of international trade, discourses about health and nutrition, and the vastly uneven worlds that consumers and producers inhabit.
This article was part of a bigger project on tobacco agriculture and farm labor, global health and corporate power, as seen in North Carolina. This project has culminated in a recent book, entitled "Tobacco Capitalism: Growers, Migrant Workers, and the Changing Face of a Global Industry." While continuing to write on issues pertaining to tobacco, he is also involved in a new research project on existentialism and the history of anthropology.
Relevant Links About the Author
Additional Work by the Author
(2008) Good Clean Tobacco: Philip Morris, Biocapitalism, and the Social Course of Stigma in North Carolina. American Ethnologist 35(3):357-379.
Benson, Peter, Edward F. Fischer, and Kedron Thomas
(2008) Resocializing Suffering: Neoliberalism, Accusation, and the Sociopolitical Context of Guatemala's New Violence. Latin American Perspectives 35(5):38-58.
Benson, Peter, and Edward F. Fischer
(2007) Broccoli and Desire. Antipode 39(5): 800-820.
Benson, Peter, and Kevin O'Neill
(2007) Facing Risk: Levinas, Ethnography, and Ethics. Anthropology of Consciousness. 18(2): 29-55.
Fischer, Edward F., and Peter Benson
(2006) Broccoli and Desire: Global Connections and Maya Struggles in Postwar Guatemala. Stanford: Stanford University Press.
Interview with Peter Benson
Richard McGrail and Rupa Pillai: Could you provide a brief description of how you understand the term "subaltern"? And, in your view, what distinguishes work on subalternity from other areas of research in anthropology?
Peter Benson: The word, ‘subaltern,’ evokes a power relation, but also a condition, an ontology and a kind of existence. It is a historical term. It tells us about historical relationships of the modern period that have been forged through the waves of colonialism, mercantilism, and globalism. Certain kinds of faces, and certain conditions, come to mind, what Roland Barthes called a ‘face-landscape,’ so that the subaltern is also a figure in place, in time, and in a relation. These are defining elements of the phenomenology of ‘subaltern,’ for me.
Subaltern studies can also be an attitude in the same way that, as they say, existentialism is. The attitude can be about looking at big things from little vantage points. This can define one’s stance with regard to nature, as seen in Hugh Raffles’ recent book, Insectopedia, where an interest in biology and in naturalism seems driven as much by questions about predictability as by questions about contingency. Or it can define a relation to sexuality or madness as seen in Foucault’s work. Disparate works then reflect and orient subaltern studies as an attitude of staying close to the ground. It is about an appreciation for the little, the contingent, and the marginal. In this way, Walter Benjamin is central in the formation of contemporary subaltern studies, not just in terms of epistemology or politics, but perhaps primarily in terms of an ethics and aesthetics.
RM and RP: Is there a danger of fetishizing the subaltern--i.e., of casting the term as a knowable and celebrated subject-position--in anthropological research? If so, should we revisit how the term is deployed both in academic work and in everyday, "common-sense" understandings? Have you seen the term used outside academic context?
PB: There is definitely a danger in casting too wide a net around the subaltern. So, it’s really important to better understand the politics of victimhood, as in, who is claiming what, how are the entitlements distributed and what does entitlement mean, and so on, which is something I’ve tried to do in my work on tobacco growers in the southern United States. Something the sociologist George Lipsitz has helped me to see, for instance, is that simply looking at the sociology of a given society – the distribution of jobs, income, property, and other forms of wealth and power – will tell you a great deal about how social and cultural dynamics work in that society.
This understanding of the subaltern is to my mind effective. I want to know how harm, vulnerability, risk, and insecurity work in contemporary societies. Differences matter, and the ways that differences are masked or maligned or monickered matter, too. The human conditions and expected life chances that many anthropologists document are often at odds with what is the common consensus or the dominant policy approach. Anthropology is thus a kind of reporting. That is not to say that anthropology is just about reporting or doing a social epidemiology. It’s also about other forms of documentation, investigation, and representation. But some element of ethnography is about reporting on what is happening in a place. The question of the subaltern is going to be central to that reporting because societies are, in general, unequal and involve various levels of conflict. So, the question isn’t about who is and who is not the subaltern. For me, the question is more about the perspective, and the levels.
RM and RP: What makes a discussion of subaltern studies particularly relevant now?
PB: The most important aspect of the subaltern studies literature and subaltern studies as a scholarly approach over the past decades, and that is of particular relevance for today, is the concern with history. The nature of the consumer society makes it seem as though history doesn’t matter or can be consumed on the fly, that history should be a set of talking points to be accessed on a cell phone. When it seems that the relationship between the present and the past isn’t vital, tense, or conflictual, then there is going to be an overall ramification in the area of political consciousness and the kind of modernity that is being lived. The key point here from subaltern studies has always been that it is not just the presence of historiography or an awareness of the past that defines a critical education, but the kind of history, the perspective on the past, the scope and scale of the archive, and the kinds of voices that are heard and that speak – these aspects of relating the present and the past are more human.
RM and RP: Would you categorize your article as subaltern studies?
PB: When I learned that my article had been selected for this volume, I was pleasantly surprised because I have felt the influence of subaltern studies in my own reading, but it doesn’t always come out in the most explicit ways in my writing. I’m studying an incredibly vulnerable population, migrant farm workers, a laboring class, a group of people who regularly contend with instability and danger. In the process, I look at how vulnerability is constituted through complex power relations linking labor, management, and the wider supply chain to the politics of corporate regulation around tobacco and international agribusiness. Yes, I believe this is subaltern studies.
RM and RP: What has inspired your work and in what ways might it contribute to a more thorough understanding of subalternity?
PB: The work of Alphonso Lingis has inspired me. It connects to the subaltern in that a lot of what he does is a phenomenology of the world laid bare, a world that is not mystified, a world that is experienced, that seems close, that seems like the world of life and labor that interested Marx. Here, Chakrabarty’s work has also been important for me. I look to work that links political economy and phenomenology, a linkage that I think broadens the scope of what subaltern studies is, or might be. One aspect of Marx that always interested me is Marx as a phenomenologist, as someone concerned with perception, with constructions of self and other, mystification, dreams, fantasies. The question is about culture and the contemporary economy and forms of consciousness and making and unmaking consciousness. I think some of the scholars whose work does this really well are Kathleen Stewart, Lauren Berlant, Anna Tsing, and Stuart Kirsch. These authors might not fit into a very narrow concept of what subaltern studies is, but each is looking at dynamics of power and what power looks like from below.
RM and RP: What advice would you offer researchers pursuing subaltern projects? What ethical responsibilities does the researcher have?
PB: In my case, working with migrant farm workers, there were ethical considerations. The population is vulnerable, largely undocumented, lives in itinerant housing, has limited access to healthcare, and faces discrimination within the ethnographic setting. Part of what I tried to do in the article was to document these conflictual relationships of stigma, stereotyping, and backbiting between the different working populations. The meaning of ethics here is linked to the stake of “getting it right,” in the sense of capturing multiple levels and making sure that the context is complex enough so that the conditions of vulnerability and conflict don’t seem parochial at the same time as they do feel local.
Another ethical consideration might be how to relate scholarly work to concrete considerations for policy and law-making. The stakes are likely to be higher when the subjects of the study are part of a subaltern group. Not all scholarly work has to end with a practical solution. In this particular article, I felt I could draw out some relevant points for farm labor policy and farm workplace occupational and safety regulations. In fact, one of the anonymous reviewers pointed out that although the article used ethnography to engage theories of structural violence, meaning, and the force of landscapes, there was also the possibility to illuminate something of interest for a policy maker as a result of this ethnography. The peer review process is a really good format for bringing out different levels of ethical engagement and practical solutions and encouraging scholars to broaden the audience without diminishing the peaks and intensity of their work.
As my work relates to the tobacco industry, there are other ethical considerations, and in this article, as elsewhere in my work, a central concern of mine has been to expose the capitalist dynamics of this harmful industry. Some solutions are not going to seem realistic. For example, trade policy plays a major role in the story I tell, as does the way that labor camps are part of the global postcolonial field. But just saying that trade policy ought to change or that global culture involves very serious kinds of danger is not going to seem like a plausible recommendation. In this context, one meaning of ethics has to do with documentation and making an archive, and this returns us to the theme of subaltern studies and the important role of using history and anthropology and other methods to enrich our understanding of the world system.
RM and RP: What are the challenges of teaching concepts related to subalternity? What kinds of teaching strategies and practices have you found effective in the classroom?
PB: There are many challenges. One of the challenges to teaching concepts related to subalternity is the pervasive myth that everyone is the same: thinks the same, feels the same, has the same beliefs, and so on. Talking about different ways of telling history, thinking about power and society, paying attention to what is happening to ordinary people – these are sometimes provocative and life changing for students and they command some bravery. Studies of different forms of consciousness, alternative reckonings of the past and autochthonous forms of morality, sovereignty, and law challenge the powerful myths of individualism, of equality, and of manifest destiny that pervade classrooms in America. So, on one level, the core concepts of subalternity challenge the core concepts of liberal education, at least in broad strokes.
These challenges are especially relevant when it comes to subaltern history. One tactic is to highlight a core method of subaltern studies: using an anecdote or a fragment to reveal something larger about a whole situation. I find that this is particularly appealing to students. In my Cultural Anthropology article, for example, the anecdote in the section, “Another Toilet Problem,” is an anecdote that I refer to all the time in class. It’s about putting port-o-potties in the fields where farmworkers are laboring as a workers’ rights legal issue and the ethnography of how the workers feel about that law in the context of social stigma, a dangerous roadside, and the freedom of the woods. These phenomenological aspects of the situation illuminate broad themes having to do with biopower and its discontents, race and injury, and the Hegelian dialectic; in other words, the ways that selves and others are made in the contemporary world.
Questions for Classroom Discussion
1. Discuss the multiple meanings of “campo”. Could campo be a synonym for subalternity?
2. Define faciality. What makes the face unique? According to Levinas, how does the face relate to ethics? How do Deleuze and Guattari understand the face?
3. How does “faciality become a mask that conceals the forces that drive labor migration in Mexico” and enable the distance between the growers and workers?
4. How are faciality and structural violence coproduced?
5. While Spivak asks “can the subaltern be heard,” Benson, through Paul Farmer, is asking can the migrant worker be seen. How are these questions related?
Agee, James, and Walker Evans
1941 Let Us Now Praise Famous Men. Boston, MA: Houghton Mifﬂin.
2002 Habitations of Modernity: Essays in the Wake of Subaltern Studies. Chicago: University of Chicago Press.
Deleuze, Gilles, and Felix Guattari
1987 A Thousand Plateaus: Capitalism and Schizophrenia, vol. 2. Brian Massumi, trans. Minneapolis: University of Minnesota Press.
2004 "An Anthropology of Structural Violence." Current Anthropology 45(3):303–325.
1969 Totality and Inﬁnity: An Essay on Exteriority. Alphonso Lingis, trans. Pittsburgh: Duquesne University Press.
1988 "Useless Suffering." In The Provocation of Levinas. Richard Cohen, trans. Robert Bernasconi and David Wood, eds. Pp. 156–167. London: Routledge.
1998 Entre Nous: On Thinking-of-the-Other. Michael B. Smith and Barbara Harshav, trans. New York: Columbia University Press.
Taussig, Michael T.
1999 Defacement: Public Secrecy and the Labor of the Negative. Palo Alto: Stanford University Press.
In the November 2008 issue of Cultural Anthropology, Peter Benson examines interlocking political, economic, and cultural processes that continually reproduce the structural violence endured by migrant farm workers in the United States. Drawing on extended fieldwork on tobacco farms and in farm labor camps in North Carolina, Benson argues that a key aspect of structural violence is what he terms “faciality” – the way people perceive each other, and imagine their relatedness. Benson builds on Deleuze and Guattari’s conception of faciality, on Levinasian face-based ethics and on Taussig’s concept of defacement, powerfully extending these frameworks to deepen understanding of what anthropologist and public health advocate Paul Farmer calls structural violence.
Benson delineates many factors constitutive of the structural violence he observed, including deplorable wages, occupational health and safety hazards, and the ever-present threat of deportation. He also shows how structural violence is sustained through regulatory neglect and illegal hiring practices, all of which benefit multinational corporations and large-scale agricultural producers. The cumulative force and cultural logic of these factors, Benson argues, needs to be understood in phenomenological terms, recognizing the power of perceptions, experiences and dynamics amongst laborers, managers, and growers. The migrant laborer does not compel the infinite responsibility idealized by Levinas, but is instead facialized as “other” and “outside.”
While Benson does not use the term “subaltern,” his essay is included in the Subaltern Studies collection for his innovative approach of understanding power as it operates in farm labor camps to marginalize and render migrant workers invisible. Further, the experience of "campo" seems synonymous with subalternity.
Respiratory health and farming: An essay
Yvon Cormier, MD
Department of Medicine, Laval Hospital, Laval University, Quebec City, Quebec
Correspondence: Dr Yvon Cormier, Department of Medicine, Laval Hospital, Laval University, Pavillon Ferdinand-Vandry, local 1229-C, Quebec City, Quebec G1K 7P4. Telephone 418-656-2131 ext 2690, fax 418-656-5990, e-mail ac.lavalu.demf@reimroC.novY
Author information ►Copyright and License information ►
Copyright © 2007, Pulsus Group Inc. All rights reserved
Can Respir J. 2007 Oct; 14(7): 419–422.
This article has been cited by other articles in PMC.
Farming, one of the oldest professions of mankind, is by far the one that employs the largest number of individuals worldwide. Although outdoor country work is supposedly healthy, farmers are at risk of respiratory diseases because of their work environment. This essay summarizes the major respiratory health risks to farmers in Canada.
Farming is a major industry in Canada. Prince Edward Island and New Brunswick have potatoes, Nova Scotia has apples, Quebec and Ontario have dairy, the Prairies have wheat and British Columbia has fruits. But then we all have pigs, lots of pigs. In Quebec, there are as many pigs as there are humans, and in Saskatchewan, there are three or four pigs per person. Canada exports hog products around the world, mostly to the United States and Asia.
Because of the importance of this industry and the potential associated health risks, most often respiratory-related, Canadian researchers have developed internationally recognized expertise in this area. As a respirologist born and raised on a small mixed farm in Prince Edward Island, research on the respiratory health impact of the farm environment was a natural choice for me. My background allowed me to communicate with farmers in their terms and to understand their interest and concerns. This connection gave me a privileged relationship with farmers in Quebec, especially dairy farmers and swine producers, and made most of my work on farmer’s lung (FL) and swine building environments possible.
Dr James Dosman from Saskatoon, Saskatchewan, is by far the champion of Canada’s research in respiratory health in farmers. He has led the way in defining the respiratory health impact of grain handling, and swine and poultry production. Besides his excellence as a researcher, he shines in his promotional and leadership role. Because of him, the research community in this field now holds a seven-year Canadian Institutes of Health Research training program, a multimillion dollar grant for the study of endotoxins in swine buildings, and recently, a large Canada Foundation for Innovation cross-Canada infrastructure grant. Dr James Dosman is what we say in French a ‘rassem-bleur’, one who brings people together for a cause. Researchers across Canada who work together largely because of his initiatives include Judy Guernsey from Halifax, Nova Scotia; Caroline Duchaine and myself from Quebec; Lynn Holness, Will Pickett and Bob Brison from Ontario; Drs Sentilsilvan and Kulig from Alberta; Martha McLeod and Helene Ward from British Columbia; and of course Dr James Dosman’s team in Saskatoon.
DUST AND PESTICIDES
Farmers can be exposed to harmful respiratory substances in the fields. In dry climates like in western Canada, high concentrations of silicate dust are produced during field work such as harrowing or harvesting. Fine particles of this dust can accumulate in the lung, leading to a silicosis-like interstitial fibrosis. Farmers need to be very careful when applying toxic pesticides, some of which are potent carcinogens, while others such as the herbicide paraquat induces interstitial fibrosis at very low doses. Anecdotally, the first lung transplant performed in Canada by Dr Joel Cooper in Toronto, Ontario, was such a case.
Soil can also be contaminated with pathogenic fungi, including Blastomyces dermatiditis, Histoplasma capsulatum and Cryptococcus neoformans. Blastomycetes and Histoplasma are prevalent in Quebec, especially in the valley of the St Lawrence river. C neoformans are typically found in areas contaminated by pigeon droppings. Blastomycosis can be quite a severe infection and typically involves the lungs, the skin and the joints. It can be successfully treated with the appropriate antifungal medication. Histoplasmosis is usually a benign condition. In some areas, it is often the cause of solitary or multiple pulmonary nodules. C neoformans can also induce lung infections with subsequent nodules, but its major interest is its propensity to invade the central nervous system.
Mice are prevalent on farms. Feces of deer mice can be contaminated with the hantavirus, which can cause a devastating infection in humans, an influenza-like syndrome that often leads to respiratory failure. Farmers should wear protective respiratory equipment when cleaning building areas where mouse droppings are present.
Farms are the usual sources of influenza outbreaks. Influenza viruses infect pigs or poultry, and from these sources, mutant viruses become contagious to humans. These animal viruses can be transferred from animals to humans even without a mutation. This has so far been the case of the Influenza A virus subtype H5N1 that, to date, only infected farmers in close contact with birds.
Although farmers are at risk of developing respiratory diseases from outside exposure, the most frequent cause of respiratory problems comes from their work inside animal housing buildings. Farming evolved from a little bit of everything, from feeding a family and trading extras for other necessities to a specialized industry where animals were taken from the outdoors and densely confined in large buildings. A short drive to any Canadian farming region will provide you with multiple examples of huge building complexes, which can raise 1000 pigs, 100,000 hens or 1,000,000 barbecue chickens. Dairy barns have also grown; cows now seldom go outside to the pasture. Last year, I visited a dairy barn in northern Quebec, in which 280 cows were tied for a life consisting of eating, drinking and producing milk. Once a year, they have the pleasure of artificial insemination. Their fate is not worse than that of laying hens that spend the six months of their egg-producing role in life cohabitating in a cubic foot cage; 2000 such cages in the henhouse. It is not surprising, therefore, that in these confinement buildings, especially in the cold winter months when ventilation is held back to conserve heat, some very high levels of bacteria and their toxins, barn mites, organic dust (feed particles and danders) and gases (carbon dioxide, ammonia, hydrogen sulphide, etc) are found.
Of all animal confinements, swine buildings pose the greatest health risks. It is actually remarkable that humans, let alone pigs, can tolerate any prolonged exposure to some of these buildings. The air within contains as many as 109 viable bacteria identified by culture per cubic metre. A worker breathes and thus filters 12 times this volume in an 8 h workday. The norm for an office is less than 103. We now know that the number of bacteria recovered by culture represents only 10–3 of the total number of bacteria present. This is explained by the fact that many bacteria are dead and that the milieu and culture environment used is inappropriate for most of the airborne bacteria present.
It is not that these bacteria cause infections; the vast majority are not pathogens. What hits the lungs is their toxins: endotoxins, peptidoglycans and other potentially toxic or immunogenic substances. Until recently, it was believed that the ill effects of swine building exposure was caused by Gram-negative bacteria and their endotoxins. A recent study by Dr Caroline Duchaine and her colleagues confirmed that over 95% of bacteria in swine buildings are Gram-positive, mostly Archaebacteria. Gram-positive bacteria do not produce endo-toxins, but do produce peptidoglycans that could also be quite harmful.
When a normal, previously unexposed individual spends between 4 h and 6 h in a swine building, he develops an acute inflammatory response, doubles the number of circulating neutrophils, has a large neutrophilic influx into the nasal passages and airways, and a transient increase in bronchial response to methacholine, frequently within the asthma range. He also produces high levels of proinflammatory cytokines such as tumour necrosis factor, interleukin-6 and interleukin-8. Farmers who work in this environment also have increased numbers of neutrophils in their airways but of much lower magnitude, and most importantly, they seldom have an increase in their circulating neutrophil or cytokine levels, or airway hyper-responsiveness. Either farmers are selected out from a few who are genetically equipped to tolerate this environment (for eg, toll-like receptor mutation) or they adapt to it. The latter is the most likely. We have shown that pig farmers have high levels of circulating soluble L-selectin. This could block the signal to increase neutrophil recruitment. If tolerance is the result of an adaptation process, how long does the adaptation last? With ever larger operations, it is often no longer the owner who works a few hours every day in his barns, but the employees who spend 8 h a day, five days a week with off days and vacations, something unheard of for the traditional farmer. Are these days off long enough to lose the adaptation advantages? We have just completed a study looking at this issue, and it seems that workers fortunately do not seem to lose their adaptation after four days of nonexposure. We did not see an increased reaction to re-exposure as has been described in cotton workers, a rebound called ‘Monday morning fever’. Although farmers seem to adapt to the swine buildings, workers do have a high prevalence of chronic bronchitis and some have mild airflow obstruction and cross-shift decline in their forced expiratory volume in 1 s.
The air in poultry houses can also contain large quantities of organic dusts composed of feed particles, dander, bacteria and gases. Dust levels and characteristics are different whether the animals are caged or whether the birds are free to move around. Fortunately, very few workers are exposed to this environment, but because of the small number of workers involved, little information is available on the short- and long-term effects of this exposure.
Of all farm animals, horses are probably the safest to house. Granted, one can be allergic to horses, but horse barns should be quite safe. The main reason for this is that horses themselves are very sensitive to mouldy hay. They have a very high tendency to develop heaves, an asthma-like syndrome caused by an allergy to Saccharopolyspora rectivirgula (SR). Because of this, hay, grain and straw produced for horses have to be very clean. Horse breeders will only use hay that is produced late in season when drying conditions are usually much better than when hay is made for cows (mid-July versus mid-June). Basically, what is good for the horse is good for the farmer.
Grain handlers in western Canada show some cross-shift decrease in their forced expiratory volume in 1 s and forced vital capacity, but this usually does not lead to significant lung function loss over time.
Hypersensitivity pneumonitis (HP) (also known as extrinsic allergic alveolitis), seen in dairy farmers, typically represents respiratory ailments of farmers and is simply called ‘farmer’s lung’. It is the earliest and best described respiratory health risk of the profession. Ramazzini described a lung disease that typically defines FL as early as 1713. We owe to Dr Jack Pepys the scientific description of FL in the late 1950s. He and his colleagues found that the cause of this disease was a bacterium that grows in mouldy hay. He may have been only partially right because we now believe that FL, like other forms of HP, may need a trigger, such as a viral infection, or coexposure with endotoxins or other microorganisms (bacteria or fungi).
FL is a form of allergic or hyperimmune response to inhaled bacteria- or mould-containing dust found in poorly conserved hay, grain or straw. Moulding occurs when these farm products are stored at too high a humidity level (above 15%); humidity allows lactobacillus growth. This results in heating of the material, which in turn favours the growth of thermoatinomycetes. SR (formerly known as Micropolyspora faeni or Polyspora poly-spora), the bacteria most commonly associated with FL, is a thermoactinomycetes. This is the bug that Dr Jack Pepys described as the causative agent of FL. There is no doubt that this actinomycete (SR for short) is implicated in most cases of HP. In some countries (France for example), different species of Aspergillus seem to be a more prevalent cause of FL.
Recent studies have focused on the possibility that a trigger is required to induce sensitization to SR or other HP antigens. Theses triggers may include viruses, endotoxins or other moulds. Patients with FL in France have a more positive serological response to multiple antigens than farmers without the disease. In a mice model, we have described an enhanced response to SR after a transient Sendai virus infection. The enhanced response persists long after the viral infection per se. Most farmers exposed to SR or other microorganisms, even those who develop serum antibodies to these microorganisms, have an immune tolerance and protects them from getting FL. This immune tolerance may be disrupted by one of these triggers or by massive exposure to the antigen. Once the hypersensitization is achieved, the subject remains highly reactive to the antigen. In this condition, the subject develops FL, which manifests itself as recurrent bouts of fever and shortness of breath, 4 h to 8 h after the exposure, thus the term delayed immune response. The capacity of diagnosing HP has been greatly helped with the advent of high-resolution computed tomography and bronchoalveolar lavage (BAL). Geographical, patchy alveolar infiltrates that predominate in the lower lung fields on high-resolution computed tomography suggest the possibility of acute HP. Of all interstitial lung diseases associated with a lymphocytic alveolitis, BAL in HP patients yields by far the higher number of lymphocytes, up to 80% of all cells recovered while, for example, approximately 40% would be expected in sarcoidosis.
FL can recur after each exposure or have a more subacute presentation without the repeated bouts of fever and chills. In both conditions, if left unchecked, permanent lung damage, either emphysema or fibrosis, or a combination of both, will likely occur. The only medical treatment for FL is oral corticosteroids. Although steroids do work in acute FL, their prolonged use is prohibited by side effects of the drug. We have recently found in a mouse model of FL that nicotinic receptor agonists may become a new class of drugs to replace corticosteroids. The idea to try these agonists came from a study by Peter Warren from Winnipeg, Manitoba, who showed years ago that smokers were less likely to develop serum antibodies to SR than nonsmokers. Subsequent studies confirmed that smokers were also less likely to develop FL than nonsmokers. The active ingredient in cigarette smoke may be nicotine. Although nicotine could not be used as a drug to treat FL, there are other nicotinic receptor agonists that may be considered because they do not cross the blood brain barrier and do not cause addiction.
Because of the major health and frequent financial impact of FL, prevention is of capital importance. Over the past 20 years, the prevalence of FL in industrialized countries has plummeted by 90%. When I started my studies on HP more than 25 years ago, FL was by far the most common type of the disease, and we saw between 15 and 20 cases each winter. Now FL accounts for only a small fraction of all HP cases, partly because other environments have been identified (eg, wood processing plants, peat moss factories, metal workers, etc) but mostly because of the decrease in its prevalence (two to three new cases per year). This decrease stems from two major factors: decrease in the number of family farms and improved methods of foliage preservation like switching from dry hay to silage or the use of better equipment to produce drier hay.
What about asthma? Three types of asthma have been described in farmers: occupational asthma, asthma-like syndrome and reactive airway dysfunction syndrome. Occupational asthma is generally of the high molecular weight type caused by an immediate type 1 allergic response to animal dander (cows and pigs), barn mites, or grain, feed or hay allergens. Asthma-like syndrome is caused by exposure to large quantities of organic dust, which contains bacteria and fungi. Endotoxins are usually blamed for this syndrome, although recent studies suggest that they may not be the sole cause. When mice tracheal smooth muscles are exposed to swine building dust, an increased response to methacholine is induced. When the endotoxin from this dust is removed, the hyper-responsiveness goes away, but when the dust only has pure endotoxin nothing happens. A hypothesis for this observation is that a combination of endotoxin and something else in the swine building dust act synergistically; what that other substance(s) is (are) is currently unknown. Reactive airway dysfunction syndrome can occur after a massive exposure to toxic gases. An example of this is exposure to poorly ventilated swine building dunk pits.
However, the news about asthma is not all bad. Many studies with farm children support the ‘dirty baby’ hypothesis. Children exposed in early life to farm buildings have less atopy and asthma than nonexposed controls. Endotoxin exposure in early life may favour a Th1 lymphocyte phenotype profile, thus protecting from type 1 allergic responses. This information led some to suggest that Jesus in his wisdom had told us that exposure in early life in a manger was good for your health. It took us over 2000 years to understand that message.
Silo filler’s disease and organic dust toxic syndrome
Silos! One cannot talk about respiratory health risks of farmers without talking about silos. Silos come in different sizes, shapes and forms, and are built to store grass, corn or other types of grain.
A silo can be a deadly place. Fortunately, farmers are now aware of this danger and only accidentally get caught. The most dangerous time to go into a silo that contains grass or green corn is within a month to six weeks after its filling. Silage contains large quantities of nitrogen, especially with the use of nitrogen-rich fertilizers to grow the grass or the corn. Shortly after harvest, some of this nitrogen is oxidized into the very toxic nitric oxide. This gas of brownish colour is denser than air and thus sits on top of the silage like a cloud. Exposure to this cloud can result in immediate death by asphyxiation due to a lack of oxygen or by toxic bronchoalveolitis known as silo filler’s disease. Approximately 20 years ago, five (or was it six?) members of the same family died in a silo in Ontario, one after the other trying to save a family member. Unfortunately, it took tragedies like that to solve the problem by education. Now, farmers who need to go into a silo will ensure proper ventilation or use appropriate respiratory protective equipment before entering. Silo filler’s disease is less dramatic but can lead to a slower death by respiratory failure. Usually, the patient will eventually recover; the only treatment is that of ventilatory support given as needed.
Silos are also places where moulds abound. Typically, moulding occurs on the top of the silage and in pockets of air that form within the silage, especially if stored too dry. Farmers are at risk of exposure to these moulds when they are volatized during silo unloading or cleaning before their refill. Decapping a mouldy silo can create a cloud of organic dust that will induce an acute toxic response known as organic dust toxic syndrome (ODTS) when inhaled. ODTS was formally known as mycotoxicosis, but the name was changed when it became known that the mouldy material contained not only fungi but also different bacteria, including SR. ODTS can be quite dramatic with high fever and excruciating cough. Fortunately, the syndrome subsides over a few days without leaving significant sequelae. Bronchoscopy performed during the acute phase shows inflamed airways, and if BAL is performed, a large number of neutrophils is obtained. BAL performed a month later will reveal normal airways and a mild lymphocytic alveolitis, probably part of the healing process.
Despite the above-mentioned respiratory health risks, farmers generally have good lungs, perhaps because of their life style. The prevalence of cigarette smokers in Canadian farmers is approximately one-half that of the general population.
In conclusion, I believe it is fair to say that when a farmer consults for respiratory problems, the context of his work environment need to be taken into account in establishing an accurate diagnosis. Most farmers with acute FL are treated with multiple antibiotics for what is initially taken as a respiratory infection before the diagnosis is even suspected. More often it is the farmer, not the doctor, who will come up with that hypothesis. A few years previously, I did a small survey of dairy farmers and family physicians in farming communities. I was astounded to find that farmers knew much more about FL then their doctors.
- Respiratory health hazards in agriculture. Am J Respir Crit Care Med. 1998;158:S1–S76.[PubMed]
Articles from Canadian Respiratory Journal are provided here courtesy of Hindawi Limited