Predictors of longitudinal changes in pulmonary function among swine confinement workers

Respiratory Diseases Associated With Organic Dust Exposure

Organic dusts are complex bioaerosol mixtures comprised of dust and par ticulate matter of organic origin. These include components from bacteria, fungi, pollen, and viruses to fragments of animals and plants commonplace to several environmental/occupational settings encompassing agriculture/farming, grain processing, waste/recycling, textile, cotton, woodworking, bird breeding, and more. Organic dust exposures are linked to development of chronic bronchitis, chronic obstructive pulmonary disease, asthma, asthma-like syndrome, byssinosis, hypersensitivity pneumonitis, and idiopathic pulmonary fibrosis. Risk factors of disease development include cumulative dust exposure, smoking, atopy, timing/duration, and nutritional factors. The immunopathogenesis predominantly involves Toll-like receptor signaling cascade, T-helper 1/T-helper 17 lymphocyte responses, neutrophil influx, and potentiation of manifestations associated with allergy. The true prevalence of airway disease directly attributed to organic dust, especially in a workplace setting, remains challenging. Diagnostic confirmation can be difficult and complicated by hesitancy from workers to seek medical care, driven by fears of potential labor-related consequence. Clinical respiratory and systemic presentations coupled with allergy testing, lung function patterns of obstructive versus restrictive disease, and radiological characteristics are typically utilized to delineate these various organic dust-associated respiratory diseases. Prevention, risk reduction, and management primarily focus on reducing exposure to the offending dust, managing symptoms, and preventing disease progression.

The association of chronic bronchitis and airflow obstruction with lifetime and current farm activities in a sample of rural adults in Iowa

OBJECTIVE

Farmers have an increased risk for chronic bronchitis and airflow obstruction. The objective of this study was to investigate the association of these health outcomes with farm activities.

METHODS

We evaluated the Keokuk County Rural Health Study (KCRHS) enrollment data for farm activities and the two health outcomes chronic bronchitis based on self-reported symptoms and airflow obstruction based on spirometry. We used logistic regression to model the health outcomes, yielding an odds ratio (OR) and 95% confidence interval (95% CI) for farm activities while adjusting for potential confounders and other risk factors.

RESULTS

Of the 1234 farmers, 104 (8.4%) had chronic bronchitis, 75 (6.1%) fulfilled the criteria for airflow obstruction, and the two outcomes overlapped by 18 participants. Chronic bronchitis without airflow obstruction (n = 86) had a statistically significant association with crop storage insecticides (OR 3.1, 95% CI 1.6, 6.1) and a low number of years (≤ 3) worked with turkeys (OR 3.3, 95% CI 1.2, 9.4). The latter result should be interpreted with caution because it is based on a small number of cases (n = 5). Airflow obstruction with or without chronic bronchitis (n = 75) was significantly associated with ever working in a hog or chicken confinement setting (OR 2.2, 95% CI 1.0, 4.5).

CONCLUSIONS

These results suggest that work with crop storage insecticides or turkeys may increase the risk for chronic bronchitis and work in hog or chicken confinement may increase the risk for airflow obstruction.

Cohort profile: the Saskatchewan Rural Health Study-adult component

OBJECTIVES

Less is known about the respiratory health of general farming and non-framing populations. A longitudinal Saskatchewan Rural Health Study (SRHS) was conducted to explore the association between individual and contextual factors with respiratory health outcomes in these populations. Hence, the objectives are to: (i) describe the updated methodology of longitudinal SRHS-an extension of baseline survey methodology published earlier; (ii) compare baseline characteristics and the prevalences of respiratory health outcomes between drops-outs and completers; and (iii) summarize key findings based on baseline survey data.

RESULTS

The SRHS was a prospective cohort study conducted in two phases: baseline survey in 2010 and a follow-up in 2014. Each survey consisted of two components, self-administered questionnaire and clinical assessments. At baseline, 8261 participants (≥ 18 years) (4624 households) and at follow-up, 4867 participants (2797 households) completed the questionnaires. Clinical assessments on lung functions and/or allergies were conducted among a sub-group of participants from both the surveys. To date, we published 15 peer-reviewed manuscripts and 40 abstracts in conference proceedings. Findings from the study will improve the knowledge of respiratory disease etiology and assist in the development and targeting of prevention programs for rural populations in Saskatchewan, Canada.

SUINOCULTOR: VIVÊNCIAS DE PRAZER E SOFRIMENTO NO TRABALHO PRECÁRIO

Resumo Este estudo teve o objetivo de analisar as vivências de prazer e de sofrimento no trabalho de suinocultores, além de caracterizar a organização do trabalho e de compreender as estratégias defensivas utilizadas. O estudo teve um delineamento qualitativo e contou com a participação de 16 suinocultores. A coleta foi realizada através de grupos focais e de observação participante. Os dados foram submetidos à análise de conteúdo. O prazer no trabalhado estava associado à manutenção da tradição familiar e ao cuidado dos animais. Nas vivências de sofrimento, destacaram-se a sobrecarga de trabalho e o desgaste consequente. As estratégias defensivas identificadas foram a negação da dor e a racionalização. Como consequências foram identificados diversos danos à saúde física e mental dos trabalhadores.

Review: Endotoxin in the environment — exposure and effects

This review deals with endotoxin in the environment and its relation to disease among exposed persons. Data are presented on levels of endotoxin in different environments with maximum values of several μg/m3. The cellular reactions of importance for inhalation exposure effects are attachment to lipopolysaccharide binding protein, CD14 cell surface protein and TLR-4 receptors. The internalisation of endotoxin in macrophages and endothelial cells results in local production of inflammatory cytokines with subsequent migration of inflammatory cells into the lung and the penetration of cytokines into the blood. These events orchestrate clinical effects in terms of toxic pneumonitis, airways' inflammation and systemic symptoms. Inhalation challenges with pure endotoxin and field studies confirm the relation between these effects and exposure to dusts containing endotoxin. It is possible that polymorphism in genes determining endotoxin reactivity, particularly TLR-4, influences the risk for disease after environmental exposures. Some data suggest that the inflammation caused by inhaled endotoxin may decrease the risk for atopic sensitisation among children and lung cancer among workers exposed to organic dust. Additional research is needed to clarify the role of other environmental agents that are present in connection with endotoxin, particularly (1→3)-β-D-glucan from mold cell walls.

Particulate matter, endotoxin, and worker respiratory health on large Californian dairies

OBJECTIVE

To assess respiratory exposures and lung function in a cross-sectional study of California dairy workers.

METHODS

Exposure of 205 dairy and 45 control (vegetable processing) workers to particulate matter and endotoxin was monitored. Pre- and postshift spirometry and interviews were conducted.

RESULTS

Geometric mean inhalable and PM2.5 concentrations were 812 and 35.3 μg/m3 versus 481.9 and 19.6 μg/m3, respectively, for dairy and control workers. Endotoxin concentrations were 329 EU/m3 or 1122 pmol/m3 and 13.5 EU/m3 or 110 pmol/m3, respectively, for dairy and control workers. In a mixed-effects model, forced vital capacity decreased across a work shift by 24.5 mL (95% confidence interval, -44.7 to -4.3; P = 0.018) with log10 (total endotoxin) and by 22.0 mL (95% confidence interval, -43.2 to -0.08; P = 0.042) per hour worked.

CONCLUSIONS

Modern California dairy endotoxin exposures and shift length were associated with a mild acute decrease in forced vital capacity.

Monitoring total endotoxin and (1 --> 3)-beta-D-glucan at the air exhaust of concentrated animal feeding operations

Mitigation of bioaerosol emissions from concentrated animal feeding operations (CAFOs) demands knowledge of bioaerosol concentrations feeding into an end-of-pipe air treatment process. The aim of this preliminary study was to measure total endotoxin and (1 --> 3)-beta-glucan concentrations at the air exhaust of 18 commercial CAFOs and to examine their variability with animal operation type (swine farrowing, swine gestation, swine weaning, swine finishing, manure belt laying hen, and tom turkey) and season (cold, mild, and hot). The measured airborne concentrations of total endotoxin ranged from 98 to 23,157 endotoxin units (EU)/m3, and the airborne concentrations of total (1 --> 3)-beta-D-glucan ranged from 2.4 to 537.9 ng/m3. Animal operation type in this study had a significant effect on airborne concentrations of total endotoxin and (1 --> 3)-beta-D-glucan but no significant effect on their concentrations in total suspended particulate (TSP). Both endotoxin and (1 --> 3)-beta-D-glucan attained their highest airborne concentrations in visited tom turkey buildings. Comparatively, season had no significant effect on airborne concentrations of total endotoxin or (1 --> 3)-beta-D-glucan. Endotoxin and (1 --> 3)-beta-glucan concentrations in TSP dust appeared to increase as the weather became warmer, and this seasonal effect was significant in swine buildings. Elevated indoor temperatures in the hot season were considered to facilitate the growth and propagation of bacteria and fungi, thus leading to higher biocomponent concentrations in TSP.

Acute pulmonary function change associated with work on large dairies in California

OBJECTIVE

To study whether dairy workers in California have lower baseline and greater cross-shift decrements in lung function than control employees.

METHODS

A cross-sectional study of 210 dairy and 47 control workers who completed questionnaires and spirometry before and after the work shift.

RESULTS

Dairy work was associated with mean baseline differences of -0.132 L (P = 0.07) and -0.131 L (P = 0.13) in forced expiratory volume in 1 second and forced vital capacity, respectively, compared with control employees, adjusting for age, height, smoking status, and days back at work since last day off. Dairy work was associated with a mean cross-shift difference of -65.2 mL (P = 0.02) and -103.1 mL (P < 0.01) in forced expiratory volume in 1 second and forced vital capacity, respectively, adjusting for smoking status and work-shift time.

CONCLUSIONS

Dairy work in California was associated with mild acute airway obstruction. The unclear long-term effect of dairy work in California merits further investigation.

Cross-shift and longitudinal changes in FEV1 among wood dust exposed workers

Objectives

Acute lung function (LF) changes might predict an accelerated decline in LF. In this study, we investigated the association between cross-shift and longitudinal changes in forced expiratory volume in 1 s (FEV₁) among woodworkers in a 6-year follow-up study.

Methods

817 woodworkers and 136 controls participated with cross-shift changes of FEV₁ at baseline and FEV₁ and forced vital capacity at follow-up. Height and weight were measured and questionnaire information on respiratory symptoms, employment and smoking habits was collected. Wood dust exposure was assessed from 3572 personal dust measurements at baseline and follow-up. Cumulative wood dust exposure was assessed by a study-specific job exposure matrix and exposure time.

Results

The median (range) of inhalable dust at baseline and cumulative wood dust exposure was 1.0 (0.2–9.8) mg/m³ and 3.8 (0–7.1) mg year/m³, respectively. Mean (SD) for %ΔFEV₁/workday and ΔFEV₁/year was 0.2 (6.0)%, and −29.1 (41.8) ml. Linear regression models adjusting for smoking, age, height and weight change showed no association between cross-shift and annual change in FEV₁ among woodworkers or controls. Including different exposure estimates, atopy or cross-shift change dichotomised or as quartiles did not change the results.

Conclusions

This study among workers exposed to low levels of wood dust does not support an association between acute LF changes and accelerated LF decline.

The Saskatchewan rural health study: an application of a population health framework to understand respiratory health outcomes

Background

Respiratory disease can impose a significant burden on the health of rural populations. The Saskatchewan Rural Health Study (SRHS) is a new large prospective cohort study of ages 6 and over currently being conducted in farming and non-farming communities to evaluate potential health determinants associated with respiratory outcomes in rural populations. In this article, we describe the rationale and methodology for the adult component.

The study is being conducted over 5 years (2009–15) in two phases, baseline and longitudinal. The baseline survey consists of two components, adults and children. The adult component consists of a questionnaire-based evaluation of individual and contextual factors of importance to respiratory health in two sub populations (a Farm Cohort and a Small Town Cohort) of rural families in Saskatchewan Rural Municipalities (RMs). Clinical studies of lung function and allergy tests are being conducted on selected sub-samples of the two cohorts based on the positive response to the last question on the baseline questionnaire: “Would you be willing to be contacted about having breathing and/or allergy tests at a nearby location?”. We adopted existing population health theory to evaluate individual factors, contextual factors, and principal covariates on the outcomes of chronic bronchitis, chronic obstructive pulmonary disease, asthma and obstructive sleep apnea.

Findings

Of the RMs selected to participate, 32 (89%) out of 36 RMs and 15 (94%) out of 16 small towns within the RMs agreed to participate. Using the mail out survey method developed by Dillman, we obtained completed questionnaires from 4264 households (8261 individuals). We obtained lung function measurements on 1609 adults, allergy skin test information on 1615 adults; both measurements were available on 1549 adults. We observed differences between farm and non-farm rural residents with respect to individual, contextual factors and covariates.

Discussion

There are differences between farm and non-farm rural residents with respect to individual and contextual factors and other variables of importance. The findings of the SRHS will improve knowledge of respiratory disease etiology, assist in the development and targeting of prevention programs, and in planning health services with farm and small town populations.

Pulmonary intravascular macrophages as proinflammatory cells in heaves, an asthma-like equine disease

Heaves, an obstructive neutrophilic airway inflammation of horses, is triggered by dust components such as endotoxin and has similarities to human asthma. Pulmonary intravascular macrophages (PIMs) increase horses' sensitivity to endotoxin-induced lung inflammation; however, their role in an airborne pathology remains unknown. Therefore, we investigated the role of PIMs in the development of heaves in horses. Clinical and inflammatory responses were evaluated following induction of heaves by moldy hay exposure and PIM depletion with gadolinium chloride (GC). Mares (N = 9) were exposed to four treatments: alfalfa cubes (Cb), alfalfa cubes + GC (Cb-GC), moldy hay (MH), and moldy hay + GC (MH-GC). Clinical scores and neutrophil concentrations in bronchoalveolar lavage (BAL) fluid were higher when mares received MH compared with MH-GC. BAL cells from MH-GC-treated mares had significantly lower IL-8 and TLR4 mRNA expression compared with MH-treated mares. In vitro LPS challenge significantly increased IL-8 but not TLR4 mRNA expression in BAL cells recovered from horses fed with MH, but not from the MH-GC treatment. In summary, PIM depletion attenuated clinical scores, reduced the alveolar migration of neutrophils, and decreased the expression of proinflammatory molecules in BAL cells of heaves horses, suggesting a proinflammatory role of PIMs in the development of airborne pathology.

Size distribution of particulate and associated endotoxin and bacteria in traditional swine barn rooms and rooms sprinkled with oil

The objective of this pilot study was to investigate if a once-a-day sprinkling of canola oil in a swine confinement facility alters the airborne concentration and distribution of particulate matter and associated compounds (endotoxin and culturable microbes). Particulate was collected using an eight-stage cascade impactor in four identical swine grower/finisher rooms of a swine barn. Particulate (mg/m(3)) and endotoxin (EU/m(3) and EU/mg) distribution was determined. A six-stage viable cascade impactor was used to quantify total bacteria, enteric bacteria, and fungi. Microbes were characterized from subcultures prepared from the 10 most predominant colony types on each stage 3 (aerodynamic size 3.3-4.7μm) of the collection plates. Results indicated that oil sprinkling reduced total dust by 86% and total endotoxin concentration by 82.5%. However, the distribution patterns indicate that reduction is observed predominantly on large dust particles. In addition, the proportion of endotoxin associated with smaller particulate sizes (i.e., particles <4.7 μm) was higher in the oil-sprinkled rooms. Oil sprinkling does not markedly alter distribution of total bacteria, enteric bacteria, or fungi. The most frequently identified species were gram-positive genera. Oil sprinkling in swine confinement grower/finisher rooms can significantly reduce airborne total dust and endotoxin; however, smaller particles and associated endotoxin appear to remain in suspension, suggesting the overall improvement in air quality is uncertain. Further distribution studies and exposure outcome studies would need to be undertaken to determine the impacts of oil sprinkling.

Excess longitudinal decline in lung function in grain farmers

Workers in intensive agricultural operations are exposed to dust and endotoxin that are associated with respiratory effects. The authors investigated the longitudinal changes in lung function in male grain farmers. In this study, male grain farmers (n = 263) and male nonfarming control subjects (n = 261) studies initially in 1990/91 were followed-up in 1994/95 and 2003/04. After controlling for potential confounders, grain farmers had an excess annual decline of 9.2 ml/year (95% confidence interval [CI]: 2.7, 15.8, p = .006) in forced vital capacity (FVC) in comparison to control. Long-term exposure to grain dust and other substances in lifetime grain farmers results in progressive loss in lung function.

Biological activities of respirable dust from Eastern Canadian peat moss factories

Bacteria, moulds, endotoxin and quartz from respirable dust of agricultural and industrial buildings are typically incriminated for the respiratory health decline of exposed workers despite that dust being an undefined mixture and quantification methods of aerosolized bacteria, moulds or endotoxin not being standardized yet. We developed an in vitro alveolar epithelial cell system in which biological activities of peat moss factories' dust might be correlated to bacteria, mould, endotoxin and quartz concentrations of the analyzed samples. Following exposure, interleukin-8 protein secretion, necrosis and apoptosis of the exposed A549 cells were monitored respectively with ELISA on cell supernatants, trypan blue exclusion and DNA fragmentation detection by flow cytometry. Respirable dust was collected with liquid impingers and respirable quartz with 10mm Dorr-Oliver cyclones. We quantified mesophilic bacteria, mesophilic moulds and endotoxins from liquid impinger samples. No correlation was observed between biological activities of dust and bacteria, mould, endotoxin or quartz concentrations under our experimental conditions. Our speculation is that simple measurements, such as dust concentrations, may not be adequate indicators of the human respiratory health hazard for a given environment.

Long-term effects of work cessation on respiratory health of textile workers: a 25-year follow-up study

RATIONALE

The degree to which chronic respiratory health effects caused by exposures to cotton dust and endotoxin is reversible after cessation of textile work is unknown.

OBJECTIVES

To investigate changes in lung function and respiratory symptoms after cessation of textile work and to determine whether past exposure to cotton dust and endotoxin or smoking history modify the associations.

METHODS

We performed a prospective cohort study consisting of 447 cotton textile workers exposed to cotton dust and 472 unexposed silk textile workers, with a 25-year follow-up. Spirometry testing and respiratory questionnaires were conducted at 5-year intervals. Generalized estimated equations were used to model the average 5-year change in FEV(1) and odds ratios of respiratory symptom prevalence.

MEASUREMENTS AND MAIN RESULTS

Years since cessation of textile work was positively associated with 11.3 ml/yr and 5.6 ml/yr gains in 5-year FEV(1) change for cotton and silk workers, respectively. Among male cotton workers, smokers gained more FEV(1) per year after cessation of exposure than did nonsmokers, and the risk of symptoms of chronic bronchitis and byssinosis was larger for smoking than for nonsmoking male cotton workers.

CONCLUSIONS

Cessation of textile work was significantly associated with improvement in lung function and respiratory symptoms. The positive effect of work cessation was greater for cotton workers than for silk workers. For cotton workers, the improvement in lung function loss after cessation of textile work was greater among smokers, but no differences were observed for silk workers.

Gender-related tumor necrosis factor-alpha responses in naïve volunteers with Toll-like receptor 4 polymorphisms exposed in a swine confinement facility

The aim of this work is to better understand the responses of people that are exposed to agricultural organic dust and other factors in modern swine production. We investigated the effects of toll-like receptor 4 (TLR4) genotype and gender on respiratory responses of naïve volunteers (18-28 years) to swine barn exposure. Non-smoking healthy subjects (16 men and 13 women) with TLR4 299 (Asp299Gly) and/or 399 (Thr399Ile) polymorphisms (TLR4 299/399) and age-sex matched subjects with TLR4 wild-type alleles spent 5 h in a nonexposed environment (baseline day) and 5 h in a swine facility (exposure day). The results showed significant decreases between baseline and exposure days in across-shift forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)), forced midexpiratory flow rate (FEF(25-75)), and FEV(1)/FVC ratio and in methacholine concentration that reduced FEV1 by 20% (PC(20)) in all groups; however, there were no differences by sex or genotype. Similarly, nasal cytokines, serum cytokines, and blood neutrophil count increased after exposure; in contrast, however, these were influenced by gender. The increase in serum tumor necrosis factor-alpha (TNF-alpha) between baseline and exposure was gender-dependent with male sex associated with a significant increase in the wild-type group and female sex associated with a significant increase in the polymorphic group. These results suggest that for persons exposed to a swine facility, one's immunological response varies with gender as well as TLR4 genotype.

Impact of production systems on swine confinement buildings bioaerosols

Hog production has been substantially intensified in Eastern Canada. Hogs are now fattened in swine confinement buildings with controlled ventilation systems and high animal densities. Newly designed buildings are equipped with conventional manure handling and management systems, shallow or deep litter systems, or source separation systems to manage the large volumes of waste. However, the impacts of those alternative production systems on bioaerosol concentrations within the barns have never been evaluated. Bioaerosols were characterized in 18 modern swine confinement buildings, and the differences in bioaerosol composition in the three different production systems were evaluated. Total dust, endotoxins, culturable actinomycetes, fungi, and bacteria were collected with various apparatuses. The total DNA of the air samples was extracted, and quantitative polymerase chain reaction (PCR) was used to assess the total number of bacterial genomes, as a total (culturable and nonculturable) bacterial assessment. The measured total dust and endotoxin concentrations were not statistically different in the three studied production systems. In buildings with sawdust beds, actinomycetes and molds were found in higher concentrations than in the conventional barns. Aspergillus, Cladosporium, Penicillium, and Scopulariopsis species were identified in all the studied swine confinement buildings. A. flavus, A. terreus, and A. versicolor were abundantly present in the facilities with sawdust beds. Thermotolerant A. fumigatus and Mucor were usually found in all the buildings. The culturable bacteria concentrations were higher in the barns with litters than in the conventional buildings, while real-time PCR revealed nonstatistically different concentrations of total bacteria in all the studied swine confinement buildings. In terms of workers' respiratory health, barns equipped with a solid/liquid separation system may offer better air quality than conventional buildings or barns with sawdust beds. The impact of ventilation rates, air distribution, or building design still has to be explored.

Role of Toll-like receptor 4 in lung inflammation following exposure to swine barn air

The authors tested a hypothesis that lung inflammation and airway hyperresponsiveness (AHR) induced following barn air exposure are dependent on Toll-like receptor 4 (TLR4) by exposing C3HeB/FeJ (intact TLR4, wild type [WT]) and C3H/HeJ (defective TLR4, mutant) mice either to the barn air (8 hours/day for 1, 5, or 20 days) or ambient air. Both strains of mice, compared to their respective controls, showed increased AHR following 5 exposures but dampened AHR after 20 exposures to show lack of effect of TLR4 on AHR. However, swine barn air induced lung inflammation with recruitment of inflammatory cells and cytokine expression was observed in WT but not in mutant mice. These data show different roles of TLR4 in lung inflammation and AHR in mice exposed to swine barn air.

Lung inflammation following a single exposure to swine barn air

Background

Exposure to swine barn air is an occupational hazard. Barn workers following an eight-hour work shift develop many signs of lung dysfunction including lung inflammation. However, the in situ cellular and molecular mechanisms responsible for lung dysfunction induced following exposure to the barn air remain largely unknown. Specifically, the recruitment and role of pulmonary intravascular monocytes/macrophages (PIMMs), which increase host susceptibility for acute lung inflammation, remain unknown in barn air induced lung inflammation. We hypothesized that barn exposure induces recruitment of PIMMs and increases susceptibility for acute lung inflammation with a secondary challenge.

Methods

Sprague-Dawley rats were exposed either to the barn or ambient air for eight hours and were euthanized at various time intervals to collect blood, broncho-alveolar lavage fluid (BALF) and lung tissue. Subsequently, following an eight hour barn or ambient air exposure, rats were challenged either with Escherichia coli (E. coli) lipopolysaccharide (LPS) or saline and euthanized 6 hours post-LPS or saline treatment. We used ANOVA (P < 0.05 means significant) to compare group differences.

Results

An eight-hour exposure to barn air induced acute lung inflammation with recruitment of granulocytes and PIMMs. Granulocyte and PIMM numbers peaked at one and 48 hour post-exposure, respectively.

Secondary challenge with E. coli LPS at 48 hour following barn exposure resulted in intense lung inflammation, greater numbers of granulocytes, increased number of cells positive for TNF-α and decreased amounts of TGF-β2 in lung tissues. We also localized TNF-α, IL-1β and TGF-β2 in PIMMs.

Conclusion

A single exposure to barn air induces lung inflammation with recruitment of PIMMs and granulocytes. Recruited PIMMs may be linked to more robust lung inflammation in barn-exposed rats exposed to LPS. These data may have implications of workers exposed to the barn air who may encounter secondary microbial challenge.

Lung function and farm size predict healthy worker effect in swine farmers

BACKGROUND

Swine farmers are exposed to a number of airborne contaminants associated with respiratory ill health.

OBJECTIVES

To examine the factors associated with healthy worker effect in the swine industry from a longitudinal follow-up of farmers at 4 years and 13 years.

DESIGN

A prospective study of swine farmers and nonexposed rural residents was conducted using similar questionnaires and same spirometer at each time point.

RESULTS

In the original observations in 1990/1991, we studied 302 swine farmers and 261 nonfarming control subjects. Four years later in 1994/1995, 217 swine farmers and 171 nonfarming control subjects of the original group participated again. In 2003/2004, 163 swine farmers and 118 control subjects were retested. Of the 163 swine farmers, 52 remained active swine farmers and 111 were no longer swine farming, thus providing the opportunity to evaluate work continuity in the industry. Among farmers studied in 2003/2004, mean values for percentage of predicted FEV(1)/FVC ratio and forced expiratory flow between 25% and 75% of FVC were lower in those who had quit swine farming compared to those still swine farming and nonfarming control subjects. The herd size in the barn at baseline in 1990/1991 and at interim follow-up in 1994/1995 was a significant predictor of quitting swine farming. In addition, percentage of predicted FEV(1)/FVC at the interim observation was a significant predictor of quitting swine farming.

CONCLUSIONS

There is a significant healthy worker effect among swine farmers. The continuation of work in the facilities may be predicted by herd size and interim lung function.

Excess respiratory symptoms in full-time male and female workers in large-scale swine operations

BACKGROUND

The respiratory health effects of working in swine operations have been previously investigated mainly in male owner/operators with intermittent exposure to indoor air contaminants.

OBJECTIVES

To examine the respiratory health of male and female workers employed full time in large-scale intensive swine operations in Saskatchewan.

DESIGN

A cross-sectional study of male and female swine workers employed full time and nonfarming control subjects.

RESULTS

In total, 374 swine farmers (240 men and 134 women) and 411 nonfarming rural control subjects (184 men and 227 women) participated in the study. After controlling for age and smoking, male and female workers were significantly more likely to have chronic and usual cough, and chronic and usual phlegm in comparison to male and female nonfarming control subjects, respectively. The risks of these symptoms were greater in female workers (chronic cough: odds ratio [OR], 5.14; 95% confidence interval, 2.67 to 9.89; chronic phlegm: OR, 4.26; 95% confidence interval, 1.86 to 9.73) than in male workers (chronic cough: OR, 3.47; 95% confidence interval, 1.77 to 6.81; chronic phlegm: OR, 3.22; 95% confidence interval, 1.76 to 5.89). These increased risks were not observed for asthma and asthma-like symptoms in female workers. Male workers had an increased risk of shortness of breath in comparison to their nonfarming counter parts.

CONCLUSIONS

Swine workers had increased risk of chronic and usual bronchitis-like symptoms. Female workers in swine operations appear to have greater risk of these symptoms. Future surveillance programs should include both male and female workers.

Pulmonary effects of exposure to pig barn air

Swine production has undergone rapid transformation from family owned operation to a large scale industrial enterprise. Since increasing number of pigs are reared on a large scale in confined buildings, some of the swine barn workers may be employed to work eight hours per day. Swine barn workers suffer from higher incidences of impaired air flow and lung inflammation, which is attributed to high intensity and interrupted exposures to pig barn air. The air in these barns contains gases, dust, microbes and endotoxin with endotoxin being the major suspect as the cause of lung dysfunction. This review attempts to describe the current state of knowledge of incidences and mechanisms of pulmonary dysfunction following exposure to the barn air.

Multiple exposures to swine barn air induce lung inflammation and airway hyper-responsiveness

Background

Swine farmers repeatedly exposed to the barn air suffer from respiratory diseases. However the mechanisms of lung dysfunction following repeated exposures to the barn air are still largely unknown. Therefore, we tested a hypothesis in a rat model that multiple interrupted exposures to the barn air will cause chronic lung inflammation and decline in lung function.

Methods

Rats were exposed either to swine barn (8 hours/day for either one or five or 20 days) or ambient air. After the exposure periods, airway hyper-responsiveness (AHR) to methacholine (Mch) was measured and rats were euthanized to collect bronchoalveolar lavage fluid (BALF), blood and lung tissues. Barn air was sampled to determine endotoxin levels and microbial load.

Results

The air in the barn used in this study had a very high concentration of endotoxin (15361.75 ± 7712.16 EU/m³). Rats exposed to barn air for one and five days showed increase in AHR compared to the 20-day exposed and controls. Lungs from the exposed groups were inflamed as indicated by recruitment of neutrophils in all three exposed groups and eosinophils and an increase in numbers of airway epithelial goblet cells in 5- and 20-day exposure groups. Rats exposed to the barn air for one day or 20 days had more total leukocytes in the BALF and 20-day exposed rats had more airway epithelial goblet cells compared to the controls and those subjected to 1 and 5 exposures (P < 0.05). Bronchus-associated lymphoid tissue (BALT) in the lungs of rats exposed for 20 days contained germinal centers and mitotic cells suggesting activation. There were no differences in the airway smooth muscle cell volume or septal macrophage recruitment among the groups.

Conclusion

We conclude that multiple exposures to endotoxin-containing swine barn air induce AHR, increase in mucus-containing airway epithelial cells and lung inflammation. The data also show that prolonged multiple exposures may also induce adaptation in AHR response in the exposed subjects.

Longitudinal Decline in Lung Function: Evaluation of Interleukin-10 Genetic Polymorphisms in Firefighters

During annual medical monitoring, some firefighters are found to have rates of decline in forced expiratory volume in one second (FEV1) far exceeding their peers. Interleukin-10 (IL-10) suppresses inflammation, and single nucleotide polymorphisms (SNPs) in the IL-10 gene may confer variable susceptibility to more rapid decline in lung function. In 1204 firefighters with at least six annual FEV1 measurements, increased age and greater initial FEV1 were associated with more rapid decline in lung function. DNA collected from 379 of these firefighters was screened for IL-10 SNPs at -1117, -854, 919, 1668, and 1812. A statistically significant difference in decline in lung function was found based on genotyping at the 1668 SNP. Evaluation of gene polymorphisms regulating lung inflammation may help to explain some of the variation in rate of decline in lung function in firefighters.

Exposure to animals and selected risk factors among Canadian farm residents with Hodgkin's disease, multiple myeloma, or soft tissue sarcoma

Exposures to farm animals has been associated with certain rare cancers. Simultaneously, using the same methodology and control group, we conducted a six-province incident, population-based study of Hodgkin's disease (HD), multiple myeloma (MM), and soft tissue sarcoma (STS). Farm residence or work was reported by 38% (n = 119) of HD, 45% (n = 178) of MM, 43% (n = 156) of STS cases and 45% (n = 673) of controls. We conducted conditional logistic regression analyses and report odds ratios (OR(adj)) and 95% confidence intervals. After adjustment for covariates, exposure to farm animals had minimal effect on risk. The independent risk factors after adjustment for covariates were a family history of cancer (MM, STS), occupational uranium exposure (HD), professional driving (MM), and personal previous cancer (MM) or shingles (HD, MM).

Endotoxin-stimulated innate immunity: A contributing factor for asthma

Exposure to airborne endotoxin in infancy may protect against asthma by promoting enhanced T(H)1 response and tolerance to allergens. On the other hand, later in life, it adversely affects patients with asthma. Endotoxin binding to receptors on macrophages and other cells generates IL-12, which inhibits IgE responses. It also generates cytokines like IL-1, TNF-alpha, and IL-8, which cause inflammation. These signal transduction pathways resemble those leading to the generation of cytokines, such as IL-4, IL-13, and IL-5, which are responsible for the inflammation of IgE-mediated allergic disease. The main difference seems to be that endotoxin recruits neutrophils, but IgE recruits eosinophils, and the details of the tissue injury from these granulocytes differ. Sources of airborne endotoxin include many agricultural dusts, aerosols from contaminated water in many industrial plants, contaminated heating and air-conditioning systems, mist-generating humidifiers, and damp or water-damaged homes. Acute inhalation of high concentrations of endotoxin can cause fever, cough, and dyspnea. Chronic inhalation of lesser amounts causes chronic bronchitis and emphysema and is associated with airway hyperresponsiveness. Airborne endotoxin adversely affects patients with asthma in 3 ways: (1) by increasing the severity of the airway inflammation; (2) by increasing the susceptibility to rhinovirus-induced colds; and (3) by causing chronic bronchitis and emphysema with development of irreversible airway obstruction after chronic exposure of adults. The most effective management is mitigating exposure. The potential of drug treatments requires further clinical investigation.

Positive human health effects of wearing a respirator in a swine barn

STUDY OBJECTIVES

A study was conducted to evaluate the acute health effects of wearing an N-95 disposable respirator in a swine confinement facility.

DESIGN

A crossover trial design was used in the study.

SETTING

The study was carried out at the research facilities of the Centre for Agricultural Medicine, the Royal University Hospital, and the Prairie Swine Centre Inc, Saskatoon, Saskatchewan, Canada.

PARTICIPANTS

Twenty-one nonsmoking healthy male subjects with no previous swine barn exposure participated in the study.

INTERVENTIONS

The subjects participated in a laboratory session (baseline day), a 4-h exposure in a traditional swine room wearing the respirator (intervention day), and a 4-hour exposure in a traditional swine room without a respirator (nonintervention day).

MEASUREMENTS

Lung function, methacholine challenge tests, blood counts, nasal lavage, and cytokines in serum and nasal lavage fluid.

RESULTS

Mean (+/- SE) shift change in FEV(1), from preexposure to postexposure, was highest on nonintervention day (-8.1+/-1.01%) and was significantly different from intervention day (0.32+/-0.62%; p<0.0001) and baseline day (1.57+/-0.51%; p<0.0001). Similar patterns were observed in the mean values of the provocative concentration of a substance (methacholine) causing a 20% fall in FEV(1) (nonintervention day, 130.4+/-36.9 mg/mL; intervention day, 242.0+/-38.0 mg/mL; and baseline day, 328.0 mg/mL +/-34.1 mg/mL). Significant increases in serum neutrophil levels and nasal cell counts were observed on the nonintervention day in comparison to the baseline and intervention days. Significant increases also were found in the levels of cytokines interleukin (IL)-6 and IL-8 in nasal lavage fluid and in the levels of IL-6 in serum for the nonintervention day in comparison to the other 2 days.

CONCLUSIONS

The results demonstrate that an N-95 disposable respirator can help to significantly reduce acute negative health effects in subjects not previously exposed to a swine barn environment.