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

Personal protective equipment use during industrial hog operation work activities and acute lung function changes in a prospective worker cohort, North Carolina 2014-2015

INTRODUCTION

Occupational activities related to industrial hog operation (IHO) worker lung function are not well defined. Therefore, we aimed to identify IHO work activities associated with diminished respiratory function and the effectiveness, if any, of personal protective equipment (PPE) use on IHOs.

METHODS

From 2014 to 2015, 103 IHO workers were enrolled and followed for 16 weeks. At each biweekly visit, work activities and PPE use were self-reported via questionnaire and lung function measurements were collected via spirometry. Generalized linear and linear fixed-effects models were fitted to cross-sectional and longitudinal data.

RESULTS

Increasing years worked on an IHO were associated with diminished lung function, but baseline and longitudinal work activities were largely inconsistent in direction and magnitude. Unexpectedly, a -0.3 L (95% confidence interval: -0.6, -0.04) difference in forced expiratory volume in the first second (FEV₁ ) was estimated when workers wore PPE consistently (≥80% of the time at work) versus those weeks they did not. In post-hoc analyses, we found that coveralls and facemasks were worn less consistently when workers experienced worse barn conditions and had more contact with pigs, but coveralls were worn more consistently as cleaning activities increased.

CONCLUSIONS

Similar to past studies, baseline estimates were likely obscured by healthy worker effect bias, but showed decrements in worker lung function as years of work increased. A challenge to disentangling the effect of work activities on lung function was the discovery that IHO workers used PPE differently according to the work task. These data suggest that interventions may be targeted toward improving barn conditions so that workers can consistently utilize IHO-provided PPE.

Respiratory health, occupation and the healthy worker effect

BACKGROUND

Workers are exposed to physical, chemical and other hazards in the workplace, which may impact their respiratory health.

AIMS

To examine the healthy worker effect in the Canadian working population and to identify the association between occupation and respiratory health.

METHODS

Data from four cycles of the Canadian Health Measures Survey were utilized. The current occupation of employed participants was classified into 10 broad categories based on National Occupation Category 2011 codes. Data relating to 15 400 subjects were analysed.

RESULTS

A significantly lower proportion of those in current employment than those not in current employment reported respiratory symptoms or diseases or had airway obstruction. Similarly, those currently employed reported better general health and had greater mean values for percent-predicted forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory flow between 25% and 75% of FVC (FEF25-75%) and FEV1/FVC ratio. Among males, females and older age groups, significant differences were observed for almost all the respiratory outcomes for those in current employment. Those in 'Occupations unique to primary industry' had a significantly greater likelihood of regular cough with sputum and ever asthma and had lower mean values of percent-predicted FEV1/FVC and FEF25-75% than those in 'Management occupations'. Those in 'Health occupations' had the highest proportion of current asthma.

CONCLUSIONS

Participants in current employment were healthier than those not in current employment providing further support for the healthy worker effect. Those in 'Occupations unique to primary industry' had an increased risk of adverse respiratory outcomes and reducing workplace exposures in these occupations has the potential to improve their respiratory health.

The use of personal protective equipment during common industrial hog operation work activities and acute lung function changes in a prospective worker cohort, North Carolina, USA

Introduction

As occupational activities related to acute industrial hog operation (IHO) worker lung function are not well defined, we aimed to identify IHO work activities associated with diminished respiratory function and the effectiveness, if any, of personal protective equipment (PPE) on IHOs.

Methods

From 2014-2015, 103 IHO workers were enrolled and followed for 16 weeks. At each bi-weekly visit, lung function measurements were collected via spirometry and work activities and PPE use were self-reported via questionnaire. Generalized linear and linear fixed-effects models were fitted to cross-sectional and longitudinal data.

Results

At baseline, increasing years worked on an IHO were associated with diminished lung function, but other activities were less consistent in direction and magnitude. In longitudinal models, only reports of working in feeding/finisher barns, showed a consistent association. However, a -0.3 L (95% confidence interval: -0.6, -0.04) difference in FEV ₁ was estimated when workers wore PPE consistently versus those weeks they did not. In post-hoc analyses, we found that coveralls and facemasks were worn less consistently when workers experienced worse barn conditions and had more contact with pigs, but coveralls were worn more consistently as cleaning activities increased.

Conclusions

Similar to past studies, baseline estimates were likely obscured by healthy worker bias. Also making it challenging to disentangle the effect of work activities on lung function was the discovery that IHO workers used PPE differently according to work task. These data suggest that interventions may be targeted toward improving barn conditions so that workers can consistently utilize IHO-provided PPE.

KEY MESSAGES

What is already known about this subject?: Working on industrial hog operations may be deleterious to long- and short-term respiratory health due to airborne bacteria, endotoxin, hazardous gases, dust, and dander in barns. In efficacy studies PPE has been shown to be protective, but studies have shown that PPE utilization among hog workers has historically been sub-optimal.What are the new findings?: As barn conditions worsened and contact with pigs increased, workers in this cohort reported wearing coveralls and face masks less often; however, they reported increased PPE use as they conducted more cleaning activities at work. During weeks when workers wore PPE their lung function declined, a possible cause being the improper use of the equipment leading to a false sense of protection or re-exposure to hazardous contaminants.How might this impact on policy or clinical practice in the foreseeable future?: Given COVID-19, the H1N1 "swine flu" pandemic, our knowledge of antimicrobial resistant pathogens, and increasing awareness about how food systems are linked to the spread of emerging infectious diseases, occupational health intervention research and workplace policies may focus on creating barn environments that are more conducive to PPE use which could help protect workers and consequently the community.

Respiratory diseases and allergy in farmers working with livestock: a EAACI position paper

Farmers constitute a large professional group worldwide. In developed countries farms tend to become larger, with a concentration of farm operations. Animal farming has been associated with negative respiratory effects such as work-related asthma and rhinitis. However, being born and raised or working on a farm reduces the risk of atopic asthma and rhinitis later in life. A risk of chronic bronchitis and bronchial obstruction/COPD has been reported in confinement buildings and livestock farmers. This position paper reviews the literature linking exposure information to intensive animal farming and the risk of work-related respiratory diseases and focuses on prevention. Animal farming is associated with exposure to organic dust containing allergens and microbial matter including alive microorganisms and viruses, endotoxins and other factors like irritant gases such as ammonia and disinfectants. These exposures have been identified as specific agents/risk factors of asthma, rhinitis, chronic bronchitis, COPD and reduced FEV₁. Published studies on dust and endotoxin exposure in livestock farmers do not show a downward trend in exposure over the last 30 years, suggesting that the workforce in these industries is still overexposed and at risk of developing respiratory disease. In cases of occupational asthma and rhinitis, avoidance of further exposure to causal agents is recommended, but it may not be obtainable in agriculture, mainly due to socio-economic considerations. Hence, there is an urgent need for focus on farming exposure in order to protect farmers and others at work in these and related industries from developing respiratory diseases and allergy.

Animal production, insecticide use and self-reported symptoms and diagnoses of COPD, including chronic bronchitis, in the Agricultural Health Study

BACKGROUND

Occupational exposure to animal production is associated with chronic bronchitis symptoms; however, few studies consider associations with chronic obstructive pulmonary disease (COPD). We estimated associations between animal production activities and prevalence of self-reported COPD among farmers in the Agricultural Health Study.

METHODS

During a 2005-2010 interview, farmers self-reported information about: their operations (i.e., size, type, number of animals, insecticide use), respiratory symptoms, and COPD diagnoses (i.e., COPD, chronic bronchitis, emphysema). Operations were classified as small or medium/large based on regulatory definitions. Farmers were classified as having a COPD diagnosis, chronic bronchitis symptoms (cough and phlegm for ≥3 months during 2 consecutive years), or both. Polytomous logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Of 22,491 participating farmers (median age: 59 years), 922 (4%) reported a COPD diagnosis only, 254 (1%) reported a diagnosis and symptoms, and 962 (4%) reported symptoms only. Compared to raising no commercial animals, raising animals on a medium/large operation was positively associated with chronic bronchitis symptoms with (OR: 1.59; 95% CI: 1.16, 2.18) and without a diagnosis (OR: 1.69; 95% CI: 1.42, 2.01). Ever use of multiple organophosphates, carbaryl, lindane, and permethrin were positively associated with chronic bronchitis symptoms.

CONCLUSION

Animal production work, including insecticide use, was positively associated with chronic bronchitis symptoms; but not consistently with COPD diagnosis alone. Our results support the need for further investigation into the role of animal production-related exposures in the etiology of COPD and better respiratory protection for agricultural workers.

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.

Resilience of Farm Women Working the Third Shift

BACKGROUND

We examined physical health and work experiences in a Saskatchewan population of farm women, and determined how participation in the "third shift" (a phenomenon where women engage in off-farm employment, farm labor, and as homemakers) relates to their demographic, physical health, and work experiences.

MATERIALS AND METHODS

This is a cross-sectional epidemiological study. Reports from 980 women who lived or worked on Saskatchewan farms were analyzed to describe their health status, comorbidities, use of medications, and exposures to farm work. Regression models were used to explore determinants of participation in the third shift.

RESULTS

Two hundred and sixteen were women [22.0%] engaged in the "third shift", and these women consistently reported significantly longer mechanized and non-mechanized farm work hours. Compared to women not involved in the third shift, participants in the third shift were more likely to be: 41-50 years of age [OR_Adj 2.06 (1.12, 3.77)], and involved in beef cattle production [OR_Adj 1.62 (1.05-2.49)], large animal chores [OR_Adj 1.66 (1.04-2.66)], use of shovels/pitchforks [OR_Adj 1.67 (1.08-2.57)], combine operation [OR_Adj 1.72 (1.08-2.74)], and have higher levels of education [e.g., OR_Adj 0.46 (0.29-0.72) for high school or less]. Descriptively, reduced engagement in the third shift was associated with "fair or poor" health status [OR_Crude 0.32 (0.14-0.76)] and more co-morbidities [e.g., OR_Crude 0.50 (0.33, 0.75) for 2 or more versus none reported].

CONCLUSION

This study found that farm women often report high levels of work, including engagement in the third shift. Women engaged in the third shift are also generally healthier than non-engaged women, consistent with a healthy worker effect.

Gender Differences in the Association of Individual and Contextual Exposures with Lung Function in a Rural Canadian Population

INTRODUCTION

To investigate the association of individual and contextual exposures with lung function by gender in rural-dwelling Canadians.

METHODS

A cross-sectional mail survey obtained completed questionnaires on exposures from 8263 individuals; a sub-sample of 1609 individuals (762 men, 847 women) additionally participated in clinical lung function testing. The three dependent variables were forced expired volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio. Independent variables included smoking, waist circumference, body mass index, indoor household exposures (secondhand smoke, dampness, mold, musty odor), occupational exposures (grain dust, pesticides, livestock, farm residence), and socioeconomic status. The primary analysis was multiple linear regression, conducted separately for each outcome. The potential modifying influence of gender was tested in multivariable models using product terms between gender and each independent variable.

RESULTS

High-risk waist circumference was related to reduced FVC and FEV₁ for both genders, but the effect was more pronounced in men. Greater pack-years smoking was associated with lower lung function values. Exposure to household smoke was related to reduced FEV₁, and exposure to livestock, with increased FEV₁. Lower income adequacy was associated with reduced FVC and FEV₁.

CONCLUSION

High-risk waist circumference was more strongly associated with reduced lung function in men than women. Longitudinal research combined with rigorous exposure assessment is needed to clarify how sex and gender interact to impact lung function in rural populations.

Comparison of Working Conditions and Prevalence of Musculoskeletal Symptoms among Dairy Farmers in Southern Sweden over a 25-Year Period

Working conditions and the prevalence of perceived musculoskeletal symptoms (MSSs) among dairy farmers in 2013 were monitored by repeating a mail survey of dairy workers in Scania, southern Sweden, using the same method for collecting data on MSSs and working conditions employed in previous surveys conducted in 1988 and 2002. All dairy enterprises in Scania (total 419) were sent two copies of a questionnaire. One or more responses were received from 232 enterprises (55.4%), of which those from 247 dairy farmers (75% men and 25% women) in 199 enterprises are included in this study. The farmers had increased their weekly working hours in 2013 compared with 2002 (males x¯= 43.9, 40.7; females x¯= 37.9, 33.9). Each male milked on average 30 cows in 1988, 44 cows in 2002, and 86 cows in 2013. The corresponding numbers milked by female farmers were 29, 60, and 102, respectively. In 1988, almost all farmers used tethered systems, while in 2013, 54.4% of male and 66.1% of female farmers instead worked with loose-housing systems. Of the farmers who used loose-housing systems, 50.7% had a robotic milking system. In 2013, 79.0% of male and 88.5% of female farmers reported MSSs on some occasion, especially in the lower back, shoulders, and knees for men, and in the shoulders, lower back, and wrists/hands for women. However, there was no statistical change compared with the frequency of MSSs in 2002. In 2013, there was a tendency for younger dairy farmers (≤35 years) to report MSSs, especially in the shoulders, elbows, lower back, and feet, more frequently than younger farmers in 2002. The males who worked with robot milking systems in 2013 indicated less discomfort in the shoulders than men who worked with other systems. The corresponding females indicated fewer problems in the lower back in 2013. Various aspects of milking system design and technology have been improved to reduce the workload and prevent MSSs in dairy farmers. Nevertheless, more improvements are needed to make the milking process more attractive and reduce health problems, especially in younger farmers currently working with milking and in new recruits.

A community-based participatory research methodology to address, redress, and reassess disparities in respiratory health among First Nations

Background

To date, determinants of respiratory health in First Nations people living on reserves and means of addressing and redressing those determinants have not been well established. Hence the Saskatchewan First Nations Lung Health Project (FNLHP) is a new prospective cohort study of aboriginal people being conducted in two First Nations reserves to evaluate potential health determinants associated with respiratory outcomes. Using the population health framework (PHF) of Health Canada, instruments designed with the communities, joint ownership of data, and based on the 4-phase concept of the First Nations Regional Longitudinal Health Survey, the project aims to evaluate individual factors, contextual factors, and principal covariates on respiratory outcomes. The objective of this report is to clearly describe the methodology of (i) the baseline survey that consists of two components, an interviewer-administered questionnaire and clinical assessment; and (ii) potential intervention programs; and present descriptive results of the baseline data of longitudinal FNLHP.

Methods

The study is being conducted over 5 years (2012–2017) in two phases, baseline and longitudinal. Baseline survey has been completed and consisted of (i) an interviewer-administered questionnaire-based evaluation of individual and contextual factors of importance to respiratory health (with special focus on chronic bronchitis, chronic obstructive pulmonary disease, asthma and obstructive sleep apnea), and (ii) clinical lung function and allergy tests with the consent of study participants. The address-redress phase consists of potential intervention programs and is currently being rolled out to address-at community level (via green light program and environmental study), and redress-at policy level (via obesity reduction and improved diagnosis and treatment of obstructive sleep apnea) the issues that have been identified by the baseline data.

Results

Interviewer-administered surveys were conducted in 2012–2013 and collected data on 874 individuals living in 406 households from two reserve communities located in Saskatchewan, Canada. Four hundred and forty six (51%) females and 428 (49%) males participated in the FNLHP.

Conclusions

The information from this project will assist in addressing and redressing many of the issues involved including the provision of adequate housing, health lifestyle practices, and in planning for health service delivery.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1137-5) contains supplementary material, which is available to authorized users.

Healthy worker survivor analysis in an occupational cohort study of Dutch agricultural workers

Objectives

High microbial exposures in farmers and agricultural workers are associated with less atopy. Although it has been speculated that healthy worker survival could be an explanation, this has not been studied so far. Therefore, we investigated the presence of healthy worker survival in a five-year follow-up study of an occupational cohort of Dutch farmers and agricultural industry (company) workers.

Methods

We compared baseline demographic characteristics, respiratory health, atopy and endotoxin exposure of 259 workers followed up with 124 workers lost to follow-up. Additionally, baseline health status of 31 participants who had changed to lower exposure jobs at follow-up was compared to those with similar or higher exposure jobs at follow-up.

Results

In general, no major healthy worker survival effect was found. Nonetheless, small differences were observed between subjects included in follow-up and those lost to follow-up. Those lost to follow-up were older, had a lower peak expiratory flow, and were less often raised on a farm. Company workers lost to follow-up with a farm childhood had more often self-reported allergy, but this was not observed for subjects with atopic sensitization or other respiratory symptoms. No differences were found for any of the studied characteristics in participants with lower exposure at follow-up compared to participants with similar or higher exposure at follow-up.

Conclusions

No major healthy worker survival is present in this organic dust exposed cohort. Differences between participants lost to follow-up and participants included in follow-up with regard to health characteristics are small and unlikely to explain the previously reported inverse associations between endotoxin exposure and atopy.

Electronic supplementary material

The online version of this article (doi:10.1007/s00420-015-1047-9) contains supplementary material, which is available to authorized users.

Agricultural work exposures and pulmonary function among hired farm workers in California (the MICASA study)

Despite California's dependence on hired farm labor, scarce research has been conducted on the respiratory health of hired farm workers. Agricultural exposures to inorganic and organic dusts can adversely affect an individual's respiratory health and differ by farm type and job task. The purpose of the present analysis was to examine associations between agricultural work exposures and pulmonary function among 450 California farm workers. Data were collected as part of the Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) study, a prospective cohort study examining occupational risk factors and health of hired farm worker families in Mendota, California. Time-weighted self-reported average (TWSRA) dust scores were calculated from assessments of past-12-month agricultural work history. Other dust exposure indicator variables included months worked in agriculture in the past 12 months and years worked in agriculture. Multiple linear regression modeled FEV1 (forced expiratory volume in 1 second), FEF(25-75%) (forced midexpiratory flow rate), FVC (forced vital capacity), FEV6, FEV1/FVC, and FEV1/FEV6 separately. Seventy-six percent of participants had worked in agriculture in the past year. In models conducted for crops and tasks separately, high TWSRA dust score was associated with better FEV6. Crop and task models showed associations between greater months worked in agriculture in the past year and better FEV1, FEF(25-75%), and FEV6. Both models also found greater years worked in agriculture to be associated with worse FEV1/FEV6. Results were generally in the opposite direction as expected given past research but not uncommon. Future research should investigate relationships between pulmonary function and agricultural dust exposure over a lifetime and changes in pulmonary function over time.

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.

Asthma and lung cancer risk: a systematic investigation by the International Lung Cancer Consortium

Asthma has been hypothesized to be associated with lung cancer (LC) risk. We conducted a pooled analysis of 16 studies in the International Lung Cancer Consortium (ILCCO) to quantitatively assess this association and compared the results with 36 previously published studies. In total, information from 585 444 individuals was used. Study-specific measures were combined using random effects models. A meta-regression and subgroup meta-analyses were performed to identify sources of heterogeneity. The overall LC relative risk (RR) associated with asthma was 1.28 [95% confidence intervals (CIs) = 1.16-1.41] but with large heterogeneity (I(2) = 73%, P < 0.001) between studies. Among ILCCO studies, an increased risk was found for squamous cell (RR = 1.69, 95%, CI = 1.26-2.26) and for small-cell carcinoma (RR = 1.71, 95% CI = 0.99-2.95) but was weaker for adenocarcinoma (RR = 1.09, 95% CI = 0.88-1.36). The increased LC risk was strongest in the 2 years after asthma diagnosis (RR = 2.13, 95% CI = 1.09-4.17) but subjects diagnosed with asthma over 10 years prior had no or little increased LC risk (RR = 1.10, 95% CI = 0.94-1.30). Because the increased incidence of LC was chiefly observed in small cell and squamous cell lung carcinomas, primarily within 2 years of asthma diagnosis and because the association was weak among never smokers, we conclude that the association may not reflect a causal effect of asthma on the risk of LC.

Predictors of early cessation of dairy farming in the French Doubs province: 12-year follow-up

BACKGROUND

A healthy worker effect due to respiratory disability has been noted in the farming population, but other factors may also interfere. Little has been published about factors influencing the early cessation of work in self-employed dairy farmers.

METHODS

Two hundred and nineteen dairy farmers were included from a cohort constituted in eastern France in 1993-1994 with a 12-year follow-up. Spirometric data, personal, and farm characteristics were registered. Cox models with delayed entry in which age was the time-scale were applied to identify the baseline predictive factors of the early cessation of dairy farming.

RESULTS

Working in a modern farm was protective against early cessation of dairy farming (hazard ratio: 0.36 [95% CI: 0.16-0.81]), especially in men. Having asthma was a predictive factor of early cessation, especially in women (hazard ratio: 16.12 [95% CI: 3.28-79.12]).

CONCLUSIONS

The most predictive factors of early cessation of dairy farming were health related in women and farm related in men.

Respiratory issues in beef and pork production: recommendations from an expert panel

This paper summarizes "Respiratory Issues in Confined Feeding Operations," a panel discussion at the Agricultural Safety and Health Council of America/National Institute for Occupational Safety and Health conference, "Be Safe, Be Profitable: Protecting Workers in Agriculture," Dallas/Fort Worth, Texas, January 27-28, 2010. Occupational exposure to confined animal feeding operations is associated with cough, wheezing, and shortness of breath. Published data shows that 20% to 40% of hog confinement workers experience such symptoms, although most are able to continue working in this industry. Endotoxin is one component of hog barn dust that is associated with respiratory disease in workers. Endotoxin levels on cattle feedlots can also be in the range linked with occupational lung disease. The cattle industry has not yet prepared guidance documents for producers, in part because much less is known about the prevalence of lung disease in its workers. However, the pork industry provides information for pork producers on reducing their respiratory health risks through a multifaceted approach, including the use of respirators. Some jobs cannot be done safely without respiratory protection, such as entering manure pits. It is less clear for other jobs when respirators should be worn. Use of respiratory protection should be considered but not mandated for all persons working in close proximity to livestock in dusty conditions. A respiratory protection program may also serve as a cost effective biosecurity measure to protect animals from human pathogens such as influenza virus. Proper design and management of barn ventilation systems is critical for maintaining temperature and humidity levels for optimal animal growth; as well as decreasing the level of gases and respirable dusts. The pork and the cattle industries support occupational health and safety; however, the governmental guidance and recommendations for such programs are limited for the agricultural industries as a whole. The industries should lead the way in the effort to improve respiratory protection for workers. Overall, a team approach that includes input from managers, workers, and veterinarians is important for the reduction of respiratory hazards on livestock farms.

Chronic lung function decline in cotton textile workers: roles of historical and recent exposures to endotoxin

BACKGROUND

Long-term occupational exposure to cotton dust that contains endotoxin is associated with chronic respiratory symptoms and excessive decline in forced expiratory volume in 1 sec (FEV1), but the mechanisms of endotoxin-related chronic airflow obstruction remain unclear.

OBJECTIVE

In the current study, we examined temporal aspects of the exposure-response relationship between airborne endotoxin exposure, longitudinal change in FEV1, and respiratory symptoms in a cohort of Chinese cotton textile workers.

METHODS

This prospective cohort study followed 447 cotton textile workers from 1981 to 2006. at approximately 5-year intervals. We used a generalized estimating equations approach to model FEV1 level and respiratory symptoms as a function of past exposure (cumulative exposure up to the start of the most recent 5-year survey interval) and cumulative exposure (within the most recent interval) to endotoxins, after adjusting for other covariates. Models were stratified by active versus retired work status and by years employed before the baseline survey (< 5 and > or = 5 years).

RESULTS AND CONCLUSIONS

Past exposure to endotoxin was associated with reduced FEV1 level among retired cotton workers. Among all cotton workers, past exposure was more strongly associated with reduced FEV1 for those hired < 5 years before baseline than for those who were hired > or = 5 years after baseline. Recent endotoxin exposure was significantly associated with byssinosis, chronic bronchitis, and chronic cough.

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.

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.

Fractionation of swine barn dust and assessment of its impact on the respiratory tract following repeated airway exposure

The effects of repeated exposure to a range of doses of swine barn dust (SBD) on airway hyperresponsiveness (AHR) and inflammation were evaluated using a mouse model system. A number of components, including endotoxin and a number of feed proteins, were identified in SBD, and mice were exposed 20 min/d for 14 d to a log dilution series of nebulized SBD suspensions. AHR to methacholine was measured using head-out whole-body plethysmography, and the methacholine concentration inducing a 20% decrease in pulmonary airflow (PC(20) MCh) was calculated. At the end of the 14-d exposure period, bronchoalveolar lavage (BAL) fluids were recovered, cytokines (interleukin [IL]-1beta, IL-6, keratinocyte-derived chemokine [KC], and tumor necrosis factor [TNF]) in BAL were measured by enzyme-linked immunosorbent assay (ELISA), and leukocytes in BAL were counted. The PC(20) MCh was significantly lower in the group of mice that were exposed to the highest concentration of SBD than in controls or the group exposed to the lowest level of dust. Likewise, the group that was exposed to the highest level of SBD had significantly higher levels of IL-1beta, KC, and TNF than controls and some other groups. There were substantially more lymphocytes and monocytes in the BAL from mice that were exposed to the higher levels of SBD for the 14-d period, but neutrophils were not a part of this response. The SBD exposures used in these experiments induced chronic inflammatory phenotype responses, as indicated by the predominance of lymphocytes and monocytes, but not neutrophils, in BAL and by inflammatory cytokines detected. The association between the PC(20)MCh and dose of SBD suggests that a threshold of susceptibility occurs after a relatively low, chronic exposure to SBD.

Detection of occult lung impairment in welders by induced sputum particles and breath oxidation

BACKGROUND

We evaluated particulate matter in combined induced sputum (IS) and oxidation in exhaled breath condensate (EBC) to test whether underlying inflammatory changes are present in asymptomatic welders.

METHODS

Thirty welders from the Israel Defense Forces exposed to aluminum/iron (Group 1) or to cadmium/chromium/iron/lead/nickel (Group 2, N = 16) and 27 non-exposed administrators were studied. IS was recovered, particle size distribution, hydrogen peroxide and pH were measured, and exhaled breath condensate was collected.

RESULTS

Group 2 had a higher % neutrophils than all other participants (P = 0.0001) and a higher % particles >2 microm in diameter (P = 0.0017). Percent particles and years of exposure highly correlated (P = 0.051). All welders EBC samples had higher concentrations of hydrogen peroxide than controls (P = 0.0001). pH was lower only for Group 2 (P = 0.0001).

CONCLUSIONS

Combined IS and EBC measurements detect underlying inflammation in airways of asymptomatic welders. It emerged that airway inflammation is present in asymptomatic welders, and that the particle burden, inflammatory cells, and level of oxidative stress are a function of the type and the duration of welding. Am. J. Ind. Med. 51:503-511, 2008.

In vitro production of tumor necrosis factor-alpha by human monocytes stimulated with lipopolysaccharide is positively correlated with increased blood monocytes after exposure to a swine barn

Recently there has been interest in the air quality in and around intensive livestock production facilities, such as modern swine production barns, where agricultural workers and surrounding residents may be exposed to elevated levels of organic dusts. The health effects of these exposures are not completely understood. The study that is reported here is a component of a larger investigation of the relationships among the acute effects of high-concentration endotoxin exposure (swine barn dust), polymorphisms in the TLR4 gene, and respiratory outcomes following exposure to swine confinement buildings. The relationships among a mediator of acute lung inflammation, tumor necrosis factor alpha (TNF-alpha), and clinical responses to acute swine barn exposure were characterized. Analysis of the results showed that in vitro stimulation of human monocytes with as little as 1 ng/ml of lipopolysaccharide (LPS) produced a significant increase in the monocytes that produced TNF-alpha. Although the proportion of TNF-alpha-positive monocytes after in vitro stimulation with 1 ng/ml of LPS was not associated with gender or TLR4 genotype, it was positively associated with the concentration of monocytes in blood after barn exposure. Thus, these two responses to different forms of LPS exposure are significantly correlated, and more responsive monocytes in vitro indicate a forthcoming relative monocytosis, post barn exposure, which may initiate a cascade of chronic inflammation.

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.