Exposure-affecting factors of dairy farmers' exposure to inhalable dust and endotoxin

A Cross Sectional Study of Respiratory and Allergy Status in Dairy Workers

INTRODUCTION

Workers on dairy farms face exposures to organic dusts and endotoxin. At the same time, a number of studies of farmers have reported a lower prevalence of asthma in farmworkers compared to persons without farm contact. The "hygiene hypothesis" suggests that early life exposures on farms could be protective against allergic disease and asthma. Such protective relationships are less well studied in adult farm workers.

METHODS

A cross-sectional analysis of respiratory function and allergy status was performed in a sample of dairy farm workers (n = 42) and community controls (n = 40). Measures of respiratory status (spirometry, exhaled nitric oxide FeNO, self-reported symptoms) and levels of total and bovine-specific IgE were compared between the groups.

RESULTS

Prevalence of self-reported asthma and most respiratory symptoms was similar in the two groups, with the exception of increased report of dyspnea among dairy workers. In the dairy workers, level of lung function was not reduced and FeNO was not increased. In unadjusted and adjusted models, dairy work was not associated with reduced lung function or increased airway inflammation. Mean IgE levels did not differ significantly between workers and controls, but elevated bovine-specific IgE was detected only among dairy workers, with an apparent association between elevated bovine IgE and increased FeNO.

CONCLUSION

While dairy workers did not demonstrate increased asthma prevalence compared to controls, sensitization to bovine antigen in several workers appeared to be associated with airway inflammation. Occupational health programs for dairy workers should consider the risk of animal allergy as part of respiratory health protection efforts.

Lung Health in Farming: A Scoping Review

OBJECTIVE

Lung disease is now recognized as an associated occupational hazard among farming and agricultural communities, however limited research surrounds lung health knowledge within our farming population. It is clear from this limited lack of knowledge that farming practices, perceptions and ideas relating to lung health are yet to be uncovered. This scoping review was conducted to identify what is known about lung health within farming and agricultural communities globally and to map the available evidence relating to lung health and lung health decline within this population. The objectives of this review were (1) focus on available lung health research from a global perspective specific to farming and agriculture relating to occupational lung exposures and (2) consolidate current knowledge, clearly identifying gaps within the literature.

METHODS

This systematic scoping review of the literature is guided by the Joanna Briggs Institute Methodology framework. There were 22 studies eligible for inclusion within the scoping review, providing an up-to-date review of research conducted on lung health and lung disease in farming occupations.

RESULTS

Results were grouped into three categories emerging from included studies: (1) focused on the prevalence of respiratory symptoms/disease within farming and agricultural occupations, (2) measurements of dust and particulate matter and correlating these with respiratory conditions, (3) common respiratory conditions linked to a decline in lung health among farming and agricultural occupations. Results identified no study focused on or referred to lung health, lung health knowledge or lung health awareness as an outcome, with all studies focusing on respiratory symptoms, development of lung disease and the common occupational hazards this population are exposed to.

CONCLUSION

This scoping review demonstrates the lack of literature to specifically map available evidence relating to lung health and farming occupations. Many respiratory symptoms and conditions can arise directly and indirectly from agricultural environments, however many of these cases could be prevented by lung health knowledge within the farming population. The results of this scoping review will be used to inform knowledge, awareness, education, health promotion and future research within this population.

Production of composted recycled manure solids from a Canadian dairy farm: Impact on microbial air quality in experimental conditions

Recycled manure solids (RMS) produced in dairy farms from fresh manure need to be sanitized before using them as bedding material. However, the impact on air quality of composting RMS remains unknown. Four RMS composting methods were tested during a 10-day aging of piles in experimental chambers: static windrow (SW), turned windrow (TW), SW following drum composting for 24 h (DC24) or SW following drum composting for 72 h (DC72). Air samples were collected using a SASS®3100 Dry Air Sampler on days 0 (pilling of the RMS), 5, and 10. Bacteria (16S rRNA genes), Penicillium/Aspergillus, A fumigatus, and 11 human pathogenic bacteria (e.g. Klebsiella pneumonia) were quantified by qPCR while endotoxins and dust particles were, respectively, measured by LAL assays and with a DustTrak^TM DRX Aerosol Monitor. On day 0, RMS produced by SW and TW yielded the lowest concentrations of airborne bacteria, while DC24 resulted in the lowest levels of Penicillium/Aspergillus and dust particles. SW method led on day 5 to the lowest concentration of bacteria and Penicillium/Aspergillus, and DC24 and DC72 to the lowest concentration of airborne dust. On day 10, SW and TW piles were associated with the lowest levels of Penicillium/Aspergillus and dust particles. A significant difference was observed between concentration of airborne bacteria, Penicillium/Aspergillus and endotoxins before and during the turnover of TW piles. None of the studied human pathogens was detected in the air samples. Results of the present study suggest that SW and TW are the most promising methods for the production of composted RMS with respect to microbial air quality. However, the experimental chambers do not accurately represent commercial dairy barns and further research on these composting methods is necessary. Finally, the study highlights that bedding material and its management may be determinant factors for air quality in dairy barns.Implications: The research evaluated the impact on microbial air quality of composting recycled manure solids (RMS) produced from fresh cow manure. RMS need to be composted or sanitized before using them as bedding material for animals. The impact on animal health of RMS still needs to be confirmed, while the effect on air quality and the health of dairy farmers is unknown. In the present study, microbial air quality associated with four RMS composting methods was investigated. Data revealed that two methods resulted in lower aerosolization of dust particles, endotoxins, molds, and bacteria.

Characterization of cultivable airborne bacteria and their antimicrobial resistance pattern in French milking parlour

The main goal of this preliminary study was to quantify airborne particles and characterize the dominant cultivable bacterial species as well as some Gram-positive species, and their antibiotic resistance pattern, from environmental samples taken inside and outside of a dairy milking parlour. Sampling was performed over 2 days, in different seasons. The small viable particulate matter < 10 μm (bioaerosols) and cultivable bacteria reached their highest concentrations in the milking parlour. The majority of airborne bacteria in the milking parlour belonged to the genera Staphylococcus (41.9%) and Bacillus (20.9%). A total of 32 different bacterial species of Staphylococcus, Aerococcus, Bacillus, Pseudomonas, Serratia and Acinetobacter were identified. Many of these bacteria may be opportunistic pathogens, causing disease in humans or animals. We found low levels of acquired resistance to the antibiotics commonly used in human or animal infections caused by these opportunistic bacteria. More specifically, resistance to tetracyclines (13.4%), penicillin G (13.4%) and macrolides (7.5%) was identified in Staphylococcus sp. as was a methicillin-resistant S. hominis and resistance to spiramycin (n = 1), lincomycin (n = 1) and streptomycin (n = 2) in Aerococcus sp. An assessment of the occupational risk run by dairy farmers for contracting infections after long- or short-term exposure to micro-organisms requires further studies on the concentration of opportunistic pathogenic bacteria in dairy farm environments.

Never-smokers with occupational COPD have better exercise capacities and ventilatory efficiency than matched smokers with COPD

Chronic obstructive pulmonary disease (COPD) in never-smokers exposed to organic dusts is still poorly characterized. Therapeutic strategies in COPD are only evaluated in smoking-related COPD. Understanding how never-smokers with COPD behave during exercise is an important prerequisite for optimal management. The objective of this study was to compare physiological parameters measured during exercise between never-smokers with COPD exposed to organic dusts and patients with smoking-related COPD matched for age, sex, and severity of airway obstruction. Healthy control subjects were also studied. Dyspnea (Borg scale), exercise tolerance, and ventilatory constraints were assessed during incremental cycle cardiopulmonary exercise testing in COPD patients at mild to moderate stages [22 exposed to organic dusts: postbronchodilator forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) z score -2.44 ± 0.72 and FEV₁ z score -1.45 ± 0.78; 22 with smoking-related COPD: FEV₁/FVC z score -2.45 ± 0.61 and FEV₁ z score -1.43 ± 0.69] and 44 healthy control subjects (including 22 never-smokers). Despite the occurrence of similar significant dynamic hyperinflation, never-smoker COPD patients exposed to organic dusts had lower dyspnea ratings than those with smoking-related COPD. They also had better ventilatory efficiency, higher peak oxygen consumption and peak power output than smoking-related COPD patients, all these parameters being similar to control subjects. Differences in exercise capacity between the two COPD groups were mainly driven by better ventilatory efficiency stemming from preserved diffusion capacity. Never-smokers exposed to organic dusts with mild to moderate COPD have better exercise capacities, better ventilatory efficiency, and better diffusion capacity than matched patients with smoking-related COPD.NEW & NOTEWORTHY It is unknown whether or not never-smokers with chronic obstructive pulmonary disease (COPD) behave like their smoking counterparts during exercise. This is the first study showing that never-smokers with mild to moderate COPD [defined by a postbronchodilator forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) < lower limit of normal] have preserved exercise capacities. They also have lower exertional dyspnea than patients with smoking-related COPD. This suggests that the two COPD groups should not be managed in the same way.

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.

Characterization of inhalable endotoxin, glucan, and dust exposures in Iowa farmers

BACKGROUND

The observed deficit of lung cancer in farmers has been partly attributed to exposure to organic dusts and endotoxins based largely on surrogate metrics. To move beyond these surrogates for etiological studies, we characterized task-based and time-weighted average (TWA) exposure to inhalable endotoxin, (1 → 3)-β-D-glucan, and dust in Iowa farmers.

METHODS

We collected 320 personal inhalable dust samples from 32 farmers during 69 sample days in 2015 and 2016. Samples were collected using Button aerosol samplers and analyzed for endotoxin using a kinetic chromogenic amebocyte lysate assay, and for (1 → 3)-β-D-glucan using a Limulus endpoint assay. We assessed relationships between bioaerosol concentrations and selected tasks and farm characteristics using linear mixed-effects models.

RESULTS

Bedding work, hog handling, and working in barn/confinement buildings, grain bins, and grain elevators were associated with higher endotoxin exposure. We found a monotonic trend between higher endotoxin concentrations and increasing number of animals. Bedding work, cleaning, and feed/grain storage work were associated with higher (1 → 3)-β-D-glucan concentrations. The median concentrations by task spanned one order of magnitude for inhalable dust and two orders of magnitude for endotoxin and (1 → 3)-β-D-glucan. Pearson correlations between endotoxin and glucan concentrations were 0.22 for TWA exposure and 0.56 for task samples.

CONCLUSIONS

This characterization of exposure factors that influence bioaerosol concentrations can support the development of refined bioaerosol exposure metrics for future etiologic analyses of cancer and other health outcomes in farmers.

A Review of Potential Public Health Impacts Associated With the Global Dairy Sector

Strong demand for dairy products has led to a global increase in dairy production. In many parts of the world, dairy systems are undergoing rapid intensification. While increased production may contribute to food security, higher dairy stocking rates in some regions have resulted in increased pressure on natural resources with the potential to affect public health and wellbeing. The aim of this review was to identify and describe the potential health harms and benefits associated with dairy production and consumption. Electronic databases Medline, Embase, Scopus, Web of Science, PubMed, and Google Scholar were searched for published literature that investigated human health impacts of dairy production and consumption. Occupational hazards, environmental health impacts, ecosystem health impacts, foodborne hazards, and diet-related chronic diseases were identified as potential public health hazards. Some impacts, notably climate change, extend beyond directly exposed populations. Dairy production and consumption are also associated with important health benefits through the provision of nutrients and economic opportunities. As the global dairy sector increases production, exposure to a range of hazards must be weighed with these benefits. The review of impacts presented here can provide an input into decision making about optimal levels of dairy production and consumption, local land use, and identification and management of specific hazards from this sector. Future research should consider multiple exposure routes, socioeconomic implications, and environmental factors, particularly in regions heavily dependent on dairy farming.

Asthma and Chronic Obstructive Pulmonary Disease Associated With Occupational Exposure in Dairy Farmers - Importance of Job Exposure Matrices

AIM

To evaluate the prevalence of chronic respiratory symptoms, lung function impairment, and chronic obstructive respiratory diseases in dairy farmers. Our objective is to then examine their relation to exposure duration and to explore the usefulness of job exposure matrices as tools for exposure assessment, and predictors for respiratory health impairment.

METHODS

A cross-sectional study was performed, including 83 dairy farmers (mean age: 52.6 ± 8.7 years; mean exposure duration: 23.7 ± 7.6 years) and 80 office workers as a control group (mean age: 52.7 ± 8.2 years) matched for age, smoking habits, and socioeconomic status. Methods of evaluating examined subjects included a questionnaire on respiratory symptoms in the last 12 months, spirometry and histamine challenge, as well as the use of job exposure matrices (JEM).

RESULTS

Dairy farmers had a significantly higher prevalence of cough (38.5), phlegm (27.7%), and wheezing (21.7%), than controls (p < 0.05). All mean baseline spirometric parameters were lower in dairy farmers compared to the controls, but statistical significance was confirmed only for MEF25, MEF50, and MEF75% (p = 0.010, p = 0.001, and p = 0.004, respectively). The prevalence of bronchial hyperresponsiveness, asthma, and chronic obstructive pulmonary disease was higher in dairy farmers but without statistical significance. JEM were useful tools for exposure assessment and predictors of factors for asthma and COPD development.

CONCLUSION

The results suggest that occupational exposure among crop farmers is associated with a higher prevalence of respiratory symptoms, lung function impairment, and a higher prevalence of chronic respiratory diseases. JEM showed good potential for farming exposure evaluation and promoted their applicability within the diagnostic algorithm focused on respiratory health assessment.

Bioaerosol Sampler Choice Should Consider Efficiency and Ability of Samplers To Cover Microbial Diversity

Bioaerosol studies aim to describe the microbial content and increase understanding of the aerosolization processes linked to diseases. Air samplers are used to collect, identify, and quantify bioaerosols. Studies comparing the performances of air samplers have typically used a culture approach or have targeted a specific microorganism in laboratory settings. The objective of this study was to use environmental field samples to compare the efficiencies of 3 high-airflow-rate samplers for describing bioaerosol diversity using a next-generation sequencing approach. Two liquid cyclonic impactors and one electrostatic filter dry sampler were used in four wastewater treatment plants to target bacterial diversity and in five dairy farms to target fungal diversity. The dry electrostatic sampler was consistently more powerful in collecting more fungal and bacterial operational taxonomic units (OTUs). Substantial differences in OTU abundances between liquid and dry sampling were revealed. The majority of the diversity revealed by dry electrostatic sampling was not identified using the cyclonic liquid impactors. The findings from this work suggest that the choice of a bioaerosol sampler should include information about the efficiency and ability of samplers to cover microbial diversity. Although these results suggest that electrostatic filters result in better coverage of the microbial diversity among the tested air samplers, further studies are needed to confirm this hypothesis. While it is difficult to determine a single universally optimal air sampler, this work provides an in-depth look at some of the considerations that are essential when choosing an air sampler for studying the microbial ecology of bioaerosols.IMPORTANCE Associating bioaerosol exposure and health problems is challenging, and adequate exposure monitoring is a priority for scientists in the field. Conclusions that can be drawn from bioaerosol exposure studies are highly dependent on the design of the study and the methodologies used. The air sampling strategy is the first methodological step leading to an accurate interpretation of what is present in the air. Applying new molecular approaches to evaluate the efficiencies of the different types of samplers used in the field is necessary in order to circumvent traditional approaches and the biases they introduce to such studies. The results and conclusions provided in this paper should be taken in consideration when conducting a bioaerosol study.

Personal exposure of dairy workers to dust, endotoxin, muramic acid, ergosterol, and ammonia on large-scale dairies in the high plains Western United States

Dairy workers experience a high degree of bioaerosol exposure, composed of an array of biological and chemical constituents, which have been tied to adverse health effects. A better understanding of the variation in the magnitude and composition of exposures by task is needed to inform worker protection strategies. To characterize the levels and types of exposures, 115 dairy workers grouped into three task categories on nine farms in the high plains Western United States underwent personal monitoring for inhalable dust, endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, ergosterol, and ammonia through one work shift. Eighty-nine percent of dairy workers were exposed to endotoxin at concentrations exceeding the recommended exposure guidelines (adjusted for a long work shift). The proportion of workers with exposures exceeding recommended guidelines was lower for inhalable dust (12%), and ammonia (1%). Ergosterol exposures were only measurable on 28% of samples, primarily among medical workers and feed handlers. Milking parlor workers were exposed to significantly higher inhalable dust, endotoxin, 3-OHFA, ammonia, and muramic acid concentrations compared to workers performing other tasks. Development of large modern dairies has successfully made progress in reducing worker exposures and lung disease prevalence. However, exposure to endotoxin, dust, and ammonia continues to present a significant risk to worker health on North American dairies, especially for workers in milking parlors. This study was among the first to concurrently evaluate occupational exposure to assayable endotoxin (lipid A), 3-hydroxy fatty acids or 3-OHFA (a chemical measure of cell bound and noncell-bound endotoxins), muramic acid, ergosterol, and ammonia among workers on Western U.S. dairies. There remains a need for cost-effective, culturally acceptable intervention strategies integrated in OHS Risk Management and production systems to further optimize worker health and farm productivity.

Spatial Variation of Endotoxin Concentrations Measured in Ambient PM10 in a Livestock-Dense Area: Implementation of a Land-Use Regression Approach

BACKGROUND

Results from studies on residential health effects of livestock farming are inconsistent, potentially due to simple exposure proxies used (e.g., livestock density). Accuracy of these proxies compared with measured exposure concentrations is unknown.

OBJECTIVES

We aimed to assess spatial variation of endotoxin in PM₁₀ (particulate matter ≤10μm) at residential level in a livestock-dense area, compare simple livestock exposure proxies to measured endotoxin concentrations, and evaluate whether land-use regression (LUR) can be used to explain spatial variation of endotoxin.

METHODS

The study area (3,000km²) was located in Netherlands. Ambient PM₁₀ was collected at 61 residential sites representing a variety of surrounding livestock-related characteristics. Three to four 2-wk averaged samples were collected at each site. A local reference site was used for temporal variation adjustment. Samples were analyzed for PM₁₀ mass by weighing and for endotoxin by using the limulus amebocyte lysate assay. Three LUR models were developed, first a model based on general livestock-related GIS predictors only, followed by models that also considered species-specific predictors and farm type-specific predictors.

RESULTS

Variation in concentrations measured between sites was substantial for endotoxin and more limited for PM₁₀ (coefficient of variation: 43%, 8%, respectively); spatial patterns differed considerably. Simple exposure proxies were associated with endotoxin concentrations although spatial variation explained was modest (R²<26%). LUR models using a combination of animal-specific livestock-related characteristics performed markedly better, with up to 64% explained spatial variation.

CONCLUSION

The considerable spatial variation of ambient endotoxin concentrations measured in a livestock-dense area can largely be explained by LUR modeling based on livestock-related characteristics. Application of endotoxin LUR models seems promising for residential exposure estimation within health studies. https://doi.org/10.1289/EHP2252.

Size, Composition, and Source Profiles of Inhalable Bioaerosols from Colorado Dairies

Particulate matter emissions from agricultural livestock operations contain both chemical and biological constituents that represent a potential human health hazard. The size and composition of these dusts, however, have not been well described. We evaluated the full size distribution (from 0 to 100 μm in aerodynamic diameter) and chemical/biological composition of inhalable dusts inside several Colorado dairy parlors. Four aerodynamic size fractions (<3, 3-10, 10-30, and >30 μm) were collected and analyzed using a combination of physiochemical techniques to understand the structure of bacterial communities and chemical constituents. Airborne particulate mass followed a bimodal size distribution (one mode at 3 μm and a second above 30 μm), which also correlated with the relative concentrations of the following microbiological markers: bacterial endotoxin, 3-hydroxy fatty acids, and muramic acid. Sequencing of the 16S-rRNA components of this aerosol revealed a microbiome derived predominantly from animal sources. Bacterial genera included Staphlyococcus, Pseudomonas, and Streptococcus, all of which have proinflammatory and pathogenic capacity. Our results suggest that the size distribution of bioaerosols emitted by dairy operations extends well above 10 μm in diameter and contains a diverse mixture of potentially hazardous constituents and opportunistic pathogens. These findings should inform the development of more effective emissions control strategies.

Pulmonary function and airway inflammation among dairy parlor workers after exposure to inhalable aerosols

BACKGROUND

Inhalation exposure to organic dust causes lung inflammation among agricultural workers. Due to changes in production and work organization, task-based inhalation exposure data, including novel lung inflammation biomarkers, will inform exposure recommendations for dairy farm workers.

METHODS

Linear regression was used to estimate the associations of airborne exposure to dust concentration, endotoxin, and muramic acid with pulmonary outcomes (i.e., FEV₁ , exhaled nitric oxide). Logistic regression was used to estimate associations with self-reported pulmonary symptoms.

RESULTS

Mean exposure concentration to inhalable dust, endotoxin, and muramic acid were 0.55 mg/m³ , 118 EU/m³ , and 3.6 mg/m³ , respectively. We found cross-shift differences for exhaled nitric oxide (P = 0.005) and self-reported pulmonary symptoms (P = 0.008) but no association of exposure with respiratory outcomes.

CONCLUSIONS

Inhalation exposures during parlor tasks, which were lower than previously reported and were not associated with cross-shift measures of pulmonary health among dairy workers. Modern milking parlor designs may be contributing to lower inhalation exposure. Am. J. Ind. Med. 60:255-263, 2017. © 2017 Wiley Periodicals, Inc.

Feedback on Measured Dust Concentrations Reduces Exposure Levels Among Farmers

BACKGROUND

The high burden of exposure to organic dust among livestock farmers warrants the establishment of effective preventive and exposure control strategies for these workers. The number of intervention studies exploring the effectiveness of exposure reduction strategies through the use of objective measurements has been limited.

OBJECTIVE

To examine whether dust exposure can be reduced by providing feedback to the farmers concerning measurements of the exposure to dust in their farm.

METHODS

The personal dust levels of farmers in 54 pig and 26 dairy cattle farms were evaluated in two measurement series performed approximately 6 months apart. Detailed information on work tasks and farm characteristics during the measurements were registered. Participating farms were randomized a priori to a control (n = 40) and an intervention group (n = 40). Shortly after the first visit, owners of intervention farms only received a letter with information on the measured dust concentrations in the farm together with some general advises on exposure reduction strategies (e.g. use of respirators during certain tasks). Relationships between measured dust concentrations and intervention status were quantified by means of linear mixed effect analysis with farm and worker id as random effects. Season, type of farming, and work tasks were treated as fixed effects. Changes in exposure over time were explored primarily at a farm level in models combined, as well as separate for pig and cattle farmers.

RESULTS

After adjustment for fixed effects, an overall reduction of 23% in personal dust exposures was estimated as a result of the intervention (P = 0.02). Exposure reductions attributable to the intervention were similar across pig and cattle farmers, but statistically significant only for pig farmers. Intervention effects among pig farmers did not depend on the individuals' information status; but among cattle farmers a significant 48% reduction in exposure was found only among individuals that reported to have been informed. No systematic differences in changes over time considering the use of respiratory protection between the intervention and control groups were observed.

CONCLUSION

The results of the present study suggest reductions between 20 and 30% in personal exposure to inhalable dust to be feasible through simple information provided to the farm owners regarding actual levels of exposure together with instructions on basic measures of prevention. The exact reasons for these effects are unclear, but likely they involve changes in behavior and working practices among intervention farmers.

Cow hair allergen concentrations in dairy farms with automatic and conventional milking systems: From stable to bedroom

Bovine hair and dander are considered to be a notable risk factor for sensitization and allergic symptoms in occupationally exposed cattle farmers due to various IgE binding proteins. Farmers are suspected not only to be exposed during their work inside the stables but also inside their homes as allergens could be transferred via hair and clothes resulting in continued bovine allergen exposure in private areas. In recent years a new sensitive sandwich ELISA (enzyme linked immunosorbent assay) test has been developed to measure the cow hair allergen (CHA) concentration in dust. The aim of the present study was to determine the CHA concentration in airborne and settled dust samples in stables and private rooms of dairy cattle farms with automatic milking systems (AM) and conventional milking systems (CM), also with respect to questionnaire data on farming characteristics. For this purpose different sampling techniques were applied, and results and practicability of the techniques were compared. Dust sampling was performed in the stable, computer room (only AM), changing room, living room and bedroom (mattress) of 12 dairy farms with automatic milking systems (AM group) and eight dairy farms with conventional milking systems (CM group). Altogether, 90 samples were taken by ALK filter dust collectors from all locations, while 32 samples were collected by an ion charging device (ICD) and 24 samples by an electronic dust fall collector (EDC) in computer rooms (AM) and/or changing and living rooms (not stables). The dust samples were extracted and analyzed for CHA content with a sandwich ELISA. At all investigated locations, CHA concentrations were above the limit of detection (LOD) of 0.1 ng/ml dust extract. The median CHA concentrations in dust collected by ALK filters ranged from 63 to 7154 μg/g dust in AM farms and from 121 to 5627 μg/g dust in CM farms with a steep concentration gradient from stables to bedrooms. ICD sampling revealed median CHA contents of 112 μg/g airborne dust in the computer rooms of the AM farms and median CHA loads of 5.6 μg/g (AM farms) and 19.8 μg/g (CM farms) in the living rooms. Passive dust sampling by EDC was performed only at two locations in the AM group resulting in median CHA values of 116 μg/m(2) (computer room) and 55.0 μg/m(2) (changing room). Except for the stable samples the median CHA load was lower in AM farms compared to CM farms. The CHA contents of ALK filter samples were significantly correlated in most locations. Differences between the farming types were not significant. Although allergen transfer to the private area of the farmers has been found and results from several locations were correlated, differences in CHA concentrations were not significant with respect to questionnaire data such as the wearing of stable clothes in living room, free access of pets to stable and home, frequency of hair washing. All sampling techniques seem to being practicable for simple and effective CHA measurement.

Exposure levels, determinants and IgE mediated sensitization to bovine allergens among Danish farmers and non-farmers

BACKGROUND

Bovine allergens can induce allergic airway diseases. High levels of allergens in dust from stables and homes of dairy farmers have been reported, but sparse knowledge about determinants for bovine allergen levels and associations between exposure level and sensitization is available.

OBJECTIVE

To investigate levels and determinants of bovine allergen exposure among dairy, pig and mink farmers (bedroom and stable), and among former and never farmers (bedroom), and to assess the prevalence of bovine allergen sensitization in these groups.

METHODS

In 2007-2008, 410 settled dust samples were collected in stables and in bedrooms using an electrostatic dust-fall collector over a 14 day period among 54 pig farmers, 27 dairy farmers, 3 mink farmers as well as 71 former and 48 never farmers in Denmark. For farmers sampling was carried out both during summer and winter. Bovine allergen levels (μg/m(2)) were measured using a sandwich ELISA. Determinants for bovine allergen exposure in stables and bedrooms were explored with mixed effect regression analyses. Skin prick test with bovine allergen was performed on 48 pig farmers, 20 dairy farmers, 54 former and 31 never farmers.

RESULTS

Bovine allergen levels varied by five orders of magnitude, as expected with substantially higher levels in stables than bedrooms, especially for dairy farmers. Bovine allergen levels in bedrooms were more than one order of magnitude higher for dairy farmers compared to pig farmers. Former and never farmers had low levels of bovine allergens in their bedroom. Bovine allergen levels during summer appeared to be somewhat higher than during winter. Increased bovine allergen levels in the bedroom were associated with being a farmer or living on a farm. Mechanical ventilation in the bedroom decreased bovine allergen level, significant for dairy farmers β=-1.4, p<0.04. No other significant effects of either sampling or residence characteristics were seen. Allergen levels in dairy stables were associated to type of dairy stable, but not to other stable or sampling characteristics. Sensitization to bovine allergens was only found in one pig farmer.

CONCLUSION

This study confirms high bovine allergen levels in dairy farms, but also suggests sensitization to bovine allergens among Danish farmers to be uncommon. Furthermore the importance of a carrier home effect on allergen load is emphasized. Whether the risk for bovine sensitization is related to the allergen level in the stable or the dwelling remains to be determined.

Dust, endotoxin, fungi, and bacteria exposure as determined by work task, season, and type of plant in a flower greenhouse

BACKGROUND

Greenhouse workers are exposed to dust, endotoxin, fungi, and bacteria potentially causing airway inflammation as well as systemic symptoms. Knowledge about determinants of exposure is a prerequisite for efficient prevention through knowledge-based reduction in exposure. The objective of this study was to assess the occupational exposure in a flower greenhouse and to investigate the impact of work tasks on the intensity and variability in exposure.

METHODS

Seventy-six personal full-shift exposure measurements were performed on 38 employees in a Danish flower greenhouse producing Campanula, Lavandula, Rhipsalideae, and Helleborus. The samples were gravimetrically analysed for inhalable dust. Endotoxin was assessed by the Limulus Amoebocyte Lysate test and culture-based quantification of bacteria and fungi was performed. Information on the performed tasks during sampling was extracted from the greenhouse electronic task logging system. Associations between log-transformed exposure outcomes, season, and work tasks were examined in linear mixed-effects regression with worker identity as random effect.

RESULTS

Measured concentrations ranged between 0.04 and 2.41mg m(-3) for inhalable dust and between 0.84 and 1097 EU m(-3) for endotoxin exposure, with the highest mean levels measured during Lavandula and Campanula handling, respectively. Personal exposure to fungi ranged between 1.8×10(2) and 3.4×10(6) colony-forming units (CFU) m(-3) and to bacteria between 1.6×10(1) and 4.2×10(5) CFU m(-3). Exposure to dust, endotoxin, fungi, and bacteria differed between seasons. Packing Lavandula, sticking, potting, and grading Rhipsalideae, and all examined tasks related to Campanula production except sticking increased dust exposure. Endotoxin exposure was increased during sticking Campanula and pinching or packing Rhipsalideae, and fungi exposure was elevated by subtasks performed in the research and development area for Campanula, and by potting, packing/dumping Campanula. Sticking and working with subtasks in the research and development area for Campanula increased bacteria exposure.

CONCLUSION

This study revealed moderate dust exposure levels compared to the levels observed in other greenhouse productions and other occupations with organic dust exposure such as farming. However, high exposures to bacteria and fungi were detected during selected tasks and the proposed health-based endotoxin exposure limit of 90 EU m(-3) was exceeded in 30% of the samples, which may have health implications for the employees. Exposure levels were found to vary depending on the tasks performed, and thereby results can be used to direct task-based initiatives to reduce workplace exposures.