Exposure to inhalable dust and endotoxin among Danish pig farmers affected by work tasks and stable characteristics

Validation of a full-shift benzene exposure empirical model developed for work on offshore petroleum installations on the Norwegian continental shelf

Workers on offshore petroleum installations might be exposed to benzene, a carcinogenic agent. Recently, a full-shift benzene exposure model was developed based on personal measurements. This study aimed to validate this exposure model by using datasets not included in the model. The exposure model was validated against an internal dataset of measurements from offshore installations owned by the same company that provided data for the model, and an external dataset from installations owned by another company. We used Tobit regression to estimate GM (geometric mean) benzene exposure overall and for individual job groups. Bias, relative bias, precision, and correlation were estimated to evaluate the agreement between measured exposures and the levels predicted by the model. Overall, the model overestimated exposure when compared to the predicted exposure level to the internal dataset with a factor of 1.7, a relative bias of 73%, a precision of 0.6, a correlation coefficient of 0.72 (p = 0.019), while the Lin's Concordance Correlation Coefficient (CCC) was 0.53. The model underestimated exposure when compared to the external dataset with a factor of about 2, with a relative bias of -45%, a precision of 1.2, a correlation coefficient of 0.31 (p = 0.544), and a Lin's CCC of 0.25. The exposure model overestimated benzene exposure in the internal validation dataset, while the precision and the correlation between the measured and predicted exposure levels were high. Differences in measurement strategies could be one of the reasons for the discrepancy. The exposure model agreed less with the external dataset.

Particulate Matter in Swine Barns: A Comprehensive Review

Particulate matter (PM) represents an air quality management challenge for confined swine production systems. Due to the limited space and ventilation rate, PM can reach relatively high concentrations in swine barns. PM in swine barns possesses different physical, chemical, and biological characteristics than that in the atmosphere and other indoor environments. As a result, it exerts different environmental and health effects and creates some unique challenges regarding PM measurement and mitigation. Numerous research efforts have been made, generating massive data and information. However, relevant review reports are sporadic. This study aims to provide an updated comprehensive review of swine barn PM, focusing on publications since 1990. It covers various topics including PM characteristics, sources, measurement methods, and in-barn mitigation technologies. As PM in swine barns is primarily of biological origins, bioaerosols are reviewed in great detail. Relevant topics include bacterial/fungal counts, viruses, microbial community composition, antibiotic-resistant bacteria, antibiotic resistance genes, endotoxins, and (1→3)-β-D-glucans. For each topic, existing knowledge is summarized and discussed and knowledge gaps are identified. Overall, PM in swine barns is complicated in chemical and biological composition and highly variable in mass concentrations, size, and microbial abundance. Feed, feces, and skins constitute the major PM sources. Regarding in-barn PM mitigation, four technologies (oil/water sprinkling, ionization, alternation of feed and feeders, and recirculating air filtration) are dominant. However, none of them have been widely used in commercial barns. A collective discussion of major knowledge gaps and future research needs is offered at the end of the report.

Self-reported work activities, eye, nose, and throat symptoms, and respiratory health outcomes among an industrial hog operation worker cohort, North Carolina, USA

INTRODUCTION

Respiratory disease among industrial hog operation (IHO) workers is well documented; however, it remains unclear whether specific work activities are more harmful and if personal protective equipment (PPE), as used by workers, can reduce adverse health outcomes.

METHODS

IHO workers (n = 103) completed baseline and up to eight bi-weekly study visits. Workers reported typical (baseline) and transient (bi-weekly) work activities, PPE use, and physical health symptoms. Baseline and longitudinal associations were assessed using generalized logistic and fixed-effects logistic regression models, respectively.

RESULTS

At baseline, reports of ever versus never drawing pig blood, applying pesticides, and increasing years worked at any IHO were positively associated with reports of eye, nose, and/or throat irritation. Over time, transient exposures, associated with dustiness in barns, cleaning of barns, and pig contact were associated with increased odds of sneezing, headache, and eye or nose irritation, particularly in the highest categories of exposure. When PPE was used, workers had lower odds of symptoms interfering with sleep (odds ratio [OR]: 0.1; 95% confidence interval [CI]: 0.01-0.8), and eye or nose irritation (OR: 0.1; 95% CI: 0.02-0.9). Similarly, when they washed their hands eight times or more per shift (median frequency) versus less frequently, the odds of any respiratory symptom were reduced (OR: 0.3; 95% CI: 0.1-0.8).

CONCLUSIONS

In this healthy volunteer worker population, increasingly unfavorable IHO activities were associated with self-reported eye, nose, throat, and respiratory health symptoms. Strong protective associations were seen between PPE use and handwashing and the odds of symptoms, warranting further investigation.

Every breath you take: Impacts of environmental dust exposure on intestinal barrier function-from the gut-lung axis to COVID-19

As countries continue to industrialize, major cities experience diminished air quality, whereas rural populations also experience poor air quality from sources such as agricultural operations. These exposures to environmental pollution from both rural and populated/industrialized sources have adverse effects on human health. Although respiratory diseases (e.g., asthma and chronic obstructive pulmonary disease) are the most commonly reported following long-term exposure to particulate matter and hazardous chemicals, gastrointestinal complications have also been associated with the increased risk of lung disease from inhalation of polluted air. The interconnectedness of these organ systems has offered valuable insights into the roles of the immune system and the micro/mycobiota as mediators of communication between the lung and the gut during disease states. A topical example of this relationship is provided by reports of multiple gastrointestinal symptoms in patients with coronavirus disease 2019 (COVID-19), whereas the rapid transmission and increased risk of COVID-19 has been linked to poor air quality and high levels of particulate matter. In this review, we focus on the mechanistic effects of environmental pollution on disease progression with special emphasis on the gut-lung axis.

Linking Environmental Exposures to Molecular Pathogenesis in Non-Hodgkin Lymphoma Subtypes

Non-Hodgkin lymphoma comprises a heterogeneous group of hematologic malignancies, with about 60 subtypes that arise via various pathogenetic mechanisms. Although establishing etiology for specific NHL subtypes has been historically difficult given their relative rarity, environmental exposures have been repeatedly implicated as risk factors across many subtypes. Large-scale epidemiologic investigations have pinpointed chemical exposures in particular, but causality has not been established, and the exact biologic mechanisms underpinning these associations are unclear. Here we review chemical exposures that have been associated with development of NHL subtypes and discuss their biologic plausibility based on current research.

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.

Archaea and Bacteria Exposure in Danish Livestock Farmers

Objectives

Methanogenic archaea have been found to make up part of the bioaerosols in pig, cattle, and poultry farms. So far no attempts have been made to determine how season, farm type, and farm characteristics may affect workers’ exposure to archaea.

Methods

Personal filter samples from 327 farmers working on 89 Danish farms were analysed for the number of 16S rRNA gene copies from archaea and bacteria and for their dust and endotoxin content. The farms were visited during summer and winter. Information on farm type and stable characteristics were collected using self-reported activity diaries and walk-through surveys. Differences in archaea and bacteria levels with farm type and stable characteristics and correlations with dust and endotoxin levels were examined.

Results

Personal archaea exposure was documented in all farm types including, for the first time, during mink farming. At 7.3*10⁴ gene copies m⁻³ the archaea levels were around two orders of magnitude lower than bacteria levels at 5.7*10⁶ gene copies m⁻³. At 1.7*10⁵ gene copies m⁻³ among pig farmers and 1.9*10⁴ gene copies m⁻³ among cattle farmers the archaea levels differed with farm type (P < 0.0005). The archaea and bacteria levels correlated weakly with a Pearson correlation coefficient of 0.17. Neither archaea nor bacteria levels differed by season. In pig farms the archaea levels differed by type of ventilation and by wetness of the floor.

Conclusions

Archaea levels were not neglible and appeared to vary greatly between farm types. In pig farms they varied with some farm characteristics. Archaea levels appeared to depend on factors that differed from those of bacteria.

The nasal and oropharyngeal microbiomes of healthy livestock workers

Little information exists on the microbiomes of livestock workers. A cross-sectional, epidemiological study was conducted enrolling 59 participants (26 of which had livestock contact) in Iowa. Participants were enrolled in one of four ways: from an existing prospective cohort study (n = 38), from the Iowa Department of Natural Resources Animal Feeding Operations database (n = 17), through Iowa county fairs (n = 3), and through snowball sampling (n = 1). We collected swabs from the nares and oropharynx of each participant to assess the microbiome via 16s rRNA sequencing. We observed livestock workers to have greater diversity in their microbiomes compared to those with no livestock contact. In the nares, there were 27 operational taxonomic units found to be different between livestock workers and non-livestock workers with the greatest difference seen with Streptococcus and Proteobacteria. In the oropharynx, livestock workers with swine exposure were more likely to carry several pathogenic organisms. The results of this study are the first to characterize the livestock worker nasal and oropharyngeal microbiomes.

Major environmental characteristics of swine husbandry that affect exposure to dust and airborne endotoxins

Inhalation of organic dust or endotoxin in the dust is considered a major risk factor for occupational respiratory illnesses. Eighteen environmental characteristics associated with animal husbandry were surveyed at 36 swine farms in seven provinces throughout South Korea. Association of these factors with levels of indoor inhalable or respirable dust or endotoxin in each type of dust was analyzed using backward stepwise multiple linear regression models. Mean levels of inhalable and respirable dust were 0.5 ± 0.35 and 0.13 ± 0.12 mg/m³ air, respectively, and mean endotoxin levels were 676 ± 463 and 48.4 ± 68.2 EU/m³, respectively, in each dust. Factors negatively associated with inhalable dust levels included pig age, indoor farm temperature, number of pigs in the building, hr/week of indoor farm work, and partly slatted floor. Factors positively associated with inhalable dust levels included floor cleaning by manual scraping and slurry deposit duration. Factors negatively associated with the level of endotoxin in inhalable dust included pig age, temperature, number of pigs, hr/week of indoor farm work, and partly slatted floor. Factors negatively associated with respirable dust level included area of the confinement building, whereas factors positively associated with respirable dust level included the number of pigs and stocking density. Endotoxin levels in respirable dust were negatively associated with h/week of indoor farm work and partly slatted floor. Overall, data suggest that husbandry variables may be adjusted to control dust and airborne endotoxin levels in swine farms.

Face Mask Use and Persistence of Livestock-associated Staphylococcus aureus Nasal Carriage among Industrial Hog Operation Workers and Household Contacts, USA

BACKGROUND

Industrial hog operation (IHO) workers may persistently carry antibiotic-resistant, livestock-associated Staphylococcus aureus in their nasal cavities. It is unclear whether IHO work activities can alter IHO workers' and their household members' exposure to these bacteria.

OBJECTIVE

Our objective was to investigate the relationship of IHO work activities with persistence of antibiotic-resistant, livestock-associated S. aureus nasal carriage among IHO workers and their household members.

METHODS

At biweekly intervals over 4 months, IHO workers and their household members completed questionnaires and provided nasal swabs that were assessed for S. aureus, multidrug-resistant S. aureus (MDRSA), and livestock-associated markers (tetracycline resistance, scn absence, spa type). We examined the association between transient and habitual IHO work activities and S. aureus nasal carriage outcomes.

RESULTS

One hundred one IHO workers and 79 household members completed 1,456 study visits. Face mask use (each 25% increase) was associated with reduced odds of nasal carriage of MDRSA (odds ratio [OR]: 0.65 [95% confidence interval (CI): 0.46, 0.92], tetracycline-resistant S. aureus [OR = 0.74 (95% CI: 0.56, 0.97)], and S. aureus clonal complex (CC) 398/CC9 [OR = 0.77 (95% CI: 0.60, 0.99)]. IHO workers who ever (vs. never) gave pigs injections had higher odds of these outcomes. Among household members, living with an IHO worker who consistently ([Formula: see text] of the time) versus sometimes or never used a face mask was associated with reduced odds of carrying scn-negative S. aureus, tetracycline-resistant S. aureus, and S. aureus CC398/CC9 (OR range: 0.12-0.20, all [Formula: see text]), and consistent IHO worker coveralls use was associated with reduced odds of household member MDRSA carriage only. Living with an IHO worker who habitually had contact with [Formula: see text] hogs (vs. [Formula: see text]) was associated with higher odds of household member livestock-associated S. aureus carriage.

CONCLUSIONS

Consistent face mask use was associated with reduced exposure to antibiotic-resistant, livestock-associated S. aureus among IHO workers and their household members. https://doi.org/10.1289/EHP3453.

Airborne MRSA and Total Staphylococcus aureus as Associated With Particles of Different Sizes on Pig Farms

Airborne methicillin-resistant Staphylococcus aureus (MRSA) have previously been found on pig farms, which may lead to nasal deposition of MRSA in humans via inhalation. The anterior nares are the main niche for S. aureus, and S. aureus can cause, e.g. wound infection and pneumonia. The aim of this study was to acquire knowledge about the potential deposition of airborne MRSA, specifically, and of total S. aureus (including both methicillin-sensitive S. aureus and MRSA, in the following called S. aureus) in the different parts of the airways during occupancy on pig farms. Measurements of airborne MRSA and S. aureus were performed on four pig farms using a six and a three-stage sampler during different work tasks, such as high-pressure cleaning and everyday inspection. MRSA were quantified using MRSA-selective agar, and S. aureus were quantified using Staphylococcus selective agar. The identity of the bacteria were confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The geometric mean (GM) concentrations of MRSA and S. aureus were 447 cfu/m3 air and 1.8 × 103 cfu/m3 air, respectively. The highest concentrations of MRSA and S. aureus were found among pigs in a weaner stable and during high-pressure cleaning of an empty stable, respectively. The lowest concentrations of MRSA and S. aureus were found in a stable with sick pigs and in feed-storages, respectively. Most MRSA and S. aureus were associated with particles between 7 and 12 µm. On average, the particle size fractions potentially depositing in the upper airways constituted 70%, in the primary and secondary bronchi 22%, and in the terminal bronchi and alveoli 8% of the inhalable MRSA and S. aureus concentration. Across the sampled areas, the geometric mean diameter (Dg) of particles with MRSA and S. aureus were 7.2 and 6.4 µm, respectively, and no significant difference was found between these Dgs. The Dg of the airborne particles with the studied bacterium was significantly associated with the different locations on the farms. The largest Dgs were found in the air samples from the aisles and on the fence to the pens, while the smallest Dgs were found in samples from the pens among the pigs and in samples taken at greater distances from the pigs: in the hallway, feed-storage, and entry room. In conclusion, airborne MRSA and S. aureus were found in sample fractions potentially depositing in all six parts of the airways. However, the majority was found to potentially deposit in the upper airways. The concentration of airborne MRSA and S. aureus and MRSA, as well as the fraction potentially depositing in the different parts of the airways, depended on the specific work task being performed and the location on the farm.

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.

Industrial hog farming is associated with altered circulating immunological markers

OBJECTIVES

The previously observed inverse association between hog farming and risk of lung cancer in the Agricultural Health Study (AHS) has been attributed to endotoxin exposure, the levels of which are particularly high in industrial hog confinement facilities. We conducted an investigation to explore the potential biological mechanisms underlying this association, as well as other immunological changes associated with hog farming.

METHODS

Serum immune marker levels were measured using a multiplexed bead-based assay in 61 active hog farmers and 61 controls matched on age, phlebotomy date and raising cattle. Both groups comprised non-smoking male AHS participants from Iowa. We compared natural log-transformed marker levels between hog farmers and controls using multivariate linear regression models.

RESULTS

Circulating levels of macrophage-derived chemokine (CCL22), a chemokine previously implicated in lung carcinogenesis, were reduced among hog farmers (17% decrease; 95% CI -28% to -4%), in particular for those with the largest operations (>6000 hogs: 26% decrease; 95% CI -39% to -10%; p_trend=0.002). We also found that hog farmers had elevated levels of other immune markers, including macrophage inflammatory protein-3 alpha (MIP-3A/CCL20; 111% increase, 95% CI 19% to 273%), basic fibroblast growth factor (FGF-2; 93% increase, 95% CI 10% to 240%) and soluble interleukin-4 receptor (12% increase, 95% CI 1% to 25%), with particularly strong associations for MIP-3A/CCL20 and FGF-2 in winter.

CONCLUSIONS

These results provide insights into potential immunomodulatory mechanisms through which endotoxin or other exposures associated with hog farming may influence lung cancer risk, and warrant further investigation with more detailed bioaerosol exposure assessment.

Performance of prototype high-flow inhalable dust sampler in a livestock production facility

A high-flow inhalable sampler, designed for operational flow rates up to 10 L/min using computer simulations and examined in wind tunnel experiments, was evaluated in the field. This prototype sampler was deployed in collocation with an IOM (the benchmark standard sampler) in a swine farrowing building to examine the sampling performance for assessing concentrations of inhalable particulate mass and endotoxin. Paired samplers were deployed for 24 hr on 19 days over a 3-month period. On each sampling day, the paired samplers were deployed at three fixed locations and data were analyzed to identify agreement and to examine systematic biases between concentrations measured by these samplers. Thirty-six paired gravimetric samples were analyzed; insignificant, unsubstantial differences between concentrations were identified between the two samplers (p = 0.16; mean difference 0.03 mg/m³). Forty-four paired samples were available for endotoxin analysis, and a significant (p = 0.001) difference in endotoxin concentration was identified: the prototype sampler, on average, had 120 EU/m³ more endotoxin than did the IOM samples. Since the same gravimetric samples were analyzed for endotoxin content, the endotoxin difference is likely attributable to differences in endotoxin extraction. The prototype's disposable thin-film polycarbonate capsule was included with the filter in the 1-hr extraction procedure while the internal plastic cassette of the IOM required a rinse procedure that is susceptible to dust losses. Endotoxin concentrations measured with standard plastic IOM inserts that follow this rinsing procedure may underestimate the true endotoxin exposure concentrations. The maximum concentrations in the study (1.55 mg/m³ gravimetric, 2328 EU/m³ endotoxin) were lower than other agricultural or industrial environments. Future work should explore the performance of the prototype sampler in dustier environments, where concentrations approach particulates not otherwise specified (PNOS) limits of 10 mg/m³, including using the prototype as a personal sampler.

Human-livestock contacts and their relationship to transmission of zoonotic pathogens, a systematic review of literature

BACKGROUND

Micro-organisms transmitted from vertebrate animals - including livestock - to humans account for an estimated 60% of human pathogens. Micro-organisms can be transmitted through inhalation, ingestion, via conjunctiva or physical contact. Close contact with animals is crucial for transmission. The role of intensity and type of contact patterns between livestock and humans for disease transmission is poorly understood. In this systematic review we aimed to summarise current knowledge regarding patterns of human-livestock contacts and their role in micro-organism transmission.

METHODS

We included peer-reviewed publications published between 1996 and 2014 in our systematic review if they reported on human-livestock contacts, human cases of livestock-related zoonotic diseases or serological epidemiology of zoonotic diseases in human samples. We extracted any information pertaining the type and intensity of human-livestock contacts and associated zoonoses.

RESULTS

1522 papers were identified, 75 were included: 7 reported on incidental zoonoses after brief animal-human contacts (e.g. farm visits), 10 on environmental exposures and 15 on zoonoses in developing countries where backyard livestock keeping is still customary. 43 studies reported zoonotic risks in different occupations. Occupations at risk included veterinarians, culling personnel, slaughterhouse workers and farmers. For culling personnel, more hours exposed to livestock resulted in more frequent occurrence of transmission. Slaughterhouse workers in contact with live animals were more often positive for zoonotic micro-organisms compared to co-workers only exposed to carcasses. Overall, little information was available about the actual mode of micro-organism transmission.

CONCLUSIONS

Little is known about the intensity and type of contact patterns between livestock and humans that result in micro-organism transmission. Studies performed in occupational settings provide some, but limited evidence of exposure response-like relationships for livestock-human contact and micro-organism transmission. Better understanding of contact patterns driving micro-organism transmission from animals to humans is needed to provide options for prevention and thus deserves more attention.

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.

Air Quality in Alternative Housing Systems May Have an Impact on Laying Hen Welfare. Part I-Dust

The new legislation for laying hens in the European Union put a ban on conventional cages. Production systems must now provide the hens with access to a nest, a perch, and material for dust bathing. These requirements will improve the behavioral aspects of animal welfare. However, when hens are kept with access to litter, it is a concern that polluted air may become an increased threat to health and therefore also a welfare problem. This article reviews the literature regarding the health and welfare effects birds experience when exposed to barn dust. Dust is composed of inorganic and organic compounds, from the birds themselves as well as from feed, litter, and building materials. Dust may be a vector for microorganisms and toxins. In general, studies indicate that housing systems where laying hens have access to litter as aviaries and floor systems consistently have higher concentrations of suspended dust than caged hens with little (furnished cages) or no access to litter (conventional cages). The higher dust levels in aviaries and floor housing are also caused by increased bird activity in the non-cage systems. There are gaps in both the basic and applied knowledge of how birds react to dust and aerosol contaminants, i.e., what levels they find aversive and/or impair health. Nevertheless, high dust levels may compromise the health and welfare of both birds and their caretakers and the poor air quality often found in new poultry housing systems needs to be addressed. It is necessary to develop prophylactic measures and to refine the production systems in order to achieve the full welfare benefits of the cage ban.

Farm animal models of organic dust exposure and toxicity: insights and implications for respiratory health

PURPOSE OF REVIEW

Modern food animal production is a major contributor to the global economy, owing to advanced intensive indoor production facilities aimed at increasing market readiness and profit. Consequences of these advances are accumulation of dusts, gases, and microbial products that diminish air quality within production facilities. Chronic inhalation exposure contributes to onset and exacerbation of respiratory symptoms and diseases in animals and workers. This article reviews literature regarding constituents of farm animal production facility dusts, animal responses to production building and organic dust exposure, and the effect of chronic inhalation exposure on pulmonary oxidative stress and inflammation.

RECENT FINDINGS

Porcine models of production facility and organic dust exposures reveal striking similarities to observations of human cells, tissues, and clinical data. Oxidative stress plays a key role in mediating respiratory diseases in animals and humans, and enhancement of antioxidant levels through nutritional supplements can improve respiratory health.

SUMMARY

Pigs are well adapted to the exposures common to swine production buildings and thus serve as excellent models for facility workers. Insight for understanding mechanisms governing organic dust associated respiratory diseases may come from parallel comparisons between farmers and the animals they raise.

Use of Recirculating Ventilation With Dust Filtration to Improve Wintertime Air Quality in a Swine Farrowing Room

The performance of a recirculating ventilation system with dust filtration was evaluated to determine its effectiveness to improve the air quality in a swine farrowing room of a concentrated animal feeding operation (CAFO). Air was exhausted from the room (0.47 m(3) sec(-1); 1000 cfm), treated with a filtration unit (Shaker-Dust Collector), and returned to the farrowing room to reduce dust concentrations while retaining heat necessary for livestock health. The air quality in the room was assessed over a winter, during which time limited fresh air is traditionally brought into the building. Over the study period, dust concentrations ranged from 0.005-0.31 mg m(-3) (respirable) and 0.17-2.09 mg m(-3) (inhalable). In-room dust concentrations were reduced (41% for respirable and 33% for inhalable) with the system in operation, while gas concentrations (ammonia [NH3], hydrogen sulfide [H2S], carbon monoxide [CO], carbon dioxide [CO2]) were unchanged. The position of the exhaust and return air systems provided reasonably uniform contaminant distributions, although the respirable dust concentrations nearest one of the exhaust ducts was statistically higher than other locations in the room, with differences averaging only 0.05 mg m(-3). Throughout the study, CO2 concentrations consistently exceeded 1540 ppm (industry recommendations) and on eight of the 18 study days it exceeded 2500 ppm (50% of the ACGIH TLV), with significantly higher concentrations near a door to a temperature-controlled hallway that was typically often left open. Alternative heaters are recommended to reduce CO2 concentrations in the room. Contaminant concentrations were modeled using production and environmental factors, with NH3 related to the number of sow in the room and outdoor temperatures and CO2 related to the number of piglets and outdoor temperatures. The recirculating ventilation system provided dust reduction without increasing concentrations of hazardous gases.

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.

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

INTRODUCTION

Studies on determinants of dairy farmers' exposure to dust and endotoxin have been sparse and so far none has addressed the combined effect of tasks and farm characteristics.

OBJECTIVE

To study whether and how work tasks and specific stable characteristics influence the level of dairy farmers' personal exposure to inhalable dust and endotoxin.

METHODS

We applied an observational design involving full-shift repeated personal measurements of inhalable dust and endotoxin exposure among 77 subjects (owners and farm workers) from 26 dairy farms. Performed tasks were self-registered in activity diaries, and information on stable characteristics was collected through personal interviews and walk-through surveys. Associations between exposure, tasks, and stable characteristics were examined in linear mixed-effect models with individual and farm treated as random effects. Separate as well as combined models for tasks and stable characteristics were elaborated.

RESULTS

The 124 personal samples collected had a geometric mean level (geometric standard deviation) of 360 EU m(-3) (3.8) for endotoxin exposure and of 1.0mg m(-3) (2.7) for dust exposure. Identified factors that increased endotoxin exposure included a lower outdoor temperature and use of slope-based or back-flushed slurry systems along with milking, distribution of bedding, and handling of feed and seeds in barns. For dust, exposure was higher when fully automatic (robotic) milking was used and during re-penning of animals, handling of feed and seeds, handling of silos and when distributing bedding. Dust exposure increased also as a result of use of rail feed dispensers in a model without fully automatic milking.

CONCLUSIONS

The current exposure to dust and in particular endotoxin among Danish dairy farmers demand effective strategies to reduce their exposure. The present findings suggest that future interventions should focus on feeding and manure handling systems. Use of respirators during handling of feed and distribution of bedding should be advised until adequate risk management measures have been established. The expected increased use of fully automatic milking in the future might increase dust exposure of dairy farmers.

Occupational exposure to aflatoxin B1 in swine production and possible contamination sources

Although the adverse health consequences of ingestion of food contaminated with aflatoxin B1 (AFB1) are known, relatively few studies are available on the adverse effects of exposure in occupational settings. Taking this into consideration, our study was developed aiming to elucidate the possible effects of occupational exposure to AFB1 in Portuguese swine production facilities using a specific biomarker to assess exposure to AFB1. In total, 28 workers participated in this study, providing blood samples, and a control group (n = 30) was composed of subjects without any type of agricultural activity. Fungal contamination was also studied by conventional methods through air, surfaces, and new and used floor coverage. Twenty-one workers (75%) showed detectable levels of AFB1 with values ranging from <1 ng/ml to 8.94 ng/ml and with a mean value of 1.91 ± 1.68 ng/ml. In the control group, the AFB1 values were all below 1 ng/ml. Twelve different Aspergillus species were identified. Aspergillus versicolor presented the highest airborne spore counts (3210 CFU/m3) and was also detected in higher values in surfaces (>300 CFU/cm2). Data indicate that exposure to AFB1 occurs in swine barns, and this site serves as a contamination source in an occupational setting.