Evaluation of agricultural exposures: the Agricultural Health Study and the Agricultural Cohort Consortium

Application and demonstration of meso-activity exposure factors to advance estimates of incidental soil ingestion among agricultural workers

BACKGROUND

Soil is an understudied and underregulated pathway of chemical exposure, particularly for agricultural workers who cultivate food in soils. Little is known about how agricultural workers spend their time and how they may contact soil while growing food. Exposure factors are behavioral and environmental variables used in exposure estimation.

OBJECTIVES

Our study aimed to derive exposure factors describing how growers engage in different tasks and use those factors to advance the use of time-activity data to estimate soil ingestion exposures among agricultural workers.

METHODS

We administered a meso-activity-based, season-specific soil contact activity questionnaire to 38 fruit and vegetable growers. We asked growers to estimate the frequency and duration of six meso-activities and describe how they completed them. We used questionnaire data to derive exposure factors and estimate empirical and simulated exposures to a hypothetical contaminant in soil via incidental ingestion using daily, hourly, and hourly-task-specific ingestion rates.

RESULTS

We generated exposure factors characterizing the frequency and duration of six meso-activities by season, and self-reported soil contact, glove use, and handwashing practices by meso-activity and season. Seasonal average daily doses (ADDs) were similar across all three forms of ingestion rates. No consistent patterns regarding task-specific contributions to seasonal or annual ADDs were observed.

Microwave Gas Sensors Based on Electrodeposited Polypyrrole-Nickel Phthalocyanine Hybrid Films

Previous studies have shown that the incorporation of sulfonated metallophthalocyanines into sensitive sensor materials can improve electron transfer and thus species detection. Herein, we propose a simple and easy alternative to the use of generally expensive sulfonated phthalocyanines by electropolymerizing polypyrrole together with nickel phthalocyanine in the presence of an anionic surfactant. The addition of the surfactant not only helps the incorporation of the water-insoluble pigment into the polypyrrole film, but the obtained structure has increased hydrophobicity, which is a key property for developing efficient gas sensors with low sensitivity to water. The obtained results show the effectiveness of the materials tested for the detection of ammonia in the range of 100 to 400 ppm. It is shown by comparing the microwave sensor responses that the film without nickel phthalocyanine (hydrophilic) produces greater variations than the film with nickel phthalocyanine (hydrophobic). These results are consistent with the expected results since the hydrophobic film is not very sensitive to residual ambient water and therefore does not interfere with the microwave response. However, although this excess response is usually a handicap, as it is a source of drift, in these experiments the microwave response shows great stability in both cases.

Chronic exposure to ammonia induces oxidative stress and enhanced glycolysis in lung of piglets

Ammonia is one of the major environmental pollutants in the pig industry that seriously affects the airway health of pigs. In this study, we aimed to investigate the metabolic profiling changes of piglets' lung tissue after the exposure of 0 ppm (CG), 20 ppm (LG) and 50 ppm (HG) ammonia for 30 days. Compared with the control group, the obvious lung lesions were observed in HG, including interstitial thickening, inflammatory cell infiltration and focal hemorrhage. The significantly increased content of malondialdehyde in HG, combined with the significantly decreased mRNA expression of antioxidase and inflammatory-regulators in exposure groups, implied that ammonia exposure induced oxidative stress and diminished the anti-inflammatory response in lung tissues. Metabolomic analyses of lung tissues revealed 15 significantly altered metabolites among the three groups including multiple amino acids, carbohydrates and lipids. The accumulation of succinic acid, linoleic acid and phosphorylethanolamine and consumption of glucose, quinolinic acid and aspartic acid in ammonia exposure groups, indicated that energy supply from glucose aerobic oxidation was suppressed and the glycolysis and lipolysis were activated in lung tissues induced by chronic ammonia exposure.

Mesothelioma in Agriculture in Lombardy, Italy: An Unrecognized Risk

Cohort studies showed consistently low risks for malignant mesothelioma (MM) among agricultural workers, however the investigated exposures did not include asbestos. Our aim is to describe sources of asbestos exposure of MM in agriculture. Twenty-six MM cases in agricultural or seed trades workers were identified through the MM registry of the Lombardy region, Italy in 2000–2016. Asbestos exposures were investigated through a standardized questionnaire. The most frequent exposure circumstances were recycled jute bags previously containing asbestos (11 cases) and maintenance and repair of asbestos roofs (12 subjects). Three subjects performed maintenance and repair of tractor asbestos brakes and two used asbestos filters for wine production. Our data suggest asbestos exposure opportunities in the agricultural setting, underlining the need to look for this exposure in subjects affected with mesothelioma.

Ammonia exposure causes lung injuries and disturbs pulmonary circadian clock gene network in a pig study

Ammonia toxicity to respiratory system in pig faming is of particular concern, but the molecular mechanism remains still unclear. The present study was devoted to assess the impacts of the ammonia exposure on the lung tissues based on a pig study using 80 ppm ammonia exposing to piglets for different days. The histology analysis revealed ammonia exposure induced lung injury and inflammatory response, as indicated by epithelial-mesenchymal transition (EMT), significant thickening of alveolar septa, infiltration of inflammatory cells and excessive mucus production. The transcriptome analysis revealed many more up-regulated genes in exposure groups when compared with the control group, and these genes were significantly enriched in the GO term of extracellular exosome, proteolysis, and regulation of circadian rhythm. The study discovered the induction of seven genes (CRY2, CIART, CREM, NR1D1, NR1D2, PER1 and PER3) that encode repressors of circadian clock. One gene (ARNTL) that encodes activator of circadian clock was down-regulated after ammonia exposure. The results of this study suggest that ammonia exposure disturbed the pulmonary circadian clock gene expression, which may establish new evidence for further understanding the toxicity of ammonia to lungs.

Occupational health and safety in agriculture. A systematic review

Introduction: The prevalence of occupational diseases in the agricultural sector is higher than in other industries, since agricultural workers are at higher risk of exposure to different chemicals and pesticides, and are more prone to occupational accidents.Objective: To conduct a review of recent literature on occupational health and risk in agriculture.Materials and methods: A literature search was conducted in PubMed, SciencieDirect and Scopus using the following search strategy: type of articles: original research papers; language: English; publication period: 2006-2016; search terms: "agricultural health", "agrarian health", "risk factors", "epidemiology", "causality" and "occupational", used in different combinations ("AND" and "OR").Results: The search yielded 350 articles, of which 102 met the inclusion criteria. Moreover, 5 articles were found in grey literature sources and included in the final analysis. Most research on this topic has been conducted in the United States, which produced 91% (97/107) of the articles included.Conclusions: Most studies on health and safety in agriculture focused primarily on the harmful effects of occupational exposure to agrochemicals and pesticides, and the consequences of occupational accidents. However, since more than 90% of these studies come from the United States, a more comprehensive approach to health in agriculture is required, since what is reported here may be far from the reality of other regions, especially Latin America.

Chronic respiratory symptoms and pulmonary function status in Ethiopian agricultural workers: a comparative study

BACKGROUND

Work-related respiratory disorders are major contributors to the global burden of respiratory diseases. Agricultural workers are exposed to a number of dusts, which may contribute to the development of respiratory disorders. However, the knowledge about the prevalence of respiratory symptoms and pulmonary function status in African farmers was limited. This study was conducted to assess the prevalence of chronic respiratory symptoms and pulmonary function status of Ethiopian farmers exposed to farming activities.

METHODS

A community based comparative cross sectional study was conducted among 288 agricultural workers (farmers) aged 18 to 65 years and 288 control subjects (non-agricultural workers). Data were collected by interviewer administered structured questionnaires adopted from British Medical Research Council respiratory questionnaire and American Thoracic Society Division of Lung Diseases questionnaire. Moreover, all study participants underwent spirometry.

RESULTS

The prevalence of chronic respiratory symptoms was higher in farmers than in controls, with significant difference for cough (20.5% vs. 9.0%, p = 0.001) and phlegm (19.1% vs. 9.0%, p = 0.001). Chronic respiratory symptoms among farmers were significantly associated with duration of agricultural exposure (p = 0.014). The mean values of all spirometric parameters were lower in farmers than in controls with significant difference for FVC, FEV1, FEF25%, FEF50%, FEF25-75% and PEFR. Moreover, the mean values of all spirometric parameters of farmers have found to be decreased with increased duration of workplace exposure. Lung function test results also showed a higher prevalence of obstructive (15.6% vs. 10.8%, p = 0.085) and restrictive type (12.8% vs. 3.1%, p <  0.001) of pulmonary function impairment in farmers than in controls. However, the difference was not significant for obstructive type of impairment.

CONCLUSION

This study indicated that farmers are at high risk for the development of chronic respiratory symptoms and reduced pulmonary function indices. Hence, a comprehensive occupational safety practices are important to maintain the respiratory health of farmers.

Fine particulate matter from pig house induced immune response by activating TLR4/MAPK/NF-κB pathway and NLRP3 inflammasome in alveolar macrophages

Fine particulate matter (PM_2.5) from livestock houses is harmful not only to the health and welfare of animals but also to the farmers working inside. As an important pollution source in the atmosphere environment, PM_2.5 can threaten public health. PM_2.5 collected from nursery pig house was studied. It included particulates of various morphologies, and the concentration of endotoxin was as high as to 681.80 EU/mg. To investigate the ability of PM_2.5 from the nursery pig house to induce an immune response, porcine alveolar macrophages 3D4/21 cells were studied. The results showed that PM_2.5 can induce cell death, ROS production and inflammatory cytokines release (IL-1β, IL-18, TNF-α and COX-2) by activating TLR4/MyD88 pathway and NLRP3 inflammasome. Furthermore, the downstream signaling pathways of TLR4/MyD88, MAPK and NF-κB, participated in NLRP3 inflammasome activation. To further study the role of endotoxin present in PM_2.5 and the oxidative stress induced by PM_2.5, polymyxin B (PMB) and N-acetylcysteine (NAC) were used to neutralize the effect of the endotoxin and inhibit the production of ROS, respectively. The results showed endotoxin and ROS played important roles in PM_2.5-induced immune response. This study suggests that PM_2.5 from pig house is a significant risk for immune response in alveolar macrophages.

The Indoor-Air Microbiota of Pig Farms Drives the Composition of the Pig Farmers' Nasal Microbiota in a Season-Dependent and Farm-Specific Manner

Prior studies have demonstrated an influence of the built environment on the human nasal microbiota. However, very little is known about the influences of working on a pig farm on the human nasal microbiota. We longitudinally collected samples from 30 pig farms (air and nasal swabs from humans and pigs) in Switzerland from 2014 to 2015. As controls, nasal swabs from cow farmers and individuals with no contact with farm animals were included. An analysis of the microbiota for all samples (n = 609) was performed based on 16S rRNA gene sequencing (MiSeq) and included the investigations of source-sink dynamics. The numbers of indoor airborne particles and bacterial loads in pig farms were also investigated and were highest in winter. Similarly, the microbiota analyses revealed that the alpha diversity values of the nares of pig farmers were increased in winter in contrast to those of samples from the nonexposed controls, which displayed low alpha diversity values throughout the seasons. Source-sink analyses revealed that bacteria from the noses of pigs are more commonly coidentified within the pig farmers' microbiota in winter but to a less extent in summer. In addition, in winter, there was a stronger intrasimilarity for samples that originated from the same farm than for samples from different farms, and this farm specificity was partially or completely lost in spring, summer, and fall. In conclusion, in contrast to nonexposed controls, a pig farmer's nasal microbiota is dynamic, as the indoor-air microbiota of pig farms drives the composition of the pig farmer's nasal microbiota in a season-dependent manner.IMPORTANCE The airborne microbiota of pig farms poses a potential health hazard and impacts both livestock and humans working in this environment. Therefore, a more thorough understanding of the microbiota composition and dynamics in this setting is needed. This study was of a prospective design (12 months) and used samples from different sites. This means that the microbiota of air, animals (pigs), and humans was simultaneously investigated. Our findings highlight that the potential health hazard might be particularly high in winter compared to that in summer.

Occupational agriculture organic dust exposure and its relationship to asthma and airway inflammation in adults

OBJECTIVE

Recent studies have made advances into understanding the complex agriculture work exposure environment in influencing asthma in adults. The objective of this study is to review studies of occupational agricultural exposures including dust, animal, and pesticide exposures with asthma in adult populations.

DATA SOURCES

PubMed databases were searched for articles pertaining to farming, agriculture, asthma, occupational asthma, airway inflammation, respiratory disease, lung disease, pesticides, and organic dust.

STUDY SELECTIONS

Studies chosen were published in or after 1999 that included adults and asthma and farming/agricultural work or agricultural exposures and airway inflammatory disease measurements.

RESULTS

The data remain inconclusive. Several retrospective studies demonstrate agricultural work to be protective against asthma in adults, especially with increased farming exposure over time. In contrast, other studies find increased risk of asthma with farming exposures, especially for the non-atopic adult. Mechanistic and genetic studies have focused on defining the wide variety and abundance of microorganisms within these complex organic dusts that trigger several pattern recognition receptor pathways to modulate the hosts' response.

CONCLUSION

Asthma risk depends on the interplay of genetic factors, gender, atopic predisposition, type of livestock, pesticide exposure, and magnitude and duration of exposure in the adult subject. Longer exposure to occupational farming is associated with decreased asthma risk. However, studies also suggest that agricultural work and multiple types of livestock are independent risk factors for developing asthma. Prospective and longitudinal studies focusing on genetic polymorphisms, objective assessments, and environmental sampling are needed to further delineate the influence of agriculture exposure in the adult worker.