Region-related risk factors for respiratory symptoms in European and Californian farmers

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Dose-independent genotoxic response in A549 cell line exposed to fungicide Iprodione

The fungicide Iprodione is widely applied in vegetables and raises concern for human health. The A549 human lung carcinoma cell line is a suitable model for assessing the toxicological effects of drugs. The goal of this work was to evaluate the genotoxicity and oxidative stress in the A549 cell line exposed to sublethal concentrations from 3 to 100 µg/mL Iprodione considering LC50 = 243.4 µg/mL Iprodione, as determined by the MTT assay. Generalized Linear Mixed Models (GLMM) were performed to determine the association between the responses NDI, MNi_m and MNi_b and the explanatory variables. Iprodione and solvent were relativized to the control whereas the concentration was included as numeric variable. ANOVA was used for the comparison of treatments. The coefficients of linear association between the explanatory variables and NDI, and the coefficients of logistic association between explanatory variables and MNi_m were not significant. However, these coefficients showed significant association with MNi_b only for Iprodione treatment but not for Iprodione concentration, indicating lack of dose-response relationship. Genotoxicity risk assessment indicated that the increase in Iprodione concentrations increased slightly the probability of belonging to the genotoxic category. ANOVA showed significant differences in MNi_b, and non-significant differences in NDI and MNi_m among treatments. The oxidative stress analysis performed at 3, 12, and 25 μg/mL Iprodione showed a significant and linear increase in SOD, and a significant and linear decrease in GSH and GST. The Dunnett test was significant for GSH at 12 and SOD at 25 μg/mL.

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, FEF_25%, FEF_50%, FEF_25–75% 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.

Combined Collagen-Induced Arthritis and Organic Dust-Induced Airway Inflammation to Model Inflammatory Lung Disease in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by extra-articular involvement including lung disease, yet the mechanisms linking the two conditions are poorly understood. The collagen-induced arthritis (CIA) model was combined with the organic dust extract (ODE) airway inflammatory model to assess bone/joint-lung inflammatory outcomes. DBA/1J mice were intranasally treated with saline or ODE daily for 5 weeks. CIA was induced on days 1 and 21. Treatment groups included sham (saline injection/saline inhalation), CIA (CIA/saline), ODE (saline/ODE), and CIA +  ODE (CIA/ODE). Arthritis inflammatory scores, bones, bronchoalveolar lavage fluid, lung tissues, and serum were assessed. In DBA/1J male mice, arthritis was increased in CIA +  ODE >  CIA >  ODE versus sham. Micro-computed tomography (µCT) demonstrated that loss of BMD and volume and deterioration of bone microarchitecture was greatest in CIA +  ODE. However, ODE-induced airway neutrophil influx and inflammatory cytokine/chemokine levels in lavage fluids were increased in ODE >  CIA +  ODE versus sham. Activated lung CD11c+ CD11b+ macrophages were increased in ODE >  CIA +  ODE >  CIA pattern, whereas lung hyaluronan, fibronectin, and amphiregulin levels were greatest in CIA +  ODE. Serum autoantibody and inflammatory marker concentrations varied among experimental groups. Compared with male mice, female mice showed less articular and pulmonary disease. The interaction of inhalation-induced airway inflammation and arthritis induction resulted in compartmentalized responses with the greatest degree of arthritis and bone loss in male mice with combined exposures. Data also support suppression of the lung inflammatory response, but increases in extracellular matrix protein deposition/interstitial disease in the setting of arthritis. This coexposure model could be exploited to better understand and treat RA-lung disease. © 2019 American Society for Bone and Mineral Research.

United Airway Disease Among Crop Farmers

Although there are observed relationships between agriculture and respiratory health problems, little attention has been given to relationship between lower and upper airway problems among farmers in the United States. The objective was to investigate the possible relationship between occupational risk factors and "united airway disease" among farmers in eastern North Carolina. Farmers and farm workers were selected from eastern North Carolina by using a cluster sampling method. A total of 180 farmers and farm workers completed the questionnaire. Data analyses were conducted to test associations and correlations between working conditions and symptoms. Lower airway symptom prevalence was 35%, and 66% had upper airway symptoms. Only 1% of farmers had physician-diagnosed rhinitis. Self-reported rhinitis and asthma symptoms were significantly correlated (r = .228, P = .003) among farmer/farm workers. Upper airway diseases are prevalent yet overlooked among farmer/farm workers. Early management of upper airway symptoms may prevent severe lower airway diseases, which will lead to increased productivity in the agricultural workforce.

Systemic IL-6 Effector Response in Mediating Systemic Bone Loss Following Inhalation of Organic Dust

Airway and skeletal diseases are prominent among agriculture workers. Repetitive inhalant exposures to agriculture organic dust extract (ODE) induces bone deterioration in mice; yet the mechanisms responsible for connecting the lung-bone inflammatory axis remain unclear. We hypothesized that the interleukin (IL)-6 effector response regulates bone deterioration following inhalant ODE exposures. Using an established intranasal inhalation exposure model, wild-type (WT) and IL-6 knockout (KO) mice were treated daily with ODE or saline for 3 weeks. ODE-induced airway neutrophil influx, cytokine/chemokine release, and lung pathology were not reduced in IL-6 KO animals compared to WT mice. Utilizing micro-computed tomography, analysis of tibia showed that loss of bone mineral density, volume, and deterioration of bone micro-architecture, and mechanical strength induced by inhalant ODE exposures in WT mice were absent in IL-6 KO animals. Compared to saline treatments, bone-resorbing osteoclasts and bone marrow osteoclast precursor populations were also increased in ODE-treated WT but not IL-6 KO mice. These results show that the systemic IL-6 effector pathway mediates bone deterioration induced by repetitive inhalant ODE exposures through an effect on osteoclasts, but a positive role for IL-6 in the airway was not demonstrated. IL-6 might be an important link in explaining the lung-bone inflammatory axis.

Evaluation of respiratory symptoms and respiratory protection behavior among poultry workers in small farming operations

Agricultural workers who work in enclosed poultry operations are at increased risk of respiratory exposure to atmospheric contaminants, including dusts, endotoxins, particulate from feathers, ammonia, and hydrogen sulfide from animal excrement. Given the relatively large number of small, family-run poultry farms in North Carolina, there has been relatively little research in the area documenting human lung function and perception of using respiratory protection among poultry workers. This study assesses respiratory health, knowledge, and perception of wearing respiratory protection among a sample of poultry workers attending a regional farm show in North Carolina. Lung function (spirometry), airway inflammation (exhaled nitric oxide), self-reported respiratory symptoms, and behavior of wearing respiratory protection were evaluated. Overall, mean lung function values were slightly lower than normal predicted values. The majority of participants ranked using respiratory protection as very important (51.9%); however, actual self-reported behavior was low (16.7%). In bivariate analysis, associations between the importance of wearing respiratory protection and the number of poultry houses (P=.04), as well as using a respirator and the number of poultry houses (P=.01) were statistically significant. Improved educational opportunities, including fit-testing and proper respiratory selection, should be emphasized for workers at small, poultry farm operations.

Systematic review of respiratory health among dairy workers

The dairy industry is changing on a global scale with larger, more efficient operations. The impact of this change on worker health and safety, specifically, associations between occupational lung disease and inhalation exposures, has yet to be reported in a comprehensive review of the scientific literature. Therefore, a three-tier process was used to identify information using a keyword search of online databases of scientific literature. Of the 147 citations reviewed, 52 met initial screening criteria, and 30 were included in this review. Dairy workers experience lung conditions such as asthma, chronic obstructive pulmonary disease, hypersensitivity pneumonitis, chronic bronchitis, and cancer. Recent pulmonary function studies have identified obstructive lung changes among dairy farm workers. The increased scale of dairy production with significant changes in technology and work practices has altered inhalation exposure patterns among dairy workers. The inhalation exposure in the dairy work environment may elicit differing inflammatory responses in relation to timing of initial exposure as well as to repeated exposures. Few studies have measured inhalation exposure while simultaneously assessing the impact of the exposure on lung function of dairy farm workers. Even fewer studies have been implemented to assess the impact of aerosol control technology to reduce inhalation exposure. Future research should evaluate worker exposure to aerosols through a task-based approach while utilizing novel methods to assess inhalation exposure and associated inflammatory responses. Finally, potential solutions should be developed and tested to reduce inhalation exposure to inflammatory agents and respiratory diseases in the dairy farm work environment.

Agricultural exposures and chronic bronchitis: findings from the AGRICAN (AGRIculture and CANcer) cohort

PURPOSE

Livestock farming has been recognized as a risk factor for chronic bronchitis (CB). The role of crop farming, however, has been less studied. We sought to assess the role of a large range of farming activities on the risk of CB in the French agricultural cohort AGRICAN (AGRIculture and CANcer).

METHODS

Data on respiratory health and farming activities were collected by questionnaire from 2005 to 2007. Associations between farming activities and self-reported doctor's diagnosis of CB were estimated by a logistic regression adjusted for confounders.

RESULTS

CB was reported by 1207 farmers (8.4%). Two farming activities were associated with CB: cattle raising (odds ratio [OR] 1.24, 95% confidence interval 1.03-1.48), and potato production (OR 1.33, 95% confidence interval 1.13-1.57). Associations were more pronounced in small-scale cattle raising and in large-scale potato production, in particular among the longest exposed workers (≥20 years). Pesticide poisoning and exposure to pesticides in potato farmers were significantly associated with CB risk (OR 1.64 and OR 1.63, respectively).

CONCLUSIONS

This analysis suggests that other agricultural settings not previously reported, such as potato production, may be a risk factor for CB. The nature and circumstances of exposure to hazardous agents need to be further explored.

Airborne microorganisms, endotoxin, and (1→3)-β-D-glucan exposure in greenhouses and assessment of respiratory symptoms among workers

OBJECTIVES

Greenhouse operations are an important sector of the horticulture industry, also known as the Green Industry. The objectives of this study were (i) to investigate exposure levels to airborne culturable fungi, bacteria (total culturable bacteria and actinomycetes), endotoxin, and (1→3)-β-D-glucan in three Midwest greenhouses during summer and winter using multiple exposure assessment methods; (ii) characterize the load of microorganisms on greenhouse floors and determine potential microbial source strengths of the floors for aerosolizing microbial biocontaminants, and (iii) to estimate the prevalence of rhinitis, wheezing, asthma, and other respiratory symptoms/conditions among greenhouse workers.

METHODS

Stationary inhalable aerosol samples were collected from each greenhouse using Button Inhalable Aerosol Samplers. Control samples were collected from offices and nearby outdoor locations. A microbial source strength tester was used to examine the aerosolization potential of microbial contaminants from greenhouse floors. Additionally, surface samples were collected by sterile cotton swabs. Temperature, relative humidity, and wind velocity were recorded. Airborne culturable fungi, bacteria, and actinomycetes were analyzed in the extracts from field samples by cultivation in nutrient agar media. Endotoxin and (1→3)-β-D-glucan in the extracts from field samples were analyzed by specific kinetic chromogenic Limulus amebocyte lysate assays. The prevalence of respiratory symptoms among greenhouse workers (n = 35) and control subjects (office workers; n = 14) was estimated with a standardized questionnaire.

RESULTS AND CONCLUSIONS

The collected data indicate that workers employed in Midwest greenhouses may be exposed to elevated levels of inhalable culturable microorganisms (fungi and bacteria collectively on the order of 10(2)-10(5) CFU m(-3)), endotoxin (10(1)-10(3) EU m(-3)), and (1→3)-β-D-glucan (10(1)-10(2) ng m(-3)). Seasonal variations were observed for some bioaerosol components. The prevalence of self-reported respiratory symptoms was generally higher among greenhouse workers compared to controls; however, the differences were not statistically significant, likely due to the relatively low statistical power of the study.

Occupational allergy to bell pepper pollen in greenhouses in the Netherlands, an 8-year follow-up study

BACKGROUND

Pollen from bell pepper plants cultivated in greenhouses are known to cause occupational allergic disease. A cross-sectional study among 472 bell pepper employees in 1999 estimated prevalences for sensitization to bell pepper pollen of 28% and for work-related allergic symptoms of 54%. There is scarce information on the incidence of work-related allergy and its risk factors. Aims of the present study were to estimate the cumulative incidence of work-related symptoms and sensitization to bell pepper pollen, and to determine risk factors for the onset of these symptoms and sensitization.

METHODS

Bell pepper employees who participated in a cross-sectional survey in 1999 were asked to take part in a follow-up study in 2007. Information on demographic characteristics, job characteristics and allergic symptoms was gathered by means of a questionnaire. Furthermore, skin tests were performed with a.o. bell pepper pollen.

RESULTS

In total, 280 of 472 employees were available for questionnaires and in 250 employees allergy tests were performed. During the 8-year follow-up, the cumulative incidence of sensitization to bell pepper pollen was 9% and of work-related rhinitis 19%. Atopy [odds ratio (OR) 5.60] and smoking (OR 3.53) were significantly associated with development of rhinitis. The cumulative incidence of work-related asthma symptoms was 8%. Again atopy (OR 5.03) and smoking (OR 11.85) were significant risk factors.

CONCLUSION

Cumulative incidences for sensitization to bell pepper pollen, work-related rhinitis and asthma symptoms were 9%, 19% and 8%, respectively. Atopy and smoking are risk factors for developing work-related symptoms among workers in bell pepper horticulture.

Lung function and respiratory symptoms in male Palestinian farmers

In a cross-sectional study of 250 farmers aged 22 to 77 years, of whom 36.4% are smokers, the authors aimed at describing lung function and respiratory symptoms and to estimate associations with exposures to pesticides and dust. Lung function was measured using a spirometer. Respiratory symptoms and exposure levels were self-reported based on a modified standardized questionnaire. Mean forced vital capacity (FVC) was 4.20 L (SD = 0.93 L), 95.51% of predicted as compared to European standards. Mean forced expiratory volume in one second (FEV(1)) was 3.28 L (SD = 0.80 L), 91.05% of predicted. The authors found high symptom prevalences: 14.0% for chronic cough; 26.4% for wheeze; and 55.2% for breathlessness. There was no clear association between exposure to pesticides or dust and lung function or between such exposures and respiratory symptoms. However, a significant association was found between smoking and respiratory symptoms such as chronic cough, cough with phlegm, and wheezes. The lack of farm exposure associations could be due to improvement in farmers' awareness to pesticides hazards as well as regulations of pesticide import, or because of inherent problems with the experimental design. Farmers who kept animals and poultry seem to have less respiratory symptoms and better lung function.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: farm lifestyles and the hygiene hypothesis

About 15 years have gone by since Strachan first proposed the idea that infections and unhygienic contact may confer protection from the development of allergic illnesses. The so-called 'hygiene hypothesis' has since undergone numerous modifications in the field of epidemiology, clinical science and immunology. Three main areas of research have been brought forward: to explore the role of overt viral and bacterial infections for the inception of allergic diseases; to investigate the significance of environmental exposure to microbial compounds on the development of allergies; and to study the effect of both exposures on underlying innate and adaptive immune responses. A concept unifying these various aspects has not been found, but various pieces of a complex interplay between immune responses of the host, characteristics of the invading microorganism, the level and variety of the environmental exposure and the interactions between an exposed subject's genetic background and the environmental exposures becomes apparent. A natural experiment relating to the hygiene hypothesis is the recurrent observation of a protective effect of growing up on a farm for asthma and allergies. This has been shown in a large number of epidemiological studies across the world among children and adults. The timing and duration of exposure are likely to play a critical role. The largest reduction in risk has been demonstrated for those exposed prenatally and continuously thereafter until adulthood. The protective factors in these farming environments have not been unravelled completely. Findings from various studies suggest that the contact with farm animals, at least in childhood, confers protection. Also the consumption of unprocessed cow's milk directly from the farm has been shown to protect from childhood asthma and allergies. Increased levels of microbial substances may, at least in part, contribute to the 'farm effect'. However, only few studies have measured microbial exposures in these environments and the results obtained so far suggest that the underlying protective microbial exposure(s) have not been identified, but a number of studies using metagenomic approaches are currently under way. The mechanisms by which such environmental exposures confer protection from respiratory allergies are also not well understood. There is good evidence for the involvement of innate immune responses, but translation into protective mechanisms for asthma and allergies is lacking. Furthermore, a number of gene x environment interactions have been observed.

Rhinitis associated with pesticide use among private pesticide applicators in the agricultural health study

Farmers commonly experience rhinitis but the risk factors are not well characterized. The aim of this study was to analyze cross-sectional data on rhinitis in the past year and pesticide use from 21,958 Iowa and North Carolina farmers in the Agricultural Health Study, enrolled 1993-1997, to evaluate pesticide predictors of rhinitis. Polytomous and logistic regression models were used to assess association between pesticide use and rhinitis while controlling for demographics and farm-related exposures. Sixty-seven percent of farmers reported current rhinitis and 39% reported 3 or more rhinitis episodes. The herbicides glyphosate [odds ratio (OR) = 1.09, 95% confidence interval (95% CI) = 1.05-1.13] and petroleum oil (OR = 1.12, 95% CI = 1.05-1.19) were associated with current rhinitis and increased rhinitis episodes. Of the insecticides, four organophosphates (chlorpyrifos, diazinon, dichlorvos, and malathion), carbaryl, and use of permethrin on animals were predictors of current rhinitis. Diazinon was significant in the overall polytomous model and was associated with an elevated OR of 13+ rhinitis episodes (13+ episodes OR = 1.23, 95% CI = 1.09-1.38). The fungicide captan was also a significant predictor of rhinitis. Use of petroleum oil, use of malathion, use of permethrin, and use of the herbicide metolachlor were significant in exposure-response polytomous models. Specific pesticides may contribute to rhinitis in farmers; agricultural activities did not explain these findings.

Pesticide exposure and respiratory health of indigenous women in Costa Rica

A cross-sectional study was conducted in 2007 to evaluate the relation between pesticide exposure and respiratory health in a population of indigenous women in Costa Rica. Exposed women (n = 69) all worked at plantain plantations. Unexposed women (n = 58) worked at organic banana plantations or other locations without pesticide exposure. Study participants were interviewed using questionnaires to estimate exposure and presence of respiratory symptoms. Spirometry tests were conducted to obtain forced vital capacity and forced expiratory volume in 1 second. Among the exposed, prevalence of wheeze was 20% and of shortness of breath was 36% versus 9% and 26%, respectively, for the unexposed. Prevalence of chronic cough, asthma, and atopic symptoms was similar for exposed and unexposed women. Among nonsmokers (n = 105), reported exposures to the organophosphate insecticides chlorpyrifos (n = 25) and terbufos (n = 38) were strongly associated with wheeze (odd ratio = 6.7, 95% confidence interval: 1.6, 28.0; odds ratio = 5.9, 95% confidence interval: 1.4, 25.6, respectively). For both insecticides, a statistically significant exposure-effect association was found. Multiple organophosphate exposure was common; 81% of exposed women were exposed to both chlorpyrifos and terbufos. Consequently, their effects could not be separated. All findings were based on questionnaire data. No relation between pesticide exposure and ventilatory lung function was found.

Occupational risk factors for rhinitis in greenhouse flower and ornamental plant growers

BACKGROUND

The purpose of this study was to assess the relationships between rhinitis, exposure to workplace air contaminants, and occupational characteristics in greenhouse flower and ornamental plant (OP) growers.

METHODS

A random sample of growers cultivating such crops and participating in the European Farmers' Study was selected for a cross-sectional assessment of (1) rhinitis in the last year, (2) sensitization to workplace allergens, and (3) occupation characteristics. Associations between variables were assessed through univariate and multivariate analyses.

RESULTS

Thirty-nine greenhouse flower and OP growers participated in the study (mean, 48.6; SD, 10.2 years; 35 men). Rhinitis was reported by 12 (31%) of them and was significantly related to sensitization to workplace allergens (odds ratio [OR], 13.20; 95% confidence interval [CI], 2.59-67.23) and pesticide application by hand pump (OR, 12.50; 95% CI, 2.00-78.05). After adjustment for these variables rhinitis emerged as significantly related to number of hours worked inside the greenhouse per day (OR, 1.85; 95% CI, 1.05-3.23).

CONCLUSION

Rhinitis is often reported by greenhouse flower and OP growers and is related to sensitization to workplace allergens and pesticide application by hand pump. The disease shows a dose-response relationship with the number of hours spent inside the greenhouse per day, a finding supporting a causal link with greenhouse exposure.

Living on a farm: impact on asthma induction and clinical course

Exposure to a farming environment protects individuals from respiratory allergy. The timing and duration of exposure seem to play critical roles. The largest reduction in risk of developing respiratory allergies is seen among those who are exposed prenatally and continuously thereafter. Contact with farm animals, at least in childhood, likely confers protection; other factors have not been completely identified. Also, the consumption of milk directly from the farm during childhood has been shown to be beneficial with respect to childhood asthma and allergies. Increased levels of microbial substances may contribute to the protective effects. The mechanisms by which such environmental exposures confer protection from respiratory allergies are not well understood. A number of gene-by-environment interactions have been observed with polymorphisms in genes of innate immunity receptors and exposure to farming environments. Increased levels of microbial exposures recognized by innate immune responses may affect adaptive immune responses resulting in decreased levels of atopic sensitization and asthma.

Nasal complaints and signs of disease in farmers--a methodological study

CONCLUSION

The methods used in this study are suitable for field studies that involve examinations of groups of workers. For individual examinations, there is no gold standard method that can discriminate work-related discomfort from other causes of rhinitis.

OBJECTIVES

Studies of the effects of occupation on farmers' health have mainly focused on lower airways; few studies have examined effects on upper airways. This study investigated nasal functions in three groups of farmers (swine, milk and grain producers) and a control group using different methods, suitable for field studies.

SUBJECTS AND METHODS

Health-related complaints were examined and several functional tests, such as expirogram, olfactory threshold test, acoustic rhinometry, nasal lavage with biomarkers of inflammation (eosinophilic cationic proteins (ECP), myeloperoxidase (MPO), tryptase, albumin) and allergy tests were performed. The different tests were correlated to nasal complaints and to each other.

RESULTS

Nasal blockage complaints were more common among farmers; overall, nasal polyps were more frequent in grain producers. Objective parameters showed more pronounced mucosal swelling in farmers and higher concentrations of ECP in nasal lavage compared with controls. Lung function, olfactory threshold, atopy frequency and allergen-specific IgE to the storage mite Lepidoglyphus destructor did not differ between farmers and controls. Mucosal swelling measured with acoustic rhinometry was more pronounced in subjects with nasal complaints, hypersensitivity, nasal polyps and symptoms from lower airways. There was a correlation between biomarkers in nasal lavage (MPO, albumin and ECP).

Pesticides and atopic and nonatopic asthma among farm women in the Agricultural Health Study

RATIONALE

Risk factors for asthma among farm women are understudied.

OBJECTIVES

We evaluated pesticide and other occupational exposures as risk factors for adult-onset asthma.

METHODS

Studying 25,814 farm women in the Agricultural Health Study, we used self-reported history of doctor-diagnosed asthma with or without eczema and/or hay fever to create two case groups: patients with atopic asthma and those with nonatopic asthma. We assessed disease-exposure associations with polytomous logistic regression.

MEASUREMENTS AND MAIN RESULTS

At enrollment (1993-1997), 702 women (2.7%) reported a doctor's diagnosis of asthma after age 19 years (282 atopic, 420 nonatopic). Growing up on a farm (61% of all farm women) was protective for atopic asthma (odds ratio [OR], 0.55; 95% confidence interval [CI], 0.43-0.70) and, to a lesser extent, for nonatopic asthma (OR, 0.83; 95%CI, 0.68-1.02; P value for difference = 0.008). Pesticide use was almost exclusively associated with atopic asthma. Any use of pesticides on the farm was associated only with atopic asthma (OR, 1.46; 95% CI, 1.14-1.87). This association with pesticides was strongest among women who had grown up on a farm. Women who grew up on farms and did not apply pesticides had the lowest overall risk of atopic asthma (OR, 0.41; 95% CI, 0.27-0.62) compared with women who neither grew up on farms nor applied pesticides. A total of 7 of 16 insecticides, 2 of 11 herbicides, and 1 of 4 fungicides were significantly associated with atopic asthma; only permethrin use on crops was associated with nonatopic asthma.

CONCLUSIONS

These findings suggest that pesticides may contribute to atopic asthma, but not nonatopic asthma, among farm women.

[Farm work, dust exposure and respiratory symptoms among farmers]

OBJECTIVE

Environmental working conditions in rural areas, notably exposure to organic and mineral dusts, have been associated with increases in respiratory diseases. The objective of this study was to evaluate the prevalence of respiratory symptoms among farmers and the associations of these with occupational risk factors.

METHODS

This cross-sectional study was undertaken in 1996 with 1,379 farmers from Southern Brazil. Sociodemographic and farming-production parameters were collected, as were levels of exposure to organic and mineral dusts. Respiratory symptoms were assessed by a modified version of American Thoracic Society-Division of Lung Disease questionnaire. Multiple logistic regression analysis was used in analyses, controlling for confounding factors.

RESULTS

The majority (52%) of interviewees worked in activities with intense exposure to dust. Workers on farms with better economic indicators had a lower prevalence of respiratory symptoms. Poultry workers showed more symptoms of chronic respiratory disease (OR=1.60; 95% CI: 1.05-2.42). Farmers exposed to high concentrations of dust had more than 70% higher risk of asthma symptoms (OR=1.71; 95% CI: 1.10-2.67) and chronic respiratory disease symptoms (OR=1.77; 95% CI: 1.25-2.50).

CONCLUSIONS

The rural workers studied herein were exposed to high levels of organic and mineral dusts. Those exposed to higher dust concentrations, such as poultry workers, showed an increased risk of work-related respiratory symptoms. The implementation of respiratory protection programs is recommended, emphasizing workers involved with poultry production.

Chronic bronchitis among nonsmoking farm women in the agricultural health study

OBJECTIVE

The purpose of this study was to examine agricultural risk factors for chronic bronchitis among nonsmoking farm women.

METHODS

We used self-reported enrollment data from the 21,541 nonsmoking women in the Agricultural Health Study to evaluate occupational risk factors for prevalent chronic bronchitis among farm women. Odds ratios (ORs) for chronic bronchitis for occupational exposures were adjusted for age, state, and related agricultural exposures.

RESULTS

Applying manure and driving combines were independently associated with chronic bronchitis. Off-farm job exposures associated with chronic bronchitis were organic dusts, asbestos, gasoline, and solvents. Five pesticides were associated with chronic bronchitis after multivariate adjustment and sensitivity analyses: dichlorvos (OR=1.63, 95% CI=1.01, 2.61), DDT (OR=1.67, 95% CI=1.13, 2.47), cyanazine (OR=1.88, 95% CI=1.00, 3.54), paraquat (OR=1.91, 95% CI=1.02, 3.55), and methyl bromide (OR=1.82, 95% CI=1.02, 3.24).

CONCLUSION

Pesticides as well as grain and dust exposures were associated with chronic bronchitis among nonsmoking farm women.

Comparative in vitro toxicity of grape- and citrus-farm dusts

Agricultural workers are exposed to a variety of airborne dusts, including crystalline silica and other inorganic minerals. This study was designed to characterize the organic and inorganic components of agricultural dusts in California grape- and citrus-farm fields and to compare their cytotoxicity using in vitro toxicity bioassays as predictors of pathogenicity. Aerosolized dusts collected from farm fields were characterized by scanning-electron-microscopic energy-dispersive x-ray analysis, x-ray diffraction, trace metal analysis by plasma emission spectroscopy, and surface area measurements. As indicators of cytotoxicity, cell viability, release of alveolar enzymes activities (lactate dehydrogenase, N-acetyl glucosaminidase), production of reactive oxygen species (ROS), such as H2O2 and hydroxyl radical (OH), and lipid peroxidation were monitored after exposure of cells to grape- and citrus-farm dusts or inorganic components of these dusts. In addition, activation of nuclear factor kappa B and activator protein-1 were evaluated at the peak time for response of 36 h postexposure. All toxicity studies were done in comparison with crystalline silica of similar particle size and diameter using the same mass concentrations as farm dusts. The results showed that inorganic minerals in the aerosolized farm dust fractions were mostly composed of aluminum silicates, crystalline silica, and free iron. Crystalline silica used in these studies was more cytotoxic than grape- and citrus-farm dusts. However, in general, citrus farm dust exhibited the greatest ability to generate ROS and induce lipid peroxidation. These results support human epidemiologic studies, reporting an increased incidence of pulmonary fibrosis in farm workers, by documenting the potential of farm dusts to induce oxidative stress and initiate disease development.

Association of allergic rhinitis with pesticide use among grape farmers in Crete, Greece

OBJECTIVE

To explore the association of allergic rhinitis with the use of pesticides among grape farmers in Crete.

METHODS

A cross-sectional study of 120 grape farmers and 100 controls at the Malevisi region in Northern Crete was conducted. The protocol consisted of a questionnaire, skin prick tests for 16 common allergens, measurement of specific IgE antibodies against 8 allergens, and spirometry before and after bronchodilatation.

RESULTS

Grape farmers who used pesticides had higher prevalence rates of allergic rhinitis symptoms (OR, 3.0; 95% CI, 1.4 to 6.2) compared with grape farmers who reported no current use of pesticides, and control subjects. Logistic regression models controlling for age, sex and smoking status showed that 6 of the 12 predefined groups of major pesticides were significantly related to allergic rhinitis symptoms. The highest risks were observed for paraquat and other bipyridyl herbicides (OR, 2.2; 95% CI, 1.0 to 4.8), dithiocarbamate fungicides (OR, 2.5; 95% CI, 1.1 to 5.3) and carbamate insecticides (OR, 3.0; 95% CI, 1.4 to 6.5). A factor analysis of pesticides used identified 3 distinct factors. The most common factor was that of multiple pesticide use that included 9 pesticides and was significantly associated with allergic rhinitis (OR, 1.5; 95% CI, 1.0 to 2.3). ORs were higher when allergic rhinitis was defined using both questionnaire data on symptoms and atopy.

CONCLUSIONS

Occupational exposure to multiple agricultural chemicals could be related to allergic rhinitis in grape farmers.

Occupational rhinitis

PURPOSE OF REVIEW

This review updates existing knowledge on occupational rhinitis based on epidemiological and clinical research studies published from 2003 to 2005.

RECENT FINDINGS

The review covers new developments on the pathophysiology, diagnosis, monitoring and management of occupational rhinitis. This article also provides updated information on the prevalence and incidence of both occupational rhinitis and work-related symptoms of rhinitis, as well as on causal agents and personal risk factors associated with this condition.

SUMMARY

Occupational rhinitis is frequently under-diagnosed due to a lack of physician awareness. Diagnosis is suspected when symptoms occur in relation to work. Differentiating between immunological sensitization and irritation may be difficult. Given the high prevalence of rhinitis in the general population from all causes, objective tests confirming the occupational origin are essential. Measures of inflammatory parameters via nasal lavage and objective assessment of nasal congestion both offer practical means of monitoring responses. Growing experience with acoustic rhinometry and peak nasal inspiratory flow suggests that these methods will have an increasingly important role in monitoring and diagnosing in the future. Recent findings indicate that work-related rhinitis is to some extent preventable. Surveillance of sensitized workers may allow early detection of occupational rhinitis.

Agricultural dust exposure and respiratory symptoms among California farm operators

OBJECTIVE

To study whether dust exposure in California agriculture is a risk factor for respiratory symptoms.

METHODS

A population-based survey of 1947 California farmers collected respiratory symptoms, occupational and personal exposures. Associations between dust and respiratory symptoms were assessed by logistic regression models.

RESULTS

The prevalence of persistent wheeze was 8.6%, chronic bronchitis 3.8%, chronic cough 4.2%, and asthma 7.8%. Persistent wheeze was independently associated with dust in a dose-response fashion odds ratio, 1.2 (95% confidence interval[CI]=0.8-2.0) and 1.8 (95% CI=1.1-3.2) for low and high time in dust. A borderline significant association between chronic bronchitis and dust exposure was found. Asthma was associated with keeping livestock, but not with dust exposure.

CONCLUSIONS

Occupational dust exposure among California farmers, only one third of whom tended animals, was independently associated with chronic respiratory symptoms.

Pesticides and respiratory symptoms among farmers

OBJECTIVE

Despite the intensive use of pesticides in agriculture there are few studies assessing the risk of respiratory conditions from this exposure. The study aimed at quantifying the prevalence of respiratory symptoms among farmers and evaluating its relationship with occupational use of pesticides and the prevalence of respiratory symptoms.

METHODS

A cross-sectional study was conducted among 1,379 farmers from two municipalities of Southern Brazil in 1996. Frequency and type of chemical exposure and pesticide poisoning were recorded for both sexes. All subjects aged 15 years or older with at least 15 weekly hours of agricultural activity were interviewed. An adapted questionnaire developed by the American Thoracic Society was used for the assessment of respiratory symptoms. Multivariate logistic regression analysis was carried out.

RESULTS

More than half (55%) of interviewees were male. The prevalence of asthma symptoms was 12% and chronic respiratory disease symptoms was 22%. Higher odds ratios for both asthma (OR=1.51; 95% CI: 1.07-2.14) and chronic respiratory disease (OR=1.34; 95% CI 1.00-1.81) symptoms were found in women. Logistic regression analysis identified associations between many forms of exposure to pesticides and increased respiratory symptoms. Occurrence of pesticide poisoning was associated with higher prevalence of asthma symptoms (OR=1.54; 95% CI: 1.04-2.58) and chronic respiratory disease symptoms (OR=1.57; 95% CI: 1.08-2.28).

CONCLUSIONS

In spite of causality limitations, the study results provide evidence that farming exposure to pesticides is associated with higher prevalence of respiratory symptoms, especially when the exposure is above two days per month.

Respiratory allergy in agricultural workers: recent developments

PURPOSE OF REVIEW

To review recent evidence on the relationship between occupational exposure to allergens and asthmagens, and risk for developing allergy and asthma and the role of modifying factors in farmers and farm workers.

RECENT FINDINGS

Recent studies identified agents that have not been associated with allergy or asthma in farming populations before. The most intriguing findings, however, are those that suggest that the development of atopy and asthma might be influenced by exposure to pathogen associated molecular patterns (PAMPs), including endotoxin.

SUMMARY

The adverse and potentially protective effects of microbial exposures in the farm environment are discussed. Recent findings indicate that it is very likely that the protective effect of exposure to PAMPs such as endotoxin is not limited to childhood age. The protective effects that probably developed during childhood can still be observed at adult age. Furthermore, it even seems likely that exposures at adult age (in occupational environments), which stimulate the innate immune system, have an effect on allergy, independently of childhood exposure. It is hypothesized that reversal of atopy might occur as a result of high exposure to endotoxins and other PAMPs.

Allergic rhinitis, asthma, and atopy among grape farmers in a rural population in Crete, Greece

STUDY OBJECTIVE

To measure the prevalence of allergic rhinitis, atopy, and asthma among grape farmers, and to compare the respiratory and atopic status in grape farmers with those of nonexposed control subjects.

DESIGN

Cross-sectional study.

SETTING

Malevisi region in northern Crete, Greece.

SUBJECTS AND METHODS

One hundred twenty grape farmers and 100 control subjects living in the Malevisi region were examined. The protocol comprised a questionnaire, skin prick tests for 16 common allergens, measurement of specific IgE antibodies against 8 allergens, and spirometry before and after bronchodilation.

RESULTS

Grape farmers were found to have an excess of respiratory symptoms. The comparison with the control group, after adjusting for age, sex, and smoking status, showed that the differences were statistically significant for rhinorrhea (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.5 to 5.1; p < 0.001), sneezing (OR, 2.2; 95% CI, 1.2 to 4.0; p < 0.01), and nasal itching (OR, 1.9; 95% CI, 1.0 to 3.6; p < 0.05), but were nonsignificant for asthma-related symptoms. In the multiple logistic regression model, grape farmers were found to have increased work-related symptoms, such as sneezing (OR, 2.9; 95% CI, 1.3 to 6.6; p < 01), rhinorrhea (OR, 2.9; 95% CI, 1.3 to 6.6; p < 0.01), cough (OR, 3.7; 95% CI, 1.2 to 11.4; p < 0.05), and dyspnea (OR, 3.8; 95% CI, 1.1 to 1.3; p < 0.05). The prevalence of allergic rhinitis was 40.8% in grape farmers and 26% in control subjects (OR, 2.0; 95% CI, 1.1 to 3.5; p < 0.02). Increased but statistically nonsignificant values of asthma prevalence were found in grape farmers (6.7%) compared with the control group (2.0%). The prevalence of atopy was 64.2% in grape farmers and 38.0% in the control group (OR, 2.2; 95% CI, 1.2 to 3.5; p < 0.01). Mean FEV1 was significantly lower in grape farmers than in control subjects (p < 0.05), after adjusting for age, sex, and smoking status. Bronchial obstruction was reversible in 23 grape farmers (19.2%) and in 6 control subjects (6%; p < 0.01).

CONCLUSIONS

The study mainly demonstrated the high prevalence of allergic rhinitis and work-related respiratory symptoms in grape farmers compared to control subjects. It also suggested that grape farming is possibly associated with increased allergic sensitization to specific pollens, low baseline FEV1, and increased bronchial hyper-responsiveness. Further studies are needed to determine the potential risk factors for these disorders among the farming population.

Polymorphisms in the CD14 gene associated with pulmonary function in farmers

RATIONALE AND OBJECTIVES

Farmers experience airway obstruction, which may be attributable in part to endotoxin inhalation. CD14 is a receptor for endotoxin.

MATERIALS AND METHODS

Based on our findings of increased circulating CD14 associated with the CD14/-159 T allele, we hypothesized that carriers of this allele would have decreased lung function among endotoxin-exposed individuals. CD14/-159TT farmers (n = 19) had significantly lower lung function as measured by FEV1 (p = 0.028) and mean forced expiratory flow during the middle half of the FVC (FEF25-75) (p = 0.05) compared with farmers with the C allele (n = 78). Also, farmers with the CD14/-1619GG genotype (n =11) were associated with lower lung function (FEV1, p = 0.008; FEF25-75, p = 0.009) compared with farmers with the A allele (n = 86).

RESULTS

No association between CD14/-550 and lung function was observed (FEV1, p = 0.32; FEF25-75, p = 0.11). Increased prevalence of wheezing was reported in farmers homozygous for CD14/-159T (p = 0.013) or CD14/-1619G (p = 0.019) compared with farmers with the CC or AA genotype, respectively. No association was found between TLR4/Asp299Gly and lung function or wheeze.

CONCLUSION

We conclude that the CD14/-159 or CD14/-1619 loci may play a role in modulating lung function and wheeze among agricultural workers.

Chronic obstructive pulmonary disease in never-smoking animal farmers working inside confinement buildings

BACKGROUND

In animal farming, respiratory disease has been associated with indoor air contaminants and an excess in FEV1 decline. Our aim was to determine the characteristics and risk factors for chronic obstructive pulmonary disease (COPD) in never-smoking European farmers working inside animal confinement buildings.

METHODS

A sample of participants in the European Farmers' Study was selected for a cross-sectional study assessing lung function and air contaminants. Dose-response relationships were assessed using logistic regression models.

RESULTS

COPD was found in 18 of 105 farmers (45.1 SD 11.7 years) (17.1%); 8 cases (7.6%) with moderate and 3 cases (2.9%) with severe disease. Dust and endotoxin showed a dose-response relationship with COPD, with the highest prevalence of COPD in subjects with high dust (low=7.9%/high=31.6%) and endotoxin exposure (low=10.5%/high=20.0%). This association was statistically significant for dust in the multivariate analysis (OR 6.60, 95% CI 1.10-39.54).

CONCLUSION

COPD in never-smoking animal farmers working inside confinement buildings is related to indoor dust exposure and may become severe.

Occupational asthma in greenhouse workers

PURPOSE OF REVIEW

A prevalence of asthma over 5% has been reported in flower farmers,and work inside greenhouses has emerged as an additional risk factor. Workplace determinants behind this high prevalence has been examined, and a prevalence of sensitization to workplace allergens over 30% has been reported being pollens, moulds, and Tetranychus urticae allergens the main sensitizers. Bronchial challenge tests in the workplace have demonstrated occupational asthma in more than 20% of the sensitized greenhouse growers.

RECENT FINDINGS

Air contamination inside greenhouses is mainly related to moulds, and is facilitated by the high indoor temperature and humidity. Cladosporium, Penicillium, Aspergillus, and Alternaria and a wide range of flower pollens are able to sensitize the greenhouse worker and cause occupational asthma. Tetranychus urticae have allergens shared with other mites, but the low prevalence of cross-sensitization between them confirm that Tetranychus urticae contains species-specific allergens that may cause respiratory symptoms. Additionally, working inside greenhouses has been related to an increase in the prevalence of chronic bronchitis in nonsmokers.

SUMMARY

The cultivation of greenhouse crops may cause occupational asthma through sensitization to workplace pollens, moulds, and Tetranychus urticae allergens. In greenhouse flower growers, skin testing identifies sensitization to these allergens in one third of the growers, and more than one fifth of the sensitized workers will develop occupational asthma. Greenhouse work has also been related to chronic bronchitis in nonsmokers, suggesting a causal effect of greenhouse air contaminants on this disease as well.

Self-reported dermatitis and skin cancer in California farm operators

BACKGROUND

High rates of skin diseases and higher non-melanoma skin cancer rates have been reported in farmers.

METHODS

Self-report of dermatitis and skin cancer was among the information collected from 1947 California farm operators, mostly men, in a telephone survey. The majority of the farmers cultivated fruits, nuts, or other field crops.

RESULTS

Dermatitis was reported by 8.9% of men and 15.8% of women during the previous 12 months. In a logistic regression model, female gender (OR 2.0, 95% confidence interval 1.3-3.0) and respiratory atopy (OR 1.4, 1.01-1.90) were the only significant independent risk factors for reported dermatosis. There was significantly less reporting of skin cancer among field farmers when compared to others. Regular sunscreen use was reported significantly more often by women (42%) as compared to men (11%).

CONCLUSIONS

More in-depth studies are needed to get information on the role of agrochemicals as risk factors for dermatitis and skin cancer.