Farming tasks and the development of rheumatoid arthritis in the agricultural health study

Occupational dust and chemical exposures and the development of autoimmune rheumatic diseases

Although the association between certain occupational exposures and the development of autoimmune rheumatic disease was first described over a century ago, this association has only become more widely recognized in the past 10 years because of the use of high-silica-content engineered stone in construction and home renovation. There is now a substantial and growing body of evidence that occupational dust and chemical exposure, be it through mining, stonemasonry, building or other trades, increases the risk of various systemic autoimmune rheumatic diseases (SARDs) including rheumatoid arthritis and systemic sclerosis. Although the pathogenic mechanisms of silica-induced autoimmunity are not fully elucidated, it is thought that alveolar macrophage ingestion of silica and the ensuing phagosomal damage is an initiating event that ultimately leads to production of autoantibodies and immune-mediated tissue injury. The purportedly causal association between occupational exposure to chemicals, such as organic solvents, and an increased risk of SARDs is less frequently recognized compared with silica dust, and its immunopathogenesis is less well understood. An appreciation of the importance of occupational dust and chemical exposures in the development of SARDs has implications for workplace health and safety regulations and offers a unique opportunity to better understand autoimmune disease pathogenesis and implement preventative strategies.

Occupational and Hobby Exposures Associated With Myositis Phenotypes in a National Myositis Patient Registry

OBJECTIVE

The objective of this study was to investigate occupational and hobby exposures to silica, solvents, and heavy metals and the odds of having the idiopathic inflammatory myopathy (IIM) phenotypes dermatomyositis (DM) and polymyositis (PM) versus inclusion body myositis (IBM), lung disease plus fever or arthritis (LD+), and systemic autoimmune rheumatic disease-associated overlap myositis (OM).

METHODS

The sample included 1,390 patients (598 with DM, 409 with PM, and 383 with IBM) aged ≥18 years from a national registry. Of these, 218 (16%) were identified with LD+, and 166 (12%) with OM. Of these, 218 (16%) were identified with LD+, and 166 (12%) with OM. We calculated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) and explored joint effects with smoking.

RESULTS

High silica exposure was associated with increased odds of having DM (OR 2.02, 95% CI 1.18-3.46, compared to no exposure; P trend = 0.004), LD+ (OR 1.75, 95% CI 1.10-2.78, vs no LD; P trend = 0.005), and OM (OR 2.07, 95% CI 1.19-3.61, P trend = 0.020). Moderate to high heavy metals exposure was associated with greater odds of having LD+ (OR 1.49, 95% CI 1.00-2.14, P trend = 0.026) and OM (OR 1.59, 95% CI 0.99-2.55, P trend = 0.051). Greater odds of having LD+ were seen among smokers with moderate to high silica exposure versus nonsmokers with low or no exposure (high-certainty assessment OR 2.53, 95% CI 1.31-4.90, P interaction = 0.061).

CONCLUSION

These findings, based on a systematic exposure assessment, suggest that occupational and hobby exposures to silica and heavy metals contribute to adult IIM phenotypes, including DM, OM, and LD+, a possible marker for antisynthetase syndrome or other autoantibody-associated lung diseases.

Associations between pesticide use and rheumatoid arthritis among older farmers in the Agricultural Health Study

Pesticides and farming have been associated with increased rheumatoid arthritis (RA) risk, but the role of specific pesticides remains unknown. We examined RA risk among licensed pesticide applicators (97% white male farmers), from North Carolina and Iowa, in the Agricultural Health Study, in relation to lifetime use of 45 pesticides reported at enrollment (1993-1997, updated 1999-2003). In 22,642 applicators ages ≥ 67 years with ≥ 24 months Fee for Service Medicare data (1999-2016), we identified 161 (0.7%) incident cases with ≥ 2 RA claims (including ≥ 1 by a rheumatologist), ≥ 30 days apart, after ≥ 12 months without RA claims. Relative risks (RR) and 95% Confidence Intervals (CI) were calculated using log-binomial models adjusted for age, state, education, smoking, and correlated pesticides. Risk was elevated (RR > 1.5 or lower CI > 0.95) for use of nine pesticides: four insecticides [malathion (RR = 1.77;95%CI = 1.14-2.73), phorate (1.40;0.96-2.04), carbaryl (1.65;1.10-2.46), carbofuran (1.41;0.99-2.01)], four herbicides [alachlor (RR = 1.40;95%CI 0.99-1.98), metolachlor (1.57;1.11-2.23), S-Ethyl dipropylthiocarbamate (1.57;1.00-2.44), metribuzin (1.45; 1.01, 2.08)], and one fungicide [benomyl (1.56;0.99-2.44)]. Exposure-response was seen for greater intensity-weighted lifetime days use of malathion and carbofuran (p-trends = 0.03 and 0.05). Some specific pesticides, including several currently approved and commonly used in agricultural, public health, or residential settings may increase RA risk among older adults.

Air Pollution and Rheumatoid Arthritis Risk and Progression: Implications for the Mucosal Origins Hypothesis and Climate Change for RA Pathogenesis

PURPOSE OF REVIEW

The goal of this review paper is to summarize the main research and findings regarding air pollution and its association with the risk and progression of rheumatoid arthritis (RA).

RECENT FINDINGS

The most studied components of air pollution included particulate matter of ≤ 2.5 microns in diameter (PM2.5), PM10, carbon monoxide (CO), nitrogen dioxide (NO2), nitric oxide (NOx), sulfur dioxide (SO2), and ozone (O3). In addition, specific occupations and occupational inhalants have been investigated for RA risk. Several studies showed that increased exposure to air pollutants increased the risk of developing RA, particularly seropositive RA. There was evidence of gene-inhalant interactions for seropositive RA risk. Fewer studies have been conducted on RA disease activity and bone erosions. Some studies suggest that patients with RA-associated interstitial lung disease may have worse outcomes if exposed to air pollution. We summarized associations between air pollution and increased RA risk, including RA-associated interstitial lung disease. Relatively few studies investigated air pollution and RA disease activity or other outcomes. These results suggest an important role of air pollution for seropositive RA development and suggest that climate change could be a driver in increasing RA incidence as air pollution increases.

Contributions of Synthetic Chemicals to Autoimmune Disease Development and Occurrence

PURPOSE OF REVIEW

Exposure to many synthetic chemicals has been linked to a variety of adverse human health effects, including autoimmune diseases. In this scoping review, we summarize recent evidence detailing the effects of synthetic environmental chemicals on autoimmune diseases and highlight current research gaps and recommendations for future studies.

RECENT FINDINGS

We identified 68 recent publications related to environmental chemical exposures and autoimmune diseases. Most studies evaluated exposure to persistent environmental chemicals and autoimmune conditions including rheumatoid arthritis (RA), systemic lupus (SLE), systemic sclerosis (SSc), and ulcerative colitis (UC) and Crohn's disease. Results of recent original research studies were mixed, and available data for some exposure-outcome associations were particularly limited. PFAS and autoimmune inflammatory bowel diseases (UC and CD) and pesticides and RA appeared to be the most frequently studied exposure-outcome associations among recent publications, despite a historical research focus on solvents. Recent studies have provided additional evidence for the associations of exposure to synthetic chemicals with certain autoimmune conditions. However, impacts on other autoimmune outcomes, particularly less prevalent conditions, remain unclear. Owing to the ubiquitous nature of many of these exposures and their potential impacts on autoimmune risk, additional studies are needed to better evaluate these relationships, particularly for understudied autoimmune conditions. Future research should include larger longitudinal studies and studies among more diverse populations to elucidate the temporal relationships between exposure-outcome pairs and to identify potential population subgroups that may be more adversely impacted by immune modulation caused by exposure to these chemicals.

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.

Occupational farm work activities influence workers' indoor home microbiome

BACKGROUND

Farm work entails a heterogeneous mixture of exposures that vary considerably across farms and farmers. Farm work is associated with various health outcomes, both adverse and beneficial. One mechanism by which farming exposures can impact health is through the microbiome, including the indoor home environment microbiome. It is unknown how individual occupational exposures shape the microbial composition in workers' homes.

OBJECTIVES

We investigated associations between farm work activities, including specific tasks and pesticide use, and the indoor microbiome in the homes of 468 male farmers.

METHODS

Participants were licensed pesticide applicators, mostly farmers, enrolled in the Agricultural Lung Health Study from 2008 to 2011. Vacuumed dust from participants' bedrooms underwent whole-genome shotgun sequencing for indoor microbiome assessment. Using questionnaire data, we evaluated 6 farm work tasks (processing of either hay, silage, animal feed, fertilizer, or soy/grains, and cleaning grain bins) and 19 pesticide ingredients currently used in the past year, plus 7 banned persistent pesticide ingredients ever used.

RESULTS

All 6 work tasks were associated with increased microbial diversity levels, with a positive dose-response for the total number of tasks performed (P = 0.001). All tasks were associated with altered microbial compositions (weighted UniFrac P = 0.001) and with higher abundance of specific microbes, including soil-based commensal microbes such as Haloterrigena. Among the 19 pesticides, current use of glyphosate and past use of lindane were associated with increased microbial diversity (P = 0.02-0.04). Ten currently used pesticides and all 7 banned pesticides were associated with altered microbial composition (P = 0.001-0.04). Six pesticides were associated with differential abundance of certain microbes.

DISCUSSION

Different farm activities and exposures can uniquely impact the dust microbiome inside homes. Our work suggests that changes to the home microbiome could serve as one pathway for how occupational exposures impact the health of workers and their cohabitating family members, offering possible future intervention targets.

Inequalities in employment and gender differences in the prevalence of work-related musculoskeletal disorders cases: a nationwide survey from Brazil, 2019

OBJECTIVES

The present study aimed to investigate the prevalence of work-related musculoskeletal disorders (WRMDs) and to determine whether differences regarding the employment status (standard and non-standard), according to gender, increased the probability of WRMDs.

STUDY DESIGN

Cross-sectional study.

METHODS

Data from the 2019 National Health Survey (NHS) in Brazil were used. In total, 50,066 participants, both women and men, aged 18-65 years were included. Data were analysed for self-reported WRMDs. The binary logistic regression model, adjusting for possible covariables, was used to evaluate the association between working in the labour market and the occurrence of WRMDs. For covariates in the multivariate analysis, a P-value of <0.20 was considered in the univariate analysis. The variables with a P-value of <0.05 remained in the model. The odds ratio (OR), together with their confidence intervals at 95% (95% CI), were estimates both in the univariate and multivariate models.

RESULTS

The prevalence of WRMDs was higher in women (4.2%) than men (1.9%). The likelihood of WRMDs was associated with the employment status only among men and proved to be lower for non-standard employment than standard employment (OR = 0.61; 95% CI = 0.43-0.87). Only among women, an increase in the likelihood of WRMDs associated with exposure to occupational noise was observed (OR = 1.77; 95% CI = 1.31-2.38) and a less favourable self-reported health (OR = 1.66; 95% CI = 1.08-2.54). Results showed higher change of WRMD for men and women associated with rheumatoid arthritis (men: OR = 3.94; 95% CI = 2.10-7.38; women: OR = 2.39; 95% CI = 1.68-3.39), depression (men: OR = 2.62; 95% CI = 1.54-4.45; women: OR = 2.39; 95% CI = 1.68-3.39) and occupational accidents (men: OR = 4.36; 95% CI = 2.34-8.14; women: OR = 2.20; 95% CI = 1.19-4.07).

CONCLUSIONS

It is possible that the "double presence" that involves both the productive and reproductive spheres explains the higher prevalence of WRMDs among women Indicators that are sensitive to the effects of gender norms are necessary to understand the context of inequalities in the prevalence of WRMDs. The results of this study should be considered when developing strategies in the workplace and public health policies to reduce the prevalence of WRMDs.

Prevention vs treatment of rheumatoid arthritis

Whether a yet chronic and not curable disease like rheumatoid arthritis (RA) can be subject to prevention or whether available resources should be focused on treatment is a classical dilemma. Similar to the case in most other chronic diseases, the focus in research as well as in clinical practice has been on the treatment of established diseases, resulting in drugs that are efficient in eliminating most joint damage but not able to cure the disease or stop needs for continuous treatment of the disease. Less effort has been spent on identifying and implementing ways to prevent the disease. We argue in this review that knowledge concerning the longitudinal evolvement of the major, 'seropositive' subset of RA has now come to a stage where prevention should be a large part of the research agenda and that we should prepare for prevention as part of clinical practice in RA. We describe briefly the knowledge basis for broad public health-based prevention as well as for a 'precision prevention' strategy. In the latter, individuals at high risk for RA will be identified, monitored, and ultimately provided with advice on how to change lifestyle/environment or be given treatment with drugs able to delay and ultimately stop the development of RA. Whether this potential of precision prevention for RA will change the broader clinical practice will depend on whether specific and long-lasting interference with disease-inducing immunity, ultimately 'tolerance therapy', will become a reality.

Occupational Farm Work Activities Influence Workers' Indoor Home Microbiome

Background

Farm work entails a heterogeneous mixture of exposures that vary considerably across farms and farmers. Farm work is associated with various health outcomes, both adverse and beneficial. One mechanism by which farming exposures can impact health is through the microbiome, including the indoor built environment microbiome. It is unknown how individual occupational exposures shape the microbial composition in workers' homes.

Objectives

We investigated associations between farm work activities, including specific tasks and pesticide use, and the indoor microbiome in the homes of 468 male farmers.

Methods

Participants were licensed pesticide applicators, mostly farmers, enrolled in the Agricultural Lung Health Study from 2008-2011. Vacuumed dust from participants' bedrooms underwent whole-genome shotgun sequencing for indoor microbiome assessment. Using questionnaire data, we evaluated 6 farm work tasks (processing of either hay, silage, animal feed, fertilizer, or soy/grains, and cleaning grain bins) and 19 pesticide ingredients currently used in the past year, plus 7 persistent banned pesticide ingredients ever used.

Results

All 6 work tasks were associated with increased within-sample microbial diversity, with a positive dose-response for the sum of tasks (p=0.001). All tasks were associated with altered overall microbial compositions (weighted UniFrac p=0.001) and with higher abundance of specific microbes, including soil-based microbes such as Haloterrigena. Among the 19 pesticides, only current use of glyphosate and past use of lindane were associated with increased within-sample diversity (p=0.02-0.04). Ten currently used pesticides and all 7 banned pesticides were associated with altered microbial composition (p=0.001-0.04). Six pesticides were associated with differential abundance of certain microbes.

Discussion

Specific farm activities and exposures can impact the dust microbiome inside homes. Our work suggests that occupational farm exposures could impact the health of workers and their families through modifying the indoor environment, specifically the microbial composition of house dust, offering possible future intervention targets.

Endocrine-disrupting chemicals and autoimmune diseases

Endocrine-disrupting chemicals (EDCs) widely exist in people's production and life which have great potential to damage human and animal health. Over the past few decades, growing attention has been paid to the impact of EDCs on human health, as well as immune system. So far, researchers have proved that EDCs (such as bisphenol A (BPA), phthalate, tetrachlorodibenzodioxin (TCDD), etc.) affect human immune function and promotes the occurrence and development of autoimmune diseases (ADs). Therefore, in order to better understand how EDCs affect ADs, we summarized the current knowledge about the impact of EDCs on ADs, and elaborated the potential mechanism of the impact of EDCs on ADs in this review.

Exploratory analysis of the association between pyrethroid exposure and rheumatoid arthritis among US adults: 2007-2014 data analysis from the National Health and Nutrition Examination Survey (NHANES)

Previous studies indicate that pesticide use may play an important role in the occurrence and development of rheumatoid arthritis (RA); however, little is known about the effect of specific pesticides on RA. The objective of this study was to evaluate whether pyrethroid exposure was linked to RA in adults. Data were originated from the 2007-2014 National Health and Nutrition Examination Survey (NHANES). The levels of pyrethroid exposure were assessed by 3-phenoxybenzoic acid (3-PBA) concentrations in urine samples. We built multivariate logistic regression models to assess associations between pyrethroid exposure and RA among US adults. A restricted cubic spline plot (three knots) was applied to test whether there was a nonlinear relationship between exposure to pyrethroid pesticides and the prevalence of RA. Finally, 4384 subjects were included in our analysis with 278 RA patients. In crude model, higher level of 3-PBA (creatinine-adjusted) was positively associated with RA (OR: 1.51, 95% CI: 1.07, 2.15). After adjustment for sex, race/ethnicity, education, body mass index, family poverty income, level of education, marital status, smoking status, alcohol usage, physical activity, hypertension, and urinary creatinine, the highest (vs lowest) quartile of 3-PBA was associated with an increased prevalence of RA (OR: 1.23, 95% CI: 0.86, 1.79). Significantly positive associations between 3-PBA concentration and RA were observed in the population aged between 40 and 59 years and with lower level of education. The restricted cubic spline plot presented an increase in trend and indicated that pyrethroid exposure was linearly associated with occurrence of RA (p for nonlinearity = 0.728). In conclusion, our study indicated that pyrethroid pesticide exposure was associated with an increased risk of RA. Higher levels of pyrethroid exposure were linearly associated with increased prevalence of RA in adults. Certainly, our findings are in great need of further corroboration by prospective studies with strict design.

A qualitative characterization of meso-activity factors to estimate soil exposure for agricultural workers

BACKGROUND

Agricultural workers' exposure to soil contaminants is not well characterized. Activity pattern data are a useful exposure assessment tool to estimate extent of soil contact, though existing data do not sufficiently capture the range and magnitude of soil contact in the agricultural context.

OBJECTIVE

We introduce meso-activity, or specific tasks, to improve traditional activity pattern methodology. We propose a conceptual framework to organize the factors that may modify soil exposure and impact soil contact estimates within each meso-activity in agriculture. We build upon models from the US EPA to demonstrate an application of this framework to dose estimation.

METHODS

We conducted in-depth interviews with sixteen fruit and vegetable growers in Maryland to characterize factors that influence soil exposure in agriculture. For illustrative purposes, we demonstrate the application of the framework to translate our qualitative data into quantitative estimates of soil contact using US EPA models for ingestion and dermal exposure.

RESULTS

Growers discussed six tasks, or meso-activities, involving interaction with soil and described ten factors that may impact the frequency, duration and intensity of soil contact. We organized these factors into four categories (i.e., Environmental, Activity, Timing and Receptor; EAT-R) and developed a framework to improve agricultural exposure estimation and guide future research. Using information from the interviews, we estimated average daily doses for several agricultural exposure scenarios. We demonstrated how the integration of EAT-R qualitative factors into quantitative tools for exposure assessment produce more rigorous estimates of exposure that better capture the true variability in agricultural work.

SIGNIFICANCE

Our study demonstrates how a meso-activity-centered framework can be used to refine estimates of exposure for agricultural workers. This framework will support the improvement of indirect exposure assessment tools (e.g., surveys and questionnaires) and inform more comprehensive and appropriate direct observation approaches to derive quantitative estimations of soil exposure.

IMPACT STATEMENT

We propose a novel classification of activity pattern data that links macro and micro-activities through the quantification and characterization of meso-activities and demonstrate how the application of our qualitative framework improves soil exposure estimation for agricultural workers. These methodological advances may inform a more rigorous approach to the evaluation of pesticide and other chemical and biological exposures incurred by persons engaged in the cultivation of agricultural commodities in soil.

Association of distance to swine concentrated animal feeding operations with immune-mediated diseases: An exploratory gene-environment study

BACKGROUND

Concentrated animal feeding operations (CAFOs) are a source of environmental pollution and have been associated with a variety of health outcomes. Immune-mediated diseases (IMD) are characterized by dysregulation of the normal immune response and, while they may be affected by gene and environmental factors, their association with living in proximity to a CAFO is unknown.

OBJECTIVES

We explored gene, environment, and gene-environment (GxE) relationships between IMD, CAFOs, and single nucleotide polymorphisms (SNPs) of prototypical xenobiotic response genes AHR, ARNT, and AHRR and prototypical immune response gene PTPN22.

METHODS

The exposure analysis cohort consisted of 6,464 participants who completed the Personalized Environment and Genes Study Health and Exposure Survey and a subset of 1,541 participants who were genotyped. We assessed the association between participants' residential proximity to a CAFO in gene, environment, and GxE models. We recombined individual associations in a transethnic model using METAL meta-analysis.

RESULTS

In White participants, ARNT SNP rs11204735 was associated with autoimmune diseases and rheumatoid arthritis (RA), and ARNT SNP rs1889740 was associated with RA. In a transethnic genetic analysis, ARNT SNPs rs11204735 and rs1889740 and PTPN22 SNP rs2476601 were associated with autoimmune diseases and RA. In participants living closer than one mile to a CAFO, the log-distance to a CAFO was associated with autoimmune diseases and RA. In a GxE interaction model, White participants with ARNT SNPs rs11204735 and rs1889740 living closer than eight miles to a CAFO had increased odds of RA and autoimmune diseases, respectively. The transethnic model revealed similar GxE interactions.

CONCLUSIONS

Our results suggest increased risk of autoimmune diseases and RA in those living in proximity to a CAFO and a potential role of the AHR-ARNT pathway in conferring risk. We also report the first association of ARNT SNPs rs11204735 and rs1889740 with RA. Our findings, if confirmed, could allow for novel genetically-targeted or other preventive approaches for certain IMD.

Epidemiologic Opportunities and Challenges in Studying Environmental Risk Factors for Rheumatic Diseases

Most rheumatic diseases have a stronger environmental than hereditary etiology. This article summarizes the key environmental risk factors for rheumatic diseases, the data sources that generated these findings, and the key pitfalls with existing research that every rheumatology clinician should know. Emerging research opportunities hold promise to revolutionize this field, and soon.

Inhalant and Additional Mucosal-Related Environmental Risks for Rheumatoid Arthritis

Rheumatoid arthritis (RA) occurs as the result of a complex interplay of environmental factors in a genetically susceptible individual. There is considerable evidence that the lungs may serve as an initial site of tolerance loss in the generation of RA-related autoimmunity, and several environmental inhalant exposures and lung diseases have been associated with RA risk. There is additional evidence that immune and microbial dysregulation of other mucosal sites, including the oral and gastrointestinal mucosa, may contribute to the development of RA. Epidemiologic evidence linking mucosal exposures to various environmental insults as risk determinants in RA will be reviewed.

Pesticide use and risk of systemic autoimmune diseases in the Agricultural Health Study

BACKGROUND

Systemic lupus erythematosus (SLE) risk has been associated with pesticide use, but evidence on specific pesticides or other agricultural exposures is lacking. We investigated history of pesticide use and risk of SLE and a related disease, Sjögren's syndrome (SS), in the Agricultural Health Study.

METHODS

The study sample (N = 54,419, 52% male, enrolled in 1993-1997) included licensed pesticide applicators from North Carolina and Iowa and spouses who completed any of the follow-up questionnaires (1999-2003, 2005-2010, 2013-2015). Self-reported cases were confirmed by medical records or medication use (total: 107 incident SLE or SS, 79% female). We examined ever use of 31 pesticides and farm tasks and exposures reported at enrollment in association with SLE/SS, using Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), with age as the timescale and adjusting for gender, state, and correlated pesticides.

RESULTS

In older participants (>62 years), SLE/SS was associated with ever use of the herbicide metribuzin (HR 5.33; 95%CI 2.19, 12.96) and applying pesticides 20+ days per year (2.97; 1.20, 7.33). Inverse associations were seen for petroleum oil/distillates (0.39; 0.18, 0.87) and the insecticide carbaryl (0.56; 0.36, 0.87). SLE/SS was inversely associated with having a childhood farm residence (0.59; 0.39, 0.91), but was not associated with other farm tasks/exposures (except welding, HR 2.65; 95%CI 0.96, 7.35).

CONCLUSIONS

These findings suggest that some agricultural pesticides may be associated with higher or lower risk of SLE/SS. However, the overall risk associated with farming appears complex, involving other factors and childhood exposures.

The impact of a 6-week community-based physical activity and health education intervention-a pilot study among Irish farmers

BACKGROUND

There is a higher prevalence of lifestyle-related diseases among Irish farmers than the general adult population. Lifestyle interventions that increase physical activity and improve dietary patterns have been associated with reduced chronic disease risk and improved quality of life among high-risk populations. The impact of lifestyle interventions among Irish farmers is unknown.

AIM

To assess the effectiveness of a community-based intervention on farmer health, cardiovascular fitness, lower limb strength endurance, and dietary intake.

METHODS

A 6-week physical activity and lifestyle education intervention involving two 60-min circuit-based exercise training sessions and one 60-min health education workshop per week was implemented. Pre- and post-measurements included total body weight, body fat percentage, lean muscle mass, resting blood pressure, fasting blood glucose, cholesterol, triglycerides, cardiovascular fitness, lower limb strength, perceived physical and mental health, and dietary intake.

RESULTS

Thirty farmers completed the intervention giving an adherence rate of 75%. At baseline, mean BMI (32.7 ± 4.1 kg/m²), body fat percent (31.7 ± 6.7), waist circumference (110.2 ± 10.4 cm), systolic (128.7 ± 7.8 mmHg) and diastolic (86.2 ± 6.8 mmHg) blood pressure were higher than recommended levels. Significant improvements (p < 0.05) were found for total body weight, BMI, waist and hip circumferences, cardiovascular fitness, lower limb strength endurance, systolic blood pressure, total energy, total fat, total unsaturated fat, monounsaturated fat, saturated fat, trans fat, total carbohydrate, sodium, cholesterol and percentage energy intakes of total fat, saturated fat, protein, and physical and mental health scores.

CONCLUSIONS

Irish farmers remain at high risk of developing chronic diseases but respond positively to lifestyle intervention.

Association of Agricultural, Occupational, and Military Inhalants With Autoantibodies and Disease Features in US Veterans With Rheumatoid Arthritis

OBJECTIVE

To determine the association of inhalant exposures with rheumatoid arthritis (RA)-related autoantibodies and severity in US veterans.

METHODS

Participants in the Veterans Affairs Rheumatoid Arthritis (VARA) registry were mailed surveys assessing occupational, agricultural, and military inhalant exposures. Demographic characteristics, disease activity, functional status, and extraarticular features were obtained from the VARA registry, while HLA-DRB1 shared epitope (SE) status, anti-cyclic citrullinated peptide (anti-CCP) antibodies, and rheumatoid factor (RF) were measured using banked DNA/serum from enrollment. Associations between inhalant exposures and RA-related factors (autoantibodies, severity, and extraarticular features) were assessed using multivariable linear and logistic regression models adjusted for age, sex, race, and tobacco use and stratified by SE status. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Questionnaires were returned by 797 of 1,566 participants (50.9%). Survey respondents were older, more often White or male, and less frequently smokers, and had lower disease activity compared to nonrespondents. Anti-CCP positivity was more common among veterans exposed to burn pits (OR 1.66 [95% CI 1.02, 2.69]) and military waste disposal (OR 1.74 [95% CI 1.04, 2.93]) independent of other factors. Among participants who were positive for SE alleles, burn pit exposure (OR 5.69 [95% CI 2.73, 11.87]) and military waste disposal exposure (OR 5.05 [95% CI 2.42, 10.54]) were numerically more strongly associated with anti-CCP positivity. Several inhalant exposures were associated with the presence of chronic lung disease, but not with the presence of RF or the level of disease activity.

CONCLUSION

Military burn pit exposure and military waste disposal exposure were independently associated with the presence of anti-CCP antibodies in RA patients. These findings are consistent with emerging evidence that various inhalant exposures influence autoantibody expression and RA risk.

Etiologies of Rheumatoid Arthritis: Update on Mucosal, Genetic, and Cellular Pathogenesis

Purpose of Review

Over the last few years, the scientific community has made significant progress in understanding the etiology of rheumatoid arthritis (RA). In this review, we summarize those key findings and trends.

Recent Findings

New data strongly implicates respiratory exposures, obesity, diet and microbiome, genetics, and their interactions in the etiology of RA. Furthermore, anti-posttranslationally modified protein antibodies (AMPAs) and abnormal glycosylation may be additional biomarkers for RA. Finally, functional genomics techniques implicate loss of certain macrophage populations and proliferation of synovial fibroblasts in RA.

Summary

These findings support the notion that RA originates at mucosal sites, augmented by genetic predisposition, and mediated by certain cell types including macrophages and fibroblasts. Weight loss, physical activity, and diet are additional modifiable factors beyond smoking cessation that can reduce risk of RA. Future epidemiologic and translational studies leveraging multi-omics approaches will help map the precise sequence of events in RA pathogenesis.

Lifestyle factors associated with incidence of rheumatoid arthritis in US adults: analysis of National Health and Nutrition Examination Survey database and meta-analysis

OBJECTIVE

To quantify rheumatoid arthritis (RA) cases attributable to selected non-genetic risk factors.

DESIGN

National Health and Nutrition Examination Survey (NHANES) and meta-analysis.

PARTICIPANTS

US adults.

DATA SOURCES

The prevalence of exposure was obtained from NHANES. Weighted analysis was performed to account for the complex sampling design in NHANES. PubMed and Web of Science up to 31 March 2019 were searched to identify epidemiological studies reported the association between non-genetic risk factors and RA in US adults. Relative risk (RR) value and the corresponding CI were pooled by meta-analysis to evaluate the associations between modifiable risk factors and RA. Population attributable fraction (PAF) was calculated based on the prevalence and RR data.

RESULTS

The weighted percentages of former smokers, current smokers and overweight or obese people were 24.84%, 23.93% and 63.97%, and the average alcohol consumption was 51.34 g/week. In the meta-analysis, we found that former smokers (RR 1.22, 95% CI 1.10 to 1.36) and current smokers (RR 1.47, 95% CI 1.29 to 1.68) had higher risks of RA. Overweight and obese individuals had 1.27-fold (95% CI 1.09 to 1.48) increased risk of RA. Each per 50 g/week increment of alcohol consumption was associated with 8% (95% CI 0% to 16%) reduction in the risk of RA. Therefore, PAF value of smoking was 14.00% (95% CI 8.13% to 23.33%). Excess body mass index (BMI) was found to account for 14.73% (95% CI 5.45% to 23.50%) of RA incidence. The fraction of RA risk attributed by low alcohol intake was 8.21% (95% CI 0.31% to 16.39%). Collectively, we found that 32.69% (95% CI 13.41% to 50.96%) of RA cases were attributable to smoking, overweight or obesity and low alcohol drinking.

CONCLUSION

Nearly 33% of RA incidence was attributed to smoking, excess BMI and low alcohol drinking in USA. Our findings could provide a basis for developing guidelines of RA prevention and control in USA.

Environment and Lifestyle: Their Influence on the Risk of RA

Background: Rheumatoid arthritis (RA) is a complex disease in which environmental agents are thought to interact with genetic factors that lead to triggering of autoimmunity. Methods: We reviewed environmental, hormonal, and dietary factors that have been suggested to be associated with the risk of RA. Results: Smoking is the most robust factor associated with the risk of RA, with a clear gene–environment interaction. Among other inhalants, silica may increase the risk of RA in men. There is less evidence for pesticides, pollution, and other occupational inhalants. Regarding female hormonal exposures, there is some epidemiological evidence, although not consistent in the literature, to suggest a link between hormonal factors and the risk of RA. Regarding dietary factors, available evidence is conflicting. A high consumption of coffee seems to be associated with an increased risk of RA, whereas a moderate consumption of alcohol is inversely associated with the risk of RA, and there is less evidence regarding other food groups. Dietary pattern analyses (Mediterranean diet, the inflammatory potential of the diet, or diet quality) suggested a potential benefit of dietary modifications for individuals at high risk of RA. Conclusion: To date, smoking and silica exposure have been reproducibly demonstrated to trigger the emergence of RA. However, many other environmental factors have been studied, mostly with a case-control design. Results were conflicting and studies rarely considered potential gene–environment interactions. There is a need for large scale prospective studies and studies in predisposed individuals to better understand and prevent the disease and its course.

A follow-up study of occupational styrene exposure and risk of autoimmune rheumatic diseases

Objectives

Increased risk has been suggested for autoimmune rheumatic diseases following solvent exposure. The evidence for specific solvents is limited, and little is known about exposure–response relations. Styrene is an aromatic, organic solvent and the objective of this study was to analyse the association between occupational styrene exposure and autoimmune rheumatic diseases in men and women.

Methods

We followed 72 212 styrene-exposed workers of the Danish reinforced plastics industry from 1979 to 2012. We modelled full work history of styrene exposure from employment history, survey data and historical styrene exposure measurements. We identified cases in the national patient registry and investigated gender-specific exposure–response relations by cumulative styrene exposure for different exposure time windows adjusting for age, calendar year and educational level.

Results

During 1 515 126 person-years of follow-up, we identified 718 cases of an autoimmune rheumatic disease, of which 73% were rheumatoid arthritis. When adjusting for potential confounders and comparing the highest with the lowest styrene exposure tertile, we observed a statistically non-significantly increased risk of systemic sclerosis among women (incidence rate ratio (IRR)=2.50; 95% CI 0.50 to 12.50) and men (IRR=1.86; 95 % CI 0.50 to 7.00), based on 9 and 22 cases, respectively. Results were inconsistent for the other autoimmune rheumatic diseases examined.

Conclusion

This study suggests an association between occupational styrene exposure and systemic sclerosis in men as well as in women but based on few cases. This is a new finding and has to be replicated before conclusions can be drawn.

Occupational exposure to organic dusts and risk of developing rheumatoid arthritis: findings from a Swedish population-based case-control study

Objectives

We estimated the association between occupational exposures to five different organic dusts: wood, animal, paper, textile and flour dust and the risk of developing rheumatoid arthritis (RA).

Methods

This population-based case–control study analysed 12 582 incident cases and 129 335 controls. Participants were identified from national public authority and quality registers. Census data on occupations were collected 1960–2010 and we estimated the exposure to organic dust with the help of job-exposure matrices. We used logistic regression to assess the OR of seropositive or seronegative RA. Estimates were adjusted for the matching variables (sex, county, age and index year), education and occupational silica exposure.

Results

Exposure to animal dust was associated with an increased risk of RA among both men and women. The OR was 1.2 (95% CI=1.1 to 1.4) for seropositive RA and 1.3 (95% CI=1.1 to 1.5) for seronegative RA among ever exposed participants compared with unexposed. The risk increased with duration of exposure for seropositive RA, and participants who had been exposed in five or more censuses had an OR of 1.6 (95% CI=1.1 to 2.2, p for trend=0.003). Exposure to textile dust also generated a significant dose–response relationship for seropositive RA (p for trend=0.014). We detected no association between exposure to wood, paper or flour dust and risk of RA.

Conclusions

Overall, exposure to animal dust and textile dust was associated with an increased risk of developing RA. These observations give further support to the notion that airborne exposures are involved in the aetiology of RA.

Lifetime Pesticide Use and Antinuclear Antibodies in Male Farmers From the Agricultural Health Study

Farming and pesticide use have been associated with systemic autoimmune diseases, and while certain organochlorine insecticides and other pesticides are suspected to influence risk, the role of specific pesticides in the development of systemic autoimmunity is not known. We measured serum antinuclear autoantibodies (ANA) by immunofluorescence on Hep-2 cells in 668 male farmers in the study of Biomarkers of Exposure and Effect in Agriculture (BEEA; 2010-2013), an Agricultural Health Study (AHS) subcohort. We examined ANA in relation to lifetime use of 46 pesticides first reported at AHS enrollment (1993-1997) and updated at intervals through BEEA enrollment. Odds ratios (OR) and 95% confidence intervals (CI) were estimated after adjusting for age, state, education, season of blood draw, current pesticide use, and correlated pesticides. Having ANA antibodies (3 or 4+ intensity at a 1:80 dilution, 21% of study participants) was associated with a reported history of seeking medical care due to exposure to pesticides (OR 2.15; 95%CI 1.17, 3.95), use of the fumigant methyl bromide (OR 3.16; 95%CI 1.05, 9.5), and use of petroleum oil/distillates (OR 1.50; 95%CI 1.00, 2.25). Using a higher threshold (3 or 4+ at a 1:160 dilution, 9%) ANA positivity was associated with the carbamate insecticide aldicarb (OR 4.82; 95%CI 1.33, 17.5) and greater combined use of four cyclodiene organochlorine insecticides (top tertile of intensity-weighted lifetime days vs. no use; OR T3 3.20; 95%CI 1.10, 9.27). By contrast, greater use of non-cyclodiene organochlorine insecticides was inversely associated with ANA (1:80 dilution 3 or 4+, OR T3 0.24; 95%CI 0.08, 0.72). Specific autoantibodies (to extractable nuclear antigens and anti-dsDNA), measured on those with ANA detected at the 1:80 dilution 3 or 4+, were seen in 15 individuals (2%), and were associated with use of two or more cyclodiene organochlorine insecticides and several other pesticides (e.g., carbofuran, ethylene dibromide). These findings suggest that specific pesticide exposures may have long-term effects on ANA prevalence and support the hypothesis that certain organochlorine insecticides may increase the risk of developing systemic autoimmunity.