A case-control study of occupational exposures and systemic sclerosis

Independent association between occupational exposure and decline of forced vital capacity in systemic sclerosis (SSc): a multicenter recruitment retrospective cohort study

BACKGROUND

Although male sex is associated with poor prognosis in Systemic Sclerosis (SSc), it is unclear whether this association is independent of confounding factors such as occupational exposure to toxicants.

RESEARCH QUESTION

What is the respective impact of sex and occupational exposure on SSc patients' characteristics with a focus on lung function decline?

STUDY DESIGN AND METHODS

Patients with SSc (n=210, 55 males) underwent standardized quantitative assessment of occupational exposure through a cumulative exposure score (CES) in a multicenter recruitment retrospective cohort. Association of the CES with patients' characteristics was assessed. Mixed linear, logistic and Cox regression models were used to identify predictors of time variation of forced vital capacity (FVC) and the hemoglobin-corrected transfer coefficient for carbon monoxide in the lung (DLCOc).

RESULTS

Male sex was strongly associated with occupational exposure (OR=10.3, p<.0001). The CES was inversely correlated (r= -.20) and independently associated with decline in FVC over time and with occurrence of FVC decline ≥10% from baseline (p<.05). By contrast, the CES was not associated with decline in DLCOc or DLCOc decline ≥15%. There was no independent association between sex and decline in FVC or DLCOc. The prevalence of interstitial lung disease was similar across sex or occupational exposure.

INTERPRETATION

Occupational exposure to toxicants appears to independently predict decline of FVC in SSc patients, regardless of sex. Assessment of occupational exposure may be useful for SSc prognostication.

Is exposure to environmental factors associated with a characteristic clinical and laboratory profile in systemic sclerosis? A retrospective analysis

To identify environmental factors (EF) in a large cohort of patients with systemic sclerosis (SSc) analyzing their clinical and laboratory presentation. A cohort of consecutive patients attended at a single Brazilian SSc outpatient clinic was analyzed regarding EF. Data were analyzed according to clinical, demographic and laboratory characteristics, as well as SSc subtype. In a cohort of 662 patients, 70 (10.6%) had known previous exposure to EF, predominantly organic solvents (51.4%), silica (20%), silicone (12.9%) and pesticides (11.4%). In the SSc cohort, patients with EF had a significantly higher frequency of male gender (p < 0.01), African-Brazilian ethnicity (p = 0.01), myopathy (p = 0.02), and pigmentary disorders (p = 0.04), with shorter disease duration (p = 0.01). When SSc subtypes were analyzed separately, there was positive association with male gender in limited (p < 0.01) and diffuse (p < 0.01) SSc, as well as African-Brazilian ethnicity (p = 0.04), severe interstitial lung disease (p < 0.01), myopathy (p = 0.02) and SD pattern at nailfold capillaroscopy (p = 0.01) in limited SSc, and negative association with esophageal hypomotility (p < 0.01) and ANA positivity (p = 0.02) in diffuse SSc. Multiple regression analyses showed that myopathy was independently associated with previous exposure to EF (OR = 2.09; 95% CI 1.15-3.82), especially silica exposure (OR = 3.09; 95% CI 1.67-5.73). This study showed that SSc patients with previous exposure to EF may have some specific clinical characteristics, mainly a higher frequency of myopathy, also showing more severe ILD, preferably in male and African-Brazilian patients, associated with a lower frequency of ANA positivity.

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.

Blue toe syndrome as a first sign of systemic sclerosis

We describe an unusual case of blue toe syndrome as the primary and solitary manifestation of systemic sclerosis. The possible cause was long-term occupational exposure in construction work. Blue toe syndrome is a small vessel disease, characterised by the sudden development of painful, blue discolouration in one or more toes. The most common aetiology is atheroembolic disease; however, it can also appear in several conditions ranging from hypercoagulability disorders to underlying systemic diseases such as vasculitis or autoimmune diseases. Here, we describe the case of a 57-year-old man who presented with blue toe syndrome without underlying atheroembolic disease. He was found to have positive anticentromere antibodies, which indicated that systemic sclerosis was the likely primary underlying cause. An extensive systemic evaluation and a thorough physical examination revealed no other symptoms associated with systemic sclerosis. He was prescribed nifedipin and rosuvastatin, and showed complete resolution of symptoms after 3 months.

The Influence of Different Solvents on Systemic Sclerosis: An Updated Meta-analysis of 14 Case-Control Studies

BACKGROUND

Several studies have collected detailed data to examine which specific solvents account for the association between solvents and risk of systemic sclerosis (SSc). These studies generally reported elevated risks associated with many of the specific solvents examined, such as toluene, xylene, and trichloroethylene. The previous meta-analysis was not able to conduct separate analyses for specific solvent subtypes.

OBJECTIVE

The aims of the new meta-analysis were to investigate a more comprehensive estimate and to consider the effect of different solvents on SSc.

METHODS

We searched PubMed, Biosis Previews, China National Knowledge Infrastructure, and Wanfang for all articles published before July 2015. Fourteen case-control studies (1657 patients and 3838 controls) were included. The quality of studies was scored according to the Newcastle-Ottawa scale. The final odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by a fixed- or random-effects model according to heterogeneity test. Publication bias was assessed using Begg test.

RESULTS

The risk of SSc was significantly different among sex, age, and exposure assessment methods. Separate analyses for specific solvent subtypes indicated that SSc was associated with aromatic solvents (OR, 2.72; 95% CI, 1.21-6.09), trichloroethylene (OR, 2.07; 95% CI, 1.34-3.17), halogenated solvents (OR, 1.49; 95% CI, 1.12-1.99), and ketones (OR, 4.20; 95% CI, 2.19-8.06).

CONCLUSIONS

Exposure to identified types solvents does seem to be a risk factor for developing SSc. Needed efforts to decrease such exposures are discussed.

Prospective study to evaluate the association between systemic sclerosis and occupational exposure and review of the literature

INTRODUCTION

Systemic sclerosis (SSc) has complex pathogenesis and likely multifactorial causes. Environmental exposures have been suggested to play a role in SSc pathogenesis, including occupational exposure to pollutants and chemicals as well as use of drugs leading to modulation of immune response. Thus, this case-control study aimed to assess: the relationship between SSc and occupational exposure; and the risk of SSc related to occupational exposure in male and female patients.

METHODS

From 2005 to 2008, 100 patients with a definite diagnosis of SSc were included in the study; 3 age, gender, and smoking habits matched controls were selected for each patient. A committee of experts evaluated blindly occupational exposure to crystalline silica, white spirit, organic solvents, ketones, welding fumes, epoxy resins, and pesticides; an occupational exposure score was calculated for all subjects. Our findings were compared with previous data in the literature.

RESULTS

Increased ORs for SSc were found for: crystalline silica (p<0.0001), white spirit (p<0.0001), aromatic solvents (p=0.0002), chlorinated solvents (p=0.014), trichlorethylene (p=0.044), ketones (p=0.002) and welding fumes (p=0.021). Elevated risk associated with high final cumulative score in SSc was observed for: crystalline silica, white spirit, chlorinated solvents, trichlorethylene, aromatic solvents, any type of solvents, ketones and welding fumes. A marked association between SSc and occupational exposure was further found for: 1) crystalline silica, chlorinated solvents, trichloroethylene, white spirit, ketones and welding fumes in male patients; and 2) white spirit, aromatic solvents, any type of solvent and ketones in female patients. Finally, we did not find an association between SSc and: 1) the use of drugs that have been speculated to play a role in SSc onset (anorexigens, pentazocine, bromocriptine, l-tryptophan); 2) implants - that are prosthesis, silicone implants, and contact lenses; and 3) dyeing hair. In the literature, SSc has been associated with occupational exposure to silica and solvents, while the association between SSc and specific organic solvents and welding fumes has been anecdotally reported.

CONCLUSION

The following occupational factors have an impact in the development of SSc: crystalline silica, white spirit, aromatic solvents, chlorinated solvents, trichlorethylene, ketones and welding fumes. The risk of SSc appears to be markedly associated with high cumulative exposure. Finally, the association between SSc and occupational exposure may be variable according to gender.

Localized cutaneous fibrosing disorders

This article acquaints the reader with disorders of the skin that might mimic systemic sclerosis but whose pathology is localized to the skin and/or has extracutaneous manifestations that are different than systemic sclerosis. These disorders include localized scleroderma (morphea), eosinophilic fasciitis, scleredema, scleromyxedema, nephrogenic systemic fibrosis, and chronic graft-versus-host disease. Particular emphasis is placed on clinical and histopathologic features that help the clinician differentiate between these disorders. Treatment options are briefly reviewed.

Organic solvents as risk factor for autoimmune diseases: a systematic review and meta-analysis

BACKGROUND

Genetic and epigenetic factors interacting with the environment over time are the main causes of complex diseases such as autoimmune diseases (ADs). Among the environmental factors are organic solvents (OSs), which are chemical compounds used routinely in commercial industries. Since controversy exists over whether ADs are caused by OSs, a systematic review and meta-analysis were performed to assess the association between OSs and ADs.

METHODS AND FINDINGS

The systematic search was done in the PubMed, SCOPUS, SciELO and LILACS databases up to February 2012. Any type of study that used accepted classification criteria for ADs and had information about exposure to OSs was selected. Out of a total of 103 articles retrieved, 33 were finally included in the meta-analysis. The final odds ratios (ORs) and 95% confidence intervals (CIs) were obtained by the random effect model. A sensitivity analysis confirmed results were not sensitive to restrictions on the data included. Publication bias was trivial. Exposure to OSs was associated to systemic sclerosis, primary systemic vasculitis and multiple sclerosis individually and also to all the ADs evaluated and taken together as a single trait (OR: 1.54; 95% CI: 1.25-1.92; p-value<0.001).

CONCLUSION

Exposure to OSs is a risk factor for developing ADs. As a corollary, individuals with non-modifiable risk factors (i.e., familial autoimmunity or carrying genetic factors) should avoid any exposure to OSs in order to avoid increasing their risk of ADs.

Epidemiology of environmental exposures and human autoimmune diseases: findings from a National Institute of Environmental Health Sciences Expert Panel Workshop

Autoimmune diseases (AID) are a collection of many complex disorders of unknown etiology resulting in immune responses to self-antigens and are thought to result from interactions between genetic and environmental factors. Here we review the epidemiologic evidence for the role of environmental factors in the development of human AID, the conclusions that can be drawn from the existing data, critical knowledge gaps, and research needed to fill these gaps and to resolve uncertainties. We specifically summarize the state of knowledge and our levels of confidence in the role of specific agents in the development of autoimmune diseases, and we define the areas of greatest impact for future investigations. Among our consensus findings we are confident that: 1) crystalline silica exposure can contribute to the development of several AID; 2) solvent exposure can contribute to the development of systemic sclerosis; 3) smoking can contribute to the development of seropositive rheumatoid arthritis; and 4) an inverse association exists between ultraviolet radiation exposure and the risk of development of multiple sclerosis. We suggest that more studies of phenotypes, genotypes, and multiple exposures are needed. Additional knowledge gaps needing investigation include: defining important windows in the timing of exposures and latencies relating to age, developmental state, and hormonal changes; understanding dose-response relationships; and elucidating mechanisms for disease development. Addressing these essential issues will require more resources to support research, particularly of rare AID, but knowledge of the risks conferred by environmental factors in specific genetic contexts could pave the way for prevention of AID in the future.

Occupational risk factors for systemic lupus erythematosus: a nationwide study based on hospitalizations in Sweden

OBJECTIVE

To investigate possible associations between occupation and hospitalization for systemic lupus erythematosus (SLE) in a nationwide study.

METHODS

A nationwide database was constructed in Sweden by linking the Swedish Census to the Hospital Discharge Register to obtain data on all first hospitalizations with a primary or secondary diagnosis of SLE in adults during the study period (1970 to 2008). Standardized incidence ratios (SIR) and 95% CI were calculated for different occupations. Two cohorts were defined based on occupational titles recorded in Swedish census data in 1970 and 1980.

RESULTS

A total of 8921 male and 42290 female hospitalizations for SLE were retrieved in individuals aged over 15 years. High education (> 12 yrs) was associated with a lower risk of hospitalization for SLE among both women (SIR = 0.73) and men (SIR = 0.72). Among men with the same occupation in 2 consecutive censuses, increased risks (SIR) > 2.0 were present among artistic workers (2.52); shop managers and assistants (3.63); miners and quarry workers (6.04); shoe and leather workers (6.93); plumbers (2.21); other construction workers (2.08); glass, ceramic and tile workers (4.43); chimney sweeps (4.54); and military personnel (3.01). Among women with the same occupation in 2 consecutive censuses, no occupation was associated with SIR > 2.0.

CONCLUSION

Occupation may carry significantly increased risk of hospital admission for SLE. Especially among men, several occupations were associated with increased risks for SLE.

Pesticide-induced scleroderma and early intensive immunosuppressive treatment

The authors report 2 children with generalized cutaneous sclerosis exposed to pesticides containing malathion and diniconazole. Treatment with immunosuppressives resulted in partial improvement in the cutaneous signs, particularly over the face, trunk, and proximal limbs. The considerable exposure to chemicals related with the initiation of symptoms and absence of organ involvement suggested a diagnosis of chemically induced scleroderma-like disorder. Although autoantibodies were negative, previously reported relevant associations of anti-kinetochore and anti-topoisomerase function of active ingredients-diniconazole and phosphorodithioate-and solvents of these pesticides are also discussed. Careful follow-up for systemic involvement is warranted, since these agents may have triggered systemic scleroderma in these patients. Elimination of chemical exposure of children is stressed.

Interaction of occupational and personal risk factors in workforce health and safety

Most diseases, injuries, and other health conditions experienced by working people are multifactorial, especially as the workforce ages. Evidence supporting the role of work and personal risk factors in the health of working people is frequently underused in developing interventions. Achieving a longer, healthy working life requires a comprehensive preventive approach. To help develop such an approach, we evaluated the influence of both occupational and personal risk factors on workforce health. We present 32 examples illustrating 4 combinatorial models of occupational hazards and personal risk factors (genetics, age, gender, chronic disease, obesity, smoking, alcohol use, prescription drug use). Models that address occupational and personal risk factors and their interactions can improve our understanding of health hazards and guide research and interventions.

Epidemiology of systemic sclerosis

Systemic sclerosis (SSc) is a multisystem auto-immune disease. The two main subtypes of SSc (limited and diffuse) typically have differing courses and prognoses. New classification criteria have been proposed to identify SSc in the earliest stages, before skin involvement. Over the past three decades, there has been an apparent increase in the incidence of SSc to approximately 20 per million, possibly due to improved diagnosis. The most extensively studied environmental associations of SSc are organic solvents and silica but no single risk factor has emerged. Recent genetic studies have identified new susceptibility factors including human leucocyte antigen (HLA) haplotypes and polymorphisms in immune regulatory genes. Despite earlier disease recognition and effective treatment for some of its complications, SSc still carries a high mortality, particularly due to cardiorespiratory complications. Although some predictors of organ involvement and outcomes have been identified, novel biomarkers are greatly needed. Due to low disease prevalence, large multicentre research collaborations are required.

Role of sodium silicate in induction of scleroderma-related autoantibodies in brown Norway rats through oral and subcutaneous administration

Silica hazard is a growing occupational problem and has been reported to be associated with scleroderma via case reports and occupational studies. The aim of this study is to demonstrate whether oral or subcutaneous silicate exposure can induce an autoimmunity and scleroderma susceptibility in immunosensitive rats. Sodium silicate in a dose of 3 mg in 0.2 ml NS was administered through oral and subcutaneous routes to 20 brown Norway rats. Autoantibodies including ANA, anti-RNP, anti-SCL70 and anti-centromere were measured and compared with pre- and post-challenge serum samples. Serum ANA and anti-RNP were high in significant number of rats (P < 0.05) of only the subcutaneous silicate group. There is an increase in the number of positive readings of autoantibodies at 14th week in comparison with the number of positive readings of autoantibodies at 7th week but P values were not significant. It may be concluded that silicate might induce autoimmunity and scleroderma and it seems to be that the longer the duration of exposure the greater the risk. This is probably the first experimental animal study demonstrating the induction of scleroderma-related autoantibodies after challenge with silicate.

Polymyalgia rheumatica prevalence in a population-based sample

OBJECTIVE

To determine polymyalgia rheumatica (PMR) prevalence using population-based administrative data, and to estimate the error associated with case ascertainment approaches when using these databases.

METHODS

Cases were ascertained using physician billing and hospitalization data from the province of Manitoba (population 1.1 million). Focusing on the population age >/=45 years, we compared 3 different case definition algorithms and also used statistical methods that accounted for imperfect case ascertainment to estimate the prevalence and the properties of the ascertainment algorithms. A hierarchical Bayesian latent class regression model was developed that also allowed us to assess differences across patient demographics (sex and region of residence).

RESULTS

Using methods that account for the imperfect nature of both billing and hospitalization databases, we estimated the prevalence of PMR in women age >/=45 years to be lower in urban areas (754.5 cases/100,000; 95% credible interval [95% CrI] 674.1-850.3) compared with rural areas (1,004 cases/100,000; 95% CrI 886.3-1,143). This regional trend was also seen in men age >/=45 years, where the prevalence was estimated at 273.6 cases/100,000 (95% CrI 219.8-347.6) in urban areas and 380.7 cases/100,000 (95% CrI 311.3-468.1) in rural areas. Billing data appeared more sensitive in ascertaining cases than hospitalization data, and a large proportion of diagnoses was made by physicians other than rheumatologists.

CONCLUSION

These data suggest a higher prevalence of PMR in rural versus urban regions. Our approach demonstrates the usefulness of methods that adjust for the imperfect nature of multiple information sources, which also allow for estimation of the sensitivity of different case ascertainment approaches.

Systemic sclerosis: environmental factors

Epidemiological evidence for the association between environmental and occupational risk factors and systemic sclerosis (SSc) has been extensively analyzed. Such exposures are frequently of long duration, and the inadequate classification of the type of exposure and other confounding variables may bias their estimated association with SSc. Environmental factors could be classified as occupational (silica, organic solvents), infectious (bacterial, viral), and non-occupational/non-infectious (drugs, pesticides, silicones). Understanding the link between environmental risk factors and the development of SSc is limited, due to the phenotypic and pathogenic heterogeneity of patients and disease, respectively, and also due to poor ability to assess environmental exposures quantitatively and the role of the gene-environment interactions in this disease. Global collaboration could increase the chance for a better use of the data obtained from a limited number of cases and also limited resources. Normalization and validation of biomarkers and questionnaires could also be very useful to reliably quantify environmental exposures.

Evidence of autoimmune-related effects of trichloroethylene exposure from studies in mice and humans

OBJECTIVE

Our objective was to examine experimental and epidemiologic studies pertaining to immune-related, and specifically autoimmune-related, effects of trichloroethylene (TCE).

DATA SOURCES AND EXTRACTION

We performed a literature search of PubMed and reviewed bibliographies in identified articles. We then systematically reviewed immune-related data, focusing on clinical and immunologic features and mechanistic studies.

DATA SYNTHESIS

Studies conducted in MRL+/+ lupus mice report an accelerated autoimmune response in relation to exposure to TCE or some metabolites. Effects have been reported after 4 weeks of exposure to TCE at doses as low as 0.1 mg/kg/day in drinking water and have included increased antinuclear antibodies and interferon-gamma (IFN-gamma) and decreased secretion of interleukin-4 (IL-4), consistent with an inflammatory response. Autoimmune hepatitis, inflammatory skin lesions, and alopecia have been found after exposures of 32-48 weeks. Recent mechanistic experiments in mice examined oxidative stress and, specifically, effects on lipid-peroxidation-derived aldehydes in TCE-induced autoimmune disease. Two studies in humans reported an increase in IL-2 or IFN-gamma and a decrease in IL-4 in relation to occupational or environmental TCE exposure. Occupational exposure to TCE has also been associated with a severe, generalized hypersensitivity skin disorder accompanied by systemic effects, including hepatitis. In three case-control studies of scleroderma with a measure of occupational TCE exposure, the combined odds ratio was 2.5 [95% confidence interval (CI), 1.1-5.4] in men and 1.2 (95% CI, 0.58-2.6) in women.

CONCLUSION

The consistency among the studies and the concordance between the studies in mice and humans support an etiologic role of TCE in autoimmune disease. Multisite collaborations and studies of preclinical immune markers are needed to further develop this field of research.

BENEFICIAL ROLE OF CURCUMIN IN SKIN DISEASES

In recent years, considerable interest has been focused on curcumin a compound, isolated from turmeric. Curcumin is used as a coloring, flavoring agent and has been traditionally used in medicine and cuisine in India. The varied biological properties of curcumin and lack of toxicity even when administered at higher doses makes it attractive to explore its use in various disorders like tumors of skin, colon, duodenum, pancreas, breast and other skin diseases. This chapter reviews the data on the use of curcumin for the chemoprevention and treatment of various skin diseases like scleroderma, psoriasis and skin cancer. Curcumin protects skin by quenching free radicals and reducing inflammation through nuclear factor-KB inhibition. Curcumin treatment also reduced wound-healing time, improved collagen deposition and increased fibroblast and vascular density in wounds thereby enhancing both normal and impaired wound-healing. Curcumin has also been shown to have beneficial effect as a proangiogenic agent in wound-healing by inducing transforming growth factor-beta, which induces both angiogenesis and accumulation of extracellular matrix, which continues through the remodeling phase of wound repair. These studies suggest the beneficial effects of curcumin and the potential of this compound to be developed as a potent nontoxic agent for treating skin diseases.

Mechanisms of Disease: environmental factors in the pathogenesis of rheumatic disease

Most rheumatic diseases are complex disorders for which pathogenetic mechanisms are poorly understood. Nonetheless, increasing evidence suggests that many of these illnesses result from one or more specific environmental exposures in genetically susceptible individuals. Although much progress has been made over the past few decades in advancing our knowledge of the genetics of rheumatic diseases, few studies have assessed environmental features and understanding of which exposures are important in pathogenesis remains limited. In this article, we review the difficulties inherent in deciphering the interacting environmental and genetic risk factors for rheumatic diseases, the current state of knowledge of infectious and noninfectious risk factors, possible mechanisms by which environmental exposures might induce pathologic processes and future directions. The advances in technologies and statistical approaches, development of collaborating consortia and focused resources that have resulted in the explosion of genetic information must now be applied to environmental studies so we can eventually interrupt pathogenesis before the onset of disease and transform the practice of medicine from curative to pre-emptive paradigms.

Systemic autoimmune disease mortality and occupational exposures

OBJECTIVE

To generate hypotheses regarding occupational exposures that may cause systemic autoimmune diseases.

METHODS

Based on examination of US death certificates, we identified deaths in 26 states for which a cause was listed as rheumatoid arthritis (RA) (n = 36,178), systemic lupus erythematosus (SLE) (n = 7,241), systemic sclerosis (n = 5,642), or other systemic autoimmune disease (n = 4,270). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to estimate associations between occupation and death from any systemic autoimmune disease, and from RA, SLE, and systemic sclerosis, specifically. Additionally, we estimated risks associated with occupational exposures, which were assigned using job-exposure matrices.

RESULTS

A broad array of occupations was associated with death from systemic autoimmune diseases, including several of a priori interest. Farming occupation was associated with death from any systemic autoimmune disease (OR 1.3 [95% CI 1.2-1.4]), and increased risk was also seen with occupational exposure to animals and pesticides. Several industrial occupations were associated with death from any systemic autoimmune disease, including mining machine operators (OR 1.3 [95% CI 1.1-1.5]), miscellaneous textile machine operators (OR 1.2 [95% CI 1.0-1.4]), and hand painting, coating, and decorating occupations (OR 1.8 [95% CI 1.0-2.9]). These occupations were also significantly associated with death from the specific autoimmune diseases examined. Certain occupations entailing exposure to the public, such as teachers, were associated with systemic autoimmune disease-related death, whereas others, such as waiters and waitresses, were not.

CONCLUSION

Our results suggest that death from systemic autoimmune diseases may be associated with occupational exposures encountered in farming and industry. The hypotheses generated in this study provide leads for future research on determinants of these diseases.

Sclérodermie systémique: épidémiologie et facteurs environnementaux

The pathophysiology of systemic sclerosis (SSc), probably multifactorial, is not yet well elucidated. Among the many endogenous and exogenous factors probably involved, environmental and occupational elements may play an essential role. SSc is a rare disease. Prevalence is estimated between 3 and 24 per 100,000 population. Reports of sporadic clusters of higher prevalence suggest environmental factors, which have not yet been defined. Silica, first suggested in 1917, plays a role in SSc development, as officially recognized in France for purposes of workers' compensation. Solvents have been associated with SSc by several rigorous case-control studies that suggest a causal role. Current data about other toxic agents (epoxy resins, vibrations, welding fumes) do not justify conclusions about their role in SSc. The severity of SSc (determined by the extent of diffuse cutaneous lesions, pulmonary involvement, and immunological profile) is probably associated with occupational exposure.

Is occupational exposure to solvents associated with an increased risk for developing systemic scleroderma?

BACKGROUND

Our study was aimed to investigate in a German collective if there are any hints for an increased occupational or environmental risk to develop systemic sclerosis, especially, focussing on work-related exposure to solvents. Moreover, we tried to evaluate the feasibility of a sampling method addressing support groups.

METHODS

A standardised questionnaire was published in two journals subscribed by members of two different support groups and all members were asked to complete the questionnaire and to return it anonymously. The subjects were not informed on the scientific hypotheses, nor did they know who of them belonged to the case group (scleroderma) or to the control group (multiple sclerosis).

RESULTS

175 questionnaires could be included in the statistical analysis. As expected, a female predominance was in our collective. In the male subpopulation, the occupational exposure to solvents was higher in the case group than in the control-group (70% versus 45.8%). Based only on the male subgroup, a tendency for an association between occupational exposure to solvents and the risk to develop systemic sclerosis was found.

CONCLUSION

According to our experience in this case-control-study exposure misclassification, qualitative or quantitative, was an eminent problem. Within such a setting, it is generally very difficult to establish an exact dose-response relationship due to incomplete, imprecise or missing data concerning duration of exposure, frequency of use and kind of solvent. Additionally, a well-known problem in studies based on self-reported questionnaires is the so-called volunteer bias. Unfortunately, but similar to other studies assessing epidemiologic factors in such a rare disease, our study was of limited power, especially in the subgroups defined by gender.

Scleroderma: from cell and molecular mechanisms to disease models

Scleroderma [also known as systemic sclerosis (SSc)] is a complex autoimmune disease characterised by pathological remodelling of connective tissues. Although the earliest and most frequent manifestations include blood vessel and immunological abnormalities, the systemic and progressive pathology suggests that fundamental interactions between microvascular damage and inflammation are mechanistically linked to obliterative tissue fibrosis. This review will focus on how model systems have provided clues to these relationships and will discuss new data from the study of novel animal disease models. These reveal how vascular damage and leukocyte accumulation generate the molecular cues that control the profiles of soluble mediators, which regulate the aberrant behaviour of mesenchymal cells within connective tissues, and how the dysregulated expression of these components and their differentiation contribute to the persistent fibrogenic response.