Childhood agricultural and adult occupational exposures to organic dusts in a population-based case–control study of systemic lupus erythematosus

Abstract

Organic dust exposure can influence the development and symptoms of immune-related diseases such as atopy and asthma, but has rarely been examined in relation to systemic autoimmunity. The present analyses explore the association of lifetime farm and occupational organic dust exposures with systemic lupus erythematosus (SLE) in recently diagnosed patients (n = 265) compared with controls (n = 355) frequency matched by age, sex and state. Questionnaire data included childhood farm residence, childhood and adult experience with specific crops, and adult work in textiles, hog or poultry processing and paper or furniture manufacture. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression models including age, sex, state, race, education and silica exposure. Overall childhood or adult farm contact and childhood farm residence were not associated with SLE. Farm contact with livestock was inversely associated with SLE (OR = 0.55, 95% CI 0.35, 0.88). This effect was most pronounced among those with childhood farm residence and both childhood and adult livestock exposure (OR = 0.19; 95% CI 0.06, 0.63), but was difficult to separate from adult exposure to grains or corn. Other adult occupational exposures were not associated with SLE risk overall, regardless of childhood farm residence or livestock exposure, although an inverse association was seen among non-smokers (OR = 0.59; 95% CI 0.33, 1.1), particularly for textile work (OR = 0.34; 95% CI 0.19, 0.64). These exploratory findings support the development of studies to specifically investigate the effects of organic dust exposure on SLE risk, with particular attention to exposure assessment and characterization of demographics, smoking and other occupational exposures.

Prevalence of systemic lupus erythematosus and systemic sclerosis in the First Nations population of Alberta, Canada

“…This may reflect a true predominance of SLE and SSc among First Nations females, and is consistent with previous studies of SARD in First Nations populations, which also reported a genetic predisposition to autoimmune disorders and more severe disease phenotypes (7)(8)(9)(10)(11). It is interesting, however, to hypothesize that this increased prevalence is a result of environmental exposures in a population predisposed to SARD, since, for example, silica exposure has been suggested as an environmental trigger for SARD (30,31). Although a protective factor conferring improved survival could also increase prevalence estimates, this seems less likely given the more severe disease phenotypes and difficulties accessing health care reported in First Nations populations.…”

Pesticides, chemical and industrial exposures in relation to systemic lupus erythematosus

“…In this same sample, there was no association of SLE with application of pesticides, an activity presumed to involve lower exposures than mixing (2). However these analyses did not adjust for other agricultural exposures (other than silica), including organic dust (livestock/grain dust) exposure (1), which was later identified as potentially protective factor. Another case-control study conducted through rheumatology centers across Canada did not find any association with occupational pesticide use (4).…”

“…Increased SLE mortality was observed in long-term follow-up of a Taiwanese population accidentally exposed to high levels of PCBs and furans through consumption of contaminated rice, with SLE deaths starting 10 years after the exposure (39). Development of a lupus-like syndrome has been observed in two different strains of mice (C57BL/6 and SNF (1)) following mid-gestation dosage with TCDD, with some differences in effect by sex (40, 41). In contrast, a study of New Zealand Black/New Zealand White F1 hybrid (B/W) mice injected with TCDD since 6 weeks of age found exposure to be suppressive of SLE disease activity (32).…”

“…An association with SLE is suggested by one large study showing SLE mortality was associated with work as a textile machine operator (OR=1.5) (5). However, no overall association was seen for work in textiles in the one case-control study to specifically ask about textile work (1). In sum, these findings, though limited, support further research on mercury and organic dust exposures.…”

“…Here we review research on the risk of SLE associated with occupational and environmental exposures, primarily drawing on studies in human populations, along with supportive findings from experimental studies and relevant research on related systemic autoimmune diseases. We review the evidence on (1) silica and silicates, (2) agricultural and residential pesticides, (3) solvents and other hydrocarbons, and other occupational exposures and summarize relevant findings from several studies published in the past decade (Table 1) (1–6). The biologic mechanisms leading to development of autoimmunity and progression to clinical SLE are not fully understood, but it seems plausible that exposures may have effects at different points in these processes (7).…”