Occupational and Environmental Associations with Antinuclear Antibodies in a General Population Sample

*This study was supported by the Division of Intramural Research, National Institute of Environmental Health Sciences (Dr. Cooper), and by ES10295 and ES10457 from the National Institute of Environmental Health Sciences to Dr. Fraser.

Abstract

Antinuclear antibodies are a hallmark feature of the autoimmune disease systemic lupus erythematosus, and can occur many years before onset of symptoms. The objective of this study was to examine the association between exposures and high-titer antinuclear antibodies in the general population (i.e., people who do not have lupus or other systemic autoimmune diseases). Serum was collected from 266 population-based controls who had been frequency-matched to the age and gender distribution of lupus cases in a 60-county study area in the southeastern United States. A detailed occupational history was collected using a structured interview; information was also collected on hair dye use. Antinuclear antibodies were assayed using HEp-2 cells as substrate. Logistic regression was used to estimate the odds ratio (OR) as a measure of association between exposures and high-titer antinuclear antibody levels, adjusting for age, gender, and race. High-titer antinuclear antibodies (≥1:160) were observed in 21 subjects (8%). A twofold increased prevalence of high-titer antinuclear antibodies was seen with some occupational exposures (silica dust, pesticides, and sunlight), although none of these individual estimates were statistically significant. The association seen with use of hair dyes was weaker (OR 1.4). There was a suggestion of a dose response with a combined measure based on the summation of exposures (ORs of 1.7, 2.1, and 5.9 for 1, 2, and ≥ 3 exposures). These data suggest that occupational exposures may influence the expression of antinuclear antibodies. Larger studies addressing these exposures may provide insights into the mechanisms by which various environmental factors affect the development of autoantibodies and the progression to clinical disease.

Notes

*This study was supported by the Division of Intramural Research, National Institute of Environmental Health Sciences (Dr. Cooper), and by ES10295 and ES10457 from the National Institute of Environmental Health Sciences to Dr. Fraser.

^a Occupational exposures based on assessment of lifetime job history data including job title, industry, and description of tasks and activities for all jobs held at least 12 mo, and specific job and materials checklists, as described for silica (Parks et al., 2002), mercury (Cooper et al., 2004), and pesticides (Cooper et al., 2004). Sunlight exposure defined as work outside 10 or more hours per week in a job held at least 12 mo (Fraser et al., 2003). Use of hair dyes defined as use of permanent hair dyes on five or more occasions (Cooper et al., 2001).

^b “Negative” includes 0 and “trace” antinuclear antibodies.

^c Estimates for each exposure from a logistic regression model, estimating the probability of high titer (≥1:160) compared with the probability of low-titer (1:40) or “negative” antinuclear antibodies, adjusting for age (continuous), gender, and race.

^d Summation of exposure to occupational silica dust, pesticides, mercury, or sunlight and use of hair dyes.