Nested case-control study of autoimmune disease in an asbestos-exposed population.
OBJECTIVE
To explore the potential association between asbestos exposure and risk of autoimmune disease, we conducted a case-control study among a cohort of 7,307 current and former residents of Libby, Montana, a community with historical occupational and environmental exposure to asbestos-contaminated vermiculite.


METHODS
Cases were defined as those who reported having one of three systemic autoimmune diseases (SAIDs): systemic lupus erythematosus, scleroderma, or rheumatoid arthritis (RA). Controls were randomly selected at a 3:1 ratio from among the remaining 6,813 screening participants using frequency-matched age and sex groupings.


RESULTS
The odds ratios (ORs) and 95% confidence intervals (CIs) for SAIDs among those >or=65 years of age who had worked for the vermiculite mining company were 2.14 (95% CI, 0.90-5.10) for all SAIDs and 3.23 (95% CI, 1.31-7.96) for RA. In this age group, exposure to asbestos while in the military was also an independent risk factor, resulting in a tripling in risk. Other measures of occupational exposure to vermiculite indicated 54% and 65% increased risk for SAIDs and RA, respectively. Those who had reported frequent contact with vermiculite through various exposure pathways also demonstrated elevated risk for SAIDs and RA. We found increasing risk estimates for SAIDs with increasing numbers of reported vermiculite exposure pathways (p<0.001).


CONCLUSIONS
These preliminary findings support the hypothesis that asbestos exposure is associated with autoimmune disease. Refined measurements of asbestos exposure and SAID status among this cohort will help to further clarify the relationship between these variables.
Noonan
Curtis W
CW
Center for Environmental Health Sciences, University of Montana, Missoula, Montana 59812, USA. curtis.noonan@umontana.edu
Pfau
Jean C
JC
Larson
Theodore C
TC
Spence
Michael R
MR
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000538:Aluminum Silicates / Q000009:adverse effects; D001194:Asbestos / Q000009:adverse effects*; D001327:Autoimmune Diseases / Q000453:epidemiology*; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009009:Montana / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D013902:Radiography, Thoracic; D012129:Respiratory Function Tests; D018570:Risk Assessment
D000538:Aluminum Silicates; C003760:vermiculite; D001194:Asbestos