Humoral Immune System Alterations in Silica Exposed Workers

Background: Crystalline silica may act as an immune adjuvant to increase inflammation and antibody production. The highest exposures to silica are known to occur in the dusty trades industries such as stone- cutting. We undertook this population based study to examine the association between occupational silica exposure and humoral immune system. Methods: In this historical cohort study, 47 workers from 10 stone-cutting factories in Rey City, south of Tehran, Iran that had more than 10 years exposure to silica were included in case group and 45 individual without any exposure to silica were selected for control group. We measured serum immunoglobulins (IgM, IgG, and IgA) of participants with ELISA method and compared the results between exposed workers and control groups. Results: The mean concentrations of two immunoglobulines (IgG, IgA) and IgM in case group in comparison with control group were higher and lower respectively but both were in normal range. IgA concentration between two groups was statistically significant (P< 0.05). Conclusion: Crystalline silica exposure may promote the humoral immune system in some individuals. Additional research is recommended in other population, using study design that minimize potential selection bias and maximize the quality of exposure assessment.