Is long-term particulate matter and nitrogen dioxide air pollution associated with incident monoclonal gammopathy of undetermined significance (MGUS)? An analysis of the Heinz Nixdorf Recall study.

Background: Exposure to air pollution activates the innate immune system and influences the adaptive immune system in experimental settings. We investigated the association of residential long-term exposure to particulate matter (PM) and NO ₂ air pollution with monoclonal gammopathy of undetermined significance (MGUS) as a marker of adaptive immune system activation.
Methods: We used data from the baseline (2000-2003), 5-year (2006-2008) and 10-year (2011-2015) follow-up examinations of the German Heinz Nixdorf Recall cohort study of 4814 participants (45-75years). Residential exposure to PM size fractions and NO ₂ was estimated by land-use regression (ESCAPE-LUR, annual mean 2008/2009) and dispersion chemistry transport models (EURAD-CTM, 3-year mean at baseline). We used logistic regression to estimate the effects of air pollutants on incident MGUS, adjusting for age, sex, education, smoking status, physical activity, and BMI. As a non-linear approach, we looked at quartiles (2-4) of the air pollutants in comparison to quartile 1.
Results: Of the 3949 participants with complete data, 100 developed MGUS during the 10-year follow-up. In the main model, only PM _coarse was associated with incident MGUS (OR per IQR (1.9μg/m ³ ): 1.32, 95% CI 1.04-1.67). We further found positive associations between PM size fractions estimated by ESCAPE-LUR and incident MGUS by quartiles of exposure (OR Q4 vs Q1: PM _2.5 2.03 (1.08-3.80); PM ₁₀ 1.97 (1.05-3.67); PM _coarse 1.98 (1.09-3.60)).
Conclusions: Our results indicate that an association between long-term exposure to PM and MGUS may exist. Further epidemiologic studies are needed to corroborate this possible link.
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