Inflammatory markers and exposure to occupational air pollutants

Introduction
To study the possible relationship between inhalation of airborne particles in the work environment of some Swedish industries and inflammatory markers in blood, a field study was designed, investigating exposure to particulates and inflammatory markers for workers.

Methods
Total dust was sampled in the breathing zone of 73 subjects working with welding, cutting, grinding and in foundries such as iron, aluminum and concrete. Stationary measurements were used to study different size fractions of particles including respirable dust, PM10 and PM2.5, the particle number concentration, the number of particles deposited in the alveoli, and total particle surface area concentration. Inflammatory markers such as interleukin-6 (IL-6), C-reactive protein (CRP), fibrinogen, D-dimer and urate were measured in plasma or serum before the first shift after the summer vacation and after the first, second and fourth shift.

Results
The mean level of total dust in the breathing zone was 0.93 mg/m3. The proxies for mean respirable dust fraction was 0.27 mg/m3, PM10 0.60 mg/m3 and PM2.5 was 0.31 mg/m3. The IL-6 values increased by 50% after the first day, but decreased after shift on the second and fourth day. CRP did not increase after the first shift but increased by 17% after the second shift. Other biomarkers were unaffected. A multiple linear regression analysis of a subgroup of 47 subjects showed a statistically significant positive relationship between particle exposure and post-shift IL-6.

Discussion
This study supports previous investigations observing increases of IL-6 at air concentrations of PM10 or PM2.5 between 0.13 and 0.3 mg/m3 among healthy subjects. This increase of IL-6 may indicate an increased risk of coronary heart disease.