Abstract
Background: Exposure to ambient particulate matter (PM) has been shown to be associated with biomarkers of inflammation in some studies. However, PM is a complex mixture of various compounds and little information is available on component specific effects. Aims: Using data from a cross-sectional pilot study in the US trucking industry, we evaluated the associations between ambient concentrations of trace metals and levels of biomarkers of systemic inflammation (interleukin 6(IL-6), C-reactive protein (hsCRP) and soluble intercellular adhesion molecule-1 (sICAM-1)). Methods: Blood samples for assessment of biomarkers were collected from 146 male trucking industry workers during the work day at trucking terminals in Carlisle, PA and Chicago, IL USA. Concurrent area-level measurements of PM2.5 were collected using 37 mm Teflon filters located in each work location. Concentrations for 51 metals were determined using X-ray fluorescence. Participants’ personal exposures were assigned based on job title for the 12 hour period within which they provided blood. An individual constituent was eligible for analysis if it was present above the minimum detection limit on at least 50% of the filters. To control for PM2.5, residuals of each constituent regressed on PM2.5 were considered in separate linear regression models for each biomarker. Due to heterogeneity between the two populations and exposures, each terminal location was analyzed separately. Results: Nineteen metals met the criteria for analysis. The patterns of correlation among the constituents were different between the two terminals. We found statistically significant positive associations for chlorine and manganese with IL-6, copper with hsCRP and IL-6, and silver with sICAM1, but only at the Carlisle terminal. Conclusions: Our results indicate different mixtures of sources at the two trucking terminals measured. Only suggestive associations between some metals and some biomarkers of inflammation were observed and these were not consistent or necessarily expected a priori.
Published Version
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