Source category-specific PM_2.5 and urinary levels of Clara cell protein CC16. The ULTRA study

Abstract

Introduction: We have previously reported that outdoor levels of fine particles (PM_2.5, diameter <2.5 μm) are associated with urinary CC16, a marker for lung damage, in Helsinki, Finland, but not in the other two ULTRA cities (Amsterdam, The Netherlands, and Erfurt, Germany). We here evaluated whether PM_2.5 from specific source categories would be more strongly associated with CC16 than (total) PM_2.5. In addition, we compared two source apportionment methods.

Methods: We collected biweekly spot urinary samples over 6 months from 121 subjects with coronary heart disease for the determination of CC16 (n = 1251). Principal component analysis (PCA) was used to apportion daily outdoor PM_2.5 between different source categories. In addition, the multilinear engine (ME) was used for the source apportionment in Amsterdam and Helsinki. We analyzed associations of source category-specific PM_2.5 and PM_2.5 absorbance, an indicator for combustion originating particles, with logarithmized values of CC16 adjusting for urinary creatinine using multivariate mixed models in STATA.

Results: In the pooled analyses, CC16 was increased by 0.6% (standard error 0.3%) per 1 × 10⁻⁵ m⁻¹ increase in the same-day levels of PM_2.5 absorbance. Source category-specific PM_2.5 concentrations were not consistently associated with the levels of CC16 in the three cities. Correlations between source category-specific PM_2.5 determined using either PCA or ME were in general high. Associations of source category-specific PM_2.5 with CC16 in Amsterdam and Helsinki were statistically less significant when ME was used.

Conclusions: The present results suggest that PM_2.5 from combustion sources increases epithelial barrier permeability in lungs.

Keywords::

• Absorbance
• CC16
• source specific PM_2.5

Declaration of interest: This study was supported by the Health Effects Institute (HEI research agreement 98-16) and was conducted within the framework of the exposure and risk assessment ULTRA Study (Exposure and Risk Assessment for Fine and Ultrafine Particles in Ambient Air), funded by the European Union Environment and Climate Research Programme (contract ENV4-CT97-0568). The reporting was financially supported by the Centre of Excellence Programme 2002–2007 of the Academy of Finland (contract 53307) and the National Technology Fund (TEKES, contract 40715/01). Bénédicte Jacquemin benefits from an Inserm post-doctoral fellowship (“poste vert”). The authors alone are responsible for the content and writing of the paper.