Traffic-related exposures and biomarkers of systemic inflammation, endothelial activation and oxidative stress: a panel study in the US trucking industry

Air pollution exposure: a novel environmental risk factor for interstitial lung disease?

Air pollution exposure is a well-established risk factor for several adverse respiratory outcomes, including airways diseases and lung cancer. Few studies have investigated the relationship between air pollution and interstitial lung disease (ILD) despite many forms of ILD arising from environmental exposures. There are potential mechanisms by which air pollution could cause, exacerbate, or accelerate the progression of certain forms of ILD via pulmonary and systemic inflammation as well as oxidative stress. This article will review the current epidemiologic and translational data supporting the plausibility of this relationship and propose a new conceptual framework for characterizing novel environmental risk factors for these forms of lung disease.

The effect of oxidative stress polymorphisms on the association between long-term black carbon exposure and lung function among elderly men

BACKGROUND

Black carbon (BC) is a pro-oxidant, traffic-related pollutant linked with lung function decline. We evaluated the influence of genetic variation in the oxidative stress pathway on the association between long-term BC exposure and lung function decline.

METHODS

Lung function parameters (FVC and FEV1) were measured during one or more study visits between 1995 and 2011 (n=651 participants) among an elderly cohort: the Normative Aging Study. Residential BC exposure levels were estimated using a spatiotemporal land use regression model. We evaluated whether oxidative stress variants, combined into a genetic score, modify the association between 1-year and 5-year moving averages of BC exposure and lung function levels and rates of decline, using linear mixed models.

RESULTS

We report stronger associations between long-term BC exposure and increased rate of lung function decline, but not baseline lung function level, among participants with higher oxidative stress allelic risk profiles compared with participants with lower risk profiles. Associations were strongest when evaluating 5-year moving averages of BC exposure. A 0.5 µg/m(3) increase in 5-year BC exposure was associated with a 0.1% yearly increase in FVC (95% CI -0.5 to 0.7) among participants with low genetic risk scores and a 1.3% yearly decrease (95% CI -1.8 to -0.8) among those with high scores (p-interaction=0.0003).

DISCUSSION

Our results suggest that elderly men with high oxidative stress genetic scores may be more susceptible to the effects of BC on lung function decline. The results, if confirmed, should inform air-quality recommendations in light of a potentially susceptible subgroup.

Short-term traffic related exposures and biomarkers of nitro-PAH exposure and oxidative DNA damage

Exposure to vehicle exhaust has been associated with cardiac and respiratory disease, lung cancer, and greater overall mortality. We investigated whether amino- polycyclic aromatic hydrocarbon (amino-PAH) metabolites of nitro-PAHs could be used as biomarkers of these exposures. Pre- and post-shift urine samples were collected at the beginning and end of a work week from 82 male U.S trucking industry workers. We used repeated-measures analysis to examine associations of total 1- and 2-aminonaphthalene (1 & 2-AN) and 1-aminopyrene (1-AP) urinary concentrations with microenvironment exposures to particulate matter (PM_2.5), elemental and organic carbon, and between 1&2-AN and 1-AP with urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG). There was an association between work week mean PM_2.5 levels and post-shift 1 & 2-AN, [141.8 pg/ml increase (95% CI:53.3, 230.2) for each IQR increase (5.54 µg/m³) in PM_2.5,] but no associations with other exposure measures. There was a statistically significant increase in 8-OHdG concentrations with 1 & 2-AN (2.38 µg/mg creatinine (95%CI: 0.19, 4.58) per 242.85 pg/mg creatinine increase in 1 & 2-AN), and suggestive associations with all other exposure measures. Our findings suggest associations between urinary amino-PAHs with vehicle exhaust related PM_2.5 as well as with a biomarker of oxidative DNA damage.

Outdoor air pollution and asthma

Traffic and power generation are the main sources of urban air pollution. The idea that outdoor air pollution can cause exacerbations of pre-existing asthma is supported by an evidence base that has been accumulating for several decades, with several studies suggesting a contribution to new-onset asthma as well. In this Series paper, we discuss the effects of particulate matter (PM), gaseous pollutants (ozone, nitrogen dioxide, and sulphur dioxide), and mixed traffic-related air pollution. We focus on clinical studies, both epidemiological and experimental, published in the previous 5 years. From a mechanistic perspective, air pollutants probably cause oxidative injury to the airways, leading to inflammation, remodelling, and increased risk of sensitisation. Although several pollutants have been linked to new-onset asthma, the strength of the evidence is variable. We also discuss clinical implications, policy issues, and research gaps relevant to air pollution and asthma.