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- Title
Nitrogen Dioxide and Ultrafine Particles Dominate the Biological Effects of Inhaled Diesel Exhaust Treated by a Catalyzed Diesel Particulate Filter.
- Authors
Karthikeyan, Subramanian; Thomson, Errol M.; Kumarathasan, Prem; Guénette, Josée; Rosenblatt, Debbie; Chan, Tak; Rideout, Greg; Vincent, Renaud
- Abstract
We studied the impact of a catalyzed diesel particulate filter (DPF) on the toxicity of diesel exhaust. Rats inhaled exhaust from a Cummins ISM heavy-duty diesel engine, with and without DPF after-treatment, or HEPA-filtered air for 4h, on 1 day (single exposure) and 3 days (repeated exposures). Biological effects were assessed after 2h (single exposure) and 20h (single and repeated exposures) recovery in clean air. Concentrations of pollutants were (1) untreated exhaust (−DPF), nitric oxide (NO), 43 ppm; nitrogen dioxide (NO2), 4 ppm; carbon monoxide (CO), 6 ppm; hydrocarbons, 11 ppm; particles, 3.2×105/cm3, 60–70nm mode, 269 μg/m3; (2) treated exhaust (+DPF), NO, 20 ppm; NO2, 16 ppm; CO, 1 ppm; hydrocarbons, 3 ppm; and particles, 4.4×105/cm3, 7–8nm mode, 2 μg/m3. Single exposures to −DPF exhaust resulted in increased neutrophils, total protein and the cytokines, growth-related oncogene/keratinocyte chemoattractant, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 in lung lavage fluid, as well as increased gene expression of interleukin-6, prostaglandin-endoperoxide synthase 2, metallothionein 2A, tumor necrosis factor-α, inducible nitric oxide synthase, glutathione S-transferase A1, heme oxygenase-1, superoxide dismutase 2, endothelin-1 (ET-1), and endothelin-converting enzyme-1 in the lung, and ET- 1 in the heart. Ratio of bigET-1 to ET-1 peptide increased in plasma in conjunction with a decrease in endothelial nitric oxide synthase gene expression in the lungs after exposure to diesel exhaust, suggesting endothelial dysfunction. Rather than reducing toxicity, +DPF exhaust resulted in heightened injury and inflammation, consistent with the 4-fold increase in NO2 concentration. The ratio of bigET-1 to ET-1 was similarly elevated after −DPF and +DPF exhaust exposures. Endothelial dysfunction, thus, appeared related to particle number deposited, rather than particle mass or NO2 concentration. The potential benefits of particulate matter reduction using a catalyzed DPF may be confounded by increase in NO2 emission and release of reactive ultrafine particles.
- Subjects
NITROGEN dioxide; DIESEL motor exhaust gas; DIESEL particulate filters; AIR pollutants; CARBON monoxide; KERATINOCYTE growth factors; INFLAMMATION; NITRIC-oxide synthases
- Publication
Toxicological Sciences, 2013, Vol 135, Issue 2, p437
- ISSN
1096-6080
- Publication type
Article
- DOI
10.1093/toxsci/kft162