Pulmonary and cardiovascular effects of traffic-related particulate matter: 4-week exposure of rats to roadside and diesel engine exhaust particles

Abstract

Traffic-related particulate matter (PM) may play an important role in the development of adverse health effects, as documented extensively in acute toxicity studies. However, rather little is known about the impacts of prolonged exposure to PM. We hypothesized that long-term exposure to PM from traffic adversely affects the pulmonary and cardiovascular system through exacerbation of an inflammatory response. To examine this hypothesis, Fisher F344 rats, with a mild pulmonary inflammation at the onset of exposure, were exposed for 4 weeks, 5 days/week for 6 h a day to: (a) diluted diesel engine exhaust (PM_DEE), or: (b) near roadside PM (PM_2.5). Ultrafine particulates, which are largely present in diesel soot, may enter the systemic circulation and directly or indirectly trigger cardiovascular effects. Hence, we assessed the effects of traffic-related PM on pulmonary inflammation and activity of procoagulants, vascular function in arteries, and cytokine levels in the heart 24 h after termination of the exposures. No major adverse health effects of prolonged exposure to traffic-related PM were detected. However, some systemic effects due to PM_DEE exposure occurred including decreased numbers of white blood cells and reduced von Willebrand factor protein in the circulation. In addition, lung tissue factor activity is reduced in conjunction with reduced lung tissue thrombin generation. To what extent these alterations contribute to thrombotic effects and vascular diseases remains to be established. In conclusion, prolonged exposure to traffic-related PM in healthy animals may not be detrimental due to various biological adaptive response mechanisms.

Keywords::

• Traffic
• particulate matter
• PM
• concentrated particles
• pulmonary inflammation
• diesel soot
• vascular function
• procoagulants
• air pollution
• toxicological

Acknowledgements

We thank the technical team under the supervision of Ruud van Kinderen and Hans Strootman from the Animal Facility Department of the National Institute of Vaccines for their skillful biotechnical assistance. We also acknowledge the assistants, Liset de la Fonteyne-Blankestijn, Yvonne Wallbrink, Piet Beekhof, and colleagues under the supervision of Henk van Loveren and Eugene Jansen, from the Laboratory for Health Protection Research of the RIVM’s Nutrition, Medicines and Consumer Safety Division for their excellent technical support.

Declaration of interest

The main part of this work was supported by a fund from the Dutch Ministry of Housing, Spatial Planning and the Environment (VROM) in the framework of research project Air Pollution and Health (M/630186 and M/630196) at the RIVM. Mark Miller and Patrick Hadoke are supported by a British Heart Foundation Programme Grant (RG/05/003). Evren Kilinç is supported by a grant of the the Netherlands Heart Foundation (grant number: 2006B064). The analyses of heart tissues conducted at the Norwegian Institute of Public Health were funded by the Research Council of Norway through the “Environment, Genetics and Health” program. This work has been presented in part at the Inhaled Particles X Conference 2008 and published in the accompanying Journal of Physics Conference Series 2009.