Tuesday, March 08, 2005

Short time exposure to diesel particulate matter causes inflammation

BrooklynDodger thinks this study helps set an occupational exposure limit to DPM.

"Ten nonsmoking healthy volunteers were exposed for 2 h at rest to a controlled concentration of DEP (monitored at 200 microg/m(3) particulate matter...Levels of exhaled CO were increased after exposure to DEP, and were maximal at 1 h ... There was an increase in sputum neutrophils and myeloperoxidase (MPO) at 4 h after DEP exposure... The investigators concluded that exposure to DEPs leads to an airway inflammatory response in normal volunteers."

The point of departure is an effect level at 200 micrograms for 2 hours at rest, among healthy non smokers for an acute effect. That would be 50 ug/m3 for 8 hours; benchmark dose methods suggest a 10 fold reduction to a no effect level, equivalent to a 10% incidence of airway inflammation. Airway inflammation is a material impairment to health.

Whether this is something special about diesel, or whether it's an effect of small carbon particles remains a subject for debate. BrooklynDodger thinks this is one more example of the effects of particles without other known toxicity at levels previously thought to be orders of magnitude below levels of concern.


Am J Respir Crit Care Med. 2000 Jul;162(1):161-6.

Airway inflammation after controlled exposure to diesel exhaust particulates.

Nightingale JA, Maggs R, Cullinan P, Donnelly LE, Rogers DF, Kinnersley R, Chung KF, Barnes PJ, Ashmore M, Newman-Taylor A.Departments of Thoracic Medicine and Occupational and Environmental Medicine, Royal Brompton Hospital and National Heart and Lung Institute, Imperial College School of Medicine, London, UK.

Epidemiologic evidence suggests a link between morbidity and mortality and levels of particulate matter in the atmosphere.

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