Friday, April 10, 2009

Mounting Evidence for Diesel Engine Emission Health Hazards

Non-cancer health effects of diesel exhaust: A critical assessment of recent human and animal toxicological literature
Authors: Thomas W. Hesterberg a; Christopher M. Long b; William B. Bunn a; Sonja N. Sax b; Charles A. Lapin c; Peter A. Valberg b
a Navistar, Inc., Warrenville, Illinois, USA
b Gradient Corporation, Cambridge, Massachusetts, USA
c Lapin & Associates, Glendale, California, USA

Critical Reviews in Toxicology, Volume 39, Issue 3 March 2009 , pages 195 - 227


We reviewed laboratory and clinical studies bearing on the non-cancer health effects of diesel exhaust (DE) published since the 2002 release of the US EPA Health Assessment Document for Diesel Engine Exhaust. We critically evaluated over 100 published articles on experimental research, focusing on their value for predicting the risk of non-cancer health effects in humans exposed to DE. Recent animal studies provide insight into the potential mechanisms underlying observed respiratory and cardiovascular health responses; however, because of Human controlled-exposure studies provide new evidence of lung inflammatory effects and thrombogenic and ischemic effects of inhaled DE, albeit for older-model diesel engines and concentrations that are much higher (~300 μg/m3) than typical ambient or even occupational levels.unrealistically high DE concentrations, the mechanisms elucidated in these studies may not be relevant at lower DE exposure levels. Although larger in number, and suggestive of possible mechanisms for non-cancer health effects at elevated DE levels, interpretation of this recent group of clinical-study findings and laboratory-animal results remains hindered by inconsistencies and variability in outcomes, potentially irrelevant DE-exposure compositions, limitations in exposure protocols and pathways, and uncertainties in extrapolation and generalization. A mechanism of action that allows reliable prediction of adverse health effects at DE-exposure levels typical of the present-day ambient and occupational environment has not emerged. Because of changing diesel-engine technology, inhalation studies using realistic environmental and occupational exposures of new-technology diesel exhaust are of critical importance.
BrooklynDodger(s) comments:
Given the source, Navistar, the conclusion that more evidence is needed to regulate isn't surprising. Certainty deniers will always be able to argue that the concentrations needed to demonstrate toxic potential in small groups of animals and people over a short period of time are "unrealistic." There are two dozen studies of truck drivers and railroad personnel - large enough groups exposed to DPM for a long enough time. These groups suffer excess mortality from lung cancer.

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