Non-cancer health effects of diesel exhaust: a critical assessment of recent human and animal toxicological literature.

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. 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. Recent animal studies provide insight into the potential mechanisms underlying observed respiratory and cardiovascular health responses; however, because of 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...