Part 4. Effects of subchronic diesel engine emissions exposure on plasma markers in rodents: report on 1- and 3-month exposures in the ACES bioassay.

Although epidemiologic and experimental studies suggest that exposure to diesel exhaust (DE*) emissions causes adverse cardiovascular effects, neither the specific components of DE nor the mechanisms by which DE exposure could induce cardiovascular dysfunction and exacerbate cardiovascular disease (CVD) are known. Moreover, because the advance of new technologies has resulted in cleaner fuels and decreased engine emissions, there is even more uncertainty about the relationship between DE exposure and cardiovascular health effects. To address this ever-changing baseline of engine emissions, we tested for exposure-, sex- and duration-dependent alterations in plasma markers following subchronic exposure of mice and rats to DE emissions from a 2007-compliant diesel engine. Many plasma markers--several recognized as known human CVD risk factors--were measured in the plasma of rodents exposed to 1 or 3 months of air (the control) or DE emissions. Few changes in plasma markers resulted from exposure to DE, although significant exposure-level-dependent increases in total cholesterol and high-density lipoprotein (HDL) cholesterol were observed in male rats after 1 month of DE exposure, an effect that was neither sustained nor observed in any other group. These data indicate that DE emissions from a 2007-compliant diesel engine as tested in this study had little adverse effect on CVD markers in rodents.