We conducted a diesel emission exposure study with rats in order to evaluate the effects of pre- and postnatal exposure to emission from the latest diesel engine on the reproductive system. SD rats were divided into three exposure groups; emission from steady operation of diesel engine (D-S), D-S and DPF regeneration (D-SR), and clean air (CA). We measured fertility, sperm production, serum testosterone, sexual development, and maturation as endpoints of effects of diesel emission on the reproductive system. The results did not indicate any changes induced by exposure to diesel emission. Exposure to emissions from the latest diesel engine with DPF did not seem to affect the reproductive system.

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In order to evaluate the effects of pre- and postnatal exposure to emission from the latest diesel engine on Central Nervous System(CNS), we conducted a diesel emission exposure study in mice. C57BL/6 mice were divided into three exposure groups; emission in steady-operation of diesel engine (D-S), D-S and emission of DPF regeneration (D-SR), and clean air (CA). We examined memory and learning, damage of dopaminergic neuron, translocation of diesel exhaust particles into brain, gene expression of neurotransmitters as endpoints of effects of diesel emission on CNS. According to the results, there were no remarkable changes induced by exposure to diesel emission in these endpoints. It seemed that the exposure to emission from the latest diesel engine with DPF did not affect CNS.

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We analyzed oxidative potential and chemical components of ambient particle extracts in order to understand the physicochemical character of ambient particles. We evaluated the differences of oxidative potential with particle size, sampling season, and sampling site. The results indicated that 1) the oxidative potential of coarse PM is more potent than that of fine PM, 2) the oxidative potential of PM in winter is more potent than that in summer, and 3) the oxidative potentials of PM along roadsides and the urban background are very similar. The analysis of the relationship between oxidative potential and chemical components in ambient PM suggested that metals in PM have important roles in exhibiting potent oxidative potential.

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It has been suggested that diesel exhaust particles (DEP) adversely affect health by inducing oxidative stress. DEP is composed of numerous chemicals, and little information is available about which chemicals contribute most to the oxidative potential in DEP. In this study, we examine a method for estimating the oxidative potential of organic chemicals (not metals) in DEP by using EDTA. Benzoquinone (BQ) and NiCl2 exhibit dose-dependent oxidative potential, but the effect of NiCl2 (not BQ) is strongly suppressed by EDTA. Furthermore, oxidative strength of DEP is increased by EDTA. These results suggest that EDTA suppress redox of some metals such as zinc in DEP. This hypothesis is supported by the result that EDTA increases the oxidative strength of a BQ and ZnCl2 mixture. In this study, we demonstrate that EDTA is useful for evaluating the contribution of chemicals to the oxidative potential of DEP.

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