DNA Adducts Derived from Diesel Emissions - Assessment of Genotoxic Potency in Vitro and Human Exposure Monitoring

Diesel particle extracts, which originated from three different diesel fuels, were used to study the activation of polycyclic aromatic hydrocarbons (PAHs). DNA adducts were analyzed in vitro calf thymus, human skin tissue culture and in lymphocytes isolated from diesel exposed workers. Direct-acting mutagens (e.g. nitro-PAHs) measured by Ames test were compared with DNA adducts formed in vitro by nitroreductive xanthine oxide enzyme. PAH-DNA adducts were analyzed by ³²P-postlabeling, and when characterizing adducts from skin DNA, a solid-phase micro extraction (SPME) method was developed for sample preparation before HPLC analysis. A good accordance between mutagenicity and DNA adducts showed that the three extracts contain higher amounts of direct-acting PAHs than the PAHs needing S9 activation. Skin DNA adducts demonstrated two-fold differences between the tissue cultures. ³²P-postlabeling and HPLC analysis did not confirm the identity of skin DNA adducts with the BPDE-DNA standard. The pilot study on 13 diesd exposed bus garage and waste collection workers showed low levels of PAH exposure (<50 ng/m³) and lymphocyte PAH-DNA adducts less than 2 adducts/10⁸ nucleotides.