Abstract 3594: Mutations and DNA adducts induced by diesel exhaust particles.

Abstract

Abstract We performed bioassay-directed fractionation and analyzed the polycyclic aromatic hydrocarbon (PAH) levels of a composite sample of diesel-exhaust particles (C-DEP) generated on site from petroleum diesel with a 30-kW 4-cylinder Deutz BF4M1008 diesel engine connected to an air compressor. C-DEP was generated to be representative of contemporary DEP. We extracted particles with dichloromethane (DCM) and determined the percentage of extractable organic material (EOM), solvent-exchanged extracts into dimethyl sulfoxide, and evaluated them for mutagenicity in Salmonella strains TA100 and TA98 +/- S9. More than 50% of the C-DEP EOM mass eluted in fraction 1, but this fraction was not mutagenic. Fraction 2 contained 6% of the mass of OEM, and had 60% of the TA100+S9 activity, suggestive of PAHs. The 3rd fraction contained 14% of the OEM mass and contributed 60% of the TA98-S9 activity, suggestive of nitroarenes. S9 mediated binding of C-DEP extracts was assessed by 32P-postlabeling analysis. Unfractionated C-DEP EOM was incubated with S9 in the presence of calf thymus DNA. The modified DNA was enzymatically hydrolyzed and then subjected to postlabeling analysis using either butanol extraction or nuclease P1 pre-enrichment. Multiple DNA adducts were produced with chromatographic mobilities consistent with PAH and nitro-PAH adducts. Although previous studies of the mutagenicity and adduct-forming potential of diesel exhaust have been reported, most of those utilized exhaust particles that were generated by older diesel engines that were not representative of contemporary diesel exhaust. Data derived from the C-DEP particles are more relevant to understanding the risks posed by contemporary diesel engines. This study provides further characterization of the biochemical potential for these particles to induce DNA damage and gene mutations, key events in the process of chemical carcinogenesis by diesel exhausts. [This is an abstract of a proposed presentation and does not necessarily reflect the views of the U.S. EPA.] Citation Format: Jeffrey A. Ross, Esra Mutlu, Charly King, Sarah H. Warren, David M. DeMarini, M. Ian Gilmour, William P. Linak, Garret B. Nelson. Mutations and DNA adducts induced by diesel exhaust particles. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3594. doi:10.1158/1538-7445.AM2013-3594