Toxicological effects of emission particles from fossil- and biodiesel-fueled diesel engine with and without DOC/POC catalytic converter

Abstract

There is increasing demand for renewable energy and the use of biodiesel in traffic is a major option when implying this increment. We investigated the toxicological activities of particulate emissions from a nonroad diesel engine, operated with conventional diesel fuel (EN590), and two biodiesels: rapeseed methyl ester (RME) and hydrotreated fresh vegetable oil (HVO). The engine was operated with all fuels either with or without catalyst (DOC/POC). The particulate matter (PM1) samples were collected from the dilution tunnel with a high-volume cascade impactor (HVCI). These samples were characterized for ions, elements, and polycyclic aromatic hydrocarbon (PAH) compounds. Mouse RAW264.7 macrophages were exposed to the PM samples for 24 h. Inflammatory mediators, (TNF-α and MIP-2), cytotoxicity, genotoxicity, and oxidative stress (reactive oxygen species [ROS]) were measured. All the samples displayed mostly dose-dependent toxicological activity. EN590 and HVO emission particles had larger inflammatory responses than RME-derived particles. The catalyst somewhat increased the responses per the same mass unit. There were no substantial differences in the cytotoxic responses between the fuels or catalyst use. Genotoxic responses by all the particulate samples were at same level, except weaker for the RME sample with catalyst. Unlike other samples, EN590-derived particles did not significantly increase ROS production. Catalyst increased the oxidative potential of the EN590 and HVO-derived particles, but decreased that with RME. Overall, the use of biodiesel fuels and catalyst decreased the particulate mass emissions compared with the EN590 fuel. Similar studies with different types of diesel engines are needed to assess the potential benefits from biofuel use in engines with modern technologies.