Cytotoxic and mutagenic effects, particle size and concentration analysis of diesel engine emissions using biodiesel and petrol diesel as fuel

Diesel engine exhaust particles (DEP) contribute substantially to ambient a ir pollution. They cause acute and chronic adverse health effects in humans . Biodiesel (rapeseed oil methyl ester, RME) is used as a "green fuel" in s everal countries. For a preliminary assessment of environmental and health effects of RME, the particulate-associated emissions from the DEP of RME an d common fossil diesel fuel (DF) and their in vitro cytotoxic and mutagenic effects were compared. A test tractor was fuelled with RME and DF and driv en in a European standard test cycle (ECE R49) on an engine dynamometer. Pa rticle numbers and size distributions of the exhausts were determined at th e load modes "idling" and "rated power". Filter-sampled particles were extr acted and their cytotoxic properties tested using the neutral red assay, Mu tagenicity was tested using the Salmonella typhimurium/microsome assay. Des pite higher total particle emissions, solid particulate matter (soot) in th e emissions from RME was lower than in the emissions from DF. While the siz e distributions and the numbers of emitted particles at "rated power" were nearly identical for the two fuels, at "idling" DF emitted substantially hi gher numbers of smaller particles than RME. The RME extracts caused fourfol d stronger toxic effects on mouse fibroblasts at "idling' but not at "rated power" than DF extracts. The extracts at both load modes were significantl y mutagenic in TA98 and TA100. However, extracts of DF showed a fourfold hi gher mutagenic effect in TA98 land twofold in TA100) than extracts of RME. These results indicate benefits as well as disadvantages for humans and the environment from the use of RME as a fuel for tractors. The lower mutageni c potency of DEP from RME compared to DEP from DF is probably due to lower emissions of polycyclic aromatic compounds. The higher toxicity is probably caused by carbonyl compounds and unburned fuel, and reduces the benefits o f the lower emissions of solid particulate matter and mutagens from RME.