Mutagenicity of Diesel Engine Exhaust Is Eliminated in the Gas Phase by an Oxidation Catalyst but Only Slightly Reduced in the Particle Phase

Abstract

Concerns about adverse health effects of diesel engine emissions prompted strong efforts to minimize this hazard, including exhaust treatment by diesel oxidation catalysts (DOC). The effectiveness of such measures is usually assessed by the analysis of the legally regulated exhaust components. In recent years additional analytical and toxicological tests were included in the test panel with the aim to fill possible analytical gaps, for example, mutagenic potency of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nPAH). This investigation focuses on the effect of a DOC on health hazards from combustion of four different fuels: rapeseed methyl ester (RME), common mineral diesel fuel (DF), SHELL V-Power Diesel (V-Power), and ARAL Ultimate Diesel containing 5% RME (B5ULT). We applied the European Stationary Cycle (ESC) to a 6.4 L turbo-charged heavy load engine fulfilling the EURO III standard. The engine was operated with and without DOC. Besides regulated emissions we measured particle size and number distributions, determined the soluble and solid fractions of the particles and characterized the bacterial mutagenicity in the gas phase and the particles of the exhaust.

Comparative mutagenicity and genotoxicity of particles and aerosols emitted by the combustion of standard vs. rapeseed methyl ester supplemented bio-diesel fuels

“…The compared mutagenicities between DF0 and RMEsupplemented fuels show that particles emitted by combustion of biodiesels appear slightly more mutagenic, but no clear relationships with the RME content can be established. RME-particles were generally reported to be less mutagenic than those issued from diesel fuel [32][33][34][35]. Nevertheless, a contrasted conclusion was also reported by Bünger et al [36] and Westphal et al [37], in accordance with the present study.…”

“…It is reported conditions or even than in the present "on line" protocol. Nevertheless, Westphal et al [35] did not find any clear difference between mutagenicity of pure RME-or 5% RME blend-condensate and diesel fuel condensate in TA98. In all cases, mutagenic activities were reduced upon S9mix addition.…”

“…The impact of after treatment devices on the gas phase mutagenicity is poorly documented. Westphal et al [35] compared the mutagenicity of condensates without or with DOC for different fuels and biodiesels in TA98. In all cases, mutagenicity was fully abolished with DOC after treatment.…”

Effects of an iron-based fuel-borne catalyst and a diesel particle filter on exhaust toxicity in lung cells in vitro

“…on the other hand. A number of studies pursuing such a combined analytical-toxicological approach have been published, for instance in [38] in combination with [19,25,39,40], but in many cases, the level of (analytical and/or toxicological) resolution is not sufficient or they suffer from the inability to find clear correlations between changes in exhaust composition and exhaust toxicity. The latter is certainly a result of the complexity of biological test systems and engine emissions, but also of the facts that for the identification of common patterns, not enough such studies have been performed and that comparison between different studies is difficult because of a lack of standardization in this field of research (e.g., different biological test systems, different exposure methods, and different biological endpoints are used).…”

Test-Methods on the Test-Bench: A Comparison of Complete Exhaust and Exhaust Particle Extracts for Genotoxicity/Mutagenicity Assessment

“…Diesel exhaust is a very complex mixture, consisting of gaseous, condensed (liquid), and solid particulate fractions, all of which contribute to genotoxicity, 7 the potential of a substance to damage genetic material and hence to act mutagenic and cancerogenic (mutagenicity is a possible consequence of genotoxicity and is characterized by the changes in the genetic material being permanent and hereditary). The gas phase consists of inorganic gases, such as carbon monoxide, carbon dioxide, nitrogen oxides, and a variety of volatile and semivolatile organic compounds.…”