Abstract
Epidemiological data indicate that exposure to diesel exhaust particles (DEPs) from traffic emissions is associated with higher risk of morbidity and mortality related to cardiovascular and pulmonary diseases, accelerated progression of atherosclerotic plaques, and possible lung cancer. While the impact of DEPs from combustion of fossil diesel fuel on human health has been extensively studied, current knowledge of DEPs from combustion of biofuels provides limited and inconsistent information about its mutagenicity and genotoxicity, as well as possible adverse health risks. The objective of the present work was to compare the genotoxicity of DEPs from combustion of two first-generation fuels, 7% fatty acid methyl esters (FAME) (B7) and 20% FAME (B20), and a second-generation 20% FAME/hydrotreated vegetable oil (SHB: synthetic hydrocarbon biofuel) fuel. Our results revealed that particulate engine emissions from each type of biodiesel fuel induced genotoxic effects in BEAS-2B and A549 cells, manifested as the increased levels of single-strand breaks, the increased frequencies of micronuclei, or the deregulated expression of genes involved in DNA damage signaling pathways. We also found that none of the tested DEPs showed the induction of oxidative DNA damage and the gamma-H2AX-detectable double-strand breaks. The most pronounced differences concerning the tested particles were observed for the induction of single-strand breaks, with the greatest genotoxicity being associated with the B7-derived DEPs. The differences in other effects between DEPs from the different biodiesel blend percentage and biodiesel feedstock were also observed, but the magnitude of these variations was limited.
Highlights
The overall impact of engine emissions on human health has been studied for a long time, mostly due to the presence of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in diesel exhaust particles (DEPs)
transmission electron microscopy (TEM) analysis revealed that all three types of DEPs were nearly spherical, and the particles were present as single particles, clusters, or chain-like aggregates
Our findings indicate that particulate engine emissions from each type of biodiesel fuel induced genotoxic effects in BEAS-2B and A549 cells, manifested either as the increased levels of single-strand breaks, the increased frequencies of micronuclei, or deregulated expression of genes involved in DNA damage signaling pathways
Summary
The overall impact of engine emissions on human health has been studied for a long time, mostly due to the presence of polycyclic aromatic hydrocarbons (PAHs) and their derivatives (nitro-PAHs) in diesel exhaust particles (DEPs). Inconsistent results were observed for the induction of micronuclei by DEPs from combustion of fossil diesel and biodiesel, showing either no difference or significant increase of chromosomal DNA damage by biodiesel-derived DEPs (Leme et al 2012; Cervena et al 2016). These contradictory trends are hard to interpret and may be caused by chance in light of relatively limited data. The expression of genes involved in DNA damage signaling was evaluated to screen for possible molecular mechanisms of toxicity
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