Scientists find diesel exhaust kills throat cells, biodiesel does not

The biggest advantages associated with biofuels are their capacity to reduce greenhouse gas emissions and the fact that they are renewable. However, more benefits are being discovered. Researchers at Deakin University's Centre for Cellular and Molecular Biology and at the Institute of Sustainability and Innovation, Victoria University, have found that diesel exhaust is far more damaging to our health than exhaust from biodiesel, the plant-based fuel. According to the scientists, the findings provide clear support for calls to move towards replacing petrol and diesel with cleaner biofuels.

Airway epithelial cells cultured on a Transwell membrane; the study found diesel exhaust kills these cells, whereas particulate emissions from biodiesel have a limited effect. Credit: Michael Hooker Microscopy Facility.

Associate Professor Leigh Ackland, Associate Head of Deakin's School of Life and Environmental Sciences, led a team of researchers who compared the effects of diesel exhaust and biodiesel exhaust on human airway cells. They found that diesel exhaust damaged and killed the cells, while biodiesel exhaust had little effect.

The findings are published as an open access article in the advance online edition of Immunology and Cell Biology, a Nature publication.

Australia's escalating need for fuel is posing a major health problem. The fumes from burning fuels, including diesel, contributes to pollution and can cause heart disease, bronchitis and asthma. Efforts are underway to replace petrol and diesel with cleaner biofuels, such as biodiesel, but there is considerable resistance to this. This study provides clear evidence that diesel exhaust is more harmful to our health than biodiesel exhaust. - Professor Leigh Ackland

As it is not possible to study in real time what happens in the real human airway, the researchers conducted their research on human airway cells grown in a culture. The cells were exposed to the particulate matter emitted in diesel and biodiesel exhaust fumes.

Particulate matter is the burnt material, including carbon particles, emitted into the air. This particulate matter is part of biodiesel and diesel fumes but the particles produced from biodiesel were much less damaging to the cells than particles produced from diesel.

Our research found that the particulate matter from diesel exhaust stimulated a 'death pathway' response that the body uses to dispose of damaged cells. This response caused the airway cells to fuse together and die. We saw hardly any cell death after treatment with biodiesel particulates. - Professor Leigh Ackland

Professor Ackland said that the results of the study provide support for calls to move towards replacing petrol and diesel with cleaner biofuels:
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It is clear that breathing in diesel fumes is going to have a far more detrimental effect on our health than biodiesel. Given the level of cell death we have found, diesel exhaust could be the cause of respiratory disorders such as asthma and could even be implicated in cancer, she said.


Image: Airway epithelial cells cultured on a Transwell membrane. NaK-ATPase (green) is on the basolateral membrane. Nuclei are labeled with Propidium Iodide (red). Cilia (gray) above apical membrane (light gray) are imaged using DIC. Tissue prepared and imaged on a LeicaSP2 confocal microscope by Dr. A. Livraghi. NaK-ATPase (green) is on the basolateral membrane. Credit: Michael Hooker Microscopy Facility.

References:
Margaret Leigh Ackland, Linda Zou, David Freestone, Simone van de Waasenburg and Agnes A Michalczyk, "Diesel exhaust particulate matter induces multinucleate cells and zinc transporter-dependent apoptosis in human airway cells", Immunology and Cell Biology, advance online publication 7 August 2007; DOI: 10.1038/sj.icb.7100109

Eurekalert: Deakin University research finds diesel exhaust kills throat cells - September 11, 2007.