Primary human bronchial epithelial cell responses to diesel and biodiesel emissions at an air-liquid interface
Introduction
Diesel emission are a major contributor to outdoor air pollution. Acute exposure to diesel emissions causes inflammation and oxidative stress in the airways (Salvi et al., 1999). Chronic, long term exposure to diesel emissions diesel emission exposure has been associated with increased COPD risk and mortality (Hart et al., 2006). These adverse effects have been associated with the high level of particulate matter in diesel emissions (Ristovski et al., 2012; Steiner et al., 2016; Ma et al., 2017). A common strategy to reduce the level of particulate matter from diesel emissions is the substitution of diesel fuel with a biodiesel (Lin et al., 2011). Coconut-biodiesel, a common biodiesel in Asia, is cost effective, has close properties to diesel and is globally available (Kalam et al., 2003; Jayed et al., 2009). Combustion of coconut oil biodiesel has been shown to decrease CO, hydrocarbon content, PAH and decrease total PM from diesel emissions (Kalam et al., 2003; Bünger et al., 2016).
Another strategy to reduce diesel particulate matter is to use a fuel additive. Triacetin is a common fuel additive. It is made from the acetylation of glycerol, which is a by-product of biodiesel transesterification (Casas et al., 2010). Therefore, this addictive is a cost-effective feedstock to add to biodiesel fuels. Triacetin increases the oxygen content of fuel (Zare et al., 2016), which improves the combustion efficiency of biodiesel and reduces emissions (Rahman et al., 2014).
Biodiesel and fuel additives are emerging interventions to address global increases in fuel consumption, global warming and the adverse effects of fossil fuels (Kulkarni and Dalai, 2006). Research has shown that coconut-biodiesel can reduce genotoxicity and mutagenicity of diesel emissions (Yang et al., 2017). However, very little is known about the potential health effects of coconut-biodiesel and triacetin as a fuel additive to biodiesel. The aim of this study was to compare the effect of biodiesel and triacetin/biodiesel blends on pHBECs to conventional diesel emissions at an air-liquid interface.
Section snippets
Cell culture
Primary HBECs were isolated and cultured from surgical resection tissue donated, with written informed consent, by patients with lung adenocarcinoma. This study was approved by the Human Research Ethics Committees of The Prince Charles Hospital and The University of Queensland. Briefly, a bronchial ring was isolated from the lung resection specimen and incubated in a dissociation mix containing Pronase (Roche, Penzberg, Germany), Minimal Essentials Media-alpha (MEMα, Invitrogen, USA),
Characterisation of fuel and emissions
When studying the effects in diesel emission exposure under physiological conditions, it is important for the diesel emission dose (particle mass as mg/m3) to be accurate to a real-life scenario. For example, the city of Beijing, China is known for its high particulate matter air pollution. Over a 9-year study, it was shown that ambient PM2.5 in Beijing can range from 0.001–1.2 mg/m3 (Liu et al., 2015). Higher doses outside this range may be considered irrelevant to the in vivo situation. In
Main results
The results of this study indicate that coconut-biodiesel and triacetin/biodiesel fuel blends may be more detrimental to pHBECs than conventional diesel emissions. This was demonstrated through four main findings. Firstly, D100, B50 and B90 fuel blends produced emissions containing nucleation mode particles from a diesel engine with a DOC and DPF after treatment device. Secondly, coconut-biodiesel emissions can decrease cell viability and increase oxidative stress when compared to conventional
Conclusions
Although biodiesel fuels and fuel additives can reduce the pollutant load in diesel emissions, very little is understood about the potential health impacts of these alternate fuels. This study has shown that biodiesel and triacetin/biodiesel can increase the adverse effects of diesel emissions of pHBECs. This has provided insight into the effect of these diesel fuel alternative on pHBECs, and supports future research into the biological responses to different fuel additives and biodiesels.
Funding
This research was funded by the Australian Research Council Discovery grant (DP120100126), The Prince Charles Hospital Foundation PhD Scholarship (PhD2014–10) and National Health and Medical Research Council Career Development Fellowship (APP1026215).
Research ethics
This study was approved by the Human Research Ethics Committee for the Metro North Hospital and Health Service and the University of Queensland (HREC/11/QPCH/196: Interventions to reduce pulmonary toxicity of ultrafine particles: SSA/11/QPCH/233).
References (29)
- et al.
A metric for health effects studies of diesel exhaust particles
J. Aerosol Sci.
(2009) Environmental aspects and challenges of oilseed produced biodiesel in Southeast Asia
Renew. Sust. Energ. Rev.
(2009)- et al.
Exhaust emission and combustion evaluation of coconut oil-powered indirect injection diesel engine
Renew. Energy
(2003) - et al.
Diesel particulate emissions from used cooking oil biodiesel
Bioresour. Technol.
(2008) Opportunities and challenges for biodiesel fuel
Appl. Energy
(2011)Exposure to particulate matter 2.5 (PM2. 5) induced macrophage-dependent inflammation, characterized by increased Th1/Th17 cytokine secretion and cytotoxicity
Int. Immunopharmacol.
(2017)Particle emissions from biodiesels with different physical properties and chemical composition
Fuel
(2014)Oxidative potential of gas phase combustion emissions-an underestimated and potentially harmful component of air pollution from combustion processes
Atmos. Environ.
(2017)Development of novel alternative biodiesel fuels for reducing PM emissions and PM-related genotoxicity
Environ. Res.
(2017)The effect of triacetin as a fuel additive to waste cooking biodiesel on engine performance and exhaust emissions
Fuel
(2016)