Comparative electrocardiographic, autonomic and systemic inflammatory responses to soy biodiesel and petroleum diesel emissions in rats

Abstract

Context: Biodiesel fuel represents an alternative to high particulate matter (PM)-emitting petroleum-based diesel fuels, yet uncertainty remains regarding potential biodiesel combustion emission health impacts.

Objective: The purpose of this study was to compare cardiovascular responses to pure and blended biodiesel fuel emissions relative to petroleum diesel exhaust (DE).

Materials and methods: Spontaneously hypertensive rats were exposed for 4 h per day for four days via whole body inhalation to combustion emissions (based on PM concentrations 50, 150 or 500 μg/m³ or filtered air) from pure (B100) or blended (B20) soy biodiesel, or to pure petroleum DE (B0). Electrocardiogram (ECG) and heart rate variability (HRV, an index of autonomic balance) were monitored before, during and after exposure while pulmonary and systemic inflammation were assessed one day after the final exposure. ECG and HRV data and inflammatory data were statistically analyzed using a linear mixed model for repeated measures and an analysis of variance, respectively.

Results: B100 and B0, but not B20, increased HRV during all exposure days at the highest concentration indicating increased parasympathetic tone. Electrocardiographic data were mixed. B100 and B0, but not B20, caused significant changes in one or more of the following: serum C-reactive protein, total protein, low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol, and blood urea nitrogen (BUN) and plasma angiotensin converting enzyme (ACE) and fibrinogen.

Discussion and conclusions: Although responses to emissions from all fuels were mixed and relatively mild, some findings point to a reduced cardiovascular impact of blended biodiesel fuel emissions.

• Autonomic
• biodiesel
• cardiovascular
• diesel
• electrocardiogram
• inflammatory
• petroleum
• soy

Acknowledgements

The authors would like to thank Dr. Christina M. Perez, Dr. Alex P. Carll and Anthony Kulukulualani for their excellent technical assistance and Drs. David DeMarini, Mike Madden and Wayne E. Cascio of the United States Environmental Protection Agency for their thorough review of this manuscript before submission.

Declaration of interest

The authors report no declarations of interest.

This paper has been reviewed and approved for release by the National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency. Approval does not signify that the contents necessarily reflect the views and policies of the U.S. EPA, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.