In an open access commentary published in Environmental Health Perspectives, researchers from University of North Carolina School of Public Health and the US EPA’s National Health and Environmental Effects Research Laboratory call for more research into the possible health effects of biodiesel exhaust.
While noting that using biodiesel fuel “is favorably viewed,” the authors also note that the suggestions that biodiesel exhaust is less likely to present risk to human health relative to petroleum diesel are speculative. Given the push for greater biodiesel use, they argue, the effects need to be more fully researched.
Currently there is a strong desire and need for an alternative fuels in this country. Employment of biodiesel fuel is favorably viewed and there are suggestions that its exhaust emissions are less likely to present any risk to human health relative to petroleum diesel emissions (Mauderly 1997). However, the speculative nature of a reduction in health effects based on chemical composition of biodiesel exhaust needs to be followed up with investigations using newer biological approaches gained from years of diesel research.
It is our opinion that biodiesel requires greater due diligence then it has received to date in the United States.
After reviewing the extant literature on biodiesel emissions, the authors recommend the study of a number of issues:
The consequences of biodiesel exhaust from blends.
The consequences of the use of additives. There are numerous additives to biodiesel, such as cetane improvers, smoke suppressors, flow enhancers, cloud-point depressors, wax anti-settling additives, detergents to reduce injector nozzle fouling, antioxidants for unsaturated oils, and controls for microbial growth. including Additives to biodiesel fuel are numerous and may impact human health. Some of these additives include metals. No emissions data are yet available for biodiesel combined with the additives required for practical application of biodiesel fuel usage on a national level.
The effect of disparate levels of aldehydes in biodiesel fuel and its exhaust emissions, which may be associated with varying impacts on indices of human health. Low quality biodiesel, which does not met high productions standards, will emit greater quantities of aldehydes due to poor post-transesterification refining. Biodiesel from some feedstock oils may have higher concentrations of aldehydes relative to those from others. It is unclear whether this might impact human health.
The affect of the new petroleum diesel engine combustion and after-treatment technologies, designed to decrease specific exhaust components such as particulate matter and nitrogen oxides.
The affect of the use of pesticides on plants with subsequent contamination of feedstocks.
(A hat-tip to Green Car Congress reader MR!)
“Biodiesel Exhaust: The Need for Health Effects Research”; Kimberly J. Swanson, Michael C. Madden and Andrew J. Ghio; Environ Health Perspect, 3 January 2007, doi:10.1289/ehp.9631