Life cycle freshwater ecotoxicity, human health cancer, and noncancer impacts of corn ethanol and gasoline in the U.S.

Life cycle studies of corn ethanol have largely centered on the fuelʹs carbon and energy benefits. However, with the recognition that this narrow focus falls short of addressing the environmental sustainability of fuel substitution, there is a growing body of literature that extends assessment to a broader range of impacts, such as eutrophication, smog formation, acidification, and water and land use. Using the USEtox impact assessment model, this study evaluates the life cycle freshwater ecotoxicity, human health cancer, and noncancer effects of U.S. corn ethanol and gasoline, which are less well understood in comparison to other impact categories. This study also takes into account spatial and temporal variations in corn production and ethanol conversion technologies. Results show that corn ethanol generates potentially larger freshwater ecotoxicity than gasoline due to releases of pesticides in corn growth, particularly, atrazine, acetochlor, chlorpyrifos, and cyfluthrin. So does corn ethanol have a higher potential noncancer impact due to releases of heavy metals through use of phosphate fertilizers. The two fuels seem to induce similar potential caner impacts. The results indicate that replacing gasoline with corn ethanol could further degrade water quality and exacerbate noncancer related human health issues. Overall, this study implies that environmental policymaking should consider a broader spectrum of impacts beyond carbon and energy to avoid or minimize potential environmental burden-shifting.