title: Hazard and risk assessment of a nanoparticulate cerium oxide-based diesel fuel additive - a case study.
abstract: Envirox is a scientifically and commercially proven diesel fuel combustion catalyst based on nanoparticulate cerium oxide and has been demonstrated to reduce fuel consumption, greenhouse gas emissions (CO(2)), and particulate emissions when added to diesel at levels of 5 mg/L. Studies have confirmed the adverse effects of particulates on respiratory and cardiac health, and while the use of Envirox contributes to a reduction in the particulate content in the air, it is necessary to demonstrate that the addition of Envirox does not alter the intrinsic toxicity of particles emitted in the exhaust. The purpose of this study was to evaluate the safety in use of Envirox by addressing the classical risk paradigm. Hazard assessment has been addressed by examining a range of in vitro cell and cell-free endpoints to assess the toxicity of cerium oxide nanoparticles as well as particulates emitted from engines using Envirox. Exposure assessment has taken data from modeling studies and from airborne monitoring sites in London and Newcastle adjacent to routes where vehicles using Envirox passed. Data have demonstrated that for the exposure levels measured, the estimated internal dose for a referential human in a chronic exposure situation is much lower than the no-observed-effect level (NOEL) in the in vitro toxicity studies. Exposure to nano-size cerium oxide as a result of the addition of Envirox to diesel fuel at the current levels of exposure in ambient air is therefore unlikely to lead to pulmonary oxidative stress and inflammation, which are the precursors for respiratory and cardiac health problems.
authors.affiliation: Oxonica plc, Yarnton, Kidlington, United Kingdom.
authors.forename: Barry
authors.initials: B
authors.lastname: Park
authors.forename: Kenneth
authors.initials: K
authors.lastname: Donaldson
authors.forename: Rodger
authors.initials: R
authors.lastname: Duffin
authors.forename: Lang
authors.initials: L
authors.lastname: Tran
authors.forename: Frank
authors.initials: F
authors.lastname: Kelly
authors.forename: Ian
authors.initials: I
authors.lastname: Mudway
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Morin
authors.forename: Robert
authors.initials: R
authors.lastname: Guest
authors.forename: Peter
authors.initials: P
authors.lastname: Jenkinson
authors.forename: Zissis
authors.initials: Z
authors.lastname: Samaras
authors.forename: Myrsini
authors.initials: M
authors.lastname: Giannouli
authors.forename: Haris
authors.initials: H
authors.lastname: Kouridis
authors.forename: Patricia
authors.initials: P
authors.lastname: Martin
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000737:chemistry; D002384:Catalysis; D002460:Cell Line; D002563:Cerium / Q000737:chemistry* / Q000633:toxicity*; D004785:Environmental Pollutants / Q000737:chemistry / Q000633:toxicity; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005742:Gasoline / Q000032:analysis*; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000201:enzymology; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity*; D010084:Oxidation-Reduction; D010316:Particle Size; D052638:Particulate Matter / Q000737:chemistry / Q000633:toxicity; D051381:Rats; D018570:Risk Assessment; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D001335:Vehicle Emissions
chemical_list: D000975:Antioxidants; D004785:Environmental Pollutants; D005742:Gasoline; D016209:Interleukin-8; D052638:Particulate Matter; D014409:Tumor Necrosis Factor-alpha; D001335:Vehicle Emissions; D002563:Cerium; C030583:ceric oxide; D000255:Adenosine Triphosphate; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione; D001205:Ascorbic Acid