title: Evaluation of carcinogenic hazard of diesel engine exhaust needs to consider revolutionary changes in diesel technology.
abstract: Diesel engines, a special type of internal combustion engine, use heat of compression, rather than electric spark, to ignite hydrocarbon fuels injected into the combustion chamber. Diesel engines have high thermal efficiency and thus, high fuel efficiency. They are widely used in commerce prompting continuous improvement in diesel engines and fuels. Concern for health effects from exposure to diesel exhaust arose in the mid-1900s and stimulated development of emissions regulations and research to improve the technology and characterize potential health hazards. This included epidemiological, controlled human exposure, laboratory animal and mechanistic studies to evaluate potential hazards of whole diesel exhaust. The International Agency for Research on Cancer (1989) classified whole diesel exhaust as - "probably carcinogenic to humans". This classification stimulated even more stringent regulations for particulate matter that required further technological developments. These included improved engine control, improved fuel injection system, enhanced exhaust cooling, use of ultra low sulfur fuel, wall-flow high-efficiency exhaust particulate filters, exhaust catalysts, and crankcase ventilation filtration. The composition of New Technology Diesel Exhaust (NTDE) is qualitatively different and the concentrations of particulate constituents are more than 90% lower than for Traditional Diesel Exhaust (TDE). We recommend that future reviews of carcinogenic hazards of diesel exhaust evaluate NTDE separately from TDE.
authors.affiliation: Toxicology and Risk Analysis, 13701 Quaking Aspen Place NE, Albuquerque, NM 87111, USA. roger.o.mcclellan@att.net
authors.forename: Roger O
authors.initials: RO
authors.lastname: McClellan
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Hesterberg
authors.forename: John C
authors.initials: JC
authors.lastname: Wall
mesh_terms: D000327:Adsorption; D000393:Air Pollutants / Q000737:chemistry / Q000633:toxicity*; D000397:Air Pollution / Q000331:legislation & jurisprudence / Q000517:prevention & control; D000818:Animals; D002274:Carcinogens, Environmental / Q000737:chemistry / Q000633:toxicity*; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005742:Gasoline / Q000592:standards*; D006077:Government Agencies; D033161:Government Regulation; D006801:Humans; D008855:Microscopy, Electron, Scanning; D018986:Motor Vehicles / Q000592:standards; D010316:Particle Size; D018570:Risk Assessment; D013499:Surface Properties; D013672:Technology / Q000458:organization & administration / Q000592:standards / Q000639:trends*; D014481:United States; D001335:Vehicle Emissions / Q000032:analysis / Q000331:legislation & jurisprudence / Q000517:prevention & control / Q000633:toxicity*
chemical_list: D000393:Air Pollutants; D002274:Carcinogens, Environmental; D005742:Gasoline; D001335:Vehicle Emissions