Carcinogenic Potential of Gasoline and Diesel Engine Oils

Used gasoline engine oils are carcinogenic in mouse skin andmutagenic in Salmonella. The toxicity of fresh gasoline engineoils and that of fresh and used diesel engine oils are lesswell defined. The present studies examined the dermal carcinogenicpotential of a series of fresh and used oils from both gasolineand diesel engines. The used oils represented a variety of operatingconditions. The objective of the study was to assess the potentialcarcinogenic hazards associated with exposure to these materials.The majority of the used gasoline engine oils tested were carcinogenicalthough one oil, collected after a relatively short drainageinterval, was inactive in the dermal carcinogenesis bioassay.Additionally, polycyclic aromatic hydrocarbon (PAH) concentrationswere elevated in the used oils in comparison to the fresh oils.The fresh gasoline engine oils and both the fresh and used dieselengine oil samples were noncarcinogenic, and there was littleevidence of elevated PAH levels in the used diesel engine oils.The carcinogenic potency of used oils from gasoline engineswas related to drainage interval, but other factors such ascontribution of the fuel due to blowby and driving cycle mayalso have been important. The used diesel engine oils were notcarcinogenic even after extended use.