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We are pleased to announce that Volume 138 of the IARC Monographs is now available online. This volume comprises six monographs: automotive gasoline and five oxygenated gasoline additives – methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-butyl alcohol (TBA), diisopropyl ether (DIPE), and tert-amyl methyl ether (TAME).
Automotive gasoline (referred to hereafter as “gasoline”), primarily used in internal combustion engines, is a complex mixture with a composition that has changed over time. It typically comprises volatile, petroleum-derived hydrocarbons, including alkanes, alkenes, and aromatics, which are blended with various additives. The oxygenated additives MTBE, ETBE, TBA, TAME, and DIPE are volatile compounds that have been used in gasoline to increase combustion efficiency, especially since the elimination of lead. All are listed as high-production-volume chemicals. The most widely used, MTBE and ETBE, are no longer added to gasoline in the USA, but are currently used in Europe, Asia, and elsewhere.
The IARC Monographs Working Group reviewed evidence from epidemiological studies in humans, cancer bioassays in experimental animals, and mechanistic studies to assess the carcinogenic hazard to humans of exposure to these agents and concluded that: automotive gasoline is carcinogenic to humans (Group 1); MTBE and ETBE are possibly carcinogenic to humans (Group 2B); and TBA, DIPE, and TAME are each not classifiable as to its carcinogenicity to humans (Group 3).
