IARC Classifies Automotive Gasoline as Carcinogenic to Humans

The International Agency for Research on Cancer has classified automotive gasoline as a Group 1 carcinogen and therefore carcinogenic to humans. Automotive gasoline is a commercial product and complex mixture primarily used as fuel in internal combustion engines that causes bladder cancer and acute myeloid leukemia in adults, IARC’s news release explains. The organization made this determination based on what it considers to be sufficient evidence for cancer in humans and experimental animals, as well as strong mechanistic evidence in humans. In addition, there is limited evidence that automotive gasoline causes other cancers, such as acute lymphoblastic leukemia in children and non-Hodgkin lymphoma, multiple myeloma, myelodysplastic syndromes, and stomach and kidney cancers in adults, IARC found.

IARC also evaluated the carcinogenicity of five gasoline additives, volatile compounds that are added to gasoline mixtures to increase combustion efficiency. Methyl tert-butyl ether and ethyl tert-butyl ether were both classified as Group 2B substances, or possibly carcinogenic to humans, based on sufficient evidence of cancer in experimental animals. The additives tert-butyl alcohol, diisopropyl ether, and tert-amyl methyl ether could not be classified as to their carcinogenicity in humans. Evidence that all five additives caused cancer in humans was deemed inadequate by IARC.

According to a Q&A document provided by IARC (PDF), automotive gasoline was previously evaluated by the organization in 1988 and classified as possibly carcinogenic to humans. It was reevaluated based on the publication of new evidence provided by several studies on cancer in humans and experimental animals, as well as the publication of scientific literature on mechanistic data. The same document clarifies that workers and members of the general population are mainly exposed to automotive gasoline and additives via gasoline vapors. However, as a research organization, IARC does not provide health and safety recommendations.

IARC’s findings are presented in a summary article in The Lancet Oncology. More information is available in the organization’s news release.