Diesel engine exhaust was classified on June 12, 2012 as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer (IARC). The reclassification of diesel engine exhaust from probably carcinogenic to humans (Group 2A) to carcinogenic to humans was based on evidence showing that exposure to diesel exhaust is associated with an increased risk for lung cancer. The IARC also noted that a positive association (limited evidence) exists for an increased risk of bladder cancer in humans. Diesel exhaust was first classified as probably carcinogenic to humans in 1988, and had been recommended for re-evaluation since 1998.

Dr. Christopher Portier, Chairman of the IARC Working Group, stated that “The scientific evidence was compelling and the Working Group’s conclusion was unanimous: diesel engine exhaust causes lung cancer in humans. Given the additional health impacts from diesel particulates, exposure to this mixture of chemicals should be reduced worldwide.”

Dr. Kurt Straif, Head of the IARC Monographs Program, added that “The main studies that led to this conclusion were in highly exposed workers. However, we have learned from other carcinogens, such as radon, that initial studies showing a risk in heavily exposed occupational groups were followed by positive findings for the general population. Therefore actions to reduce exposures should encompass workers and the general population.”

The Working Group also concluded that gasoline exhaust was possibly carcinogenic to humans (Group 2B), a finding unchanged from the previous evaluation in 1989.

About IARC

The International Agency for Research on Cancer (IARC) is part of the World Health Organization. Its mission is to coordinate and conduct research on the causes of human cancer, the mechanisms of carcinogenesis, and to develop scientific strategies for cancer control. The Agency is involved in both epidemiological and laboratory research and disseminates scientific information through publications, meetings, courses, and fellowships.

Click here for the IARC press release or listen to the press conference.

Photograph: Oil Lamp by Zsuzsanna Kilian, Budapest, Hungary.

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