World Health Organization Classifies Diesel Exhaust a Human Carcinogen ► NCI Cancer Bulletin for June 26, 2012 - National Cancer Institute

NCI Cancer Bulletin for June 26, 2012 - National Cancer Institute

World Health Organization Classifies Diesel Exhaust a Human Carcinogen

On June 12, the International Agency for Research on Cancer (IARC), part of the World Health Organization, classified diesel engine exhaust as carcinogenic to humans (a group 1 carcinogen ). The decision was based on an IARC working group’s opinion that the body of evidence supports an association between diesel exhaust exposure and an increased risk of lung cancer. The working group also found a positive association—though with limited evidence—between diesel exhaust exposure and bladder cancer.

IARC published a summary of the working group’s evaluation in Lancet Oncology on June 18.
In 1988, IARC classified diesel exhaust as probably carcinogenic to humans (a group 2A carcinogen ), and in 1998 an agency advisory group recommended a priority review of the association. The revised classification is based on results from several large human studies, including the recently published Diesel Exhaust in Miners Study (DEMS), led by NCI and the National Institute for Occupational Safety and Health.

“We are pleased that data from our study played an important role in the re-evaluation by providing some of the strongest evidence of an association between diesel exhaust and lung cancer risk,” said Dr. Debra Silverman, chief of the Occupational and Environmental Epidemiology Branch in NCI’s Division of Cancer Epidemiology and Genetics and a lead investigator on the DEMS study.

“There was a tremendous amount of scientific evidence…around the potential harmful effects of diesel exhaust: dozens of epidemiological studies, dozens if not hundreds of laboratory studies in laboratory animals, and then literally thousands of molecular biology and other types of studies looking at fundamental cellular processes and how they’re affected” by diesel exhaust or its constituents, said Dr. Christopher Portier, chair of the IARC working group, at a press conference.

“Our role has been to summarize the scientific evidence and to put that into the public domain” but not to address permissible levels of exposure or other regulatory issues, explained IARC Director Dr. Christopher Wild. “Having provided that evidence base, it’s really then up to national and international regulatory authorities to weigh that [in] the balance with other factors,” he added.

These issues may be particularly important in the developing world, where older, more polluting diesel technology is still widely used and where emissions regulations are lacking, he concluded.