UN health agency re-classifies diesel engine exhaust as ‘carcinogenic to humans’

Photo: IRIN/David Swanson

12 June 2012 – More than a decade after it was classified as ‘probably carcinogenic to humans,’ the UN health agency today classified diesel engine exhaust as ‘carcinogenic to humans.’

The International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), announced the re-classification today, after a week-long meeting of international experts, and based its decision on sufficient evidence that exposure is associated with an increased risk for lung cancer.

“The scientific evidence was compelling and the working group’s conclusion was unanimous: diesel engine exhaust causes lung cancer in humans,” said the chairperson of the IARC working group which reviewed the evidence, Dr. Christopher Portier, in a news release.

“Given the additional health impacts from diesel particulates, exposure to this mixture of chemicals should be reduced worldwide,” he added.

According to IARC, large populations are exposed to diesel exhaust in everyday life, whether through their occupation or through the ambient air. People are exposed not only to motor vehicle exhausts but also to exhausts from other diesel engines, including from other modes of transport, such as diesel trains and ships, and from power generators.

There had been mounting concern about the cancer-causing potential of diesel exhaust, particularly based on findings in epidemiological studies of workers exposed in various settings, the research agency noted.

The IARC working group reviewed the evidence and, overall, it concluded that there was sufficient evidence in humans for the carcinogenicity of diesel exhaust. In particular, it found that there was sufficient evidence to determine that diesel exhaust is a cause of lung cancer, and noted that there a positive association with an increased risk of bladder cancer.

The working group also concluded that gasoline exhaust was possibly carcinogenic to humans, a finding unchanged from a previous evaluation in 1989.

IARC stated that governments and other decision-makers now have a valuable evidence-base on which to consider environmental standards for diesel exhaust emissions and to continue to work with the engine and fuel manufacturers towards those goals.

“While IARC’s remit is to establish the evidence-base for regulatory decisions at national and international level, today’s conclusion sends a strong signal that public health action is warranted,” said the Director of IARC, Dr. Christopher Wild. “This emphasis is needed globally, including among the more vulnerable populations in developing countries where new technology and protective measures may otherwise take many years to be adopted.”

In 1988, IARC had classified diesel exhaust as probably carcinogenic to humans. An Advisory Group, which reviews and recommends future priorities for the agency, had recommended diesel exhaust as a high priority for re-evaluation since 1998.


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