In a press release (12 June 2012), the International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), officially announced the re-classification for the carcinogenicity of diesel engine exhaust. The agency has finally classified diesel engine exhaust as carcinogenic to humans. As emphasized by Dr Christopher Portier, Chairman of the IARC Working Group, that “The scientific evidence was compelling and the Working Group’s conclusion was unanimous: diesel engine exhaust causes lung cancer in humans.” Then he added: “Given the additional health impacts from diesel particulates, exposure to this mixture of chemicals should be reduced worldwide. “
In 1988, IARC classified diesel exhaust as probably carcinogenic to humans. But since 1998, an Advisory Group which reviews and recommends future priorities for the IARC Monographs Program had recommended diesel exhaust as a high priority for re-evaluation. There has 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 IARC working group reviewed the evidence and, overall, it concluded that there was sufficient evidence in humans for the carcinogenicity of diesel exhaust. The Working Group found that diesel exhaust is a cause of lung cancer (sufficient evidence) and also noted a positive association (limited evidence) with an increased risk of bladder cancer. The Working Group also concluded that gasoline exhaust was possibly carcinogenic to humans, a finding unchanged from the previous evaluation in 1989.
Dr Kurt Straif, Head of the IARC Monographs Program, indicated 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.” 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 (e.g. diesel trains and ships) and from power generators.
Given the Working Group’s rigorous, independent assessment of the science, governments and other decision-makers 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. For diesel engines, this required changes in the fuel such as marked decreases in sulfur content, changes in engine design to burn diesel fuel more efficiently and reductions in emissions through exhaust control technology. Though the changes can reduce the amount of particulates and chemicals, further research is still needed to ensure how the quantitative and qualitative changes may translate into altered health effects.
Dr Christopher Wild, Director, IARC, said that “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. 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.”
Increasing environmental concerns over the past two decades have resulted in regulatory action in North America, Europe and elsewhere with successively tighter emission standards for both diesel and gasoline engines. There is a strong interplay between standards and technology – standards drive technology and new technology enables more stringent standards. However, it is also notable that many parts of the developing world lack regulatory standards, and data on the occurrence and impact of diesel exhaust are limited.
(Source: www.who.int)
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