IARC: DIESEL ENGINE EXHAUST CARCINOGENIC

PRESS RELEASE
N° 213
12 June 2012
IARC: DIESEL ENGINE EXHAUST CARCINOGENIC

Lyon, France, June 12, 2012 ‐‐ After a week-long meeting of international experts, the International
Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), today
classified diesel engine exhaust as carcinogenic to humans (Group 1), based on sufficient evidence
that exposure is associated with an increased risk for lung cancer.
Background
In 1988, IARC classified diesel exhaust as probably carcinogenic to humans (Group 2A). 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 since 1998.
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. This was re-emphasized by
the publication in March 2012 of the results of a large US National Cancer Institute/National Institute for
Occupational Safety and Health study of occupational exposure to such emissions in underground miners,
which showed an increased risk of death from lung cancer in exposed workers (1).
Evaluation
The scientific evidence was reviewed thoroughly by the Working Group and overall it was 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 (Group 1).
The Working Group concluded that gasoline exhaust was possibly carcinogenic to humans (Group 2B), a
finding unchanged from the previous evaluation in 1989.
Public health
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.
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. 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.
However, while the amount of particulates and chemicals are reduced with these changes, it is not yet
clear how the quantitative and qualitative changes may translate into altered health effects; research into
this question is needed. In addition, existing fuels and vehicles without these modifications will take many
years to be replaced, particularly in less developed countries, where regulatory measures are currently
also less stringent. It is notable that many parts of the developing world lack regulatory standards, and
data on the occurrence and impact of diesel exhaust are limited.
Conclusions
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.” Dr Portier continued: “Given the additional health impacts from diesel particulates,
exposure to this mixture of chemicals should be reduced worldwide.“(2)
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.”
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.”
Summary evaluation
The summary of the evaluation will appear in The Lancet Oncology as an online publication ahead of print
on June 15, 2012.
(1) JNCI J Natl Cancer Inst (2012) doi:10.1093/jnci/djs034
http://jnci.oxfordjournals.org/content/early/2012/03/05/jnci.djs034.abstract; and
JNCI J Natl Cancer Inst (2012) doi: 10.1093/jnci/djs035
http://jnci.oxfordjournals.org/content/early/2012/03/05/jnci.djs035.abstract
(2) Dr Portier is Director of the National Center for Environmental Health and the Agency for Toxic
Substances and Disease Registry at the Centers for Disease Control and Prevention (USA).
For more information, please contact
Dr Kurt Straif, IARC Monographs Section, at +33 472 738 507, or straifk@iarc.fr;
Dr Lamia Tallaa, IARC Monographs Section, at +33 472 738 385, or tallaal@iarc.fr;
Nicolas Gaudin, IARC Communications Group, at +33 472 738 478, or com@iarc.fr;
Fadela Chaib, WHO News Team, at +41 79 475 55 56, or chaibf@who.int.
Link to the audio file posted shortly after the media briefing:
http://terrance.who.int/mediacentre/audio/press_briefings/
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.