The specialized cancer agency of the World Health Organization, the International Agency for Research on Cancer (IARC), has announced that it has classified outdoor air pollution as carcinogenic to humans (Group 1*).
After reviewing the latest available scientific literature, the experts convened by the IARC Monographs Programme concluded that there is sufficient evidence that exposure to outdoor air pollution causes lung cancer (Group 1*). They also noted a positive association with an increased risk of bladder cancer. Particulate matter, small particles that make up a major component of outdoor air pollution, was evaluated separately and was also classified as carcinogenic to humans (Group 1*).
The IARC evaluation showed an increasing risk of lung cancer with increasing levels of exposure to particulate matter and air pollution. Although the composition of air pollution and levels of exposure can vary dramatically between locations, the conclusions of the Working Group apply to all regions of the world.
*Group 1 Definition: The agent is carcinogenic to humans. This category is used when there is sufficient evidence of carcinogenicityin humans. Exceptionally, an agent may be placed in this category when evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent acts through a relevant mechanism of carcinogenicity.
Associate Professor Adrian Barnett is a Principal Research Fellow in the Faculty of Health at Queensland University of Technology. He comments:
“This is an important change to the classification of outdoor air pollution, and one that Australian policy makers should listen to. There is a generally complacent attitude to air quality in Australia, which is based on our air being cleaner than other countries, such as China, and the fact that most air pollutants are invisible and odourless. But just because we can’t see the pollutants doesn’t mean they aren’t harming us. Studies in Australia have shown associations between increased outdoor air pollution and: hospital admissions in children and the elderly, reduced lung function in children, asthma, shorter gestations for pregnant women and death.
A lack of any serious policy action has meant that there’s been no clear improvement in air quality in the last decade in Australia’s major cities for the two important air pollutants of ozone and particulate matter. Traffic is the major source of pollution in Australian cities, so if we want cleaner air then we either need cleaner cars or fewer cars.”
Emeritus Professor Michael Moore is a toxicologist and former director of the National Research Centre for Environmental Toxicology at the University of Queensland. He is currently Chairman of the Board of Water Quality Research Australia comments:
“It has been clear for some time that components of airborne pollution are carcinogenic. Secondary tobacco smoke and some hydrocarbons are obvious examples. The current smoke from bush fires might also fit into this category. It is equally likely that some components of air pollution, although undesirable, are unlikely to be carcinogenic. As always, the dose determines the poison and this needs further exploration in respect of the IARC statement. That said this is a welcome ‘wake-up’ call in respect of the negative effects of poor air quality and the range of outcomes associated with it.”
COMMENTS FROM THE UK SMC
Professor David Phillips of King’s College London and member of the Working Group for this IARC evaluation comments:
“There is clear evidence, stemming from human, experimental and mechanistic studies, that polluted outdoor air is harmful to human health and a major cause of cancer. As the major sources are man-made, much can and should be done to protect the world’s population from exposure, particularly those in urban and industrialised environments. Reductions in emissions will have significant long-term benefits for disease prevention.”