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IARC: Outdoor air pollution a leading environmental cause of cancer

18 October 2013

The International Agency for Research on Cancer (IARC), an agency of the World Health Organization, has classified outdoor air pollution as carcinogenic to humans (IARC Group 1). The experts convened by the IARC Monographs Programme concluded that there is sufficient evidence that exposure to outdoor air pollution causes lung cancer. They also noted a positive association with an increased risk of bladder cancer.

Particulate matter, a major component of outdoor air pollution, was evaluated separately and was also classified as carcinogenic to humans (IARC 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 IARC Working Group apply to all regions of the world, said IARC.

Air pollution has been known to increase risks for a range of diseases, such as respiratory and heart diseases. In recent years exposure levels have increased significantly in some parts of the world, particularly in rapidly industrializing countries with large populations. According to IARC estimates, in 2010, 223,000 deaths from lung cancer worldwide resulted from air pollution.

“The air we breathe has become polluted with a mixture of cancer-causing substances,” said Dr Kurt Straif, Head of the IARC Monographs Section. “We now know that outdoor air pollution is not only a major risk to health in general, but also a leading environmental cause of cancer deaths.”

The IARC Monographs Programme reviews and analyzes scientific evidence on cancer-causing substances and exposures. In the past, the Programme evaluated many individual chemicals and specific mixtures that occur in outdoor air pollution. These included diesel engine exhaust—classified as carcinogenic to humans (Group 1) in June 2012—solvents, metals, and dusts. It is the first time that outdoor air pollution has been classified as a cause of cancer.

Volume 109 of the IARC Monographs is based on a review of more than 1000 scientific papers from studies on five continents. The reviewed studies analyse the carcinogenicity of various pollutants present in outdoor air pollution, especially particulate matter and transportation-related pollution. A summary evaluation will be published by The Lancet Oncology online on 24 October 2013.

The predominant sources of outdoor air pollution—said IARC—include transportation, stationary power generation, industrial and agricultural emissions, residential heating and cooking, as well as some natural sources.

Source: IARC