Long-term exposure to fine particles of air pollution - from cars, trucks, power plants and manufacturing facilities -- is tied to an increased risk of dying from several kinds of cancer, a new study suggests.
The study, involving more than 66,000 older residents of Hong Kong, found an increased risk of dying from cancer for even small increases in exposure to these tiny particles of air pollution, which are measured in micrograms per cubic meter (mcg/m3). For example, the overall risk of dying from cancer increased 22 percent with every additional 10 mcg/m3 of exposure, the researchers said.
The raised risk seemed higher for some cancers than others: The additional air pollution was linked to a 42 percent rise in the risk of dying from cancer in the upper digestive tract, and a 35 percent increased risk of dying from liver, bile duct, gall bladder and pancreatic cancer, according to researchers.
Among women, the increased exposure was tied to an 80 percent heightened risk of dying from breast cancer. Among men, the higher pollution levels carried a 36 percent increased risk of dying of lung cancer, the study authors said.
Although the role of air pollution in cancer is not fully understood, it could include defects in DNA repair, alterations in the immune response or inflammation that triggers the growth of new blood vessels that allow cancer to spread. In cancer of the digestive organs, heavy metal pollution could also affect gut bacteria and promote development of cancer.
In the study, it was not known whether any of the people had cancer before the study began. Researchers followed the residents until 2011. Causes of deaths were provided by Hong Kong death registries.
To gauge the exposure to tiny particles of air pollution, the researchers relied on estimates from satellite data and air quality monitors. The researchers also adjusted their findings for smoking, and excluded deaths that happened up to three years after people were enrolled in the study.
The risk of death from cancer is not the only harm that air pollution has been tied to recently. A study published April 27 in the journal Environmental Health Perspectives found that being exposed to just a small amount of air pollution during pregnancy may raise the risk of a complication that can cause premature birth and long-term health problems in children.