Researchers have shown that long-term exposure to fine particles is associated with an increased risk of death from cancer in the elderly.
Long-term exposure to environmental pollutants has been associated with an increased risk of mortality from many types of cancer. This is what emerges from a study carried out jointly by the universities of Birmingham (England) and Hong Kong (China). These works published in Cancer Epidemiology, Biomarkers & Prevention were conducted on an elderly population residing on this Chinese island, a former British colony.
For this study, the researchers recruited 66,280 people aged 65 or over between 1998 and 2001. These participants were followed until 2011.
After taking into account the risk factors (tobacco), the study showed that for every 10 ug / m³ of increased exposure to PM2.5, the risk of dying from any form of cancer is increased by 22%. Long-term exposure to PM2.5 particles has been mainly associated with deaths from cardiopulmonary causes and linked to lung cancer. In men, the risk of dying from the latter pathology would thus increase by 36% in people particularly exposed.
But the authors also found a similar effect on the risk of cancers affecting other areas of the body.
Results to be confirmed in other cities
For example, for every 10 ug / m³ increase in exposure to PM2.5, the risk of death from cancer in the upper digestive tract increases by 42%, and that from cancers affecting secondary digestive organs (the liver, bile ducts, gallbladder and pancreas) by 35%.
Finally, for women, an increase in exposure of 10 ug / m³ to PM2.5 is associated with an 80% increase in the risk of death from breast cancer.
As explanations for these results, the authors point to fine particle pollution of all ailments: “DNA repair defects, alterations in the immune response, inflammation that can trigger angiogenesis or even the growth of new blood vessels which allows tumors to spread ‘. ” In the case of the digestive organs, pollution by heavy metals could affect the intestinal microbiota and influence the development of cancer ”, they add..
Faced with so much worrying data, Dr Neil Thomas of the University of Birmingham announces that “the next step is to determine if other countries are experiencing similar associations between PM2.5 and cancer deaths. This study, combined with existing research, suggests that other urban populations may bear the same risks but we would be ready to explore the question further, ”he says.
Dr Thuan Quoc Thach of the University of Hong Kong concludes, however: “We have to be careful with these results, pollution is just a risk factor for cancer, there are many others, such as poor diet. , lack of exercise, etc. “.
As a reminder, the International Agency for Research on Cancer (IARC) of the World Health Organization classified, in 2013, outdoor air pollution and, independently, microparticles, as carcinogenic factors for humans, of group 1, that is to say proven or certain.
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