Living in an area with high levels of air pollutants may be linked to a heightened risk of developing mouth cancer, new research suggests.
The number of new cases of – and deaths from – mouth cancer is increasing in many parts of the world, according to the study, published in the Journal of Investigative Medicine.
Known risk factors include smoking, drinking alcohol, human papilloma virus (HPV) , and in parts of South East Asia, the chewing of betel quid (‘paan’), a mix of ingredients wrapped in betel leaf. But scientists now believe air pollutants, especially fine particulate matter (PM2.5), could be a contributing factor.
PM2.5 is the name given to fine matter which is two and one half microns in width or less. The tiny particles of pollution come from a variety of sources, ranging from metal waste lost during the construction of buildings to the burning of fuels such as wood.
To find out if air pollutants might have a role in the development of mouth cancer, the researchers mined national cancer, health, insurance and air quality databases.
They drew on average levels of air pollutants (sulphur dioxide, carbon monoxide, ozone, nitrogen monoxide, nitrogen dioxide, and varying sizes of fine particulate matter), measured in 2009 at 66 air quality monitoring stations across Taiwan.
In 2012-13, they checked the health records of 482,659 men aged 40 and older who had attended preventive health services, and had provided information on smoking and betel quid chewing.
They found 1,617 cases of mouth cancer. Unsurprisingly, smoking and frequent betel quid chewing were significantly associated with heightened risk of diagnosis - but so too were high levels of PM2.5, with risk calculated as much as 43 per cent.
The researchers stressed their work was an observational study, and as such air pollution couldn’t be established as a definite cause of mouth cancer. However, they noted the small diameter of PM2.5 means it is easily absorbed into the body. They added that further research is needed to investigate exactly how air pollutants might contribute to mouth cancer.
The study concludes: “This study, with a large sample size, is the first to associate oral cancer with PM2.5. These findings add to the growing evidence on the adverse effects of PM2.5 on human health.”