Air pollution may increase mouth cancer risk

High levels of air pollutants may be linked to an increased risk of developing mouth cancer, the BMJ has found. Fine particulate matter (PM2.5) and ozone are the main culprits.

Risk factors for mouth cancer, which is increasing across the world, include smoking, drinking and human papilloma virus.

Exposure to heavy metals and emissions from petrochemical plants are also thought to be implicated in the development of the disease.

However, increasing levels of air pollutants, especially fine particulate matter, or PM2.5, have now been associated with a higher risk of developing the disease.

For the new study, which is the first of its kind, researchers from the BMJ mined national cancer, health, insurance and air quality databases, drawing on average levels of air pollutants including sulphur dioxide, carbon monoxide, ozone and nitrogen monoxide that were measured in 2009 at 66 air quality monitoring stations across Taiwan, explained a statement.

From 2012 to 2013, they then checked the health records of more than 480,000 men aged 40 and above, with diagnoses of mouth cancer linked to local area readings for air pollutants taken in 2009. After taking account of potentially influential factors, increasing levels of PM2.5 were associated with an increasing risk of mouth cancer.

“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,” commented the researchers.

When compared with levels below 26.74 ug/m3, those above 40.37 ug/ m3 were associated with a 43 per cent heightened risk of a mouth cancer diagnosis. A significant association was also observed for ozone levels below 28.69-30.97 parts per billion, according to the statement.

Some of the components of PM2.5 include heavy metals and known cancer-causing compounds, such as polycyclic aromatic hydrocarbons. Furthermore, the smaller diameter but larger surface area of PM2.5 means that it can be relatively easily absorbed by the body.

Because the study is observational, it cannot establish cause, and there is a lack of data on how much PM2.5 enters the mouth or on long term exposure to this pollutant, with further research needed.

Photo credit: 君勇 林/CC BY-NC 2.0

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