Air pollution linked to higher risk of mouth cancer

Exposure to air pollution has been linked to a raised risk of developing mouth cancer in the first study of its kind.

Higher levels of small particles in air pollution were linked to a

43 per cent greater chance of being diagnosed with the disease, it found.

Cases of mouth cancer, which can be fatal, are increasing in many parts of the world. Over the past 20 years rates have risen by

71 per cent in Britain, according to Cancer Research UK. About

5300 men and 2500 women a year have oral cancer diagnosed and about 2500 die. Smoking, drinking and the human papilloma virus are known risk factors.

Researchers set out to establish whether air pollutants could play a part and used health records of 482,659 men in Taiwan aged 40 and older to look for links. Using data at air quality monitoring stations they found that high levels of PM2.5, tiny particulate matter in pollution, increased the risk of a mouth cancer diagnosis.

PM2.5 refers to matter with a diameter of less than 2.5 micrometres, about 3 per cent the width of a human hair. It can travel through lungs into the bloodstream and has already been linked to lung and cardiovascular disease. The London Air Quality Network at King’s College London said the average

PM2.5 level for the last year was

13 micrograms per cubic metre, but it had recorded levels as high as 192 µg/m3. In the study men exposed to levels above 40.37 µg/

m3 were 43 per cent more likely to have mouth cancer diagnosed than those exposed to levels below 26.74 µg/m3.

Campaigners said that the study, published in the Journal of Investigative Medicine, underlined the urgent need to tackle air pollution.

The researchers, from Asia University and Chung Shan Medical University in Taiwan, stressed that as an observational study there was no clear mechanism to explain how pollutants contribute to the development of mouth cancer.

Exposure to heavy metals or emissions from petrochemical plants have previously been implicated. Some components of PM2.5 include arsenic, nickel and chromium, as well as other known carcinogens. The researchers said that their findings ‘‘add to the growing evidence on the adverse effects of PM2.5 on human health’’.

The British annual limit for fine particles is 25 µg/m3 and the World Health Organisation has a target of 10 µg/m3.

Georgina Hill, from Cancer Research UK, said: ‘‘We know that air pollution can increase the risk of lung cancer. But less is known about its effect on other cancer types. Levels of air pollution are much higher in Taiwan than in the UK, so more research is needed to see if this link applies in the UK too.’’ – The Times