New research has linked air pollution nanoparticles to brain cancer for the first time.

New research has linked air pollution nanoparticles to brain cancer for the first time.

The ultra-fine particles (UFPs) are produced by fuel burning, particularly in diesel vehicles, and higher exposures significantly increase people’s chances of getting the deadly cancer. Previous work has shown that nanoparticles can get into the brain and that they can carry carcinogenic chemicals.

Brain cancers are rare, and the scientists have calculated that an increase in pollution exposure roughly equivalent to moving from a quiet city street to a busy one leads to one extra case of brain cancer for every 100,000 people exposed.

“Environmental risks like air pollution are not large in magnitude – their importance comes because everyone in the population is exposed,” said Scott Weichenthal, at McGill University in Canada, who led the study. “So when you multiply these small risks by lots of people, all of sudden there can be lots of cases. In a large city, it could be a meaningful number, particularly given the fact that these tumours are often fatal.”

The research analysed the medical records and pollution exposure of 1.9 million adult Canadians from 1991 to 2016. Such large studies provide strong evidence, though not a causal link. Weichenthal said the correlation seen between brain cancer and nanoparticles was “surprisingly consistent”, but as this is the first study, it is important that other researchers replicate it.

The discovery of abundant toxic nanoparticles from air pollution in human brains was made in 2016. A comprehensive global review earlier in 2019 concluded that air pollution may be damaging every organ and virtually every cell in the human body.

The World Health Organization says air pollution is a “ silent public health emergency”.

The new study, published in the journal Epidemiology , found that a one-year increase in pollution exposure of 10,000 nanoparticles per cubic centimetre – the approximate difference between quiet and busy city streets – increased the risk of brain cancer by more than 10%.

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