Air pollution nanoparticles from motor traffic have now been linked to brain cancer by new research. For the first time, a study found that the particles can invade the brain and carry carcinogens that cause tumors.
The microscopic particles – called ultrafine particles (UFPs) – are produced when fuel is burned (diesel vehicles in particular). The higher the exposure, the greater a person’s chances of getting the deadly cancer. While previous research revealed that nanoparticles can get into the brain and that they can carry carcinogenic chemicals, this new study shows that the amount of exposure increases risk.
It’s been complicated to find figures because brain cancers are rare. However, scientists finally managed to calculate that if 100,000 people moved from a quiet city street to a busy one, one of them would get brain cancer. That’s all the extra exposure needed to make a difference.
Scott Weichenthal, of McGill University in Canada, who led the study, said:
Environmental risks like air pollution are not large in magnitude – their importance comes because everyone in the population is exposed. 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 tumors are often fatal.
The Study
- The pollution exposure and medical records of 1.9 million Canadian adults from 1991 to 2016 were analyzed.
- Being that it was such an extensively large study, there is a higher chance for reliable evidence, though not a causal link.
- The study has been published in the journal Epidemiology.
The Results
- A one-year increase in pollution exposure of 10,000 nanoparticles per cubic centimeter – the approximate difference between quiet and busy city streets – increased the risk of brain cancer by over 10%.
- The correlation between nanoparticles and brain cancer was “surprisingly consistent,” said Weichenthal.
- Now, other researchers must replicate the results because this is the first and only study on the subject so far.
Conclusion
Although there is no proof of pollution causing tumors, toxic air has been linked to other ill effects on the brain, such as considerable reductions in intelligence, mental health problems in all age ranges, and dementia. Therefore, it is entirely reasonable to say that the carcinogenic chemicals (which have already been found to make their way into the brain in a 2016 study) could cause brain tumors.
Prof Barbara Maher, at the University of Lancaster, UK, said:
Iron-rich nanoparticles from traffic pollution are likely to be carcinogenic and are therefore a plausible possible cause of brain cancer. Nanoparticles are not regulated and are rarely even measured.
A separate global review published in 2019 found that air pollution may be harming every organ and every cell in the human body. According to the World Health Organization, air pollution is a “silent public health emergency.”
Weichenthal said:
We don’t know a lot about the causes of brain tumors, so any environmental factors we can identify are helpful in increasing understanding.
At an individual level, it is always a good idea to reduce your exposure to pollutants. But the more important actions are at a regulatory level, where you can take action that reduces everyone’s exposure – that is where the real benefits come in.
He advises avoiding heavily polluted streets when walking and cycling at all costs possible until regulatory actions on the governmental level can finally stop air pollution from its source.
