For the first time, brain cancer was linked to air pollution nanoparticles as per new research. The fuel burning in motor traffic, especially in diesel vehicles, produce ultra-fine particles (UFPs) that significantly increase the chances of getting deadly cancer. The nanoparticles can invade the brain, and they can carry carcinogenic chemicals, previous work has shown.
Although brain cancers are rare, for every 100,000 people exposed, scientists have calculated one new case of brain cancer due to an increase in pollution exposure, which includes moving from a quiet city street to a busy one.
“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 pollution exposure of 1.9 million from 1991 to 2016 and medical records were analyzed in the research and provide strong evidence. According to Weichenthal, the correlation between brain cancer and nanoparticles was “surprisingly consistent.” However, being the first study, other researchers must replicate it.
Abundant toxic nanoparticles in human brains from air pollution had been discovered in 2016. Earlier in 2019, a comprehensive global review concluded that air pollution might be damaging every organ in the human body, including every cell.
The impacts of toxic air on the brain include considerable reductions in intelligence, dementia, and mental health problems in both adults and children. The World Health Organization declared, air pollution is a “silent public health emergency.”
As per the new study published in the journal Epidemiology, the one-year increase in exposure to pollution of 10,000 nanoparticles per cubic centimeter, which is the approximate difference between quiet and busy city streets, the risk of brain cancer increased by more than 10%.
In Toronto and Montreal, the pollution levels studied is ranged from 6,000/cm3 to 97,000/cm3. People living with pollution of 50,000/cm3 have a 50% higher risk of brain cancer compared to those living with 15,000/cm3, Weichenthal explained.
“I think [Toronto and Montreal] are typical of major cities,” he said. “I wouldn’t expect the nanoparticles to be any less harmful anywhere else.” The researchers considered many factors, including income, smoking and obesity, and whether people moved house in the analysis.
“We don’t know a lot about the causes of brain tumours, so any environmental factors we can identify are helpful in increasing understanding,” Weichenthal said. The research team only had air pollution data for the more recent period of the study and assumed that in the past, while the differences between different streets and districts were the same. “We think this is reasonable because major highways don’t move around,” he said.
Prof Jordi Sunyer, associated with the Barcelona Institute for Global Health in Spain, who was not part of the new research, said: “This is an important finding, given that UFPs are directly emitted by combustion cars and several studies in animals have shown UFPs could be more toxic than larger particles.”
According to Prof Barbara Maher, at the University of Lancaster, UK nanoparticles from traffic pollution were a plausible possible cause of brain cancer because these iron-rich are likely to be carcinogenic. Nanoparticles were not regulated and were rarely even measured, she said.
The three-year averages of nanoparticle levels were used in the research. However, Maher said it is crucial to understand the health impact of repeated exposure to short-lived spikes: “We have measured these outside primary schools in the UK, where UFP particle numbers regularly exceed 150,000 per cubic centimeter of playground air.”
Weichenthal avoided heavily polluted streets while walking and cycling. “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.”
