The Surprising Link Between Environmental Pollution and Cancer Risk: New Research Uncovers the Mechanisms Behind Air Pollution’s Danger

The relationship between cancer and environmental pollution has been proven for years by different evidences. In particular, the lung cancerwhose main cause continues to be the tobacco. But 250,000 people die every year in the world from respiratory tumors after breathing stale air. Between 7 and 8 million deaths in the world are related to pollution, not only because it causes cancer, but also multiple diseases. To all intents and purposes, polluted air kills as much as tobacco.

However, as the British oncologist points out Charles Swanton“As there are fewer and fewer smokers in some countries, the proportion of lung cancer among non-smokers has risen remarkably”. And here he began to be intrigued by something: Was everything that is taught in colleges about the conditions for a tumor to occur correct? Is it the accumulation of mutations, caused by smoking or toxic breathing, that triggers the risk of cancer? He believed that there must be something more.

“It turns out that we were in for a surprise here,” he explained in a meeting with the media organized by the UK SMC. Lung cancers from smokers leave a very clear genetic mark, full of mutations that do not appear in such numbers among non-smokers. That implied something: how important is the mutation as what something triggered the uncontrolled multiplication of cellsthat is, the tumor. And that something that unleashes cancer may well be environmental pollution, among non-smokers.

Specifically, when there is a genetic basis and exposure to PM2.5 particles. They are the finest, coming out of exhaust pipes and some factory chimneys. It is known to be worse in the cities, where they are reported 1.8 million deaths a year from breathing those fine particles. But now they have spun more epidemiological data and, above all, the mechanisms that link this type of contamination with lung cancer.

Swanton, along with epidemiologists and data analysts from the Francis Crick Institute and University College London, has published in Nature the results of an investigation on almost 40,000 cancers in England, Taiwan, South Korea and Canada. He combined them with data from 400,000 patients – not cancer specifically – from the UK biobank. Just three years of exposure to high levels of pollution they may be enough for cancer to arise, among cells with certain genetics. These data have been accompanied by experiments with mice to understand the underlying mechanisms of cancer caused by air pollution.

Exhaust pipe pollution, worse for cancer, the heart and the covid

contaminants PM2.5 are those that have the greatest impact on mortality risk. They are particles with a diameter 100 times thinner than a human hair. They can cross the lung alveoli and enter the bloodstream. This has been known for a long time, “hence why they are especially related to cardiovascular diseases,” Professor Newtral explained to Newtral. Aurelio Tobiasenvironmental epidemiologist at IDAEA-CSIC, who participated in another study of air and mortality in 652 cities around the world, between 1986 and 2015.

Since 2021, the WHO considers that we should not be exposed to concentrations above 5 micrograms per cubic meter of air breathed for long periods of time. The EU, which is reviewing its recommendations, considers that above 15 µg/m3 the air quality is poor.

Prolonged exposure to PM pollution is linked to various diseases –including covid– but also to a worse response to vaccine protection. In another studypublished this Wednesday by a team from ISGlobal in Barcelona, ​​shows that those who usually live or work in more contaminated areas developed fewer protective antibodies against SARS-CoV-2 after receiving the vaccines.

Pollution causes cancer, cardiorespiratory problems, a more serious covid and even less effective vaccines.

In particular, exposure to PM2.5, nitrogen dioxide, and soot was associated with about a 10% decrease in IgM and IgG antibody responses in previously uninfected people. The authors are convinced that this is further evidence that inhaled pollution alters the immune system.

Swanton’s study on cancer reaches a similar conclusion: pollution, Rather than causing mutations, it disrupts our defenses. And that ends up leading to tumors. Thus, once they penetrate PM2.5 deep in the lungs “They trigger inflammatory processes,” explains the doctor to questions from Newtral.es. The interaction between the environmental triggers and associated mutations with lung cancer are clear in genes such as the so-called EGFR or the KRAS. These two tend to appear altered among those with non-small cell lung cancer. But these alterations or mutations are known to arise spontaneously according to our birthday.

It is inflammation that ends up causing cancer when unleashed by pollution

The question is whether the contamination causes these mutations or those are already there before the tumor occurs. What is clear is that the more inflammation, the more proliferation of these mutated cells. And the more mutated cells, the more ballots in the cancer lottery.

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Let’s go with the first part of the process. The authors found that PM2.5 appears to trigger an abundance of immune cells (macrophages) and the release of an inflammatory substance: interleuquina-1β. The lungs become a battlefield that sometimes ends up damaging its most intimate structure: DNA. Specifically, the cells of the alveoli (the bags of the lungs that filter the oxygen that will pass into the blood). But they also promote the reproduction of previously mutated cells.

That is, it is not just that there is a mutation in the lungs that favors the appearance of cancer. The pollution gives that necessary push when it enters in particle form and unleashes the pro-inflammatory interleukin.

They have been able to ‘see’ this in action in mice and in laboratory cells grown in organoids. It was shown that stopping interleukin-1β during exposure to PM2.5 prevents the development of cancer when the gene is involved EGFR. So there is no doubt that the suspect is the culprit. We don’t know if she has accomplices.

The entire population, smoke or not, is increasingly susceptible

Explain Alan Balmain (University of California-San Francisco) that these experiments by his colleagues, now published, show how the polluted air can be as bad as smoking, through experiments similar to those first carried out on tobacco more than 50 years ago. “Particles and chemical components of air pollution and tobacco smoke were tested in the 1960s, using the same mouse skin model, and they were found to have such cancer-promoting activity. Nature.

Now, with the new evidence, in addition to showing how pollution causes cancer, it also explains how tobacco not only leads to tumors by making lung cells mutate. It is capable of causing a state of inflammation that favors the appearance of tumors when there are already mutations that arise naturally and spontaneously.

From Spain –which has not been monitored in particular in this study– Victor Breezea researcher at the National Center for Environmental Health of the Carlos III Health Institute, appreciates the contribution of this work to leave no doubt that the risk is widespread among the population.

In it SMC of Spain, explains that it shows how “this type of mutations –in lung cells– accumulate naturally with age and are not the result of other environmental factors (such as tobacco or pollution itself)”. This is important, because “all people are susceptible to them; hence the importance of reducing the levels of environmental pollution”.

From the unreal ‘anti-pollution injection’ to the anti-inflammatory diet

Now, if we know that inflammation increases the risk of cancer, would it be possible ‘take a pill’ or anti-inflammatory injection against pollution? “Preventing pollution-induced lung cancer by treating millions of people worldwide with expensive anti-IL-1β antibodies it is not possible”, explains Dr Ballmain. In the study, they mention canakinumab, an injectable against gout that does seem to correlate with fewer cancers, but is not recommended as a public health prevention strategy.

The authors, however, do not rule out that a healthy lifestyle can prevent a good number of these cancers. In particular, would adhering to a anti-inflammatory diet, such as the Mediterranean? Swanton invites studies focused on this aspect. Ballmain – who has not worked on this investigation – thinks so. “Some dietary factors reduce the incidence of TPA-promoted skin cancers in mice.”

In part, a certain eating pattern slows down these interleukin and other inflammatory mediators. The published work reports hundreds of studies of mouse skin tumor prevention using antioxidant molecules, anti-inflammatory agents, or antibodies against various inflammatory mediators. But Swanton is clear: “You have to promote policies that reduce pollution”. That is first. Because, furthermore, it is not clear that there is a minimum security threshold with which ‘nothing happens’. “There is a continuous risk, so the less contamination the better.”