Air pollution a factor in spiking cancer cases, report says

New estimates from the World Health Organization (WHO) predict a 77% increase in cancer cases globally by 2050. The report points to air pollution as one of the factors driving the expected increase in cancer rates, even though it does not have the same effect on everyone.

As a global health watchdog, the WHO rarely has good news. It stayed true to its mission ahead of World Cancer Day, when its International Agency for Research on Cancer released a report on February 1 predicting an increase of some 35 million new cases of cancer by 2050. This represents an increase of 77% compared to 2022, noted WHO.  

Among the factors driving the expected increase in cancer rates was air pollution.

Fine particles lead to cell dysfunction

“This mainly concerns fine particle pollution”, said Dr Emmanuel Ricard, a spokesperson for the French League Against Cancer.

Diesel exhaust is one of the main sources of these particles, he said. The finest of these particles can descend into the lungs, all the way down to the alveoli. These are the tiny air sacs located at the end of the respiratory tree-like structure of the lung, where the blood exchanges oxygen and carbon dioxide during the process of breathing in and breathing out.

The body’s defence cells will “want” to remove these particles, and inflammation follows. This ends up disrupting the cells which, instead of continuing to replicate in a healthy way, will begin to “dysfunction”, becoming cancerous. “These cancer cells will multiply, and form a tumour,” Ricard said.

More people, and older 

At least several factors indicated by the study are unrelated to pollution. The rapidly growing global cancer rate reflects population growth: as the number of human beings on the planet continues to increase, the total number of cancer cases will also increase.

And while humans are becoming more numerous, the species is also living longer. “Cancer is a problem of immunity, and immunity declines the older we get. As a result, the longer the population’s life expectancy, the more it will be at risk of getting cancer,” said Ricard.

Another classic illusion in the epidemiological data is linked to the improvement of cancer diagnosis itself. These are cases that already existed in the past, but which escaped medical radars. Now, as they are being detected, they contribute to an increase in overall cancer cases.

There are also situations of “overdiagnosis”, in which the presence of cancer cells is confused with cancer as such, said Catherine Hill, a French epidemiologist.

A classic case is prostate cancer. According to the French Institute for Public Health Surveillance (InVs), 30% of 30-year-old men and 80% of 80-year-old men have cancer cells in their prostate. “This is extremely common. It’s obvious that not all of these cancer cells give rise to symptomatic cancers,” said Hill.

Mental health

More and more studies are establishing – although it has yet to be confirmed – a link between pollution and the deterioration of health, including mental health. Pollution even supposedly aggravates depression.

These are “trends” full of scientific estimations, said Hill. After tobacco, alcohol consumption is the leading cause of cancer in France according to WHO, said Hill. “Pollution causes 50 times less cancer in France than tobacco, and 20 times less than alcohol,” she added, quoting a study by WHO’s International Agency for Research on Cancer.

Yet it would be wrong to consider the factors of cancer as isolated, said Ricard. An individual exposed to several factors will have a higher risk of getting cancer. The knowledge that exists on the effect that tobacco and alcohol together can have on cancer rates can be applied elsewhere, he said. “We were thus able to find, in the case of lung cancer, genes that were just as impacted by cigarettes as by atmospheric pollution,” said Ricard.  

The dangers of the world’s ‘dumping ground’

Yet the pollution factor is not the same for everyone, since humans do not breathe the same air. “In the big cities of China, India, South America, Antananarivo [in Madagascar], and even Cairo, clouds of particles form out of the pollution. Under this ‘smog’, people develop lung cancer, just like in England during the industrial revolution,” said Ricard.

There is now a transfer of pollution towards the “South”, which is used as a “dumping ground for the world”, Ricard added. “Besides the ‘at-risk’ factories that industrialized countries prefer to relocate, developing economies are sold low-cost oil derivatives of inferior quality.”

Those who have visited the megacities of developing countries will agree: the pollution seems stronger there. This is indeed because it is more aggressive: “The diesel fuels used there are even richer in sulphur and nitrogen than those emitted in Europe,” said Ricard.

For Richard, WHO’s report highlights an epidemiological transition. The countries previously impacted by infectious diseases, which are declining, will soon face a surge of diseases, like cancer, common to Western countries.

An ecological wake-up call?

In France, for instance, air quality has improved over the past 30 years. In the Toulouse metropolitan area, the presence of fine particles and nitrogen oxide fell respectively by 40% and 17% between 2009 and 2019. This has had a positive impact on cardiovascular diseases, strokes, heart attacks and cancers, said Ricard.

Less encouraging is the study carried out in the Toulouse region, which concludes that the economically disadvantaged population is more exposed to air pollution, and more concerned by deaths attributable to long-term exposure.

Beyond these socio-economic disparities, Xavier Briffault, a researcher working in social sciences and epistemology of mental health at the French National Centre for Scientific Research (CNRS) saw potential for an ecological wake-up call. By demonstrating a direct correlation between health and environmental degradation, science could take us from environmental protection, driven by ethics, to ecological awareness, driven by public health concerns. 

Health is not an end in itself but also a means in our fight for a greener world, said Briffault. By mobilizing our fears, the health issue also allows citizens to put pressure on politicians with the message: “Not only are you killing the planet, but you are killing us.”

The rallying cry that “polluting is bad” is bound to disappear, to be replaced by a new logic: Pollution is killing us.

This article was translated from the original in French.

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