Air Pollution And Cancer: Is There A Link?

Air pollution has been linked to an increased risk of developing cancer, with outdoor air pollution being classified as a class I human carcinogen by the World Health Organization. Air pollution is estimated to cause nearly seven million deaths per year, with low- and middle-income countries paying the heaviest toll.

Outdoor air pollution has been associated with an increased risk of lung, head and neck, and nasopharyngeal cancers, as well as breast, liver, and pancreatic cancer. These cancers have also been linked to smoking, suggesting that air pollution may trigger similar carcinogenic effects.

The specific carcinogenic effects of air pollution are still being investigated, but studies have shown that exposure to air pollution can cause changes in airway cells that trigger lung cancer, as well as DNA and protein damage. Additionally, air pollution can affect the gut microbiota, which may influence the development of cancer.

While the link between air pollution and cancer is well-established, the mechanisms underlying this association are complex and require further research.

Air pollution is a leading environmental cause of cancer deaths, according to the World Health Organization

Air pollution is a significant and far-reaching threat to public health, with 99% of the world's population breathing unhealthy air, according to the World Health Organization (WHO). The risks associated with air pollution are similar to those caused by smoking tobacco. Exposure to air pollution can lead to cancer, stroke, respiratory and cardiovascular diseases, and other health issues.

Outdoor air pollution is a major contributor to the global disease burden. Most of the global population resides in places where air pollution levels, due to emissions from industry, power generation, transportation, and domestic burning, considerably exceed the WHO's health-based air quality guidelines. Outdoor air pollution poses an urgent worldwide public health challenge because it is ubiquitous and has numerous serious adverse health effects, including cancer.

The global cost of health damages associated with exposure to air pollution is estimated at USD 8.1 trillion, equivalent to 6.1% of global GDP.

According to the WHO, nearly half of lung cancer cases in people who have never smoked are estimated to be related to air pollution. Lung cancer is the most commonly diagnosed cancer worldwide and the leading cause of cancer death, with an estimated 2.1 million new cases and 1.8 million deaths occurring in 2018.

There is substantial evidence from studies of humans and experimental animals, as well as mechanistic evidence, to support a causal link between outdoor air pollution, particularly particulate matter (PM), and lung cancer incidence and mortality. It is estimated that hundreds of thousands of lung cancer deaths worldwide are attributable to PM air pollution each year.

In 2013, the International Agency for Research on Cancer (IARC) classified outdoor air pollution and PM in outdoor air pollution as Group 1 human carcinogens for lung cancer. In 2022, the IARC further announced that it had classified outdoor air pollution and PM as carcinogenic to humans, causing lung cancer. The IARC also noted a positive association between such pollution and an increased risk of bladder cancer.

Air pollution is associated with increased risk of mortality for several types of cancer, including breast, liver, and pancreatic cancer

Air pollution has been linked to lung cancer, and a new study suggests that it is also associated with an increased risk of mortality from several other types of cancer, including breast, liver, and pancreatic cancer.

The study, which was conducted by researchers in Hong Kong and the United Kingdom, found that long-term exposure to fine particulate matter in the air, known as PM2.5, was associated with a higher risk of dying from cancer. For every 10 microgram per cubic meter (µg/m3) increase in PM2.5 exposure, the risk of dying from any cancer rose by 22%. The risk of mortality from cancers of the upper digestive tract was 42% higher, while the risk of mortality from cancers of the accessory digestive organs, including the liver, bile ducts, gallbladder, and pancreas, was 35% higher. The risk of mortality from breast cancer was 80% higher, and the risk of mortality from lung cancer was 36% higher.

The authors of the study identified several potential explanations for the increased risk of cancer mortality associated with air pollution, including defects in DNA repair function, alterations in the body's immune response, and inflammation that triggers angiogenesis, the growth of new blood vessels that allows tumors to spread. In the case of digestive organ cancers, pollution could also affect gut microbiota and influence cancer development.

The findings of this study have important implications for public health and highlight the need for better regulation to protect the public from the harmful effects of air pollution.

Air pollution is linked to cancers of the upper aerodigestive tract, including lung cancer, head and neck cancer, and nasopharyngeal cancer

Air pollution is a significant threat to public health, with 99% of the world's population inhaling unhealthy air. It is a major contributor to the global disease burden, causing an estimated seven million deaths per year—a figure comparable to the excess mortality caused by COVID-19 in 2020 and 2021.

Air pollution is associated with an increased risk of cancers of the upper aerodigestive tract, including lung cancer, head and neck cancer, and nasopharyngeal cancer. These cancers affect the respiratory tract and are often linked to smoking. However, nearly half of lung cancer cases in people who have never smoked are estimated to be related to air pollution.

Particulate matter, especially PM2.5 (particulate matter 2.5 micrometres or smaller in diameter), is a significant contributor to air pollution. It includes soil, dust, soot, and smoke and comes from sources such as coal- and natural gas-fired plants, cars, agriculture, wildfires, and wood-burning stoves. Exposure to PM2.5 can cause changes in airway cells that trigger lung cancer. These changes are visible in about half of people with lung cancer who have never smoked.

Studies have found a significant association between PM2.5 exposure and head and neck cancer, with the strongest correlation observed after a five-year lag period. Additionally, other types of cancer, such as bladder and breast cancer, have also been linked to air pollution, although the epidemiological evidence is more limited.

The International Agency for Research on Cancer has classified outdoor air pollution and PM2.5 as Group 1 human carcinogens for lung cancer, indicating a causal link between air pollution and cancer development.

Addressing air pollution is crucial not only for cancer prevention but also for overall health and well-being. Actions to reduce air pollution, such as increasing green spaces, transitioning to cleaner energy sources, and promoting active transportation, can have far-reaching health benefits.

Air pollution may cause DNA damage and protein adducts, which have been linked to cancer

Air pollution is a mix of solid particles and liquid droplets that can penetrate deep into the lungs and even enter the bloodstream. It contains several mutagens and carcinogens, including polycyclic aromatic hydrocarbons (PAHs), dioxins, sulfur-containing compounds, and 3-nitrobenzanthrone. PAHs are a class of compounds associated with human cancer risk due to their ability to generate DNA adducts.

One study found that air pollution exposure was associated with changes in DNAm from the earliest stages of development onwards, which may contribute to disease development. Another study found that air pollution exposure was associated with a decrease in DNAm on average across the CpGs measured on Illumina 450K chips, with substantial demethylation of promoter regions of genes in the MAPK and NF-κB pathways.

Air pollution has been linked to several epigenetic modifications, including changes to post-translational modifications of histones, 5-hydroxymethylation, and most notably DNA methylation (DNAm). DNAm is a biochemical change that occurs in cytosines, particularly at the CpG context, and modifies gene expression as well as several other functions.

A study found that air pollution exposure was associated with a decrease in DNAm in a study of blood DNAm data from 92 volunteers. Another study found that exposure to freshly generated diesel exhaust (DE) (standardized to 300 μg/m3 of PM2.5) for 2 h modulated DNAm at 2827 CpG sites in blood samples collected 30 h later, relative to filtered air exposure.

Overall, air pollution may cause DNA damage and protein adducts, which have been linked to cancer.

Air pollution is a modifiable risk factor for lung cancer

The International Agency for Research on Cancer (IARC) has classified outdoor air pollution and particulate matter in outdoor air as Group 1 human carcinogens for lung cancer. This means that there is sufficient evidence from studies of humans and experimental animals, as well as strong mechanistic evidence, to support a causal link between air pollution and lung cancer.

The risk of developing lung cancer from air pollution is lower than from smoking, but it is a significant and preventable risk factor. Nearly half of lung cancer cases in people who have never smoked are estimated to be related to air pollution. Additionally, air pollution is estimated to cause hundreds of thousands of lung cancer deaths annually worldwide.

Reducing air pollution is crucial to mitigate the risk of developing lung cancer. This can be achieved through various interventions such as transitioning to cleaner energy sources, reducing vehicle emissions, and promoting active transportation like walking and cycling. Addressing indoor air pollution, particularly from solid fuels used for cooking and heating, is also essential.

Furthermore, air pollution can negatively impact the quality of life of people living with cancer and may interfere with their treatments. Therefore, it is important to prioritise the reduction of air pollution to protect public health and reduce the burden of cancer worldwide.

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