Air Pollutants: A Cancer Risk?

Air pollution is a serious issue that has been linked to various health issues, including respiratory and heart diseases. But can it also cause cancer? The answer is yes. According to the World Health Organization's cancer agency, the air we breathe contains cancer-causing substances, and air pollution is now officially classified as carcinogenic to humans. This classification is based on extensive research and evidence, including studies that tracked populations over decades and animal experiments. The impact of air pollution on cancer risk is significant, with an estimated 223,000 lung cancer deaths worldwide in 2010 attributed to air pollution. Additionally, recent studies suggest that air pollution may also increase the risk of other types of cancer, such as breast, liver, and pancreatic cancer, as well as rare childhood cancers.

Outdoor air pollution and cancer

Outdoor air pollution is a major contributor to the global disease burden. Most people live in areas where air pollution levels, caused by emissions from industry, power generation, transportation, and domestic burning, far exceed the World Health Organization's (WHO) health-based guidelines. Outdoor air pollution is a serious public health issue as it is ubiquitous and has severe adverse health effects, including cancer.

Outdoor Air Pollution and Lung Cancer

There is substantial evidence from human and animal studies, as well as mechanistic evidence, supporting a causal link between outdoor air pollution, particularly particulate matter (PM), and lung cancer incidence and mortality. Hundreds of thousands of lung cancer deaths worldwide are attributable to PM air pollution each year.

Outdoor Air Pollution and Other Types of Cancer

The evidence on outdoor air pollution and the risk of other types of cancer is more limited. However, adverse associations have been reported in a growing number of studies. In addition to lung cancer, cigarette smoking is also considered a cause of cancers of the oral cavity, nasal cavity, pharynx, nasopharynx, larynx, oesophagus, stomach, colorectum, pancreas, liver/bile duct, kidney, renal pelvis/ureter, bladder, ovary, cervix, and myeloid leukaemia.

Biological Mechanisms of Air Pollution-Derived Carcinogenesis

The biological mechanisms behind air pollution-related carcinogenesis are not yet fully understood. However, extensive evidence from indirect models shows how outdoor air pollution contributes to abnormal cell proliferation and cancer. Air pollution contains several mutagens and carcinogens, including polycyclic aromatic hydrocarbons (PAHs), dioxins, and sulfur-containing compounds. PAHs are associated with human cancer risk due to their ability to generate DNA adducts.

Public Health/Policy Recommendations

Implementing measures to reduce cancer caused by outdoor air pollution is challenging due to the numerous combustion sources and emissions involved. Based on the understanding of carcinogenesis, a linear non-threshold relationship between exposure and risk can be assumed. From a regulatory perspective, this implies that any exposure poses some risk, and lowering exposure as much as possible should be the goal.

Interventions to reduce air pollution exposure can occur at various scales, including individual, community, industrial, and regional levels. Specific roles for the medical and healthcare communities in prevention, advocacy, and further research are also described.

There is clear and substantial evidence of a link between outdoor air pollution, particularly PM, and lung cancer incidence and mortality, causing hundreds of thousands of lung cancer deaths annually worldwide. This burden represents an urgent global public health challenge requiring multi-level public health and policy interventions for cancer prevention. Further research on cancer incidence and survival at other cancer sites is needed, especially in low- and middle-income countries.

Indoor air pollution and cancer

Indoor air pollution is a serious issue that can have detrimental effects on human health, including an increased risk of developing cancer. This article will explore the relationship between indoor air pollution and cancer, focusing on the types of cancer associated with indoor air pollution, the mechanisms by which it may increase cancer risk, and the populations most at risk.

Types of Cancer Associated with Indoor Air Pollution

Lung cancer is the most well-studied and established type of cancer associated with indoor air pollution. Research has consistently shown a link between indoor air pollution and lung cancer risk, particularly among non-smoking women. Additionally, indoor air pollution has been linked to an increased risk of head and neck cancers, including oral, laryngeal, and pharyngeal cancers.

Mechanisms of Cancer Development

Indoor air pollution contains a mixture of pollutants, including particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. These pollutants can build up in the lungs, causing DNA damage and altering cell division, which can lead to cancer. PAHs and heavy metals have also been found to induce inheritable DNA mutations, suggesting a potential genetic risk for cancer development.

Populations at Risk

Several factors increase the risk of cancer from indoor air pollution. Exposure to second-hand smoke, solid fuel use for cooking and heating, and inadequate ventilation are key risk factors. Populations in Asia, particularly in highly industrialized or urbanized areas, are at a higher risk due to the prevalence of these risk factors. Additionally, women who regularly cook at home, especially with high-temperature frying, are at an increased risk of developing lung cancer.

Indoor air pollution is a significant public health concern, contributing to an increased risk of cancer, particularly lung cancer, among those exposed. Further research and public health interventions are necessary to reduce indoor air pollution levels and mitigate the associated cancer risk.

Air pollution and lung cancer

Air pollution has been linked to lung cancer, with research showing that particle pollution in the outdoor air we breathe can cause the disease. This includes fumes from vehicles, smoke from burning fuels, and industrial sources such as power plants. These particles are a mix of tiny solid and liquid particles in the air, which can be made up of acids, organic chemicals, metals, soil, and dust.

In 2013, the World Health Organization (WHO) reviewed the available science and concluded that particulate matter causes lung cancer. A separate study in Hong Kong and the UK showed that for every 10 micrograms per cubic meter (µg/m3) of increased exposure to fine particulate matter, the risk of dying from lung cancer rose by 36%.

While smoking is a much bigger cause of lung cancer than air pollution, the impact of air pollution on lung cancer cannot be understated. In the UK, outdoor air pollution causes roughly 1 in 10 cases of lung cancer. In China, an eight-year-old girl became the country's youngest lung cancer patient, with her doctor attributing her diagnosis to air pollution.

Research is ongoing to determine how the size of and different compounds in these particles affect human health. However, it is known that smaller particles are more dangerous as they get trapped deep in the lungs and can even enter the bloodstream, causing damage.

To reduce the risk of developing lung cancer, individuals can check the air quality index forecast and limit their activity if pollution levels are high. On a broader level, governments and organizations are working to reduce air pollution and protect public health.

Air pollution and DNA damage

Air pollution has been classified as a class I human carcinogen by the World Health Organization (WHO). Evidence from around the world shows that air pollution is associated with an increased risk of lung, head and neck, and nasopharyngeal cancers. These cancers have also been linked to smoking.

In 2013, the International Agency for Research on Cancer (IARC), the WHO's specialised cancer agency, officially classified outdoor air pollution and particulate matter (PM) as IARC Group 1 carcinogens. This announcement acknowledges the importance and global impact of air pollution, a leading environmental factor in cancer deaths worldwide.

In addition to cancers, air pollution has been linked to other serious health impacts such as asthma and heart disease. Toxic air pollution can enter the body when it is breathed in, disrupting the way cells are produced in the body and mutating DNA.

A recent study by researchers in Hong Kong and the United Kingdom found that long-term exposure to ambient fine particulate matter, a mixture of environmental pollutants that come from transportation and power generation, is associated with an increased risk of mortality for several types of cancer, including breast, liver, and pancreatic cancer. The study showed that for every 10 microgram per cubic meter (µg/m3) of increased exposure to PM2.5, the risk of dying from any cancer rose by 22 percent.

The authors of the study identified a few potential explanations for the increased association, including the possibility that pollution might spark defects in DNA repair function, alterations in the body’s immune response, or inflammation that triggers angiogenesis, the growth of new blood vessels that allows tumours to spread.

Several large-scale studies in the US have also demonstrated a link between air pollution and lung cancer risk. For example, a multi-city study with 8,111 subjects showed that air pollution was positively associated with lung cancer mortality. Another study showed that among 6,338 non-smoking adults in California, air pollution was associated with an increased risk of developing lung cancer during a 15-year follow-up.

A growing body of research indicates that genotoxic substances in outdoor air result in systemic DNA damage, some of which is likely due to oxidative stress. DNA damage caused by air pollution can take the form of DNA adducts or protein adducts, which have been found in human populations in polluted regions and may be linked to cancer.

In summary, air pollution has been linked to an increased risk of various types of cancer and other serious health issues. The evidence suggests that air pollution can cause DNA damage, which may be a key mechanism for cancer development. More research is needed to fully understand the carcinogenic effects of air pollution and to develop effective interventions and policies to reduce the impact on public health.

Air pollution and protein adducts

Air pollution has been classified as a class I human carcinogen by the World Health Organization (WHO). Evidence from across the globe shows that polluted air is associated with an increased risk of various cancers, including lung, head, neck, and nasopharyngeal cancers.

Chemicals in polluted air can cause DNA damage and protein adducts. Protein adducts are abnormal additions of small molecules to proteins that can impair their function. They are formed when a protein molecule interacts with a chemical, often a carcinogen, and becomes covalently modified.

Several studies have found protein adducts caused by air pollution in human adults and children in polluted areas. For example, benzopyrene-hemoglobin adducts and 4-aminophenyl-hemoglobin adducts have been detected in human blood samples from polluted areas. These adducts are known to be caused by exposure to air pollutants, particularly polycyclic aromatic hydrocarbons (PAHs).

The specific health effects of these air pollution-induced protein adducts are yet to be fully understood and require further experimental investigation. However, it is clear that air pollution poses a serious genetic risk to humans, which may be linked to an increased predisposition to diseases, including cancer.

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