World Cancer Day: Can Air Pollution Be Linked To Cancer? Our Expert Tells
World Cancer Day: Pollutants in the air are absorbed into the circulatory system and pumped all around the body. They can also get deposited on soil, water, and other natural sources, increasing human exposure. Find out more about how air pollution can be linked to cancer.
Cancer day 2020: Air pollution increases inflammation, which in turn could increase risk of cancer
- Air pollution can cause respiratory problems
- Being exposed to harmful air can increase oxidative stress
- This oxidative stress can cause DNA damage
World Cancer Day: The entire North Indian belt has been breathing extremely polluted air over the past few months. Though the PM 2.5 levels have dropped, there are no signs of air quality entering safe limits. Year after year, the story repeats itself. Hazy blanket of smog engulfs the sky, especially during annual post-harvest burning of crop stubble in surrounding areas. Re-search indicates that inhaling this polluted air is akin to smoking about 50 cigarettes a day and can be detrimental to everyone - the elderly, children, and pregnant women, in particular. This is a public health emergency and the local industry, coal-fired power plants, and increasing number of cars on the road are only adding to the burden.
Air pollution and cancer: What's the link?
Air pollution is a killer and the level of toxins can lead to several health conditions. Apart from severe respiratory conditions like asthma and chronic obstructive pulmonary disease (COPD), cardiovascular problems and hypertension, stroke, impaired mental health, anxiety, low birth weight babies, pre-term delivery and depression, air pollution can also be linked to cancer. Pollutants in the air are absorbed into the circulatory system and pumped all around the body. They can also get deposited on soil, water, and other natural sources, increasing human exposure. In a recent meta-analysis, it was found that exposure to the main air pollutants is associated with increased mortality from all cancers1. For instance, radon, which is a radioactive gas, that can accumulate indoors is one of the leading risk factors for lung cancer.
These deleterious effects are not just limited to the lungs and the particulate pollutants can travel to other organs such as the liver, kidneys, and brain increasing a person's susceptibility to cancer over time. Different types of particulate matter increase the mortality rates associated with the disease. For instance, PM 2.5 exposure is a risk factor for cancers of the liver, colorectal, bladder, and kidney; and PM10 for pancreas and larynx cancer.
Finding the link
Although a clear connection is yet to be established between air pollution and cancer, there are two possible mechanisms for how exposure can lead to it. On one hand, the oxidative stress caused by pollutants can cause DNA damage. These reactive oxygen species such as sulphur dioxide and carbon monoxide are generated in response to the particulate matter in air. Undue oxidative stress has further been linked to cell proliferation, genetic instability, and mutations2.
The second mechanism could possibly involve inflammation. In a study, it was found that in-haled gaseous and particulate pollutants trigger an increase in the production of pro-inflammatory cytokines in the body. This increases the risk of gastric cancer and non-Hodgkin's lymphoma3. Thus, inflammation can result in mortality due to cancer over time in exposed individuals.
Air pollution and lung cancer
Air pollution has emerged as a major factor for lung cancer in India, particularly in people be-low the age of 404. The alarming fact is that half of these people are non-smokers. The culprit once again is PM 2.5 or particulate matter less than 2.5 microns in size. This pollutant, which is 30 times finer than a human hair, can penetrate deep into human lungs and system leading to lung cancer in the long run. Inhaling PM 2.5 has been equated to smoking at least one cigarette a day.
It is imperative to watch out for recurrent symptoms such as persistent cough, breathing difficulties, blood in sputum, chest pain that exacerbates with deep breathing or coughing, hoarse-ness and loss of weight or appetite loss. These should be a cause of alarm, and one must consult a specialist immediately. There is also a need to make people aware of taking precautionary measures and understand that even indoor air can be polluted.
Air pollution has no geographical boundaries and therefore, everyone who is breathing is at risk. It is a major public health challenge in India currently and therefore, the urgent need of the hour is to address it in a proactive manner. There is a need for specialised research, and a targeted and innovative approach to tackle the health crisis for the results to percolate to all levels. The health sector is just one of the players here and for them to be successful in their efforts, other stakeholders including municipalities, state and central governments would also need to come together.
4Study conducted by Sir Ganga Ram Hospital (SGRH), Delhi, along with Lung Care Foundation.
(Dr Udaya Kumar Maiya, Oncology Specialist and Consultant, Portea Medical)
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