As you may or may not know by now, radon is a radioactive element derived from uranium, thorium, and other radioactive elements that decay in soil, rocks, and groundwater. Radon is a potentially toxic gas known for almost two centuries. It is an invisible, colorless, and odorless gas. Because of these features, radon cannot be detected using only human senses.
The main attribute that has helped radon evade human research for many years is its invisibility. Since we tend to believe what we see and throw suspicion to what we can't see, the awareness around radon gas is slow to spread.
The dangerous thing about radon is that it emits radiation in alpha particles that are potentially harmful to human health. What is more damaging is that after its alpha emission, it gets converted into certain daughter elements, which continue to release radiation in the lungs for decades. This article mainly focuses on the invisible story of radon and how this invisible gas is a potential threat to human health.
Radon: The Leading Cause of Lung Cancer
Radon is one of the most extensively investigated human lung carcinogens. It has been known for several years as the potential cause of lung cancer among miners. However, radon does not remain confined to mines. Research also indicates that the number of cases of lung cancer due to residential exposure to radon ranges from 3,000 to 33,000, making it the second cause of lung cancer after cigarette smoking. Apart from lung cancer, radon exposure is also associated with other malignancies such as leukemia.
According to the health authority, radon exposure is a category one cause of lung cancer. As other studies have shown, radon exposure is the second leading cause of death in patients with lung cancer. About 10 to 40 thousand Canadians succumb to lung cancer due to radon exposure every year. A statistical report also shows a significant rise in lung cancer cases, mainly due to the exposure of contaminants including radon, asbestos, and heavy metals.
Pathogenesis of Lung Cancer After Radon Exposure
This story begins in an environment of high radon concentration. Whenever someone inhales air in such an environment, radon becomes trapped in the lungs. Radon disintegrates into its daughter radioactive elements in the lungs by releasing highly ionizing radiation (alpha particles). This radiation produces oxygen free radicals that damage the core of life – DNA (genetic material carrying complete life information)—the damaged DNA results in the development of mutations that are the primary setting for cancer.
However, cancer takes decades to develop. In addition, other changes have been noticed in the lungs of patients who have only years of history of radon exposure. In these patients, the daughter elements of radon keep on emitting radiation in the lungs, resulting in the formation of fibrosis within the tissues. This fibrosis is the leading cause of restrictive lung diseases characterized by difficult inspiration.
Signs & Symptoms of Radon Exposure
As you can't see, feel, or smell radon, you do not know when you are inhaling radon unless some signs or symptoms appear. Hence, it is pretty important to look for the early signs and symptoms of radon poisoning because if they are left untreated, they can lead to the development of lung cancer.
The classical sign of radon poisoning is a persistent cough due to respiratory distress. Other pulmonary (related to lung) symptoms include recurrent attacks of bronchitis or pneumonia, coughing up blood, chest pain, wheezing, and hoarseness of voice. Some patients also report weight loss, fatigue, and loss of appetite. Whenever such symptoms arise, you must get yourself a thorough medical examination.
Radon: Equally Disastrous to Smokers and Non-Smokers?
A pronounced study clearly states the differential effects of radon exposure among smokers and non-smokers. According to this study, 260 out of 1000 smokers will develop lung cancer if exposed to 20 pCi/L of radon during their lifetime. Similarly, but not as bad, 36 individuals will develop lung cancer in every 1000 non-smokers.
It is clear from this study that regardless of the potentially disastrous synergistic effect of smoking and radon exposure, radon exposure is more than enough to cause lung cancer. That’s why it is known as the element of risk. Every year, about 21000 deaths occur due to radon exposure, and only 2900 of those are non-smokers.
How Damaging is Radon Exposure in Indoor Environments?
Radon is an invisible gas that accumulates in closed buildings. More specifically, buildings with poor ventilation provide a more favorable environment for the dramatic accumulation of radon. Once it becomes concentrated within a confined area, it creates a lung cancer inducing situation similar to that which was observed in miners. Therefore, the most favorable radon concentration locations are the buildings' basements.
As proven from various research studies, radon is a carcinogen found in homes, offices, warehouses, mines, etc. Therefore, all those who have several years of indoor radiation exposure due to radon are at risk of developing cancer and other lung disorders.
Environmental Factors Influencing Indoor Radon Concentration
Significant data demonstrate the effect of environmental factors on radiation exposure by radon in indoor environments, including homes, schools, offices, and other buildings. One of the particular factors is the outdoor temperature. It has been observed that the indoor radon concentration is significantly higher in winter-autumn than in spring-summer.
This detailed analysis further demonstrates that the indoor concentration of radon is inversely related to the indoor humidity, outdoor wind speed, and outdoor dew point temperature. It concludes that whenever indoor humidity is higher, there are fewer chances for the radon to accumulate in that area.
In addition, rain has been observed to increase the radon concentration indoors.
Indoor Sources of Radon
The primary sources of indoor radon includes soil gas, building materials, and tap water. Soil gas infiltration is by far the major contributor to indoor radon concentration. Here arises a question - How can we determine the points of entry for soil gas? The answer lies in the facts that are discussed later.
Among soil particles, specific tiny spaces are filled with water or air in the ground. The gases that are occupying these spaces are collectively termed soil gas. Soil gas is composed of nitrogen, oxygen, and carbon dioxide. It also contains additional gases like nitric oxide, methane, and ammonia.
Building materials like brick, marble, and granite have a basal level of radioactivity due to some radioactive minerals. They are also likely to possess radon in significant amounts, leading to a higher level of radiation.
Drinking water is only a minor source of radon. Due to drinking contaminated water, radiation exposure is only associated with a negligible risk of stomach cancer and other gastrointestinal malignancies.
Preventive Measures Against Radon Exposure
Primary health care providers must understand the role of radon in causing lung cancer and what precautions should be taken by the general public to avoid undesirable outcomes. These actions begin with getting your house tested for radon exposure. If you are following the E.P.A. radon exposure guideline of 4 pCi/L, and you test higher than that, then action is required to reduce radon levels and therefore minimize radon exposure.
General Preventive Measures
The best cure to any illness is prevention. Individuals should be guided to quit smoking, as radon and smoking have a synergistic effect in causing lung cancer. Nutrition-rich fruits, high in antioxidants, and vegetables may also help the body fight the carcinogens. In some cases, carotenes supplements are also prescribed to individuals at risk of high radon exposure. These supplements lower the chances of cancer development.
Environmental Measures to Reduce Exposure
According to a statistical report, about 42% of radiation exposure worldwide is because of radon. To our surprise, only 0.9% of the global radiation exposure is because of the nuclear industry. It is clear from this finding that radon is dramatically increasing in our local environment and is causing severe health effects. Thus, it is the recommendation of health authorities to get buildings – houses, schools, offices, government - tested for the presence of radon. Environmental testing would be the best preventive measure against radon exposure, which would help to eventually reduce radon-related lung cancer cases because we would be able to identify which buildings require mitigation.