Radon is a naturally occurring radioactive gas that lacks color, smell, or taste, making it undetectable by human senses. Leukemia is a type of cancer affecting the blood and bone marrow, characterized by the rapid growth of abnormal blood cells that can crowd out healthy blood cells. This article explores radon exposure and its potential link to leukemia.
Understanding Radon and Exposure Pathways
Radon originates from the natural decay of uranium found in nearly all soils and rocks. This radioactive gas moves through the ground and can enter homes and buildings through various openings where the structure contacts the soil. Common entry points include cracks in foundations and floor slabs, construction joints, gaps around pipes, floor drains, and sump pits. Once inside an enclosed space, radon can accumulate to elevated levels, as it does not dilute as quickly as it does outdoors.
People are primarily exposed to radon through the inhalation of its radioactive decay products. While radon itself is a gas, it quickly breaks down into tiny radioactive particles. These particles can attach to airborne dust and, when inhaled, become trapped in the lungs. Although less common, radon can also enter homes through well water and certain building materials.
Radon’s Established Link to Lung Cancer
Scientific consensus establishes radon as a significant cause of lung cancer. It is recognized as the second leading cause of lung cancer overall, and the primary cause among non-smokers. The U.S. Environmental Protection Agency (EPA) estimates that radon contributes to approximately 21,000 lung cancer deaths annually in the United States. The World Health Organization (WHO) also estimates that radon causes between 3% and 14% of all lung cancers globally, depending on regional radon levels and smoking prevalence.
When the radioactive decay products of radon are inhaled, they can damage the DNA of cells lining the airways and lungs. This cellular damage can lead to the development of lung cancer over many years. The risk of lung cancer from radon exposure is higher for individuals who smoke, with smokers 25 times more at risk than non-smokers. This synergistic effect means the combined risk is greater than the sum of risks from either factor alone.
Investigating Radon’s Connection to Leukemia
While radon is a known lung carcinogen, evidence for a direct causal link to leukemia is less definitive. Some studies have suggested a possible association, particularly concerning childhood leukemia. For instance, a recent large-scale study covering over 700 counties in multiple U.S. states indicated a link between radon gas levels and childhood leukemia rates. This study found that children exposed to radon concentrations of 2.0 pCi/L or higher had an 8% increased risk of leukemia, with females showing a 12% higher risk.
However, other comprehensive analyses, including meta-analyses, note that while a potential positive association between radon exposure and leukemia risk may exist, the statistical significance is not robust enough to draw definitive conclusions. The observed heterogeneity across studies underscores the need for further research with standardized methods. Researchers are exploring theoretical mechanisms by which radon’s alpha particle radiation could affect blood-forming cells, but these mechanisms are not as well-established as those for lung cancer. The primary health concern associated with radon exposure continues to be lung cancer.
Steps to Reduce Radon Risk
Given radon’s established health risks, taking steps to reduce exposure is important. The only way to determine the radon level in a home is through testing, as the gas is odorless and invisible. Readily available test kits can be purchased, or professional services can be hired to measure radon levels. The U.S. EPA recommends taking action to reduce radon levels if they are 4 picocuries per liter (pCi/L) or higher.
If elevated radon levels are detected, mitigation strategies can effectively lower indoor concentrations. Common approaches include sealing cracks and other openings in foundations, walls, and floors to prevent radon entry. Additionally, sub-slab depressurization systems, which use a fan and vent pipes to draw radon from beneath the home and release it safely outdoors, are highly effective. Regular retesting after mitigation ensures that radon levels remain low.