Radon is a naturally occurring, invisible, odorless, and tasteless radioactive gas that results from the breakdown of uranium found in nearly all soil and rock. When this gas accumulates indoors, it poses a long-term health risk through the emission of alpha particles. Lymphoma is a type of cancer that begins in the lymphatic system, a network of tissues and organs that help rid the body of toxins and waste. The question of whether residential radon exposure can cause lymphoma has led to ongoing scientific investigation, and this article explores the specific evidence regarding this potential link.
Established Health Risks of Radon Exposure
The established health risk associated with long-term radon exposure is lung cancer. Radon is recognized as the second leading cause of lung cancer overall, surpassed only by smoking, and is the leading cause among people who have never smoked. The danger comes not from the gas itself, but from its short-lived decay products, such as Polonium-218 and Polonium-214, which are tiny radioactive particles.
When inhaled, these decay particles become trapped in the lungs, releasing bursts of alpha radiation. This radiation directly damages the DNA of cells lining the airways and lungs, which can lead to the development of malignant tumors. Estimates suggest that radon contributes to approximately 21,000 lung cancer deaths each year in the United States. This clear pathway of localized cellular damage firmly establishes radon’s pulmonary carcinogenicity.
Scientific Evidence Linking Radon to Lymphoma
While the link between radon and lung cancer is definitive, the evidence connecting residential radon exposure directly to non-pulmonary cancers, such as lymphoma, is inconclusive and weaker. The biological plausibility for a systemic effect suggests that inhaled radioactive decay products could potentially travel beyond the lungs. Modeling studies indicate that a small dose of alpha radiation might be delivered to the bone marrow, the site of blood cell production. This theoretical exposure could relate to the risk of hematologic cancers, including lymphoma, leukemia, and myeloma.
Epidemiological research attempting to confirm this systemic link has yielded mixed results. One prospective, population-based study found a statistically significant association between high residential radon levels and a 63% increased risk of hematologic cancer in women, but not in men. The authors cautioned that this finding requires replication to fully understand the association and any potential sex-specific differences.
Case-control studies focusing specifically on lymphoma have also shown variable outcomes. A large study of childhood lymphoma in Texas found no overall positive association with residential radon exposure. However, that study did report a marginal increase in one specific subtype, Diffuse Large B-cell Lymphoma (DLBCL), in areas with the highest radon concentrations. Other international studies have similarly reported inconsistent or weak positive associations for specific lymphoma subtypes, emphasizing the need for more robust, long-term data.
Understanding Radon Entry and Accumulation in Homes
Radon is continually generated through the natural decay of uranium within the earth’s crust, making it a ubiquitous environmental factor. The gas moves upward through the soil and rock, finding pathways into structures built on top of the source. Common entry points include cracks in the foundation slab, construction joints, gaps around utility service pipes, and sump pits.
The primary mechanism drawing radon into a house is the “stack effect.” This occurs because warmer indoor air rises and escapes through upper leaks, creating a slight negative pressure in the lower areas. This pressure difference acts like a suction, pulling replacement air from the soil directly into the basement or ground floor. The stack effect is strongest during colder months when the temperature differential is greatest, leading to peak radon accumulation.
Practical Steps for Radon Testing and Reduction
Testing is the only reliable method to determine the radon concentration within a home, as the gas is otherwise undetectable. Homeowners can use a short-term test kit, which measures levels over two to 90 days, for a quick snapshot of the concentration. For a more representative average of year-round exposure, a long-term test, remaining in the home for more than 90 days, is recommended.
The U.S. Environmental Protection Agency (EPA) recommends taking action if the result is 4 picocuries per liter (pCi/L) or higher. The EPA also suggests considering mitigation if levels are between 2 and 4 pCi/L, while the World Health Organization recommends intervention at 2.7 pCi/L. The most common and effective reduction method is Active Soil Depressurization (ASD). This system uses a vent pipe and a fan to draw radon gas from beneath the foundation slab and safely exhaust it above the roofline.