Radon is a naturally occurring radioactive gas. As an invisible, odorless, and tasteless substance, radon can accumulate in indoor environments. Its established link to lung cancer is a significant concern, but questions also arise regarding its possible association with other cancers, including breast cancer. This article addresses the current scientific evidence concerning radon’s connection to breast cancer.
Understanding Radon
Radon is a radioactive gas formed from the natural decay of uranium and thorium found in nearly all soils, rocks, and groundwater. This gas moves freely through the ground and can enter homes and buildings through various openings. Common entry points include cracks in foundations, floor slabs, and walls, as well as gaps around utility pipes, floor drains, and sump pumps.
Once inside a building, radon can become trapped and accumulate to high levels, particularly in basements and lower levels where it is closest to its source. While outdoor air contains low levels of radon, the confined spaces of indoor environments allow it to concentrate, making it a significant source of radiation exposure. Radon can also enter homes through well water, though the soil is the primary source of indoor radon problems.
Radon’s General Health Impact
When radon gas decays, it produces tiny radioactive particles. If inhaled, these particles can become trapped in the lungs. These radioactive particles emit alpha radiation, a form of ionizing radiation, which can damage the DNA within lung cells.
Over time, this cellular and DNA damage can lead to lung cancer. Radon is recognized as the second leading cause of lung cancer deaths overall, surpassed only by cigarette smoking. For individuals who have never smoked, radon is considered the primary cause of lung cancer.
The Link Between Radon and Breast Cancer
While radon’s link to lung cancer is well-established, its potential association with breast cancer is a more complex research area. Radon decay products, once inhaled, can enter the bloodstream and distribute throughout the body, including breast tissue, where they could theoretically cause cellular damage. However, establishing a direct causal link between environmental radon exposure and breast cancer has proven challenging.
Some studies have explored this connection with varying results. A long-term population-based study from Finland suggested an association between high radon exposure and an elevated risk of overall breast cancer incidence. This study observed a 10% higher overall breast cancer incidence among women exposed to high radon levels compared to those with lower exposure.
Conversely, a large prospective analysis, the Nurses’ Health Study II, did not find an association between overall environmental radon exposure and the risk of invasive breast cancer. However, this study observed a suggestive elevated risk for specific breast cancer subtypes, particularly hormone receptor-negative (ER-/PR-) tumors, among women with higher radon exposure. These tumor types are sometimes linked to genetic mutations that impair DNA repair, which could align with radon’s DNA-damaging potential. Other ecological studies, which examine data at a population level, have generally shown no association between county-level radon levels and breast cancer incidence.
Reducing Radon Exposure
Given the established health risks associated with radon, particularly lung cancer, reducing exposure is an important health measure. The first step in addressing radon in a home is to test for its presence, since it is undetectable without specialized equipment. Do-it-yourself radon test kits are widely available and provide an initial assessment of indoor radon levels. Professional testing services are available for comprehensive evaluations.
If testing reveals elevated radon levels, above 4 picocuries per liter (pCi/L), as recommended by the U.S. Environmental Protection Agency, mitigation is advised. The most common method for reducing indoor radon is a system called sub-slab depressurization. This system involves installing a pipe through the foundation and using a fan to draw radon gas from beneath the house and vent it safely outside. Sealing cracks and other entry points in the foundation can also help reduce radon infiltration, although it is usually used in conjunction with a depressurization system rather than as a standalone solution.