Recent research from scientists in the US, Canada, and Europe show that residential radon can increase the risk of hematological cancers, particularly of follicular lymphoma and diffuse large B-cell lymphoma. The study analyzed data from 140,652 people in 20 US states and over nearly two decades that were grouped into low (< 74 Becquerel/m³), medium (74-148 Becquerel/m³), and high exposure to radon in homes (> 148 Becquerel/m³). The study found a nearly linear correlation between residential radon levels and rates of lymphomas. For example, women who lived in areas with high radon levels had a 63% increase in blood cancer rates than those who lived in areas with low radon levels.

Epigenetic inactivation by radon of tumor suppressor genes (these are genes that can prevent cancer from happening) such as CDKN2A and MGMT was previously shown in several different cancers including lung cancers, glioblastoma, and lymphoma. The current study, however, did not research the potential epigenetic basis of radon-associated cancers in this particular group of patients, which remains to be determined.

Radon is a natural byproduct of radium, itself a decay product of uranium and thorium, the most common radioactive compounds on earth. Radon is an odorless, colorless, and tasteless radioactive gas, found in small amounts outdoors, but infiltrates homes where it can accumulate to dangerous levels. In addition, radon gas decays into solid radon dust particles that can stick to lung airways and potentially cause lung cancer. According to the World Health Organization (WHO), radon is the second leading cause of cancer after smoking, and its carcinogenic effects are dramatically increased by smoking. Thus, smokers who are exposed to radon at home or through occupational hazard have a 25-times higher risk of developing cancer than non-smokers exposed to radon.

According to the US Environmental Protection Agency (EPA), some 8 million homes in the US have dangerous radon levels. The highest levels in the US (> 148 Becquerel/m³) are found in Iowa, followed by North Dakota, South Dakota, Maine, Minnesota, Illinois, Kansas, Montana, Idaho, Wyoming, Colorado, Pennsylvania, and Virginia. In Europe, moderate to high levels of radon have been recorded in Austria (97 Becquerel/m³), Slovakia and Sweden (108 Becquerel/m³), Luxembourg (115 Becquerel/m³), Finland (120 Becquerel/m³), the Czech Republic (140 Becquerel/m³), and in Serbia-Montenegro (144 Becquerel/m³).

Radon in households can be reduced by increasing ventilation, particularly in the basement and ground floor, and by building in suction pipes into the concrete base of the house. Through a fan connected to the pipes, radon gas is released above the house where it dilutes quickly and below dangerous levels in the outdoors. The number of suction pipes needed vary depending on the nature of the rock underneath the foundation of the house and the strength of the radon source.

Radon can also be “imported” into a household that resides in an area of the world with low levels of radon irradiation. This can for example be the case if the floor or wall tiles, or the kitchen, bathroom, or bar countertops are made up of rocks (such as marble or granite) that were imported from an area with high radon content (Cancer Epigenetics Society news, May 20, 2016).