Radon, a naturally occurring radioactive gas produced when metals comparable to uranium and radium break down in rocks and soil, is a known reason behind lung cancer. Recent research has found that exposure to high levels of this indoor air pollutant is related to an increased risk of one other disease in middle age in older women after ischemic stroke. The study was published within the January 3, 2024 online issue of the journal Neurology^®, the medical journal of the American Academy of Neurology. Ischemic stroke is brought on by blockage of blood flow to the brain and is probably the most common kind of stroke.

A condition called clonal hematopoiesis of indeterminate potential (CHIP) develops when some hematopoietic stem cells, the constructing blocks of all blood cells, undergo genetic mutations as we age. Cells with such mutations replicate faster than cells without them. Previous research has shown that folks with CHIP could have a better risk of blood cancers comparable to leukemia and heart problems, including stroke.

Radon is a known mutagen, which suggests it will possibly cause genetic mutations. It’s also a growing problem because the gas leaks into homes and exposure to it increases as modern constructing practices make homes more airtight. We wanted to find out whether exposure to high levels of radon is related to a disease called CHIP, brought on by genetic mutations in hematopoietic stem cells.”

Eric A. Whitsel, MD, MPH, study writer from the University of North Carolina at Chapel Hill

The study involved 10,799 women whose average age was 67 years. About half of the participants had a stroke or blood clots.

To find out radon exposure, researchers linked participants’ home addresses to U.S. Environmental Protection Agency (EPA) data on average indoor radon concentrations by county. The EPA recommends that average indoor radon concentrations shouldn’t exceed 4 picocuries per liter (pCi/L).

The participants were divided into three groups. The most important group lived in areas where the common radon concentration exceeded 4 pCi/l. The center group lived in areas with average concentrations of two to 4 pCi/l. The bottom group lived in areas with average concentrations of lower than two pCi/l.

The researchers then used genetic testing to find out which participants had mutations typical of CHIP. The researchers found that 9.0% of participants living in areas with the best radon concentrations had CHIP, in comparison with 8.4% of participants living in areas with intermediate concentrations and seven.7% of those living in areas with the bottom concentrations.

After adjusting for aspects comparable to age, education, race and ethnicity, the researchers found that folks with ischemic stroke living in areas with the best radon concentrations had a 46% increased risk of CHIP, while those living in areas with intermediate concentrations had a lower CHIP risk. 39% increased risk in comparison with people living in areas with the bottom radon concentrations. The danger didn’t increase in participants without stroke.

“Although the outcomes don’t generally support an association between radon and CHIP amongst participants, they do suggest an association between radon and CHIP amongst participants with ischemic stroke,” Whitsel said. “The rationale for this link has not yet been confirmed. “Future research is required to further investigate possible links between radon exposure and stroke, especially since current public health screening and radon prevention efforts focus exclusively on lung cancer.”

A limitation of the study was that it only included middle-aged or older participants, so the outcomes is probably not the identical for other populations.

The study was funded by the National Heart, Blood and Lung Institute and the National Institute of Environmental Health Sciences.