Moderate radon exposure linked to higher stroke risk

Women's health initiative links radon exposure to stroke risk.


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A new study in Minneapolis found that radon, a colorless and odorless gas, is linked to an increased risk of stroke. The research focused on middle-aged to older women and discovered a higher stroke risk in those exposed to high or even moderate levels of radon compared to those with lower exposure.

The study, published in the January 31, 2024, online issue of Neurology®, the American Academy of Neurology medical journal, does not prove that radon causes stroke but shows an association. Radon is a radioactive gas that occurs naturally when certain metals break down in rocks and soil, and it can enter homes through cracks and gaps.

Study author Eric A. Whitsel, MD, MPH, of the University of North Carolina in Chapel Hill, said, “Radon is an indoor air pollutant that can only be detected through testing that measures gas concentrations in homes. Our research found an increased risk of stroke among participants exposed to radon above —and as many as two picocuries per liter (pCi/L) below — concentrations that usually trigger Environmental Protection Agency recommendations to install a home radon mitigation system.”

The study included 158,910 women, around 63 years old on average, who were stroke-free at the beginning. Over 13 years, researchers observed 6,979 strokes among the participants.

To measure radon exposure, researchers used the home addresses of the participants. They linked them to radon concentration data from the U.S. Geological Survey and the U.S. Environmental Protection Agency (EPA).

The EPA suggests indoor radon levels should not exceed four picocuries per liter (pCi/L). If classes are this high, the EPA recommends installing a radon mitigation system to reduce radon in the home.

Participants were split into three groups based on radon levels. The highest group had homes with radon concentrations above four pCi/L, the middle group had concentrations between two and four pCi/L, and the lowest group had concentrations below two pCi/L.

In the group with the highest radon levels, there were 349 strokes per 100,000 person-years, compared to 343 in the middle group and 333 in the lowest group. Person-years account for the number of people in the study and the time each person spends.

After considering factors like smoking, diabetes, and high blood pressure, researchers found that those in the highest group had a 14% higher stroke risk than those in the lowest group. In comparison, the middle group had a 6% increased risk.

Whitsel said, “It’s important to note that we found increased stroke risk among those exposed to radon concentrations as much as two pCi/L below the current lung cancer-based threshold for recommending radon mitigation. More studies are needed to confirm our findings. Confirmation would present an opportunity to improve public health by addressing an emerging risk factor for stroke.”

One limitation of the study is that it only looked at middle-aged and older white women as participants. This means the findings might only apply to some groups of people.

This study highlights a potential association between exposure to even moderate levels of radon and an increased risk of stroke. While the findings indicate a correlation, further research involving diverse populations is necessary to establish broader implications.

Journal reference:

  1. Sophie F. Buchheit, Jason M. Collins et al., Radon Exposure and Incident Stroke Risk in the Women’s Health Initiative. Radon Exposure and Incident Stroke Risk in the Women’s Health Initiative. Neurology. DOI: 10.1212/WNL.0000000000209143.


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