Could radon potentially cause other cancers? Researchers from the geography department and the School of Medicine & Health Sciences at the University of North Dakota teamed up to explore that possibility.
The collaboration resulted in two research papers recently published in Future Oncology - and even more questions.
Along with a high incidence of radon, North Dakota also has the highest rate in the nation of chronic lymphocytic leukemia, or CLL. No one knows what causes this cancer, which usually is found in people over age 70. It is not curable but is treatable for some patients.
"Every other leukemia may be caused by radiation," said Gary Schwartz, professor and chair of population health at the UND School of Medicine & Health Sciences and an expert in radiation and cancer. "CLL is supposed to be the exception."
More than lung cancer?
Schwartz wanted to know more, so he teamed with Marilyn Klug, population health associate professor, for the first paper, and then with Brad Rundquist and Cristina Oancea on the second paper, to explore whether there could be a correlation between CLL and radon occurrence.
"We took an ecological approach," said Rundquist, professor of geography and associate dean of the College of Arts and Sciences at UND. "We looked at where diseases occur and what's happening in the social and natural settings." He added that the link between radon and lung cancer was established when researchers looked at high rates of lung cancer among uranium miners, and it was later verified among homeowners whose homes had high radon levels.
Rundquist used GIS (Geographic Information Systems) software to map environmental factors and CLL.
"GIS can take disease, socioeconomic data, and environmental data and compare it at various locations," Rundquist said.
Oancea, assistant professor of population health at SMHS and lead epidemiologist for the North Dakota Statewide Cancer Registry, drilled into the statistics and investigated CLL occurrence by county.
"Not only as a faculty member, but also as the lead epidemiologist for the North Dakota Statewide Cancer Registry, it is of outmost importance to me to investigate factors, including environmental ones, which could possibly be associated with the incidence of various cancers in the state," Oancea said.
"The cancer registry data has helped us evaluate the association between indoor radon exposure and the incidence of CLL at the county level in North Dakota," she continued. "We found this association to be statistically significant, and plan to continue our research. We don't know for sure what causes CLL, and hope that our future research will help us shed more light on this problem.
"What we found is a suggestion, not an answer," said Schwartz. "It's frustrating. The answer to what causes CLL may never be known."
Mitigate and prevent
As the investigation continues, all three researchers have a recommendation: mitigate radon.
"Radon is a big problem," said Rundquist. "It is second only to smoking as a cause of lung cancer. You could live in a house with radon, never smoke, and still get lung cancer. It's a proven risk for lung cancer."
"Radon causes 22,000 deaths a year from lung cancer," said Schwartz. "It causes more deaths than drunk driving and is preventable in theory."
Preventing cancer caused by radon is fairly simple, the researchers said. Free testing kits are available from the North Dakota Department of Health, and mitigation could be as simple as purchasing a rubber cover for sump pump holes or sealing basement cracks. The cost is generally less than $2,000.
Still, said Schwartz, it's difficult to convince people to test for and mitigate radon.
"How do you to motivate people about a peril that's invisible, can't be tasted or smelled, and costs money if found?"
Radon can be mitigated, said Rundquist. "It helps to keep windows cracked in winter, when the concentration is worse. Newer houses are more airtight with better construction."
Will remediating your home lower the risk of CLL?
"I don't know," said Schwartz. "But it should lower the risk of lung cancer."
"Our research is important for our state," said Oancea. "We do know indoor radon is a possible risk factor for CLL. I advise everyone to test for it in their homes, especially if they have a basement and spend significant time there."
"It's the sword in the stone," Schwartz said. "The cause of CLL may be hiding in plain sight, and we have the highest rates in the nation. That's very unusual. We have the opportunity to solve problems for North Dakotans and those outside of the state. The discovery of the cause for CLL could be made here."