New research suggests there is a significant positive association between high levels of residential radon and the risk of hematologic malignancies in women.
The study is the first prospective, population-based study of residential radon exposure and hematologic malignancy risk.
Therefore, the researchers caution that it requires replication to better understand the association and whether it truly differs by sex.
Lauren Teras, PhD, of the American Cancer Society in Atlanta, Georgia, and her colleagues conducted this study and reported the results in Environmental Research.
Radon is a naturally occurring byproduct of the decay of radium and is a known human lung carcinogen. It is the second-leading cause of lung cancer in the US.
Modeling studies have shown that radon delivers a non-negligible dose of alpha radiation to the bone marrow and therefore could increase the risk of hematologic malignancies. However, studies investigating the link between radon and hematologic malignancies have produced inconsistent results.
For the current study, Dr Teras and her colleagues used data from the American Cancer Society Cancer Prevention Study-II Nutrition Cohort to examine the association between county-level residential radon exposure and the risk of hematologic cancer.
The analysis included 140,652 participants, including 3019 who had hematologic malignancies during 19 years of follow-up (1992 to 2011).
The researchers found that women living in counties with the highest mean radon concentration (> 148 Bq/m3) had a significantly higher risk of developing a hematologic malignancy than women living in counties with the lowest radon levels (< 74 Bq/m3).
The adjusted hazard ratio (adjusted for age, race, family history of hematologic malignancy, etc.) was 1.63 (P=0.0010).
The researchers also found evidence of a dose-response relationship, with an adjusted hazard ratio of 1.38 (P=0.001).
The team said there was evidence of a positive exposure-response relationship between radon concentration and the risk of all lymphoid malignancy subtypes in women. But the highest risk was observed for follicular lymphoma, with an adjusted hazard ratio of 2.74 (P=0.02).
On the other hand, there was a non-significant inverse association between radon and myeloid leukemias in women.
There was no association between hematologic malignancy and radon exposure among the men.
The researchers said a possible explanation for this finding is that men may have a higher baseline risk of hematologic malignancy, possibly because of more exposure to occupational or other risk factors, which would reduce the impact of any additional risk from residential radon.
In women, who have a smaller baseline risk, residential radon exposure might be a larger contributor to overall risk.
Another reason for the sex difference observed in this study may be that the women of this generation spent more time in their homes, so they had more residential exposure than men.
“The overall lifetime risk of hematological cancers in the United States is about 2%, so even a 60% relative increase would still mean a relatively small absolute risk,” Dr Teras noted.
“Nonetheless, radon is already associated with lung cancer, and if other studies confirm the link to blood cancers, we think it would warrant strengthened public health efforts to mitigate residential radon risks.”
