A study published in Environmental Research found that residential radon exposure – from contaminated soil, groundwater, and surrounding air – may be a risk factor for lymphoid malignancies in women. This is the first large, prospective, population study to analyze the association between county-level radon exposure and the risk of hematologic malignancies, the authors, led by Lauren R. Teras, PhD, the director of hematologic cancer research at the American Cancer Society, said.
“Dosimetric models show that radon, an established cause of lung cancer, delivers a non-negligible dose of alpha radiation to the bone marrow, as well as to lymphocytes in the tracheobronchial epithelium, and therefore could be related to the risk of hematologic cancers,” the authors explained.
Using data from the American Cancer Society (ACS) Cancer Prevention Study-II Nutrition Cohort, which was established in 1992 and included data from 140,652 participants (66,572 men, 74,080 women), the researchers established historical radon exposure levels based on the participants’ county of residence in 1982 (to establish baseline), then calculated the number of years between the survey return date (1992 or 1993) and follow-up (2011).
During the 19-year follow-up period, 3,019 incident case of hematologic cancers occurred in the population cohort: 1,711 in men and 1,308 in women. The median radon volume among the 1,322 counties included was 45.9 Bq/m3 (range = 6.3-265.7 Bq/m3). The researchers observed a statistically significant positive association between high county-level residential radon exposure and hematologic cancer risk that differed based on sex (p=0.002): Women experienced a statistically significant risk of hematologic cancer (hazard ratio [HR] per 100 Bq/m3 = 1.38; 95% CI 1.15-1.65; p=0.001). The same risk was not observed in men (HR per 100 Bq/m3 = 0.96; 95% CI 0.8-1.16).
Women’s risk increased by 37 percent when exposed to moderate radon (100-124 Bq/m3) compared with the lowest category, and women in the highest radon exposure category (>148 Bq/m3) had a 63 percent increased risk of hematologic cancer.
The researchers also observed a positive response between higher radon concentration level and the risk of all lymphoid malignancies in women, with follicular lymphoma having the highest risk association (HR=2.74 [95% CI 1.18-6.37] for >148 Bq/m3 vs. <74 Bq/m3).
Future replication studies are needed to confirm and better understand these findings.
The study was limited by being population-based, and thus limited in the potential confounding factors that could be measured, as well as not being able to measure radon exposure on an individual patient basis.
Source: Teras LR, Diver WR, Turner MC. Residential radon exposure and risk of incident hematologic malignancies in the Cancer Prevention Study-II nutrition cohort. Environ Res. 2016;148:46-54.