"'Radon,' a Lung Cancer Carcinogen, Also Increases Leukemia Risk"

Moon Jin-young, Resident in Occupational and Environmental Medicine at Seoul St. Mary's Hospital
Multifaceted Analysis of Radon in Residential Spaces and Leukemia
Confirmed Association with Childhood and Lymphocytic Leukemia Incidence

Jinyoung Moon, Resident in the Department of Occupational and Environmental Medicine, Seoul St. Mary's Hospital.

[Asia Economy Reporter Lee Gwan-joo] A study has found that 'radon,' a substance well known to cause lung cancer, also increases the risk of developing leukemia.

On the 21st, a research team led by Jin-young Moon, a resident in the Department of Occupational and Environmental Medicine at Seoul St. Mary's Hospital, Catholic University (corresponding author and first author), conducted a dose-response meta-analysis of studies published in international journals up to November 2020 on low-level radon exposure in residential spaces and its association with leukemia incidence. The results showed a statistically significant correlation between radon exposure and leukemia occurrence.

Radon is widely recognized as a lung cancer-causing substance. The International Agency for Research on Cancer (IARC), under the World Health Organization (WHO), classifies radon as a Group 1 carcinogen?the highest grade?for lung cancer. However, due to insufficient evidence regarding leukemia, radon is currently classified as Group 2A, one level lower.

The research team analyzed eight ecological studies, nine case-control studies, and fifteen ecological-cohort studies. Among these, the 'ecological-cohort study' is a new category devised by the team, not present in traditional research classification systems. The unit of exposure measurement ranges from administrative districts to areas within a certain radius and down to individual levels, and similarly, the unit of leukemia incidence measurement also varies from administrative districts to individual levels. Due to the diverse units of exposure and outcome measurements across individual studies, the team categorized all studies along this continuous spectrum?from ecological to cohort studies?as 'ecological-cohort studies.'

The results showed that in ecological studies, the Pearson correlation coefficient was 0.48 (95% confidence interval 0.41?0.54), indicating a correlation between the two variables. In meta-ANOVA, the correlation coefficient was significantly higher in the children’s group (0.67) than in the adult group (0.46). Additionally, in the case-control studies, the dose-response meta-analysis revealed that the odds ratio (OR) increased by 1.0308 (95% confidence interval 1.0050?1.0573) for every 100 Bq/m³ (becquerel, a unit of radiation measurement) increase in radon radiation dose.

When analyzed by leukemia type and by children and adult groups, the lymphocytic leukemia group showed an odds ratio increase of 1.0361 (95% confidence interval 1.0014?1.0720) per 100 Bq/m³ increase in radon radiation dose, whereas the myeloid leukemia group showed an odds ratio change of 0.9665 (95% confidence interval 0.9171?1.0186), indicating a slight decrease in risk. In the children’s group, the odds ratio increased by 1.0309 (95% confidence interval 1.0050?1.0575) per 100 Bq/m³ increase in radon radiation dose, while in the adult group, the odds ratio increased by 1.0147 (95% confidence interval 0.6121?1.6821) for the same increase in radon dose.

In conclusion, the regression coefficients from the dose-response meta-analysis were statistically significant only in the lymphocytic leukemia group and the children’s group, but not in the myeloid leukemia group or the adult group. The greater impact on children is presumed to be because gaseous radon affects lymphocytes, which are particularly abundant in the bronchial epithelium of children, leading to a higher absorbed dose compared to adults.

In the ecological-cohort studies, the relative risk increased by 1.1221 (95% confidence interval 1.0184?1.2363) for every 100 Bq/m³ increase in radon radiation dose. Contrary to the case-control studies, the regression coefficients were statistically significant only in the myeloid leukemia group and the adult group, with relative risks increasing by 1.2257 (95% confidence interval 1.0034?1.4972) and 1.2503 (95% confidence interval 1.0233?1.5276), respectively, per 100 Bq/m³ increase in radon radiation dose. However, the research team noted that since these are not individual-level exposure and outcome measurements like in traditional cohort studies, the risk might be overestimated, and thus conservative interpretation is necessary.

Resident Jin-young Moon explained, “This study is significant in that it systematically synthesized all existing studies through dose-response meta-analysis by creating a new classification category called ‘ecological-cohort studies’ along with ecological studies, and for the first time systematically summarized the risk of leukemia occurrence according to the increase in radiation dose emitted from radon.”

The study results were recently published in the international journal Environmental Research.

This content was produced with the assistance of AI translation services.