Estimated rate of mortality due to solid cancer increased by 52 percent per Gy with cumulative dose, lagged by 10 years.
Protracted exposure to low-dose ionizing radiation is associated with an increased risk for solid cancer mortality, according to a study published online Aug. 16 in The BMJ.
David B. Richardson, Ph.D., from the University of California in Irvine, and colleagues examined the effect of protracted low-dose exposure to ionizing radiation on the risk for cancer in a multinational cohort study involving workers in the nuclear industry in France, the United Kingdom, and the United States. Participants included 309,932 workers with individual monitoring data for external exposure to ionizing radiation, with follow-up of 10.7 million person-years.
The researchers identified 103,553 deaths, including 28,089 due to solid cancers. There was a 52 percent increase in the estimated rate of mortality due to solid cancer with cumulative dose per Gy, which lagged by 10 years. The estimate of association was approximately doubled on restriction of the analysis to the low cumulative dose range (0 to 100 mGy) and with restricting the analysis to workers hired in more recent years, when estimates of occupational external radiation were more accurate. The estimated magnitude of the association was modestly affected by exclusion of deaths from lung cancer and pleural cancer, indirectly indicating that the association was not substantially confounded by smoking or asbestos exposure.
“The study provides evidence in support of a linear association between protracted low-dose external exposure to ionizing radiation and solid cancer mortality,” the authors write.