Identifying radiation-induced symptoms from an interview survey

Studies on the atomic bomb have reported a relatively high incidence of acute symptoms, even at below the threshold dose of radiation, and are therefore assumed to include symptoms caused by non-radiation factors. In this study, to investigate the influence of external injuries and burns on symptom expression and the possibility of distinguishing radiation-induced symptoms, we reanalysed data from the survey conducted immediately after the atomic bombing of Nagasaki. The adjusted odds ratios (ORs) of radiation per 1 Gy for the occurrence of 16 symptoms ranged from 1.14 to 1.46, based on sex, age at the time of the bombing, radiation dose, external injuries, and burns. This study also included 243 deaths, and thus provides information not seen in other studies, such as the frequency of symptoms in deaths and ORs for symptom occurrence. However, the adjusted ORs for external injuries or burns were smaller than the unadjusted ORs, suggesting that external injuries and burns confound the development of radiation-induced symptoms. Symptom data obtained from interviews such as those used in this study may not be appropriate for use alone because such data include non-radiation factors. Radiation-induced symptoms are often considered to be a syndrome, and the multiple correspondence analyses also revealed that high-dose exposure is associated with nausea and vomiting, subsequent epilation and bleeding tendency as a bone marrow disorder, and inflammation symptoms due to a weakened immune system. Thus, radiation exposure may be indicated by not just one, but rather, a combination of symptoms.