Mortality survey of Japanese radiological technologists during the period 1969-1993

A cohort study of 12,133 Japanese male radiological technologists born before 1950 was begun in 1981 and followed up from 1969 to 1993. All deaths were confirmed using registered permanent addresses (Koseki) and death certificates. Cumulative occupational doses were estimated by the Yamamoto method for the 3461 technologists, born before 1933. The average dose was 466.0 mCy (SD 273.0 mGy). The standard mortality ratios for deaths from all causes, all malignant neoplasms, leukaemia, lung and stomach cancers were 0.64 (95%CI: 0.60-0.69), 0.81 (95%CI: 0.74-0.89), 1.31 (95%CI: 0.80-2.02), 0.62 (95%CI: 0.47-0.80) and 0.65 (95%CI: 0.53-0.79) respectively. The SMRs for colon cancer and brain tumour (ICD 9:191) were 1.29 (95%CI: 0.90-1.80) and 3.58 (95%CI: 1.64-6.79) respectively. No significant correlation was observed between relative risks for cancers of major sites, stroke and circulatory heart disease and the estimated cumulative doses.