50. Cancer Mortality among Radiological Technologists in Japan: Updated Analysis of Follow-up Data from 1969 to 1993

Shinji Yoshinaga, Takahashi Aoyama, Yasuhiko Yoshimoto, and Tsutornu Sugahara

Keywords: radiation, cancer mortality, radiological technologists, healthy worker effect, standardized mor tality ratio

A retrospective cohort study was conducted for 12,195 male radiological technologists who received occupational exposure to low dose radiation over a long term. A total of 1,097 deaths including 435 from cancer were ascertained by Koseki and by death certificates from 1969 to 1993. Cancer mortality among the study population was basically cormpared with that of all Japanese men. Significant low SMRs were obtained for all cancers, stomach and lung cancer partly due to the Healthy Worker Effect, unlike the results of the earlier reports with some inappropriateness in the methods. Apparent high risks of lymphatic and hematopoietic cancers were observed, although none of the site-specific cancers revealed a statistically significant increase. For these cancers, the SMRs of old sub-cohort were somewhat higher than those of young sub-cohort, whereas similar SMRs for solid cancer were obtained between the two sub-cohorts. The SMR for leukemia reached a statistically significant level of 1.75 (95%CI: 1.07-2.71) when all whole professional and technical workers as a standard population. The study results seem to suggest that the chronic exposure to low-dose radiation enhanced the risk of lym phatic and hematopouetuc cancers.

Pubicatuon:
Yoshinaga, S., Aoyama, T., Yoshimoto, Y., and Sugahara, T. : Journal of Epidemiology, 9, 61-72 1999.