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Abstract: 51-1

51-1

Mortality from Cancer Following Low-Dose Ionising Radiation Exposure

Authors:
Marina Di Giorgio (ARN - Autoridad Regulatoria Nuclear)

Abstract:

The international system of radiological protection is mainly based on epidemiological studies of the cohort of Japanese survivors of the atomic bombings in 1945, who were exposed to relatively high doses delivered at high dose rates that changed very much over time. Some studies have suggested that these outcomes might not be applicable to other groups subjected to different exposure conditions. A group that has been studied is that of nuclear industry workers, who usually are subjected to relatively small radiation doses (limited by radiation protection standards), which normally are incurred at relatively low dose rates usually not very variable over time. Recent studies, such as the International Nuclear Workers Study (INWORKS), have produced results by combining large numbers of workers and including early workers reaching an age when serious illness and death become likely. Some studies have encountered problems with data reliability and suspiciously high cancer risk estimates for certain groups. The latest research from INWORKS provides risk estimates for mortality from all solid cancers combined, based on a study involving 309,932 workers from the USA, UK and France with a combined follow-up of 10.72 million person-years. The authors claim that the findings revealed that there was a positive association between cumulative radiation dose and cancer mortality, with the risk increasing with higher levels of cumulative radiation exposure. However, even at lower doses below 100 mGy, it was estimated a small but significant increase in cancer mortality, observation that contradicts conclusions by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) that radiation health effects are not attributable to situations involving low doses comparable to background doses. The present paper discusses this apparent contradiction. It should be noted that the estimates currently serving as the basis for radiation protection are the UNSCEAR estimates, which are reported to the United Nations General Assembly and used by all relevant organizations of the United Nations system in their radiation protection standards.

Keywords:
 Low dose, Cancer mortality, Nuclear industry , workers