Verifying Canadian Nuclear Energy Worker Radiation Risk: A Reanalysis of Cancer Mortality in Canadian Nuclear Energy Workers (1957-1994)

Read the report: Verifying Canadian Nuclear Energy Worker Radiation Risk: A Reanalysis of Cancer Mortality in Canadian Nuclear Energy Workers (1957-1994) (INFO-0811)

Read the British Journal of Cancer article: A reanalysis of cancer mortality in Canadian nuclear workers (1957-1994) based on revised exposure and cohort data

Read the British Journal of Cancer editorial: Nuclear worker studies: promise and pitfalls (R. Wakeford)

In 2005, the International Agency for Research on Cancer (IARC) released a 15-country study on the mortality of nuclear energy workers (NEWs). This study showed a statistically significant increase in the risk of mortality from all cancers excluding leukemia in relation to radiation exposure, with Canadian data the chief driving force behind the worldwide results. An earlier Canadian study, based on the same data that contributed to the 15-country study, found very different results. This apparent discrepancy in the results between the Canadian and the 15-country studies has attracted considerable attention and questions.

The CNSC commissioned a reanalysis of the Canadian portion of the data to understand the unexpected findings. The main findings from this reanalysis report are as follows:

• There is no increase in risk of solid cancer mortality in relation to radiation exposure among any Canadian nuclear power plant NEWs for any time period or for AECL NEWs first employed since 1965.
• While the data suggests a statistically significant increase in risk of solid cancer mortality for AECL NEWs first employed before 1965 (1956-1964), comparison with the Canadian Mortality Database shows statistically significant lower rates of all causes of death and cancer mortality for this group than for the general Canadian population.
• The CNSC does not have confidence in the historical dose data for AECL NEWs from 1956 to 1964. Further investigation of this group of early AECL NEWs is necessary to ensure accuracy and completeness of radiation dose records in the National Dose Registry.

This important CNSC-funded study was scientifically peer reviewed.

Read the report: Verifying Canadian Nuclear Energy Worker Radiation Risk: A Reanalysis of Cancer Mortality in Canadian Nuclear Energy Workers (1957-1994) (INFO-0811)

In November 2013, the CNSC's reanalysis was published in the British Journal of Cancer (BJC). The journal article entitled "A reanalysis of cancer mortality in Canadian nuclear workers (1957-1994) based on revised exposure and cohort data" provides an in-depth discussion of the results, and includes an analysis of tritium doses among nuclear workers. No evidence was found of an increased risk from tritium exposure. The BJC highlighted the CNSC article in an editorial "Nuclear worker studies: promise and pitfalls (R. Wakeford)".

Read the British Journal of Cancer article: A reanalysis of cancer mortality in Canadian nuclear workers (1957-1994) based on revised exposure and cohort data

Read the British Journal of Cancer editorial: Nuclear worker studies: promise and pitfalls (R. Wakeford)