Incorrect Estimates of the All-Cause Standardized Mortality Ratio (SMR) for Cosmonauts, Including Comparison with Astronauts from the United States (R.J. Reynolds et al.)

Cosmonauts and astronauts, as well as pilots, are regarded as occupational groups exposed to continual exposure to cosmic radiation, including low LET radiation and dense ionizing particles. The data from Table II in R.J. Reynolds et al. (2014), in terms of the Standardized Mortality Ratio (SMR) from all causes for cosmonauts compared with the Soviet/Russian general population and with US astronauts (1960–2013) were analyzed. The data on the mortality of cosmonauts were taken by the authors from the site “Soviet/Russian cosmonaut biographies,” and the source of information on the mortality rates for the population of the Soviet Union/Russia is not indicated. R.J. Reynolds et al., firstly, claim a 9- to 10-fold decrease in the overall mortality of cosmonauts compared to the general population of the Soviet Union/Russia, although a similar value in terms of the ‘healthy worker effect’ is unknown for any other types of employment in developed countries. Secondly, when recalculating the SMR of astronauts in comparison with the population of the Soviet Union/Russia, the value of SMR begins to amount to negligible, indicating an allegedly 17–29 times lower mortality (life expectancy is inversely proportional to the SMR). Thirdly, based on the SMR index for astronauts compared to the general population of the United States (R.J. Reynolds and S.M. Day, 2010), which was 0.59, when recalculating the SMR for cosmonauts to the general population of the United States, SMR = 1.1–1.7 times. That is, compared to the US population, Soviet/Russian cosmonauts allegedly have a life expectancy reduced by up to 1.7 times, although a similar level of the SMR is shown only in a few studies of asbestos and chemical production. In their summary R.J. Reynolds et al. (2014) include data on increased SMRs of cosmonauts compared to astronauts, but no other details. It is concluded that, due to the stated absurd data, the study of the cosmonaut SMR performed in the United States cannot be considered correct and should not be used for citation, nor for professional or social comparisons or conclusions.