Incorrect estimates of all causes Standardized mortality ratio (SMR) for cosmonauts, including comparative with astronauts, in study from the USA (R.J. Reynolds et al.)

Cosmonauts and astronauts, as well as pilots, are regarded as occupational groups exposed to permanent exposure to cosmic radiation, including low LET radiation and dense ionizing particles. The data from Table II of Reynolds R.J. et al., 2014, USA, in terms of Standardized mortality ratio (SMR) from all causes for cosmonauts compared with the USSR/Russia general population and with US astronauts (1960–2013) were analysed. The data on the mortality of cosmonauts were taken by the authors from the site ‘USSR/Russian cosmonaut biographies’, and the source of information on mortality rates for the population of the USSR/Russia is not indicated. R.J. Reynolds and co-authors, firstly, claim a 9–10-fold decrease in the overall mortality of cosmonauts compared to the general population of the USSR/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 USSR/Russia, the value of SMR begins to amount to negligible, indicating an allegedly 17–29 times lower mortality (life expectancy is inversely proportional to SMR). Thirdly, based on the SMR index for astronauts compared to the general population of the United States (Reynolds R.J., Day S.M., 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 SMR is shown only in a few studies of asbestos and chemical production. In your summary Reynolds R.J. et al., 2014 includes 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 cosmonaut SMR performed in the USA cannot be considered correct and should not be used for citation, as well as for professional or social comparisons or conclusions.