Comment on "Stress induction in the bacteria Shewanella oneidensis and Deinococcus radiodurans in response to below-background ionizing radiation", Castillo, et al. Int. J. Rad. Biol., 2015; Early Online DOI:10.3109/09553002.2015.1062571

J. I. Katz

Castillo, et al. report hormesis by background levels of radiation, at which there is $<10^{-3}$ ionization per bacterium in a replication time. This suggests radiation products a…