Comment on "On the Origin of the Highest Energy Cosmic Rays"
  We show that the photodisintegration of heavy cosmic ray nuclei with energies above 10^20 eV is dominated by interactions with photons from the cosmic microwave background radiation, rather than from infrared ones. This implies that the observed air shower events with energies 2-3 10^20 eV cannot originate from Fe nuclei coming from distances beyond 10 Mpc 
Luis N. Epele and Esteban Roulet