The title of the article by Rafnsson et al,1 “Cosmic Radiation Increases the Risk of Nuclear Cataract in Airline Pilots,” essentially contends that atmospheric ionizing radiation (AIR) causes nuclear cataracts. That assertion suffers from lack of radiobiological plausibility and from missing support by the data reported.
The alleged cause of nuclear cataracts is exposure to AIR at a maximum effective dose (defined to assess carcinogenic risk) of 48 mSv. In AIR, slightly more than 50% of the effective dose is produced by sparsely ionizing radiation with a relative biological effectiveness (RBE) of about 1; the remaining dose is due to energetic neutrons with poorly defined RBE for cataractogenesis at low doses. The neutron contribution to the effective dose of less than 24 mSv corresponds to an absorbed dose of 2 mGy at most.
Facius R. No Evidence for the Causation by Cosmic Radiation of Nuclear Cataracts in Pilots. Arch Ophthalmol. 2006;124(9):1369-1370. doi:10.1001/archopht.124.9.1369