AW: [ RadSafe ] Antioxidants could provide all-purpose radiationprotection
Rainer.Facius at dlr.de
Rainer.Facius at dlr.de
Tue Nov 6 05:18:18 CST 2007
interesting as Shamsuddin's results are, upon a second look they also arouse confusion - at least as reported here.
First of all, contrary to Shamsuddin's claim, radiation damage from non-ionizing UV radiation (UVB in this case) and ionizing radiation on the initial molecular level has as much in common as it has not. UV radiation creates molecular species which can and are not generated by ionizing radiation and vice versa. So his claim "Radiation damage is radiation damage, regardless of the source,..." is an improper generalization.
Secondly, in experiments with ionizing radiation increased apoptosis more often is associated with a reduction of transformed/cancerous cells, since those too heavily damaged to be reconstituted to their proper functioning by the primary cellular repair machinery are removed from the tissue. After all - at low doses - "A dead cell is a good cell". Hence, the decrease of apoptosis in IP6 fed mice would imply an increase of cancer incidence rather than a decrease after ionizing radiation exposure.
Thirdly, exactly the opposite was reported "... that when mice engineered to be prone to skin cancer were given drinking water containing a two-percent solution of IP6, they were much less likely to develop tumors." although "Untreated skin cells were more likely to undergo apoptosis... ".(and hence less prone to become malignant).
Maybe the initially mentioned (disclaimed) difference between non-ionizing and ionizing radiation is part of the solution of this discrepancy. Hence, the expectation that these compounds may be useful for cancer prophylaxis for people exposed to low dose and dose rate of ionizing radiation cannot be substantiated by these findings - notwithstanding the fact that indeed they might have this property.
Finally, the radiation field which air crew and passengers - and even more so astronauts(!) - are exposed to is sufficiently different from ordinary terrestrial radiations that even if their protective efficacy could be demonstrated here, an unqualified extrapolation to the cosmic radiation exposure would be unwarranted.
Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Voice: +49 2203 601 3147 or 3150
FAX: +49 2203 61970
More information about the RadSafe