sesssevosl ‘Subj: ” Redfological( -2ards From cn ABD, Neutrons STiTUS OF XNO.LEDGE (Cont'd): as excellent indicators of the integrated biological effect of bomb neutrons even in the ebsence of physical spectral data; and their use in conjunction with limited physical date allows them to be employed es relative neutron dosimeters. As predicted, the imoortance of neutron biological effect connared with bomb gamma varied markedly with weapon design and yield, ranging from insignificant where vreapon design end yiele vere unfavorable to neutrons to a factor at least as preat as gemma (et the range of mid-lethal dosage) in cases favorable to neutron rclease from the fission assembly. Nevsde test Gata shored neutrons penetrate soil less well than gemmes; although foxholes provided less protection from scettered neutrons than from scattered gammes. Neutron induced activity in biological meterial has been show bo present no personnel hezara. opine Because of its sensitivity to specific Lonization, zenetic material hes proven useful in differentiating the importance of gamma and neutron effects rhen both are present. Menger date concerning neutron spectrum and relating neutron effects to animal size and svecies differences has made extrapolation of the weapons test information to man extremely unreliable. A qualitative theory hes been esteblished permitting the mouse field data to be viewed es the upper limit to the neutron respvonse (in term of REM units) to be expected in men, but there is little experimental confirmation of the assumptions involved. Physical theory predicts that the range of nucleer redia- tion effects, includingneutrons, will be very greatly increased at high altitudes. The above limitations on the extrapolation of reapons test neutron data to man do not permit an accurate estimate of the increase in neutron biological effects to be anticipated under these circumstences. There is no current tork being done with high doses of neutrons Celivered et very high dose rates, comperable with canme experimentetion now in progress where a prompt biological response has been demonstrated under similar circumstenccs. CONCLUSIONS: The biclozical data suggest that the mechanisms of resnonse to neutrons may be somevshat different from those to x-rays in a riven species. Tne effect on neutron REM values of protective lend henis- pheres used i in the past. = pap has been improperly eveluated | Pikeics

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