Rediscovery of an old article reporting that the area around the epicenter in Hiroshima was heavily contaminated with residual radiation,indicating that exposure doses of A-bomb survivors were largely underestimated

The a-bomb blast released a huge amount of energy: thermal radiation (35%),blast energy (50%),and nuclear radiation (15%). of the 15%,5% was initial radiation released within 30 s and 10% was residual radiation,the majority of which was fallout. exposure doses of hibakusha (a-bomb survivors) were estimated solely on the basis of the initial radiation. the effects of the residual radiation on hibakusha have been considered controversial; some groups assert that the residual radiation was negligible,but others refute that assertion. i recently discovered a six-decade-old article written in japanese by a medical doctor,gensaku obo,from hiroshima city. this article clearly indicates that the area around the epicenter in hiroshima was heavily contaminated with residual radiation. it reports that non-hibakusha who entered hiroshima soon after the blast suffered from severe acute radiation sickness,including burns,external injuries,fever,diarrhea,skin bleeding,sore throat and loss of hair-as if they were real hibakusha. this means that (i) some of those who entered hiroshima in the early days after the blast could be regarded as indirect hibakusha; (ii) 'in-the-city-control' people in the life span study (lss) must have been irradiated more or less from residual radiation and could not function properly as the negative control; (iii) exposure doses of hibakusha were largely underestimated; and (iv) cancer risk in the lss was largely overestimated. obo's article is very important to understand the health effects of a-bombs so that the essence of it is translated from japanese to english with the permission of the publisher. © 2017 the author.