CC ▁grew ▁rapidly ▁in ▁ 1 9 4 8 ▁and ▁ 1 9 4 9 . ▁Their ▁staff ▁numbers ▁quad ru ple d ▁in ▁just ▁one ▁year . ▁By ▁ 1 9 5 1 ▁the ▁total ▁stood ▁at ▁ 1 0 6 3 ▁employees ▁– ▁ 1 4 3 ▁al lied ▁and ▁ 9 2 0 ▁Japanese ▁personnel . ▁Perhaps ▁the ▁most ▁important ▁research ▁undert aken ▁by ▁the ▁AB CC ▁was ▁the ▁gen et ics ▁study , ▁which ▁focused ▁its ▁study ▁on ▁the ▁un cert aint ies ▁surrounding ▁the ▁possible ▁long - term ▁effects ▁of ▁ion izing ▁radiation ▁in ▁pre gn ant ▁women ▁and ▁their ▁un born ▁children . ▁The ▁study ▁did ▁not ▁find ▁evidence ▁of ▁w ides p read ▁gen etic ▁damage . ▁It ▁did , ▁however , ▁find ▁increased ▁inc idence ▁of ▁micro ce ph aly ▁and ▁mental ▁ret ard ation ▁in ▁children ▁most ▁proxim ally ▁exposed ▁in ▁u tero ▁to ▁the ▁bomb s ' ▁radiation . ▁The ▁gen et ics ▁project ▁studied ▁the ▁effects ▁of ▁radiation ▁on ▁the ▁surv iv ors ▁and ▁their ▁children . ▁This ▁project ▁turned ▁out ▁to ▁be ▁the ▁largest ▁and ▁most ▁interactive ▁of ▁the ▁AB CC ▁programs . ▁In ▁ 1 9 5 7 , ▁Japan ▁passed ▁the ▁At omic ▁Bomb ▁Sur viv ors ▁Rel ief ▁Law , ▁which ▁qualified ▁certain ▁people ▁for ▁two ▁medical ▁ex ams ▁per ▁year . ▁The ▁Japanese ▁term ▁for ▁the ▁surv iv ors ▁of ▁the ▁atomic ▁bomb s ▁is ▁h ib ak ush a . ▁The ▁qual ifications ▁for ▁medical ▁care