as a contribution to the third ukems collaborative trial , ethyl methanesulphonate ( ems ) , benzo [ a ] pyrene ( b [ a ] p ) and benzidine ( bzd ) were examined for mutagenicity at the hprt locus in chinese hamster v79 cells , as assessed by 6-thioguanine ( 6tg ) resistance .
C1708726
locus
C0007634
cells