using xeroderma pigmentosum fibroblasts , deficient in excision repair , as controls to measure the initial rate of ( +/- ) 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo [ a ] pyrene ( b [ a ] pde ) -- dna adducts removal in normal human fibroblasts , it was found that the maximum amount of carcinogen dna adducts occurred 1 h after the addition of b [ a ] pde , and that during the first hour approximately 12 % of the dna -- carcinogen adducts had already been removed .
C0242958
carcinogen dna
C0012854
dna