Detection of aflatoxin B1-DNA adducts in human placenta and cord blood

Human placenta and cord blood are readily available specimens that respond to maternal environmental insult and are being used to investigate metabolism, bioactivation, and transplacental transfer of procarcinogens. Enzyme-linked immunosorbent assay was used to quantitate 120 placentas and 56 cord bloods from term, uncomplicated pregnancies at Taipei Chang Gung Memorial Hospital, Taiwan, for the presence of the imidazole ring-opened form of aflatoxin B1-DNA (AFB1-DNA) adducts. Of the 120 samples of placentas, 69 (57.5%) contained AFB1-DNA adducts in levels from 0.6 to 6.3 mumol/mol DNA. Of the 56 samples of cord bloods, 5 (8.9%) contained AFB1-DNA adducts in levels from 1.4 to 2.7 mumol/mol DNA. A higher positive rate was found in samples collected in the summer than in the winter. These results indicate that a significant number of individuals in an area of high liver cancer risk have been exposed to AFB1, and it is possible to transfer AFB1 and its metabolites to the progeny through the transplacental unit. Thus, monitoring adduct levels in human specimens may provide information not only on carcinogen exposure but also on the relationship among infection with hepatitis B/C virus, dietary exposure to AFB1, and liver cancer.