Evaluation of Methods for Quantitation of Aflatoxin-Albumin Adducts and Their Application to Human Exposure Assessment1

Aflatoxin (AF) albumin adducts are found in peripheral blood after exposure to aflatoxin B, (AI-H,) and the measurement of these adducts is potentially a useful tool in the epidemiolÃ3gica!study of the role of AFBi in the etiology of liver cancer. Three complementary approaches to the quantitation of AF-albumin adducts are described: (a) enzymelinked immunosorbent assay (ELISA) performed directly on intact al bumin (direct ELISA); (b) ELISA performed on an albumin hydrolysate (hydrolysis ELISA); (e) high-performance liquid Chromatographie fluo rescence detection of AF-lysine adduct after albumin hydrolysis and immunoaffinity purification. These techniques have been validated by direct comparison with rat albumin samples modified to a known extent. Detection limits of 100. 5.0, and 5.0 pg AF/mg human albumin were determined for the three methods, respectively. Samples obtained from individuals from Thailand, The Gambia, Kenya, and France have been used to validate the measurement of AF-albumin adducts by these three methods. Levels of 7 to 338 pg AF/mg albumin were observed in the former two countries while no adducts were detected in samples from France. The relative properties of the three assays, with special regard to their application in epidemiolÃ3gica!studies, are considered. A combi nation of the hydrolysis ELISA for large scale screening followed by confirmatory analyses in positive samples by high-performance liquid Chromatographie fluorescence is suggested as an optimum methodology.