Variability in aflatoxin-albumin adduct levels and effects of hepatitis B and C virus infection and glutathione S-transferase M1 and T1 genotype

Exposure to aflatoxin B-1 (AFB(1)), an important cofactor in the etiology o f hepatocellular carcinoma in Taiwan, is influenced by dietary and other fa ctors. The present study examined the intraindividual variability in AFB(1) -albumin adducts, the most reliable long-term biomarker of AFB(1) exposure, and whether the baseline or follow-up adduct levels and the intraindividua l variability in adduct levels are modified by endogenous and environmental factors. The study measured AFB(1)-albumin adduct levels among 264 healthy male residents of three townships (Hu-Hsi, Ma-Kung, and Pai-Hsa) of Penghu Islets, Taiwan, at two different time points with a median interval of 1.6 8 years (range 1.00-3.17 years). There was a generalized reduction in the a dduct levels, with the median values being 22.1 pmol/mg (range 5.0-355.8 pm ol/mg) at time 1 and 14.3 pmol/mg (range 5.0-205.2 pmol/mg) at time 2. This intraindividual variability in adduct levels was inversely associated with the age of subjects and the tirne interval between the two blood draws. Th e variability in adduct levels was lower among subjects in Hu-Hsi and Pai-H sa townships as compared to those in Ma-Kung. No significant association wa s observed for the intraindividual variability in AFB(1)-albumin adducts wi th regard to the season when blood was drawn. There was also no significant association between intraindividual variability and hepatitis B surface an tigen, anti-hepatitis C virus (anti-HCV, glutathione S-transferase (GST) M1 , or GSTT1 status. In conclusion, we found substantial intraindividual vari ability in the AFB(1) exposure (as determined by AFB(1)-albumin adducts) in Taiwan, which was probably more likely related to dietary or other environ mental influences rather than to endogenous factors (e.g., hepatitis B/C vi ral infection or GST M1/T1 genetic status).