Lifetime cancer potency of alfatoxin was assessed based on the Yeh et
al. study from China in which both aflatoxin exposure and hepatitis B
prevalence were measured. This study provides the best available infor
mation for estimating the carcinogenic risk posed by aflatoxin to the
U.S. population. Cancer potency of aflatoxin was estimated using a bio
logically motivated risk assessment model. The best estimate of aflato
xin potency was 9 (mg/kg/day)-1 for individuals negative for hepatitis
B and 230 (mg/kg/day)-1 for individuals positive for hepatitis B.