A review of epidemiology literature revealed that only studies conducted in Africa and Asia included data adequate to permit quantitative assessment of the dose-response relationship between
aflatoxin exposure levels and
liver cancer rates. Although these studies were judged adequate, their direct use to predict risks in U.S. populations may be questioned since hepatitis B virus (HBV)
infections are far more common in the studied areas than in the U.S. Recent research indicates that, if
aflatoxin contributes to the development of
liver cancer, it almost always does so in the presence of HBV
infection. The African/Asian data do not permit us to estimate the potency of
aflatoxin in the absence of HBV. Recognizing this, these data can only be used to establish upper limits for the predicted excess lifetime risk for
liver cancer in the U.S. When used in conjunction with
aflatoxin exposure estimates for the Southeast U.S., these data predict a
liver cancer rate, due to
aflatoxin alone, far above that actually observed due to all causes; this provides an indication of the conservatism of this approach. Data from the Southeast U.S. may be used to estimate an excess lifetime risk for
liver cancer of 2.17 x 10(-6) x (
aflatoxin intake, ng/kg/day).