Estimates have been made of the
cancer potency of
aflatoxin exposure among the U.S. population. Risk modeling is used to assess the dose-response relationship between
aflatoxin exposure and primary
liver cancer, controlling for hepatitis B virus (HBV), based on data provided by the Yeh et al. study in China. A relative risk model is proposed as a more appropriate alternative to the additive ("absolute" risk) model for transportation of risk coefficients between populations with different baseline rates. Several general relative risk models were examined; the exponential model provided the best fit. The Poisson regression method was used to fit the relative risk model to the grouped data. The effects of exposure to
aflatoxin (AFB1) and
hepatitis B infection were both found to be statistically significant. The risk of death from
liver cancer for those exposed to AFB1 relative to the unexposed population, increases by 0.05% per ng/kg/day exposure of AFB1 (p less than 0.001). The results also indicated a 25-fold increase in the risk of death from
liver cancer among those infected with hepatitis B virus, relative to noncarriers (p less than 0.0001). With a
hepatitis prevalence rate of 1%, the
aflatoxin intake level associated with
liver cancer lifetime excess risk of 1 x 10(-5) for the U.S. population was estimated as 253 ng/day, based on a
liver cancer baseline rate of 3.4/100,000/yr.