Project I: Molecular Biomarkers for Human Liver Cancer. Hepatocellular carcinoma (HCC) is one of the most common cancers in parts of China and sub-Saharan Africa and the poor prognosis of this tumor results in it being one of the three leading causes of cancer deaths world-wide with at least 200,000 deaths per year. Human epidemiology and experimental data have provided the statistical association and biological information necessary to implicate aflatoxins and chronic infection with hepatitis B virus (HBV) as major risk factors for this cancer. The degree that aflatoxins and HBV contribute to the causation of this disease may be affected by a number of factors including; the level of carcinogen exposure, intrinsic cytochrome P-450 and glutathione-S-transferase activation/detoxification pathways for aflatoxins, and the nutritional status of the person. Primary prevention measures by vaccination against HBV and food safety techniques to lower aflatoxin exposure could significantly lower liver cancer rates. While HBV vaccination is an effective form of prevention, the large economic resources required for vaccination have led to a focusing of intervention to high risk populations or high risk individuals within a population. For aflatoxins a similar targeted intervention could be envisaged, but for this to be effective requires determination of the relative role and mechanism of action of aflatoxin and HBV in the etiopathogenesis of liver cancer. These questions can now be addressed due to the development of individual markers of aflatoxin exposure including; urinary DNA and serum albumin adducts.