The goals of this Project are to incorporate the use of biomarkers into primary and secondary (chemoprevention) interventions in high risk populations exposed to aflatoxins. In all preventive interventions there must be objective metrics with which to quantify success. Subsequently, the cost-benefit balance of the intervention can be analyzed and appropriately targeted toward high risk subgroups or individuals within a population. One of the tenets of the molecular epidemiology paradigm is that a mechanistic understanding of the actions of carcinogens can lead to novel prevention technologies. Therefore, the aims of this Project are 3-fold. First, it is to improve existent liquid chromatography-electrospray ionization tandem mass spectroscopy (LC-ESI-MS/MS) methodology for quantitative analysis of major urinary aflatoxin metabolites (e.g., aflatoxin-N7-guanine, aflatoxin M1, aflatoxin P1, aflatoxin-mercapturic acid). Second, it is to determine the impact of primary prevention strategies in West Africa using targeted contamination reduction strategies in community settings. The investigators will develop interventions aimed at: (1) mothers and young children during the weaning period when mycotoxin-contaminated maize-based foods are first introduced into the child?s diet; and (2) local subsistence farmers attempting to reduce contamination of their dietary staple crops, groundnuts and maize. Aflatoxin and fumonisin biomarkers will be used as outcome measures, while in part (1) the investigators will also examine the effects of intervention on child growth and immune parameters. Third, it is to follow up initial results of the investigators' chlorophyllin intervention where they demonstrated a significantly reduced excretion of aflatoxin-N7-guanine at 3 months by examining the impact of the intervention on biomarker modulation at additional time points. They will also analyze urine samples collected during the course of a one-year long intervention with oltipraz in Qidong for magnitude and persistence of modulatory effects on DNA adduct and other aflatoxin biomarkers. It is the hypothesis that levels of biomarkers for the biologically effective dose of carcinogens will be predictive of the efficacy of primary and chemopreventive interventions. The specific aims of this Project have been designed to translate the biomarkers developed and validated in Projects 1 and 4 into metrics to determine the impact of the interventions in high risk populations.