The presence of aflatoxin B1 in agricultural soil poses a potential health risk to farmers from exposure to aerosolized soil dust during plowing and cultivation activities. In addition, aflatoxin B1 may constitute a health risk through contamination of surface water or groundwater. The primary purpose of this project is to investigate the presence and concentrations of aflatoxin B1 in Iowa. Supercritical fluid extraction (SFE), flow injection renewable surface immunoassay (FIRSI) with fluorescence detection, and HPLC/ES/MS methods will be developed and used for the determination of aflatoxin B1 and its transformation products in soil. This study will provide needed data to support external funding of a more detailed regional investigation of the fate and potential health risk of aflatoxin B1, as well as potential control and detoxification mechanisms.